Oil well pipes and oil well pipe threaded joints

Abstract

The present invention provides a chemical agent which is environmentally friendly and a solid lubrication coating. Provided is a chemical agent for forming a solid lubrication coating on a metal surface. The main components are a solid lubricant, a binder resin, and a solvent. The solvent has water as the main component thereof, and a lower alcohol with a carbon number of three or less is added as an additive to the water. The volume of the additive is 0.5-45 with respect to a volume of 100 of the water in the solvent. Not less than 95% of the volume of the solvent is constituted by water and the additive. At least a metal soap is contained as the solid lubricant. The metal soap component is not less than 95% of the total combined weight of the metal soap and an alkali soap component. The particle size of the metal soap does not exceed the film thickness of the solid lubrication coating. The binder resin is constituted by a water-soluble or water-dispersible polymer and a copolymer. The binder resin contains a copolymer and a polymer having an acrylate or methacrylate structure in an amount of not less than 90% of the total weight of the binder resin.

Description

[Technical Field]

[0001] This disclosure relates to an agent for forming a solid lubricant coating that imparts lubricity and corrosion resistance to metal surfaces, and to a technology using the agent. This disclosure also relates to an agent that can simultaneously improve lubrication and prevent rust between two sliding objects made of metal surfaces, and to a solid lubricant coating formed thereby. This disclosure primarily relates to a solid lubricant coating intended for the lubrication and rust prevention of oil country pipe threads. This disclosure also aims to simultaneously achieve sufficient lubrication and rust prevention in the operating environment, even under actual make-up and make-back conditions in wells. It also aims to enable rapid drying during film formation, including by leaving the material to dry in the air, using a blower, using a hot air blower, irradiating with infrared rays, irradiating with ultraviolet rays, and heat treatment.

[0002] At the same time, consider what happens when there is trouble in the well or when workover occurs. Consider the case where the full-length pins are removed one by one or in groups of two or three and recovered near the well. In onshore wells, for example, the full-length pins are removed one by one. In offshore wells, for example, they are removed in groups of two or three. In this case, the oil well tubular goods are lined up and cleaned. The present disclosure is also intended to be utilized as a chemical agent applied to the thread surface for rust prevention protection, and as a coating formed by the agent. [Background technology]

[0003] Techniques similar to the present disclosure include those described in Patent Documents 1 to 3, for example. Patent Document 1 gives an example of a steel pipe threaded joint that is primarily made of a UV-curable resin film and has an acrylic / silicone surface layer. Patent Document 1 gives an example of an epoxy acrylic-based UV-curable resin, and while oil-based and water-based systems are also acceptable, it also clearly states that oil-based systems are preferred. In other words, it does not actively recommend the use of water-based systems. Patent Document 1 also gives an example of a quick-drying lacquer-based acrylic / silicone surface film, and one that contains metal soap as a solid lubricant.

[0004] Patent Document 2 is an example of an oil country pipe threaded joint in which a dry solid coating is further formed on a viscous liquid or semi-solid lubricating coating. It exemplifies the formation of either a water-soluble or water-dispersible polymer compound or an organic solvent-based composition in the dry lubricating coating. Patent Document 2 also exemplifies the use of a metal soap in a viscous liquid or semi-solid lubricating coating. However, Patent Document 2 is an example in which the metal soap is used as a thickener. It should be noted that Patent Document 2 does not aim to achieve the effect of the metal soap as a solid lubricant.

[0005] Patent Document 3 defines a lubricating coating composed of rosin and / or calcium fluoride, metal soap, wax, and basic aromatic organic acid metal salt. Examples of optional additives include thermoplastic resins and acrylic resins. Examples of solvents include those using volatile organic compounds.

[0006] Furthermore, examples of conventional techniques that take into consideration tightening in actual wells include Patent Documents 4 and 5 and Non-Patent Document 1. Patent Document 4 describes that a vertical power tong was used to simulate misalignment, and the initial set was tested at an angle of 6 degrees using a 7" short pin. Patent Document 5 is an example of a test evaluation using a vertical power tong and a 9-5 / 8" short pin to measure misalignment at 5 degrees. Non-Patent Document 1 is a paper that evaluates lubrication using a vertical power tong, and describes placing a 5 kN weight on the tip of the short pin opposite the tightening side, that is, on the top end of the pin when tightening the pin in an upright position. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2016-028211 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-537062 [Patent Document 3] Republished Publication No. 2009-057754 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-327874 [Patent Document 5] WO2017 / 110685 [Non-patent literature]

[0008] [Non-Patent Document 1] Tsutome et al.: Journal of the Japanese Association for Petroleum Technology, Vol. 61, No. 6 (1996), pp. 527-536. [Non-patent document 2] Kawamura Chemical Industries, Ltd., Solubility of Metal Soaps, SOLUBILITY, Internet<https: / / www.kawamura-kasei.co.jp / solubility_table.html> Summary of the Invention [Problem to be solved by the invention]

[0009] This disclosure relates to an agent that simultaneously improves lubrication between two sliding objects and provides rust prevention, and to a solid lubricant coating realized thereby. This disclosure is primarily intended for a solid lubricant coating intended for lubrication and rust prevention of oil country pipe threads. This disclosure is intended to simultaneously achieve sufficient lubrication and rust prevention in the operating environment, even under actual make-up and make-back conditions in wells. To achieve these goals, this disclosure relates to an agent containing a water-soluble or water-dispersible polymer containing a component primarily composed of a metal soap as a solid lubricant. This disclosure also relates to a solid lubricant coating formed using this agent. The water-soluble or water-dispersible polymer is a water-based polymer. The term "waterborne polymer" as used herein refers to a polymer that has hydrophilic properties due to the inclusion of polar or charged functional groups in the polymer structure, such as carboxyl groups, amine functional groups, sulfonic acid groups, etc. in the main chain or side chain.

[0010] However, conventionally, there are the following problems. (1) There is no idea about the technology to mix metal soap into a water-based polymer solvent without using oils, ethers, or VOCs (volatile organic compounds), and without using a group of chemicals called thinners. Conventionally, there has been no idea how to make a metal soap, which is originally thought to be insoluble in water and insoluble in alcohol, cloudy when mixed with water-based acrylic. (2) When alkaline soap is added to a water-based polymer, the soap dissolves in water. Therefore, when alkaline soap is added to a water-based polymer, the solvent water tends to become viscous and gelatinous. This has not been addressed in the past with regard to oil country tubular goods. (3) In the case of a chemical agent using a water-based polymer and a solvent made of water, there is a high concern that it will take a long time to dry.

[0011] Here, among solvents other than water, volatile organic solvents such as xylene, toluene, and benzene must be avoided. These cannot be used in a no-open flame environment, and consideration must be given to the safety and health of workers, as well as the installation of drafts and other facilities. For this reason, it is preferable to avoid the use of VOCs (volatile organic compounds), especially the group of chemicals known as thinners. The methods exemplified in Patent Documents 1 to 3 use highly volatile VOCs and are not designed for use in a no-open flame environment such as at the wellhead. For this reason, they cannot be used with oil well tubular goods.

[0012] It is also conceivable to use highly volatile but nonflammable fluorine-based solvents and binder resins to achieve fast drying. However, these are practically unusable. Under the US Toxic Substances Control Act (TSCA), a rule revision at the end of April 2021 retroactively prohibits the use of all chemicals containing PFAS, even if they have previously been approved. PFAS refers to fluorine-containing acrylic groups, including PFOS and PFOA. Furthermore, given the recent rise in environmental awareness, other countries may follow suit. Therefore, while methods other than fluorine-based or VOA cannot achieve fast drying (i.e., immediate drying) for water-based polymers, it is preferable to achieve fast drying within 30 minutes at room temperature. This fast drying should preferably be achieved within 15 minutes, and preferably within 5 minutes. Furthermore, extreme conditions, such as open flames, exist near oil and gas drilling sites. Since neither heat treatment furnaces nor electricity are available, it is necessary to assume an open-air environment. Therefore, it is not possible to imagine a process of removing the solvent by heat treatment at around 50-300°C at the wellhead. The UV-curable resin described in Patent Document 1 also requires equipment capable of irradiating UV rays at the wellhead. Therefore, Patent Document 1 requires equipment capable of doing so and facilities such as an electricity distribution system, making it difficult to say whether it is feasible.

[0013] Factories that manufacture products with solid lubricant coatings on their surfaces are not in environments where open flames are strictly prohibited, like wellheads. In these cases, it is easy to prepare drying enhancement equipment such as large fans, hot air dryers, heat treatment, infrared light, and ultraviolet light. When drying using such equipment designed to accelerate drying, it is preferable to dry within 5 minutes, preferably within 3 minutes, and even more preferably within 1 minute. To accommodate this without slowing down the conventional line speed, it is necessary to dry within the takt time of the production line.

[0014] (4) In response to the recent increase in environmental awareness, there is a need to design the system so that it does not use heavy metals and chemicals containing PFAS. However, this issue is likely to be resolved automatically if the above-mentioned issues are resolved. (5) The inventors have found that it is important to evaluate the lubricating performance of the solid lubricant coatings and agents disclosed herein using an evaluation method suited to the environment in which they will be used in an actual well, and to set upper and lower limits for the parameters. In other words, conventional laboratory evaluations using short pins of about 1 m have the problem that they do not provide an evaluation method that is in line with actual usage conditions.

[0015] For example, as in the methods shown in Patent Documents 4 and 5, even if a misalignment of 5 or 6 degrees is set and a make-up test is performed using a short pin, parameters that should actually be considered "fail" are erroneously judged as "pass." As a result, the methods shown in Patent Documents 4 and 5 have the problem of not being able to verify the upper and lower limit specifications for parameters. Consider the case where a make-up / loosening test is performed using a short pin with a misalignment of 5 or 6 degrees. In this case, the inclination of the pin thread is mechanically determined by the incomplete thread portion of the box thread and the tapered portion at the tip of the pin thread. For this reason, the screw structure makes it difficult to set and insert the pin at a 5 or 6 degree inclination. Oil well pipe threads have a tapered thread structure, and their taper angle is approximately this level. However, it is structurally impossible for the pin to be inclined at this angle relative to the coupling. However, the threads can be simply placed without engaging with each other. However, this has no effect on the lubrication behavior. The initial set position is only momentarily different, and after that, the threads simply tighten along the thread taper.

[0016] Furthermore, the pin screw should be inserted and set along the taper of the screw. The screw threads should have some tilt due to the play between the threads when inserted. When inserting the pin screw into the box screw, it is structurally difficult to set a constant tilt of around 5 degrees. Due to the play between the threads, it is estimated that only a tilt of around 1 to 2 degrees can be set. In reality, even in this state, once the threads engage, the pin screw will immediately straighten out. Therefore, even if the threads are barely engaging, tilting the screw at around 5 degrees will cause minimal damage to the solid lubricant coating, and it is estimated that this does not simulate actual well conditions.

[0017] Furthermore, the method described in Non-Patent Document 1, in which a 500 kN weight is placed on the pin screw to apply the load of a single actual pin, also presents problems for evaluation. As will be explained in detail in the following invention, the initial setting position is important for simulating the rattle of the pin screw in an actual well. In Non-Patent Document 1, as evidenced by Figure 5, if the screw is manually tightened to a position where it can be tightened about half a turn, the weight acts as a balancer, resulting in a straight, ideal pin. Therefore, it is not possible to simulate the harsh conditions in an actual well, where the pin screw is tightened and retightened with rattle, based on the slight bending of the long pin in its elastic range. The harsh conditions are, for example, similar to those in an actual well.

[0018] The inventors have found that unless the initial setting position of the pin screw is intentionally set as follows and then tightened and loosened, it is impossible to estimate results that correspond to the situation in an actual well or a simulated well. This setting is such that the pin screw is exposed from the box screw, and furthermore, a weight equivalent to one to three actual-size pins is placed on the end of the pin. It should be noted that, unlike lubrication using conventional viscous liquid compounds, evaluation of the lubrication of solid lubricating coatings using a simple short pin tends to deviate from the results in an actual well. Specifically, the evaluation results tend to be too lenient. In other words, even if the evaluation using a short pin is successful, it does not mean that the well will pass. For this reason, in the case of solid lubricating coatings, unless the lubrication is properly evaluated, the upper and lower limit specifications for parameters will not provide evidence that the well will be able to withstand the lubrication.

[0019] The present disclosure has been made in response to the above-mentioned problems, and aims to provide a solid lubricating coating that is environmentally friendly even when it is a water-soluble agent, using a water-soluble or water-dispersible polymer as the binder resin and a metal soap as the main solid lubricant, and that has lubrication properties that can withstand use in an actual well. [Means for solving the problem]

[0020] With regard to the lubrication of oil well pipe threads, there has been a recent trend toward limiting the chemicals that can be used as agents and the components of lubricating films due to increased environmental awareness. Traditionally, lubrication of oil well pipe threads has consisted of a combination of lubricating compounds containing harmful heavy metals and a surface treatment on the box thread side. The surface treatment, for example, consists of a manganese phosphate primer or an electroplated layer. However, the commonly used API-mod compound, i.e., a wet lubricant, is already becoming unusable in environmentally conscious areas. Specifically, API-mod compound contains harmful heavy metals, such as Pb and Zn, as its main components. Therefore, there is concern that harmful heavy metals may be washed away or overflow to the outside during tightening, resulting in marine pollution.

[0021] In this disclosure, a solid lubricating coating is used instead of these lubricating compounds. Furthermore, this disclosure employs a water-soluble or water-dispersible polymer as the binder resin for the solid lubricating coating. This aims to avoid the problem of harmful heavy metals being released into the environment. The agent for forming a solid lubricant coating, which is the subject of this application, uses water as the solvent and is itself considered to have no environmental resistance issues. It is sufficient for the binder resin and solid lubricant to comply with international regulations and rules for chemicals. This will simultaneously achieve HSE and ensure the safety and health of workers. Replacing the conventional lubrication of oil country pipe threads with a solid lubricant coating is also effective in resolving HSE issues. HSE stands for health, safety, and environment.

[0022] Furthermore, in many cases, the wet compounds used in conventional lubrication methods are different in the compounds used during lubrication and during storage. The technology of replacing wet compound lubrication methods with solid lubricating coatings must be consistent in that it is a dry film, even for rust prevention during storage. Also, using conventional wet compounds to protect pin threads from rust is not recommended except in emergencies. In other words, it is considered preferable that a solid lubricating coating be designed to function as a lubricating film as well as a coating that has rust prevention properties during storage.

[0023] Furthermore, it is important to note that the lubricating compounds and anti-corrosion compounds used in the past were viscous liquid compounds, which functioned while wet. In other words, there was no need to consider drying time for wet compounds. On the other hand, solid lubricating coatings are dry films that function in a dry state, so when forming a solid lubricating coating, the chemicals must be designed taking into account the process of evaporating the solvent from the applied chemical to form a film, as well as the time required for this. Here, there are already existing techniques for designing dry, soft polymer-based resin films using agents with a water-soluble or water-dispersible polymer matrix, particularly for use in surface lubrication of oil country pipe threaded joints. Regarding solid lubricants, there are also already existing techniques for achieving high lubrication using metal soap as the main component.

[0024] However, there is no known combination of these, in which a metal soap is dispersed as the main component of a solid lubricant in a dry, soft polymer-based resin film formed using a simple water-soluble or water-dispersible polymer, where the polymer-based resin film is the matrix component. It has been thought that adding water-repellent and water-insoluble metal soap to a water-based solvent alone is difficult, assuming that no oil or thinner is mixed in. While it is not impossible to use metal soap as a solid lubricant in a water-based solvent alone, it is difficult to achieve under the conditions targeted by this disclosure. Metal soap is water-repellent, and even if you try to simply mix it with water, it floats on the surface and does not disperse or dissolve.

[0025] This disclosure relates to a design in which a dry, soft polymer-based resin film is formed using a water-soluble or water-dispersible polymer, and a solid lubricant is dispersed and distributed in the film. Furthermore, this disclosure positions a metal soap as the main component of the solid lubricant. Metal soap itself is water-repellent and insoluble in water. At the same time, metal soap itself is said to be insoluble in alcohols. The substances that metal soap itself is said to be slightly soluble in are VOCs (volatile organic compounds), which are a group of chemicals called paint thinners. However, these chemicals are often considered harmful to health and are often broadly referred to as paint thinners. These chemicals are classified as VOCs and ethers, such as toluene, xylene, benzene, and mineral spirits, as well as oils, such as mineral oil. This information is widely known and publicly known.

[0026] Therefore, it has been considered difficult to directly mix metal soaps with water-based polymers. Therefore, metal soaps have traditionally been dissolved in the VOCs listed above and then mixed with a water-based solvent. Methods using thinners or the like are described in, for example, Patent Documents 1 to 3. However, as will be described later, due to concerns about worker safety and the environment, and due to concerns about the environment, this method is unlikely to be usable in places where open flames are strictly prohibited, such as in oil / gas drilling environments.

[0027] The present disclosure also contemplates the case where an alkaline soap is also dispersed. Here, the alkaline soap is either a sodium salt or a potassium salt of a fatty acid, or both. Hereinafter, the alkaline soap will also be referred to simply as soap. In this disclosure, it is also contemplated that a small amount of alkaline soap may be used to assist or reinforce lubrication. To reiterate, the present disclosure is designed such that a water-soluble or water-dispersible polymer forms a dry, soft polymer-based resin film, and a solid lubricant is dispersed and distributed within the film.

[0028] Unlike metal soaps, soaps are soluble in water. Therefore, alkaline soaps have the disadvantage of being difficult to use with the chemicals and solid lubricant coatings considered in this disclosure. Furthermore, there have been few examples of their application to date. When a water-based polymer is designed with a certain amount of alkaline soap added, the entire liquid gels and solidifies. This results in increased fluidity, which is characteristic of water-based polymers. This means that the easy-to-apply feature disappears, and rapid drying tends to be difficult. On the other hand, there are many soap-based lubricants available on the market, even for industrial use, that are used while wet. However, these lubricants utilize the lubrication in a hard gel state without drying. Therefore, this is a different technology from that disclosed herein.

[0029] As mentioned above, traditionally, water-based polymers refer to polymers that use water as a solvent, and the water component must be dried and removed before film formation. Water-based polymers are either water-soluble or water-dispersible. Because water is the solvent, water-based polymers require heating the target surface. Alternatively, the target surface can be heated before application. In either case, without a process to promote water evaporation, the coated product must remain in the production plant until it dries. This significantly reduces production efficiency. In other words, drying in the air requires a significant drying time, necessitating the securing of a drying space. Therefore, unless a method is found to rapidly dry water-based polymers, production efficiency declines, resulting in higher production costs. In other words, rapid drying requires the use of drying equipment and heat treatment furnaces. However, this increases installation and running costs.

[0030] Meanwhile, a technique for quickly drying water-based polymers by adding a volatile organic solvent and utilizing the volatile heat generated to form a film is also known. Patent Document 1 states that since the acrylic / silicone surface film becomes a dry film at a relatively low temperature in a short time, it is advisable to select an oil-based material, and that it is particularly preferable to use a room-temperature curing type. In other words, Patent Document 1 is an example of using the evaporation of an oil-based solvent to achieve rapid drying without selecting a water-based material.

[0031] Patent Document 2 lists three examples: a purely water-based system, a system containing water and a volatile organic solvent, and a system using an ultraviolet-curable resin. Of these three, the latter two are capable of rapid drying. However, the first example, a purely water-based polymer system, requires some method for evaporating the water. However, Patent Document 2 does not explicitly state how this method can be achieved.

[0032] Patent Document 3 discloses a method for shortening drying time by using a volatile solvent with a flash point of 30°C or higher. However, in hot regions such as desert regions in midsummer, a flash point of around 30°C raises concerns that a spark or other risk factor could ignite the wellhead. Furthermore, even if the material is processed in a workshop some distance from the well, the risk of fire cannot be ruled out. Thus, materials with low flash points pose a high risk of fire and other accidents unless used in a well-controlled environment. In other words, there has traditionally been a challenge in how to achieve safe and rapid drying. Materials with low flash points are easily flammable.

[0033] In contrast, the present disclosure uses a solid lubricating coating that is mainly composed of a water-soluble or water-dispersible polymer. One possible way to speed up the drying of aqueous solvents is to use VOCs (volatile organic compounds), particularly thinners, taking advantage of their volatility. However, due to VOC emission control regulations and to avoid placing workers in a hostile environment, the inventors determined that toluene, xylene, benzene, and other organic solvents, no matter how volatile they are and how effective they are at speeding up drying, should be avoided. Even providing an exhaust system would likely require a large capital investment. Furthermore, when forming a solid lubricating coating, it is difficult to use volatile organic solvents, which are harmful to the body. Therefore, the inventors determined that VOCs (volatile organic compounds), particularly thinners, which are both harmful to health and too volatile, could not be used to speed up drying. In addition, there has been a recent shift away from using fluorine-based solvents, which are naturally quick-drying, and fluorine-based resins, which can be dissolved in them to become binder resin components of paint. Fluorine-based solvents are being used as substitutes for fluorocarbons, etc.

[0034] Traditionally, fluorine compounds have been treated as the king of surface treatments due to their quick-drying properties, excellent lubrication and corrosion prevention. However, due to recent tightening of rules, fluorine compounds are becoming unusable. Under the US TSCA (Toxic Substances Control Act) and the European REACH chemical regulations, fluorine-based alkyl compounds (F-(CF2) n Until now, only PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid) were subject to regulation (chemical species containing eight carbon atoms). Substances with fewer carbon atoms were usable without any particular concerns. However, the April 2021 revision of the U.S. TSCA retroactively banned the import, use, and production of PFAS (organic fluorine compounds: perfluoroalkyl and polyfluoroalkyl compounds) into the United States. This means that binder resins containing fluorine compounds (PFAS) are no longer usable. This means that the only fluorine-containing chemicals and products that can be used are Teflon® (PTFE: polytetrafluoroethylene) and PFPE (perfluoropolyether), which are exempt from TSCA. Furthermore, the international trend toward designing fluorine-free solid lubricant coatings can no longer be ignored.

[0035] In light of the above, the present disclosure is based on the idea of ​​using water as a solvent to be environmentally friendly, making the binder resin a chemical agent with a water-soluble composition, and creating a chemical agent from appropriate solid lubricants and other additives, and then using this chemical agent to form a solid lubricating coating. However, water as a solvent is difficult to volatilize and takes a long time to evaporate, and drying requires large-scale capital investment, such as a heat treatment furnace, which poses a number of challenges.

[0036] Furthermore, when applying a solid lubricant coating to the threads of oil country tubular goods (OCTG), the tubular goods are produced and transported away from the oil / gas wells. Therefore, when creating a solid lubricant coating based on a water-soluble or water-dispersible polymer at the production site, it may seem possible to address all issues related to quick drying. In other words, because water-based polymers are difficult to dry, measures may be taken, such as creating equipment to dry them slowly or using heat treatment equipment to accelerate drying. In this case, if heat treatment equipment is not used, adding a volatile organic solvent to accelerate drying may be considered. Furthermore, in many cases, this can be achieved by providing an exhaust system and taking measures to prevent ignition.

[0037] However, when a chemical agent for forming a solid lubricating coating and the solid lubricating coating formed using that agent are used in an OCTG threaded joint, and that OCTG threaded joint is then used in a well, the following problem arises: the solid lubricating coating is not necessarily manufactured or formed only at a production site far from the well. When considering problems with the lubricating coating formed on oil well tubular goods, it is necessary to consider the possibility of using chemicals for forming solid lubricating coatings at the wellhead. Open flames are strictly prohibited at the wellhead, and there are also situations where the footing is not stable. Furthermore, when applying water-soluble or water-dispersible polymers at the wellhead, there is a demand for them to dry quickly.

[0038] The reason for this is that when a problem occurs in a well, the tubing threads are often pulled up from the well in groups of one to three, while being tightened. In this case, the pulled pins (oil well pipes) must be lined up side by side, their surfaces cleaned with water or steam, and then coated with a similar anti-corrosion paint. In contrast, conventional methods for OCTG threads do not involve the application of a wet lubricating compound containing Pb and Zn, such as API-mod compound, but rather the application of a compound known as a wet storage compound. In contrast, in the case of solid lubricating coatings, in order to complete the process using only solid lubricating coating technology, unlike wet compounds, a solid coating base that can dry quickly must be formed at the wellhead. However, open flames are strictly prohibited at the wellhead. It is not possible to use organic solvents with low flash points and good volatility that would promote quick drying due to the danger.

[0039] Patent documents 1 to 3 are examples, but all of these have used highly volatile organic solvents with low or likely low flash points to quickly form a film. Furthermore, it appears that the chemicals are designed on the assumption that OCTG is produced and transported away from oil / gas wells. Chemicals based on low flash points are extremely dangerous to use near oil / gas wells, where open flames are strictly prohibited. The present disclosure provides a drug that minimizes the use of highly volatile organic solvents.

[0040] Furthermore, the inventors do not intend to address the issues of corrosion resistance and lubrication that are the subject of the present disclosure at a level that can be evaluated simply through simple laboratory experiments or simulations, which are often performed on a daily basis. The inventors have considered conventional laboratory tests and have come to the realization that they must be set up to be able to withstand even the most severe conditions that can be imagined. In this disclosure, corrosion resistance is not simply considered in the as-deposited state, but is assumed to be a situation in which the solid lubricating coating has been damaged. It is assumed that corrosion resistance must be maintained after the solid lubricating coating surface of an oil country pipe thread is tightened and loosened with a protector under what can be considered the most severe conditions. In other words, this disclosure assumes that corrosion resistance must be maintained even when the solid lubricating coating has been damaged by contact with the protector.

[0041] At the same time, this disclosure assumes that good lubricity must be guaranteed under sliding conditions involving high loads. When considering actual wells, it is necessary to assume that a certain amount of solid lubricant coating will inevitably be scraped off during make-up and tightening. The inventors have discovered that the scraped-off debris can cause seizure problems in the following cases: when it gets stuck in the gap between the box thread or pin thread, or when a high or uneven load is applied to the joint, causing part of the film to be completely torn off. Furthermore, they have discovered that unless upper and lower limits for the components of the solid lubricant coating are set by simulating conditions in an actual well or conditions similar to those in a well, the specifications for lubrication performance will be meaningless in an actual well.

[0042] A commonly used test heretofore has been a laboratory clamping test using a short pin of about 1 m. In this clamping test, if the lubrication of the solid lubricant coating, which is the subject of this disclosure, is judged NG, it will also be NG in an actual well. However, the inventors have found that even if this conventional test using a short pin of about 1 m gives a pass, this does not guarantee that the result will be OK in an actual well. However, in the specified ranges for the lubrication performance of solid lubricant coatings in past patent documents, there are very few that take such points into consideration when selecting the specified ranges for solid lubricant coatings. In the case of viscous liquid lubricating compounds, which are commonly used to lubricate conventional oil well pipe threads, there is not much difference between the tightening and tightening evaluation using a short pin in the laboratory and the situation in an actual well. Furthermore, the judgment in an actual well tends to be linked to the laboratory evaluation. This is because, because the lubricating compound is a viscous liquid, it is assumed that the compound moves in tandem during tightening and tightening.

[0043] On the other hand, in the case of solid lubricating coatings, the debris that is inevitably scraped off does not necessarily move in conjunction with tightening and loosening. For this reason, in actual wells where debris is inevitably generated in large amounts, the debris is likely to clog the well. Furthermore, when significant peeling occurs, seizure occurs in areas where the solid lubricating coating has become thin or has disappeared. Based on this knowledge, the inventors have come to the realization that solid lubricating coatings must be evaluated taking this into account.

[0044] This finding will now be explained in more detail. In actual wells, the actual length pin threads tightened into the box threads are not idealized as described in textbooks. Ideally, the actual length pin would be positioned upright, inserted, and tightened straight into the box thread. However, this is not the case. The structure of OCTG threads creates an incomplete thread when the pin threads are inserted into the box threads. This backlash often causes the pin to be set slightly at an angle during initial tightening. When the threads are initially tightened, the pin threads move around due to the play. Therefore, by the time the threads engage, the solid lubricant coating is subjected to a combination of the pin's own weight, a large load, and the offset load caused by the pin's uneven movement. This inevitably increases the risk of the solid lubricant coating being excessively scraped off or completely peeled off. On the other hand, wet lubricating compounds, being viscous liquids, move in conjunction with tightening and loosening. This contrasts sharply with the fact that for lubricating compounds, the results obtained when evaluating lubrication in the laboratory using short pins are nearly identical to the results obtained in actual wells.

[0045] This is specifically shown in Figures 2 and 3. The examples shown in Figures 2 and 3 are examples of tightening and tightening test conditions, where the screw was rotated at 15 to 25 rpm until torque was reached, and then rotated at 2.5 to 1.5 rpm once torque was reached. This is the result of testing under severe conditions, i.e., at a high rotation speed, exceeding the conditions specified in the screw handling instructions, i.e., the tightening instructions in the technical package. The examples shown in Figures 2 and 3 are examples of well tightening materials and strength grades, using 9-5 / 8" 53.5# Q125 material, and JFELION TM This is an example of evaluation of a solid lubricant coating on a screw.

[0046] Figure 2 shows a torque-turn chart based on the conventional laboratory evaluation method, using a short pin of approximately 1 m and tightening with vertical power tongs. Because the pin is short, it is easy to handle and can be set straight. This means that the pin can be set by hand until the pin threads are barely exposed (Figure 2(b)). In this case, the torque-turn chart shows that torque begins to build up from the beginning of tightening, and the tightening is completed after passing the shoulder torque bending point. In other words, this results in a very typical chart (Figure 2(a)). The reason the torque builds up so quickly is because the pin thread and box screw are fully engaged during the initial set stage, and tightening is carried out from the preset position.

[0047] Figure 3, on the other hand, shows the torque-turn chart for Range-3, using a single full-size pin just over 40 feet (just over 12 m). Figure 3 also shows the results of a test conducted in a simulated well. The units (size) on the horizontal axis are different from those in Figure 2. Note that the simulated well is not an actual oil or gas producing well; rather, it is an experimental well with a simulated hole drilled so that just over three full-size pins can be inserted underground. The simulated well also refers to a laboratory facility with a rig above which two or three connected pins can be suspended and set, allowing for tightening and tightening tests. This example shows the trend under conditions similar to those observed in an actual well, but differs from the case of the short-length pin in Figure 2. In this example, steady torque does not develop until approximately 6.3 rotations, and irregular spikes of torque are occasionally observed during this rotation. The inventors have discovered that this phenomenon is directly linked to damage to the solid lubricant coating, and that this fact suggests the importance of evaluating the solid lubricant coating.

[0048] The torque chart example in Figure 3 shows what happens when setting and tightening a Range-3 pin, or a pin just over 40 feet (just over 12 m). In this case, because the actual pin is just over 12 m, it cannot be set perfectly straight and is almost always inserted at an angle. This is similar to the conditions in a real well. As a result, even when setting the pin by hand, the pin thread and box screw will partially butt up too tightly. As a result, more than five threads of the pin, often about half of the total threads, will be exposed from the box when tightened by hand, preventing further advancement. From this point, tightening with tongs begins. In most cases, the threads are not fully engaged, and some parts will inadvertently butt up too tightly, preventing further advancement. As a result, with actual-size pins, the box screw and pin screw will butt up under uneven loads before they fully engage. This means that damage will occur. Based on this, we have come to the realization that, without evaluating the solid lubricant coating, as already mentioned above, if something is NG in an evaluation using a short pin, it will be NG in an actual well, but if something is OK in an evaluation using a short pin, it does not necessarily mean OK in an actual well. For this reason, we have come to the realization that in past inventions, when the upper and lower limits of components, conditions, and other parameters were evaluated based on OK in an evaluation using a short pin, it does not necessarily mean that it is within a good range in an actual well. Here, the methods of Patent Documents 4 and 5 are examples of test evaluations using short pins, and do not necessarily intend to provide a favorable range.

[0049] Furthermore, in Non-Patent Document 1, lubrication is evaluated by placing a 5 kN weight on the top end of the pin when it is tightened upright. Judging from the torque-turn chart for a 7" 29# pin, Non-Patent Document 1 appears to be intending to apply the weight of one actual-length pin, or approximately 40 feet (approximately 12 m) of pin. However, judging from the torque-turn chart, i.e., Fig. 5 in Non-Patent Document 1, it appears to be premised on conducting the test with a tightening behavior closer to Fig. 2, rather than Fig. 3. In other words, Non-Patent Document 1 appears to be premised on conducting the tightening test from a state in which the initial set position is tightened by hand to a level where the pin thread is not exposed, and the pin thread and box thread are fully engaged. For this reason, it is not necessarily possible to determine a favorable range.

[0050] From the above, the problems that can be extracted from the present disclosure are described below. This disclosure is based on the premise that no oils or volatile organic solvents such as thinners are used. Based on this premise, this disclosure considers creating a chemical agent by dispersing solid lubricant components, primarily metal soaps, in a binder resin made of a water-soluble or water-dispersible polymer. Furthermore, it considers using this chemical agent to create a corrosion-resistant lubricating film made of a solid lubricant coating. It was found that such a configuration has the following problems, and that further improvements are necessary.

[0051] (First issue) This is an issue when mixing metal soaps into water-based polymers. In other words, when mixing water-insoluble metal soaps, it is necessary to devise a way to make the mixture turbid without using oils or volatile organic compounds, and without using chemicals known as thinners.

[0052] (Second issue) When alkaline soap is added to a water-based polymer, the solvent tends to become viscous and gelatinous because the alkaline soap dissolves in water. Therefore, even if the alkaline soap is intended to provide lubrication, it may take a long time to form a film. At the same time, it is necessary to specify the appropriate amount of alkaline soap to create a dry solid lubricating coating.

[0053] (Third issue) Because it uses a water-based polymer and water as a solvent, there is a high concern that it will take a long time to dry after application. Therefore, some kind of ingenuity is needed to achieve quick drying, which is an issue. In short, it is preferable to be able to apply it anywhere and dry quickly. In extreme situations, such as environments where open flames are strictly prohibited, neither heat treatment furnaces nor electricity can be used, and the material is left exposed to the atmosphere. However, this disclosure envisions that this solid lubricant coating and chemicals can be used not only at oil well tubular goods manufacturing sites, but also at wellheads. Therefore, to improve quick-drying performance, it is necessary to avoid the use of thinner-based VOCs at wellheads where open flames are strictly prohibited. At the same time, consideration must be given to the safety and health of workers, including the installation of drafts, etc. Therefore, solid lubricant coatings and chemicals must be designed with the assumption that the use of thinner-based VOCs should be avoided.

[0054] (Fourth issue) In response to the recent increase in environmental awareness, it is necessary to eliminate the use of a range of chemicals containing heavy metals and PFAS (fluorine-containing acrylic groups, including PFOS and PFOA).

[0055] (Fifth Problem) It is important to evaluate the solid lubricant coatings and chemicals disclosed herein using an evaluation method suited to the environment in which they will be used in an actual well, and to set upper and lower limits for parameters. However, conventional evaluation methods using short pins of about 1 m do not provide an evaluation method suited to actual usage conditions.

[0056] The means for solving each problem in this disclosure will be described below. The present disclosure relates to an agent that uses a water-soluble or water-dispersible polymer, i.e., a water-based polymer, as a binder resin, a metal soap as the main component of a solid lubricant, and water as the main component of a solvent, and also to a solid lubricating coating formed by the agent. Metal soaps function as solid lubricants with water repellency. Being water repellent means that they are insoluble in water. Assuming that the metal soap can be successfully formulated in the agent, it is considered that good lubricity, corrosion resistance, quick drying, and other properties can be achieved within the ranges specified in this disclosure. In order to solve the above problems, this disclosure defines the following solutions and constitutes an invention.

[0057] The method for solving the first problem involves a technique for effectively mixing metal soap with the solvent water. Metal soaps are generally described as insoluble in both water and alcohol, and are said to dissolve in thinner-type volatile organic solvents, ether-based solvents, and oil-based solvents. For example, Non-Patent Document 2 clearly states that metal soaps are insoluble in ethyl alcohol, methyl alcohol, and butyl alcohol. In other words, metal soaps can be dissolved if water is selected as the solvent, a VOC that readily evaporates even at room temperature is used, and a thinner-type solvent that requires workers to wear special masks or have a draft facility is used. However, until now, it was thought that there was no solution to making metal soaps dissolve in water as long as one chose not to use such substances. Furthermore, when considering the lubrication of oil well pipe threads and the application of chemicals at the wellhead, the use of thinner-based solvents in a wellhead environment where open flames are strictly prohibited is a serious problem.Though thinner-based solvents are solvent substances that do not remain in the formed film, they cannot be used.

[0058] The inventors conducted an experiment to investigate mixing a water-insoluble metal soap with a water-soluble or water-dispersible polymer, i.e., water, which is a solvent for water-based polymers. During the experiment, they noticed that although the metal soap is insoluble in both water and ethanol, when actually dissolved, the dispersibility of the metal soap differs when compared with water and lower alcohols such as ethanol.

[0059] Specifically, they found that in lower alcohols such as ethanol, metal soaps tend not to clump and tend to break down into fine particles, making it possible to maintain the metal soaps as fine particles. After mixing the metal soap with alcohol, they can be stirred vigorously or vibrated with ultrasound. However, in water, the metal soaps aggregate and grow into clumps, making it impossible for them to be uniformly dispersed. From this, we learned that it is possible to dissolve metal soap in a lower alcohol such as ethanol, and disperse the metal soap in an insoluble state. We then discovered that by spreading and mixing the metal soap in a water-based polymer, we can obtain a homogeneous drug.

[0060] When the agent of the present disclosure is left standing, the metal soap separates over time. However, when the container containing the agent of the present disclosure is shaken before use (i.e., when applying), and the agent is re-mixed and then applied, it has been confirmed that when the water solvent is evaporated after application, a homogeneous solid lubricating coating is formed. Furthermore, when metal soap is directly dissolved in water, the metal soap tends to form lumps, which increases the risk of the resulting solid lubricating coating becoming uneven.

[0061] The reasons for this are not very clear. Qualitatively, water is simply a polar solvent. On the other hand, lower alcohols such as ethanol tend to dissolve in water and also be slightly soluble in oil. Metal soaps are insoluble in water, but are generally described as being insoluble in alcohol as well. However, metal soaps can dissolve in oil and VOCs such as paint thinners. Therefore, it is presumed that the level of insolubility is likely responsible for the differences in the phenomena described above, as there are differences at the molecular level.

[0062] On the other hand, lower alcohols such as ethanol are also highly volatile and fall into the VOC category. Therefore, there is a concern that they may be flammable in environments where open flames are strictly prohibited. Therefore, it is necessary to specify upper limits for the amount of lower alcohol that can be used to dissolve the above-mentioned metal soap and its concentration in the agent. From this perspective, the present disclosure specifies upper limits for lower alcohols. Furthermore, the more metal soap dissolved, the better, as it can be used as a solid lubricant. However, the upper limit of the amount of metal soap that can be dissolved is determined by the limit of alcohol dissolution, as well as volatility and flash point. The lower limit of the amount of metal soap is determined by the minimum amount that can achieve lubrication.

[0063] The second challenge is how to mix in a small amount of alkaline soap to support lubrication. In other words, the question is how to mix a small amount of alkaline soap into a system that uses a water-based polymer as the binder resin, metal soap as the main component of the solid lubricant, and water as the solvent, without adding VOCs such as thinner.

[0064] Alkaline soap dissolves in water, so it can be mixed in. However, if too much alkaline soap is mixed in, the water solvent tends to become viscous and gelatinous. This makes it difficult for the agent to dry when applied, and it takes a long time to dry as a solid film. Even when it dries, it becomes a semi-solid, viscous film. Furthermore, a semi-solid to viscoelastic film leaves a sticky feeling on the surface, which makes it easy for dirt and sand to adhere. Once dirt and other debris are attached, it becomes difficult to remove. This creates resistance when tightening and loosening, and the necessary lubrication may not be achieved. From the above, it is necessary to add a trace amount of alkaline soap and set an upper limit so that the amount added can support the effect of solid lubrication by containing the alkaline soap and does not change the viscosity of the water solvent. From this perspective, the present disclosure specifies the amount of alkaline soap to be added.

[0065] The third problem is that because water-based polymers use water as a solvent, it may take a long time for the chemical to dry after application. In this disclosure, adding large amounts of VOCs and using their volatility to evaporate water is not acceptable, considering the possibility of using open flames in certain environments. Toluene, xylene, and benzene-based VOCs, commonly known as thinners, cannot be used due to worker health and safety considerations. It is also necessary to safely dry the film, even in environments where electric heaters cannot be used or where the film will dry and form simply by being left outdoors in the local environment.

[0066] In this disclosure, the lower alcohols mentioned in the first problem, i.e., alcohols such as ethanol, methanol, isopropyl alcohol, normal propyl alcohol, and industrial ethanol, are used to dissolve metal soaps. As mentioned above, they can be mixed within acceptable ranges in terms of volatility and flash point so that they can be used in environments where open flames are strictly prohibited. To enable use in environments where open flames are strictly prohibited, the flash point of the agent must be 60°C or higher, preferably 150°C or higher, and even more preferably 250°C or higher. Under these conditions, an excess of lower alcohols is added beyond what is necessary to dissolve the metal soap, making use of their volatility. However, the higher the flash point, the less alcohol should be added or contained. However, it is preferable to contain at least 0.5% or more of lower alcohols.

[0067] At the same time, aqueous ammonia may be added and its volatility may be utilized. Aqueous ammonia can also be used to adjust the pH of paints. When used for pH adjustment, additional ammonia is added to the formulation to shift the pH toward the upper limit of the specified pH of the agent, i.e., toward the high pH side. Furthermore, if no pH adjustment is specified, volatility can be promoted by adding ammonia water (28-30%) up to 1% vol / vol% relative to the water solvent. In this disclosure, we conducted experiments to clarify the conditions for simultaneous use of ethanol and ammonia and to clarify the optimal range. Ammonia water is commercially available in dilute concentrations such as 10% and 5%. However, this disclosure will be discussed based on concentrated ammonia water (28-30%).

[0068] At the same time, in this disclosure, the particle size of the metal soap is selected to be small, and the metal soap is dispersed in the agent so as not to aggregate, thereby increasing the contact surface area of ​​the metal soap and realizing rapid drying. The size of the metal soap is 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less, on average, to promote drying of the applied agent. Also, to disperse and mix these into the agent, as explained in the response to the first problem, the agent is prepared by dissolving them in a lower alcohol such as ethanol. It is also important to adjust the viscosity of the agent. It is important to lower the viscosity to make it easier to apply thinly, and to make it difficult to apply thickly.

[0069] If the chemical is applied to the metal surface of a cylinder while rotating the cylinder, excess chemical will inevitably drip off from the 6 o'clock position, the lowest position. Similarly, if the cylinder is not rotated, the excess chemical will inevitably drip off from the 6 o'clock position, although the 6 o'clock position tends to be slightly thicker. Even when applying to a plate-shaped object, if the object is propped up at an angle, excess chemical will drip off under its own weight. This creates conditions that make it easier for the chemical to dry quickly. Therefore, in order to achieve quick drying, even when the metal surface to which the agent has been applied is left in an atmospheric environment, indoors or outdoors, the following conditions must be met: The conditions are a combination of using the above-mentioned alcohol and ammonia, selecting the particle size of the metal soap to prevent the metal soap from associating and forming clumps, and adjusting the viscosity of the agent to prevent it from being applied too thickly.

[0070] The fourth challenge is how to design products that avoid heavy metals and a suite of chemicals containing PFAS, which refers to fluorine-containing acrylic groups, including PFOS and PFOA. In contrast, the present disclosure is made using a water-based polymer and does not use harmful substances, so by implementing the solutions to the above problems 1 to 3, the problems can be solved automatically. The fifth issue is the need to define upper and lower limits for each material by evaluating the properties of this lubricating and anticorrosive film using appropriate evaluation methods.

[0071] First, the corrosion prevention and corrosion resistance of this disclosure assumes the most stringent conditions, such as the lubrication of oil country pipe threaded joints. Simply evaluating the corrosion resistance of a film on a plate or the lubrication behavior using a short pin may allow for the selection of NG cases, but it cannot be said with certainty that they pass. In this disclosure, corrosion resistance is not limited to the corrosion resistance of a film formed by applying a chemical agent; in other words, it is necessary to consider the possibility that when the protector is tightened, the film may come into partial contact with the protector, causing damage to the film.

[0072] Regarding lubrication, in actual wells, Range-3 full-length pins, that is, pins of about 40 feet (about 12 m) long, are set up and hung by a derrick crane or similar and tightened. In the worst case scenario, the entire weight of the full-length pin could be applied to the box screw side. Note that one 9-5 / 8" 53.8# piece is equivalent to about 1 ton. Due to this large load, it is necessary to consider the possibility that the solid lubricant coating could be severely damaged. Regarding the initial setting position of full-length pins, unlike short pins, we assume a situation where the pin cannot be set until almost all of its threads are hidden by the box screw. In other words, we need to evaluate lubrication assuming a situation where the screw cannot be advanced any further, that is, it can only be tightened up to the position where the threads are exposed. For example, in an actual well, the pin screw can only be set to the position corresponding to symbol 1a(10) in Figure 3(b). However, evaluating the solid lubrication behavior of oil country pipe threads in an actual well or a simulated well is not realistic from the standpoint of cost and the time required to arrange experiments.

[0073] The solution to this is as follows: One to three full-length pins are attached to the upper end of the short pin. Furthermore, the initial setting position of the screw is set to a position where about half of the pin thread is exposed to the box screw. This allows the weight to be applied during tightening and not during tightening, simulating tightening in an actual well, and the upper and lower parameter limits are determined in accordance with the actual conditions. That is, in this disclosure, the initial setting position of the pin screw is intentionally set so that the pin screw is exposed from the box screw. Furthermore, in this disclosure, a weight equivalent to one to three full-size pins is placed on the end of the pin, and the evaluation is performed by tightening and loosening. During tightening, a weight equivalent to one to three full-size pins is applied. Note that the weight equivalent to one pin is assumed to be used in an onshore well, and the weight equivalent to three pins is assumed to be used in an offshore well. During loosening, the weight is suspended by an overhead crane to adjust the load, reducing the load to zero and loosening. If the weight is left hanging during loosening, the weight acts as a balancer, causing the pin to rise straight up without rattle. This results in a situation where the solid lubricating coating is not damaged at all on either the box screw or the pin screw, which means that the simulation does not simulate what occurs in an actual well. [Effects of the Invention]

[0074] The agent of the present disclosure is an agent in which the main component of the solid lubricant is a metal soap, the main component of the binder resin is a water-soluble or water-dispersible polymer, and the main component of the solvent is water. While the agent of the present disclosure is based on the above configuration, it is possible to provide an environmentally friendly agent that does not use a group of agents known as thinners, or a set of agents including heavy metals and PFAS. In addition, the agent disclosed herein can achieve rapid drying without the use of thinners. This allows it to be used in environments where open flames are strictly prohibited. PFAS refers to fluorine-containing acrylic groups, including PFOS and PFOA. Furthermore, the agent of the present disclosure can provide a solid lubricating coating that has lubricity and corrosion resistance sufficient for use in an actual well. [Brief explanation of the drawings]

[0075] [Figure 1] 1 is a diagram showing an oil well pipe and an oil well pipe threaded joint. FIG. [Figure 2] FIG. 1(a) shows a tightening chart for a conventional laboratory test, and FIG. 1(b) shows the initial set position for that test. [Figure 3](a) shows the tightening chart for an actual well, and (b) shows the initial set position. [Figure 4] Schematic diagrams of fastening charts, where (a) is for an actual well and (b) is for a conventional laboratory test. [Figure 5] FIG. 1 is a diagram illustrating new laboratory test conditions (weight tongs). [Figure 6] FIG. 10 is a diagram showing an example of weight placement under new laboratory test conditions (weight tongs). [Figure 7] 7 is a schematic diagram illustrating a state in which a pin screw and a box screw are set. In FIG. 7, the illustration of threads and the like is omitted. [Figure 8] FIG. 10 is a schematic diagram showing an example of a method for applying paint to a pipe using a brush. DETAILED DESCRIPTION OF THE INVENTION

[0076] This disclosure relates to a solid lubricating coating and an agent for forming the same, which is formed on one or both sides of a lubrication surface, for example, when two opposing objects made of the same metal are required to slide against each other with high lubrication. This disclosure is particularly directed to a solid lubricating coating and an agent for forming the same in the lubrication of thread profiles, and further to the lubrication of oil country tubular goods threads.

[0077] The present disclosure also aims to provide corrosion protection through the lubricating film, and to ensure sufficient lubrication of the threaded portion even under the make-up and make-back conditions in actual oil and natural gas wells. This disclosure uses a solid lubricant component primarily composed of metal soap, with a water-soluble or water-dispersible polymer as the binder resin. Furthermore, when applying the agent and forming it into a solid lubricant coating, instant drying is not expected. However, the objective is to achieve rapid drying, such as drying within about 30 minutes, even when the agent is left to dry in the air after application.

[0078] This disclosure covers the surface with a soft film to provide corrosion protection. This disclosure also aims to achieve lubrication by using this soft film as a film that simultaneously functions as a lubricant. This disclosure also addresses chemicals for creating these films. This disclosure focuses on environmental resistance and compliance with international agreements regarding chemicals, and was designed to be easy to use, including quick drying. The chemicals disclosed herein are also intended for use in the event of well trouble or workover. The chemicals disclosed herein are also intended to be used when full-length pins are removed one by one or in groups of two or three, collected near the well, lined up, and cleaned, and then used as a protective coating to form on the thread surface to prevent rust. Removing full-length pins one by one is intended for onshore wells, while removing them in groups of two or three is intended for offshore wells.

[0079] Next, an embodiment of the present invention will be described. In this embodiment, an oil well tubular good is assumed as the metal part having a surface to which lubrication performance is to be imparted, but the present invention may be applied to other metal parts.

[0080] (composition) <Drugs> The agent of this embodiment is an agent for imparting lubricity and corrosion resistance to the metal surface of metal parts such as oil country tubular goods. The agent is composed of a solid lubricant, a binder resin, and a solvent component, and may contain small amounts of additive components depending on the situation.

[0081] [Solvent component] The solvent component is primarily water. A lower alcohol with three or fewer carbon atoms is added to the water as an additive. The volume of the additive relative to the water is 0.5 to 45 parts by volume per 100 parts by volume of water. One of the characteristics of the composition of the solvent of the present disclosure is that 95% or more of the volume of the solvent is made up of the water and the lower alcohol, and the solvent is a component system mainly made up of water. The lower alcohol may be, for example, one or more lower alcohols selected from methanol, ethanol, isopropyl alcohol, normal propyl alcohol, and industrial ethanol.

[0082] The additive may further include at least one of aqueous ammonia and a primary amine. The content of at least one of aqueous ammonia and a primary amine is, for example, 2 parts or less per 100 parts by volume of water. The above-mentioned lower alcohol, aqueous ammonia, and primary amine are added to utilize their volatility to promote rapid drying of the coating. At the same time, the lower alcohol functions as follows in the solvent of the present disclosure, which is characterized by its water-solubility, i.e., a solvent mainly composed of water. That is, when dissolving a solid lubricant, the lower alcohol functions effectively when dissolving a water-repellent solid lubricant. Furthermore, the lower alcohol helps to dissolve and disperse the solid lubricant throughout the solvent, avoiding extreme association.

[0083] If the lower alcohol with three or fewer carbon atoms is added in a ratio of 0.5 or more per 100 parts by volume of water, the water-repellent solid lubricant will not be uniformly dispersed and will phase separate from the water. In many cases, the lower alcohol will remain on the water surface. On the other hand, lower alcohols have low flash points. Consider a scenario in which lower alcohols are used to lubricate oil well pipe threads and are applied at the wellhead, where open flames are strictly prohibited. In this case, there is a risk that lower alcohols could cause a fire and become a very dangerous agent. Therefore, the upper limit for the amount of lower alcohol added is set at 45 parts.

[0084] The solid lubricating coating formed by drying does not contain any solvent components, including lower alcohols. The solvent components only affect the drying time of the agent. Therefore, unless the environment is one where open flames are strictly prohibited, it is acceptable to use a large amount of lower alcohol to speed up drying. The preferred range for the addition of lower alcohol is 20 or less. This also correlates with the vaporization point, which will be described later, but a value of 20 or less makes it easier to achieve rapid drying. Furthermore, this range ensures that the vaporization point is 70°C or higher, or a level at which the coating is treated as non-flammable, further increasing the possibility of safe use in wellhead fire-free sites. Furthermore, in the worst case scenario, adding a large amount of lower alcohol in the hope of rapid drying can lead to the following problem: The coating dries too quickly, increasing the inhomogeneity of the solid lubricant coating, which can crack and deteriorate the film quality.

[0085] [Solid lubricant] The solid lubricant contains a soap component containing at least a metal soap selected from a metal soap and an alkali soap component. The metal soap component accounts for 95% or more of the total weight of the metal soap and alkali soap components. In other words, the main component of the solid lubricant is the metal soap. The weight of the metal soap should be 95% or more of the total weight of the metal soap and alkaline soap. If there is a large amount of alkaline soap, it may dissolve in the water-based solvent, causing the viscosity of the solvent to become too high, making it difficult to apply uniformly and slowing down the drying of the film. In other words, by reducing the alkaline soap content, the above concerns can be alleviated. However, if there is no alkaline soap, the lubrication improvement effect brought about by the alkaline soap cannot be expected, so it is preferable to design the ingredients to contain it.

[0086] At the same time, the particle size of the metal soap must not exceed the thickness of the solid lubricating coating. The preferred range is an average particle size of 10 μm or less. If the particle size exceeds the thickness of the solid lubricating coating, the metal soap penetrates the solid lubricating coating and is present. In this case, tightening and loosening with a strong torque will cause greater damage to the solid lubricating coating than when the metal soap is dispersed within the solid lubricating coating. For example, significant peeling may occur, resulting in poor lubrication properties. Therefore, the particle size must be less than the thickness of the solid lubricating coating. On the other hand, assuming a thin film thickness necessary for the solid lubricating coating to achieve lubrication and rust prevention, a film thickness of at least 10 μm is required. Therefore, a particle size of 10 μm or less is preferred.

[0087] The metal soap and alkaline soap components constituting the solid lubricant contain one or more types of soaps that are compounds consisting of a fatty acid selected from Group A below and a metal element selected from Group B below. Group A: stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid B group: Na, K, Mg, Ca, Zn

[0088] [Binder resin] The binder resin is a polymer or copolymer made of a water-soluble or water-dispersible polymer, and contains a polymer having an acrylate or methacrylate structure in an amount of 90% or more by weight of the total weight of the binder resin. The water-soluble or water-dispersible polymer constituting the binder resin is, for example, a polymer composed of one or more monomers selected from the following (1) to (4), or a copolymer composed of two or more monomers.

[0089] (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Monomers containing acrylates, methacrylates, and their respective derivatives, as well as monomers containing alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and their respective derivatives. (3) Monomer grafted onto (1) and (2) above (4) Monomers of either or both of vinyl compounds and urethane compounds

[0090] In this specification, the phrase "comprised of a water-soluble or water-dispersible polymer, and containing a polymer having an acrylate or methacrylate structure in an amount of 90% or more of the total weight of the binder resin" is interpreted as follows: In other words, in the case of a copolymer, if the copolymer structure contains even a portion of an acrylate or methacrylate structure, the binder resin of the copolymer will be treated as a "polymer having an acrylate or methacrylate structure" regardless of the weight of the incorporated structure other than the acrylate or methacrylate structure. The polymers that are acceptable for inclusion if their content is less than 10% refer to those that do not form copolymers with the polymers having acrylate or methacrylate structures that are the subject of this application. In other words, structures that contain acryloyl groups, vinyl groups, etc. in the monomers are excluded.

[0091] Furthermore, since the drug of the present disclosure is dissolved in an aqueous solvent, the polymer that can be mixed must be water-soluble in addition to the above information. Examples of water-soluble polymers include polyamide-imide resin, phenolic resin, and urea resin (urea formaldehyde). For example, when the volume of the solvent is converted into weight assuming that the specific gravity of the solvent is 1, the weight of the solvent is preferably 0.7 to 100 times the total weight of the solid lubricant and the binder resin. The weight of the solid lubricant is preferably 0.1 to 1.0 times the weight of the binder resin. By adjusting the above components, it is preferable to make the flash point of the agent higher than 60° C. or to make it flame-retardant (non-flammable). It is also preferable to adjust the viscosity of the drug to 1000 mPa·sec or less by adjusting the above components.

[0092] The appropriate and preferred ranges of these parameters can be defined as follows. First, the lower limit of the solvent weight is 0.7 or more because it is specified as the amount of solvent required to dissolve the solid lubricant. In fact, metal soap, the main component of solid lubricants, was soluble up to 0.7, as shown in the examples below. Furthermore, 0.5 would result in the lubricant components being insufficiently dissolved, so 0.7 was set as the lower limit. The lubricant components to be incorporated include metal soap components, alkali soap components, and others. While an upper limit of 100 times or less is expected, 10 times or less is preferable. A high solvent weight ratio means a high concentration of chemicals and a thin film. Film components include binder resin components, solid lubricant components, and others. If multiple coats, such as repeated application and drying, are desired, a 100-fold upper limit is not particularly problematic. On the other hand, if the effort of multiple coats and drying is not a problem, a 100-fold upper limit is acceptable. At the same time, a thin chemical composition increases the risk of uneven film quality. This reduces the number of times you can tighten and loosen the bolt, but it may still be usable. Hereinafter, the "number of tightening / loosening operations" will also be referred to as the "number of M / B operations."

[0093] The preferred range is 10 times or less. A ratio of 10 times or less makes it easier to form the required film thickness using any conceivable coating method, for example, one to three coats, with a good M / B count and no particular deterioration. In the examples described below, it has been confirmed that a solid lubricating coating can be formed without any problems and the required lubrication properties can be achieved up to a weight ratio of 7.6 or less. Therefore, a ratio of 7.6 or less can be said to be an even more preferred range. Regarding rust prevention, a lower solvent weight is also preferable, as will be described later. In the present application, the solvent is primarily water. Therefore, to prevent rust in insufficiently dried areas, a ratio of 2 times or less is even more desirable.

[0094] Next, the ratio of the weight of the solid lubricant to the weight of the binder resin should preferably be 0.1 times or more and 1.0 times or less. If the amount of solid lubricant is too small relative to the binder resin, the total amount of solid lubricant, which is mainly responsible for lubrication, is small, and lubrication tends to deteriorate. Conversely, if the amount is too large, more than necessary may be contained, causing interference between the solid lubricants, resulting in saturation or deterioration of the improvement in lubrication properties. In the examples shown below, the actual degradation of properties to a passing level at the lower limit of the M / B number range was 0.08 at the lower limit and 5.0 at the upper limit within the experimental range.

[0095] The preferred flash point range is 60°C or higher, and even better, it should be classified as non-flammable. However, in oil and gas wells, if there are locations or areas where temperatures below 60°C are possible, the agents and films used to create the solid lubricant coatings of this application can be used. These parameters are determined purely based on the safety of workers and the well site. They are not factors that affect lubrication, which is evaluated by the number of M / Bs. With the exception of alternative fluorocarbons, a low flash point often indicates high volatility, which leads to the agent drying out quickly and forming a film quickly. Considering the usage environment in wells, the flash point should be set to 60°C or higher, and even higher temperatures or a non-flammable design are preferable.

[0096] The viscosity of a chemical agent is defined as the result of mixing it with solvents, solid lubricants, binder resins, and other additives. Viscosity varies depending on the concentration of the mixture. In this application, a viscosity of 1000 mPa·sec or less is preferred to prevent uneven application of the agent and uneven film thickness. This is because high viscosity increases the tendency for uneven film thickness to occur. In the examples below, no particular deterioration was observed at 740 mPa·sec or less, so this is considered a more preferable range. In addition, by adjusting the above ingredients, the agent can be applied to the metal surface at a rate of 0.1 g / mm 2Consider the case where the coating is applied as follows: In this case, it is preferable to adjust the coating to have quick drying properties that allow it to dry within 30 minutes when left to dry in a windless atmospheric environment at room temperature. Alternatively, by adjusting the above ingredients, the agent can be applied to the metal surface at a rate of 0.1 g / mm 2 Consider the case where the coating is applied as follows. In this case, it is preferable to adjust the coating to have quick drying properties, so that it can dry within 5 minutes when dried in an atmospheric environment at room temperature with air blown at a speed of 1 m / sec or more. The term "room temperature" refers to a temperature range of 15 to 30°C.

[0097] Application amount: 0.1g / mm 2 "Below" refers to a typical coating amount achieved by a spin coating method using a 50mm bristle width JIS No. 20 brush, with a single stroke in one direction. This defines the drying time. It is preferable to achieve a drying time of 30 minutes or less when left to dry, and 5 minutes or less when dried with a blast of 1m / sec or more. This is achieved using multiple parameters specified in this application. The volatility of at least one of lower alcohol and aqueous ammonia is utilized by incorporating metallic soap, a solid lubricant, in a dispersed form with an appropriate size, increasing the volatility surface area, thereby enhancing drying.

[0098] <Drug manufacturing method> The agent is preferably prepared by dispersing and clouding the metal soap in a lower alcohol, and then adding the resulting mixture to the water solvent.

[0099] <How to apply the medication> It is preferable to shake and agitate the drug container before applying it. Furthermore, when applying the agent of this embodiment to the surface of a tubular part, it is preferable to apply the agent in the circumferential direction while rotating the tubular part about its axis.

[0100] <Oil country tubular goods and oil country tubular goods threaded joints> The oil country tubular good is, as shown in FIG. 1, a box 2 having a female thread 2a or a pin 1 having a male thread 1a. As shown in Figure 1, an oil country pipe threaded joint consists of a box 2, such as a coupling, having a female thread 2a, and a pin 1 having a male thread 1a. A lubricating coating comprising the solid lubricating coating of the present disclosure is formed on the contact surface (fastening surface 10) of the threaded portion of at least one of the box 2 and pin 1.

[0101] A lubricating coating having a solid lubricating coating is formed on the thread portion of the oil country tubular good of this embodiment. The solid lubricating coating has a binder resin and a solid lubricant dispersed in the binder resin. The solid lubricant contains a soap component containing at least a metal soap out of a metal soap and an alkaline soap component, and the metal soap component accounts for 95% or more of the total weight of the metal soap and alkaline soap components. The metal soap and alkaline soap components constituting the solid lubricant include, for example, one or more soaps that are compounds consisting of a fatty acid selected from Group A below and a metal element selected from Group B below. Group A: stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid B group: Na, K, Mg, Ca, Zn

[0102] The weight of the metal soap is, for example, 95% or more of the total weight of the metal soap and the alkali soap. The particle size of the metal soap is preferably 10 μm or less. The binder resin is made of a water-soluble or water-dispersible polymer, and the polymer is a polymer or copolymer containing 90% or more of monomers belonging to the acrylate or methacrylate group. The water-soluble or water-dispersible polymer constituting the binder resin is, for example, a polymer composed of one or more monomers selected from the following (1) to (4). The copolymer is a copolymer composed of two or more of these monomers.

[0103] (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Monomers containing acrylates, methacrylates, and their respective derivatives, as well as monomers containing alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and their respective derivatives. (3) Monomer grafted onto (1) and (2) above (4) Monomers of either or both of vinyl compounds and urethane compounds

[0104] The phrase "comprised of a water-soluble or water-dispersible polymer, containing a polymer having an acrylate or methacrylate structure in an amount of 90% or more of the total weight of the binder resin" is interpreted as follows: In other words, in the case of a copolymer, if the copolymer structure contains even a portion of an acrylate or methacrylate structure, the binder resin of the copolymer is treated as a "polymer having an acrylate or methacrylate structure" regardless of the weight of the incorporated components other than the acrylate or methacrylate structure. It does not simply mean the weight of "acrylate or methacrylate."

[0105] The solid lubricating coating has a thickness of, for example, 1 μm or more and 100 μm or less, and is soft, with a pencil hardness of H or less. A base film (not shown) may be provided below the solid lubricating coating. At least one of the oil country tubular goods of the box and the pin is made of an oil country tubular goods on which the lubricating coating of the present disclosure is formed. When one of the oil country tubular goods of the box and the pin is an oil country tubular goods on which the lubricating coating of the present disclosure is formed, it is preferable that a coating having a harder hardness than the solid lubricating coating is formed on the thread portion of the other oil country tubular goods.

[0106] The minimum film thickness of 1 μm or more is determined to comply with regulations requiring a film thickness sufficient for lubrication and large enough that the size of the metal soap particles does not penetrate the solid lubricant film. The maximum film thickness of 100 μm or less is determined by the clearance between the female and male threads (coupling / pin) of OCTG threads. The solid lubricant film inevitably undergoes some wear during tightening and loosening. Furthermore, the worn-off solid lubricant film material either moves in tandem with the powder material during tightening and loosening, reforms and reattaches, or fails to do so and becomes lodged in the thread gap, increasing the risk of seizure. Depending on the type of thread, the thread gap (between the pin crest and the coupling valley) is approximately 100 μm wide. Meanwhile, the thread gap (between the pin valley and the coupling crest) is tightly fitted. If the solid lubricant film exceeds 100 μm, the solid lubricant film will inevitably be worn off to a certain extent when tightening and loosening, and it is estimated that the amount will exceed the amount that can be absorbed by the above-mentioned gap, and in fact, seizure will occur frequently. Therefore, the upper limit is set to 100 μm or less as the preferred range. If it exceeds that, it is difficult to say that it is always NG, but the number of M / B times will not meet the specified number, and seizure will become more likely to occur.

[0107] As described above, the agent of the present disclosure has a binder resin component primarily composed of a water-soluble or water-dispersible polymer. Furthermore, a metal soap is used as the main component of the solid lubricant, to which trace amounts of alkaline soap and other additives that function as solid lubricants are added. Furthermore, the agent of the present disclosure is composed of a component system that allows the addition of a small amount of organic solvent to a solvent primarily composed of water. This chemical composition allows for rapid drying after application, and the solid lubricating coating formed using this coating provides lubrication and rust prevention that can withstand use in wells. This disclosure is intended for use in the lubrication of threaded joints in oil well pipes, which are used in the most severe environments.

[0108] The details of the provisions for each element are explained below. In this disclosure, the agent and the solid lubricating coating formed using this agent are expected to have fast drying properties, corrosion resistance, and lubricating properties. However, the parameters that realize each required characteristic are interrelated with the required characteristics and are realized within the upper and lower limit ranges specified in this disclosure. First, the target required characteristics will be described, and then the ranges and meanings of each parameter will be explained.

[0109] "Targeted early drying, corrosion resistance, and lubrication properties" In the present disclosure, the term "quick drying" refers to the ability to dry within 5 minutes, preferably within 1 minute, without heating and by blowing air, or the ability to dry within 30 minutes, preferably within 15 minutes, and more preferably within 5 minutes, when left outdoors or indoors at room temperature. The term "dry" used here refers to a state that is beyond dry to the touch, and is either semi-hardened or hardened and dry. The paint terms "dry to the touch" and "semi-hard" are defined in accordance with JIS K5500-2000.

[0110] However, when applied to oil well pipe threads, this disclosure aims to develop a coating agent with low viscosity and good fluidity. Therefore, it is inevitable that the coating agent will collect at the 6 o'clock position, i.e., the lowest position, and the liquid may pool or drip there. Therefore, in the discussion of the above-mentioned rapid drying, we will focus on the dryness of the screw positions on the upper side of a watch, from 8 o'clock to 4 o'clock. The areas between 4 o'clock and 8 o'clock, or more precisely, the 5 o'clock to 7 o'clock positions where the coating agent pools or drips and remains undried, are excluded from the rapid drying analysis. The reason for excluding this area is as follows: Although the coating agent may pool and remain semi-wet, the lowest layer of the coating liquid applied to those areas constitutes a solid lubricating coating, and this does not affect the integrity of the film in terms of corrosion prevention. In other words, there are only insufficiently dried areas between the dried lowest layer of film from the pipe surface and the outermost layer of film in contact with the atmosphere, but in terms of rust prevention, a solid lubricating film formed by drying at the lowest layer is achieved.

[0111] The corrosion resistance in this disclosure does not only refer to the corrosion resistance of surfaces that have been coated with a chemical and allowed to evaporate. The corrosion resistance in this disclosure assumes the most severe conditions, that is, a tubular structure with a thread, such as an oil country pipe thread. Furthermore, this disclosure targets corrosion resistance after a protective cover, such as a protector, has been tightened and tightened, i.e., installed once and then removed again, with the protector removed. This assumes slightly more severe conditions than the actual required characteristics. In actual oil country pipe threads, after a solid lubricating coating has formed, when a protector is attached, it is possible to imagine a situation in which the solid lubricating coating comes into partial contact with the protector and is damaged, because the protector is attached in that state and the thread is left standing indoors or outdoors.

[0112] In this disclosure, the lubrication characteristics are ensured by evaluation results in an actual well or a simulated well, or by a tightening test using a power tong that can approximate the same. This disclosure does not evaluate the lubricity of a solid lubricating coating simply by a conventional tightening / untightening test using a short pin. The inventors have found that a solid lubricating coating cannot be properly evaluated using a conventional short pin. Lubrication using lubricating compounds has traditionally been, and still is, the mainstream method for lubricating oil well pipe threaded joints. Because lubricating compounds are viscous liquids, they move in conjunction with tightening and loosening, improving lubrication. Therefore, there is little difference between lubrication evaluations in a laboratory using a short pin and evaluations in an actual well. However, with lubrication using a solid lubricating coating as disclosed herein, the solid lubricating coating may inevitably be scraped off, and the resulting debris or powder may not be able to move in conjunction with tightening and loosening, as with a compound. Regarding this issue, as will be discussed in more detail later, we devise a laboratory evaluation method under conditions similar to those of an actual well, and use the lubrication behavior evaluated in this devised test to determine the acceptability of the solid lubricating coating.

[0113] "Water-soluble or water-dispersible polymers" In the present disclosure, a water-soluble or water-dispersible polymer is used as the binder resin. In this disclosure, we are considering polymers that become films after the water evaporates, i.e., after volatilization or evaporation, and therefore the term "polymer" in this disclosure refers to synthetic polymers in the narrow sense. The polymers in this disclosure exclude well-known natural polymers such as pectin, agar, starch-based materials, cellulose-based materials, and natural gums (alginate-based) materials. Furthermore, the polymers in this disclosure also exclude those that remain semi-dry and moist even after drying, i.e., after the water has evaporated. If a polymer does not dry completely, there is a concern that the water may cause corrosion when applied to carbon steel. Specifically, the water-soluble or water-dispersible polymer in this disclosure includes both those composed of a single polymer and copolymers composed of two or more monomers. The individual monomers correspond to the following monomers (1) to (4):

[0114] (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Furthermore, in addition to these acrylates, methacrylates, and their respective derivatives, monomers containing alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and their respective derivatives are also included because they are water-based. (3) Monomer grafted onto (1) and (2) above (4) Monomers of either vinyl compounds or urethane compounds, or both

[0115] The present disclosure includes at least one polymer or copolymer of two or more monomers defined in (1) to (4), or a polymer composed of either a single monomer of (1) to (3) or a copolymer of (1) to (3), or both of which are copolymerized with (4) or other compounds. The other compounds refer to monomers such as maleic acid, sulfonic acid, styrene, carboxylic acid, and salts thereof.

[0116] The phrase "comprised of a water-soluble or water-dispersible polymer, containing a polymer having an acrylate or methacrylate structure at 90% or more of the total weight of the binder resin" is interpreted as follows: In the case of a copolymer, if even a portion of the copolymer structure contains an acrylate or methacrylate structure, the binder resin of the copolymer is treated as a "polymer having an acrylate or methacrylate structure," regardless of the weight of the portion other than the incorporated acrylate or methacrylate structure. This does not simply mean the weight of "acrylate or methacrylate." The term "water-based polymer" as used here refers to a polymer that has hydrophilic properties due to the inclusion of polar or charged functional groups in the polymer structure. For example, it refers to a polymer that contains a carboxyl group, an amine functional group, a sulfonic acid group, or the like in the main chain or side chain.

[0117] The binder resin of the present disclosure is dissolved in a solvent whose main component is water, and when the agent is applied, the water is driven off, that is, evaporated and volatilized, forming a film. Furthermore, since this disclosure is based on the basic premise of being environmentally friendly, the disclosed agents are designed without using materials containing heavy metals such as lead, which have recently become a problem, or alkyl groups containing F (fluorine), a group known as PFAS. The requirements for realizing quick drying of the film after application of the agent directly and indirectly affect the film properties of the agent. Next, the items related to quick drying will be described in detail.

[0118] It is desirable that the final film be a polymer or copolymer containing 90% or more of acrylate or methacrylate monomers. Note that when copolymerization is performed, if acrylate or methacrylate is included and other monomers are copolymerized, it is considered to be an acrylate or methacrylate polymer and meets the above requirement of 90% or more. The reason we set the limit at 90% or more is that most of the material is made up of acrylate and methacrylate polymers, and it is acceptable to have up to 10% of other polymers. In reality, as a copolymer, we assume that the acrylate and methacrylate polymers are close to 100%.

[0119] "Why quick drying is necessary and what the target value is." The reason that rapid drying is necessary is simply because the agent of the present disclosure and the solid lubricating coating formed using it are used to form a film at the manufacturing site, and there is a reality that they are also required to be used at the site of use. In particular, when considering application to oil well pipe threaded joints, the following chemicals are also envisioned. Specifically, the chemicals are envisioned for use when temporarily pulling up oil well pipe for tubing due to a problem at the wellhead, or when seizing occurs and the oil well pipe needs to be removed and sent to a workshop. In this case, the work must be completed within the category of a clean, green solid lubricant coating. After the oil well pipe is pulled up from the well, it is washed with water or the like, and a solid lubricant anti-corrosion film can be formed using the chemicals disclosed herein to prevent rust on the threads. Naturally, such demand exists when used at the wellhead.

[0120] In this case, if you use a conventional wet compound, in most cases you will apply a preservative compound. For example, KENDEX TM Apply an oil-based viscous liquid such as OCTG ORANGE CORROSION INHIBITOR & STORAGE COMPOUND. Also, if storage compounds are not available, lubricating compounds containing heavy metals such as Pb and Zn will be applied to prevent rust. In this case, the compound will no longer be green. In other words, a product containing harmful heavy metals will be used. In contrast, the present disclosure is intended to be applied in a wellhead environment, where the agent forms a solid lubricating coating. In other words, the present disclosure requires that the agent dry as quickly as possible to form a solid lubricating coating, in an environment where open flames are strictly prohibited and without the use of heaters or other devices that could cause a fire.

[0121] From another perspective, when cutting threads locally, there is a need to deal with cases where there are deficiencies in the production system of individual workshops. Thread cutting workshops have sufficient equipment for machining. With conventional compound methods, surface treatment of box screws is often outsourced and rarely done in-house. Surface treatments include manganese phosphate treatment and copper plating. At the same time, pin screws are not required to be coated with a viscous liquid storage compound and left to dry. For this reason, pin screws are usually shipped with a protector applied immediately after application, without undergoing a drying process. If the chemical agent of the present disclosure is used at this site, it is deemed difficult to rely on heat treatment equipment such as a blower or hot air dryer. Therefore, it was determined that the chemical agent of the present disclosure must be able to dry by leaving it indoors or outdoors for 30 minutes or less, preferably 15 minutes, and even more preferably 5 minutes or less.

[0122] The 30-minute period is assumed to be the time required for one worker to lay out and line up approximately 30 pin screws or box screws, paint one end of each OCTG from end to end, then return to the original position and paint the other end from end to end, repeating the process. The 30-minute period is also assumed to be the time required for the OCTG to be nearly dry by the time the worker returns. It is also set as the time required for the worker to prepare the protectors and tighten them one by one without waiting. A drying time of 15 minutes would be no problem even when processing a smaller number of OCTG. Drying in 5 minutes or less is the ideal target.

[0123] However, factories that manufacture products with lubricating coatings can expect to have ventilation equipment and other facilities. Therefore, rather than simply leaving the material to dry in the atmosphere, drying can be accelerated by passing it through a ventilation system such as a jet fan, a heater that can emit hot air, or a heat treatment furnace. In such cases, it is preferable to dry it within 5 minutes, preferably within 3 minutes, and even more preferably within 1 minute. It is preferable to keep the drying time within this range so as not to impede line speed or handling at the manufacturing site where products with solid lubricating coatings that have excellent lubrication and corrosion resistance are manufactured, or to keep any impediments to a low level. When talking about the airflow rate of a fan or blower, a typical electrically operated fan has an airflow rate of 2 to 4 m / s. However, since this disclosure assumes that drying can be performed using a weak handheld fan, the drying time will be evaluated assuming an airflow rate of 1 m / s.

[0124] "How to apply the drug" The basic composition of the agent of the present disclosure is a solvent (water + trace amounts of lower alcohol, ammonia, and primary amine), a binder resin (mainly water-based polymer), and a solid lubricant (metal soap + trace amounts of alkaline soap). The viscosity of the agent is also an important parameter. As one element for realizing rapid drying, it is preferable to design the liquid so that the viscosity of the agent is on the low side. In this case, if it is applied to an inclined surface, it should tend to flow rather than remain there. In other words, it is preferable to adjust the viscosity of the agent so that it flows when applied.

[0125] For example, a viscosity of 1000 mPa·sec or less is preferable. This level is the level at which, when applied to an obliquely placed member or tubular member, the liquid feels like it flows along the slope. Note that the viscosity in this disclosure refers to the viscosity when the drug is opened or at the stage at which application begins. This viscosity specification can prevent the formation of an inadvertent thick film when applying the drug. There is no set lower limit for viscosity, but it should be, for example, 40 mPa·sec or more. When a water-soluble or water-dispersible polymer material is added and mixed with a water-soluble solvent, the viscosity tends to increase, rather than reaching the viscosity of water, which is 1 mPa·sec. For this reason, the minimum viscosity is approximately 40 mPa·sec.

[0126] By reducing the viscosity of the agent to 1000 mPa·sec or less, it becomes difficult to apply multiple coats or build-up paint, but the advantage is that the paint film can be made uniform and thin. Viscosity can be adjusted by selecting the monomers that make up the water-based polymer, adjusting the concentration of the metal soap and alkaline soap, and adjusting the blending ratio including the solvent. On the other hand, because the viscosity of the agent is less than 1000 mPa·sec, it has low viscosity and flows easily. As a result, the agent in the wet areas tends to drip and accumulate at the 6 o'clock position on a clock. This causes an unintentional thick film in that area, so even if the base has dried and formed a film, the accumulated area may not dry within the drying time mentioned above.

[0127] For this reason, the target drying time mentioned above, when lubricating a tubular structure, is measured at the 12 o'clock position on a clock, or more broadly, the upper half of the lubricant from 9 o'clock to 3 o'clock. While some liquid does accumulate at the 6 o'clock position, it is simply the wet lubricant accumulating on top of the already dry portion. Therefore, the lower portion is dry at the initial stage of application. Any method of application is acceptable, including brushing, spraying, dipping, hand application, and machine application. Taking advantage of the tendency for the paint to drip, the object being coated can be turned downwards or tilted at an angle after application so that the paint runs down. For tubular metal parts, it is better to paint with a brush or spray while rotating the metal part rather than leaving it to stand. This enhances drying, and the remaining amount of paint that has not formed a film is re-applied evenly to the metal surface as it rotates, helping to create a uniform film. It also prevents the paint from accumulating in one place.

[0128] "Ingenuity to achieve quick drying" In the present disclosure, in order to realize the rapid drying property of a water-soluble or water-dispersible polymer, essential and preferred configurations consisting of the following four configurations have been devised and utilized.

[0129] <Required configuration> One of the essential components is a lower alcohol. In other words, lower alcohols are volatile organic solvents whose concentration is adjusted to have a flash point of 60°C or higher, so that they can be used in environments where open flames are strictly prohibited, and they are used to promote rapid drying. The flash point of the agent should preferably be adjusted to 150°C or higher, and even more preferably 250°C or higher. Furthermore, the use of thinner-based VOCs should be avoided. This is to ensure worker safety and health, and to allow work to be carried out without the need for exhaust equipment such as drafts.

[0130] Another component of choice is aqueous ammonia. Depending on the situation, the volatility of ammonia water can also be utilized to control these concentrations within an appropriate range so that they can be used without a draft facility. One of the components is the concentration and particle size of the metal soap. Rapid drying is achieved by controlling the concentration and particle size of the metal soap contained within an appropriate range. The particle size of the metal soap is 10 μm or less. By using a particle size of preferably 5 μm or less, and more preferably 1 μm or less, the surface area of ​​the metal soap is increased, thereby enhancing drying. At this time, it is necessary to devise a way to prevent the metal soaps from associating with each other and forming clumps, which would result in the apparent size of the soaps becoming larger than the individual soaps themselves. This can be achieved by first dissolving the metal soaps in the lower alcohol and then mixing them into a mixture of a water-based solvent and a water-based polymer.

[0131] Metal soap also functions as the main component of the lubricant, and the total weight of the solid lubricant, including the alkaline soap described below, should consist of metal soap at least. Regarding the overall mixing ratio, when the solvent has evaporated and a solid lubricant film has been formed, the total weight of the solid lubricant should be 0.05 to 1.0 per 100 weight parts of the binder resin. The total weight of the solid lubricant should consist of 95% or more metal soap.

[0132] In the present disclosure, alkaline soap may be used to support lubrication. However, adding soap that dissolves easily in water tends to cause the solvent water to become viscous and gelatinous. This has the adverse effect of increasing the viscosity of the agent and slowing film formation. If the agent gels too much, the water will not be able to be completely removed, making it impossible to achieve a dry solid lubricant coating. Therefore, it is necessary to specify an upper limit for the appropriate amount of alkaline soap at a trace level. This should be within the appropriate viscosity range described below. Furthermore, the main component of the solid lubricant should be 95% or more of the metal soap, meaning the upper limit for the alkaline soap component should be 5% or less.

[0133] The viscosity of the drug is adjusted to 1000 mPa·sec or less. This viscosity is necessary when compounded as a drug, including water-soluble or water-dispersible polymer materials, additives such as metal soaps, and the lower alcohols mentioned above. The aim is to achieve a low viscosity, thin liquid. There is no set lower limit for viscosity, but it will be approximately 40 mPa·sec or higher. When water-soluble or water-dispersible polymer materials are added and compounded with a water-soluble solvent, the viscosity will not be the same as that of water (1 mPa·sec), but will be high. This level is approximately 40 mPa·sec.

[0134] <Preferred configuration> When applying the agent to a tubular metal part that is a structure, it is preferable to apply the agent while rotating the tubular structure. It is also preferable to continue rotating the tubular structure after application. This is because the rotation prevents the agent that has not yet dried after application from accumulating at the 6 o'clock position, and it is expected to have the same effect as promoting drying by blowing air, etc. Furthermore, in the case of tubular metal parts (structures), the liquid inevitably accumulates at the 6 o'clock position, and only the outermost layer takes a long time to dry. It takes a long time for the entire surface, including the liquid, to dry completely. Therefore, when applying to the outside of the tube, it is preferable to take advantage of the dripping from the 6 o'clock position. Alternatively, whether applying to the outside or inside of the tube, it is preferable to tilt the tube at an angle to allow the liquid that tends to accumulate at the 6 o'clock position to drain out. Furthermore, rapid drying may be achieved by utilizing processes that enhance drying, such as air blower drying, hot air blower drying, infrared irradiation, ultraviolet irradiation, heat treatment, etc. In this case, a synergistic effect can be expected with the above-mentioned configuration.

[0135] "The use of lower alcohols, ammonia, and primary amines, and the flash point of the drug as a whole" In this disclosure, we take advantage of the volatility of lower alcohols and ammonia and select a finer metal soap as the main component of the solid lubricant. This increases the surface area, allowing for quicker drying and reducing the viscosity of the agent itself, making it more fluid. This prevents the formation of a thick film and promotes the volatilization and evaporation of water. The lower alcohol referred to here refers to one or a combination of two or more selected from the group consisting of methanol, ethanol, isopropyl alcohol, normal propyl alcohol, and industrial ethanol.

[0136] Among lower alcohols, those with four or more carbon atoms, i.e., butanol or higher, tend to be less soluble in water. For this reason, the present disclosure uses lower alcohols with three or fewer carbon atoms. However, these have low flash points at high concentrations and cannot be used in environments where open flames are strictly prohibited. Therefore, the agent is formulated so that the flash point of the final formulated agent is 60°C or higher, preferably 150°C or higher. More preferably, it is formulated to a level that can be classified as non-flammable. By containing at least 0.5% or more of lower alcohols, volatility can be utilized to achieve rapid drying. Most desirable is a state in which no flash point is established or measured, which is defined as non-flammable.

[0137] The lower alcohols are used to strengthen the drying process, and also to prevent the metal soap additive from clumping and from aggregating at the size it was at when it was added. If you simply dissolve metal soap in water, the water-repellent properties of the metal soap will prevent it from mixing with the water and cause the particles to clump together. Even if you try to mix metal soap particles below the specified particle size into a coating paint, if you mix the metal soap directly into water, it will not disperse sufficiently. As a result, even if a film is formed, it will be unevenly distributed, which is not good for lubrication or corrosion resistance.

[0138] In the present disclosure, a metal soap is first dissolved in a lower alcohol. Then, the resulting mixture of lower alcohol and metal soap is mixed with a dispersion of a water-soluble or water-dispersible polymer and water. In this process, the concentration of the lower alcohol and the content of the metal soap must be adjusted to fall within the ranges specified in the present disclosure. In order to enhance rapid drying, a lower alcohol may be used as the main component, and the volatility of ammonia or a primary amine may also be utilized. The ammonia referred to here is aqueous ammonia. It is a commercially available chemical, and is prepared at 28-30% ammonia. Incidentally, aqueous ammonia itself is non-flammable. There are also commercially available ammonia solutions at dilute levels such as 10% or 5%. However, in this disclosure, we will use concentrated aqueous ammonia (28-30%) as the basis for our discussion.

[0139] Aqueous ammonia is sometimes used as a chemical to prepare aqueous polymers in the neutral pH range, which is considered to be preferable, specifically, a pH of about 5 to 9. Aqueous ammonia may be used in conjunction with the volatilizing effect of lower alcohols. The use of highly volatile primary amines is also permitted as long as the pH does not exceed the above range. The primary amine may be added to shift the pH toward the alkaline side. The ammonia and primary amine added to shift the pH from neutral to alkaline are then used to utilize their combined volatility.

[0140] However, when it comes to primary amines, care must be taken when handling methylamine in particular. Aqueous ammonia can be handled as non-flammable. On the other hand, methylamine is highly flammable, so adding large amounts increases the risk of accidents. Therefore, while primary amines can be used in small amounts, they should be handled with care. In order to dry and strengthen the solvent by evaporation, the weight of lower alcohols, ammonia, and primary amines must be 30% or less of the total solvent. The upper limit is limited by factors such as flash point.

[0141] The chemicals disclosed herein do not contain water-insoluble alternative fluorocarbon solvents, halogenated solvents such as trichloroethylene and tetrachloroethylene, or thinners. These chemicals are not recommended for use due to their adverse effects on the global environment and health. Furthermore, thinners, a VOC, are often considered harmful to health and include toluene, xylene, benzene, mineral spirits, and ethers, as well as oils such as mineral oil.

[0142] The reason for setting the flash point of the agent disclosed herein to 60°C is as follows: The temperature that can be expected to occur at an actual wellhead when tightening and laying an oil well pipe threaded joint is thought to be below 60°C at most. Therefore, the first step is to ensure that the temperature does not fall below this temperature. This reduces the risk of ignition and fire caused by a volatile agent, essentially eliminating it. The reason for setting the flash point as 150°C and the more desirable flash point as 250°C is as follows: In other words, 250°C is the highest temperature at the wellhead, and 150°C is the highest temperature that can be expected to reach the wellhead after heat transfer, so these values ​​were set accordingly. To eliminate the risk, the flash point must be unmeasurable and the agent must be classified as non-flammable.

[0143] "Metal soap particle size and concentration, alkaline soap content" In this disclosure, metal soaps and alkaline soaps function as solid lubricants. Furthermore, to enhance rapid drying, the metallic soaps increase the surface area by reducing the particle size of the metallic soap, thereby accelerating drying. The alkaline soaps dissolve in the water-based solvent and are then incorporated into the film, or the soap precipitates on the surface or inside the film. However, because the alkaline soaps are not ultimately liquid, they are treated as solid lubricants. In the following description, the solid lubricant refers to a soap component containing metal soap and alkaline soap.

[0144] In this disclosure, the enhancement of rapid drying is achieved by simultaneously achieving multiple factors. The volatility of the aforementioned additives, consisting of the volatile lower alcohol group, ammonia, and primary amine, is utilized by adding appropriate amounts to the solvent. Based on promoting the evaporation of the aqueous solvent, the size of the metal soap is specified and dispersed uniformly without clumping. Furthermore, the viscosity of the agent is set to 1000 mPa·sec or less to prevent the agent from being applied too thickly. At the same time, the amounts of metal soap and alkaline soap added must be adjusted to simultaneously achieve lubricity and corrosion resistance.

[0145] The average particle size of the metal soap should be 10 μm or less, preferably 5 μm or less, and even more preferably 1 μm or less. This increases the surface area of ​​the metal soap, thereby enhancing drying. The smaller the particle size of the metal soap, the faster the chemical dries. However, it is important that the metal soap particles are dispersed, maintaining their particle size and preventing clumping. At the same time, to ensure the integrity of the solid lubricant film, the particle size of the metal soap must not exceed the film thickness of the solid lubricant film. If the film thickness is exceeded, the metal soap will appear to protrude from the film. When a strong torque is applied, damage to the film, such as peeling or scraping, will occur. On the other hand, since alkaline soap dissolves in water, there are no regulations regarding its size.

[0146] Metal soap is the main component of solid lubricants and is key to strengthening the dry state, while alkaline soap is formulated to play a supporting role in lubrication. In actual wells, when a full-size pin is set into a box screw, it is rare for the pin thread to be inserted straight into the box screw and then manually tightened, as is assumed under ideal conditions. In practice, the pin thread is inevitably set at a slight angle. Therefore, even when manually tightening the pin screw, only about half of the pin threads are exposed. This can lead to uneven contact between the threads during the initial tightening process, which can damage the surface of the solid lubricant coating. In this case, the alkaline soap is expected to provide lubrication support, sliding the box screw and pin screw from a fully engaged state to a stable position. The alkaline soap is expected to provide lubrication by sliding the screw into a stable position, preventing the spike-like torque seen in Figure 3 from building up before torque is applied.

[0147] Additionally, metal soaps are water-repellent. Therefore, even if the solid lubricant coating is slightly damaged, its water-repellent effect can be expected to effectively improve corrosion resistance. In other words, metal soaps ensure corrosion resistance. Solid lubricants are assumed to be 95% or more by weight of metal soap and alkaline soap. In essence, the mixing of about 5% of other solid lubricants is permitted, but the intention is that most of the solid lubricants be made up of materials broadly belonging to the soap category.

[0148] As mentioned above, the content of metal soap or alkaline soap is considered based on the balance of the total chemicals. In this case, when the volume of the solvent is converted to weight with a specific gravity of 1, it is formulated so that it accounts for 0.7 to 100 times the weight of all solid lubricant components that form the film. The weight of all solid lubricant components is the sum of the weights of the solid lubricant and the binder resin. In other words, a wide range of formulations is acceptable for water-based solvents, except for extremely concentrated or diluted solutions. If the ratio exceeds 100, there is too much water, making drying difficult. Furthermore, because there is a concern that water itself may cause rust, it is preferable that the ratio be no more than 10 times, and more preferably no more than 2 times.

[0149] The solvent evaporates during drying, so what remains as a film is the binder resin component and solid lubricant. The weight ratio of solid lubricant to binder resin is preferably 0.01 to 1, with the metal soap preferably accounting for 95% or more of the weight of the solid lubricant. The lower limit is 0.1 because, if the ratio is less than that, there is too little support for the solid lubricant, and the lubrication improvement effect cannot be expected. In this case, if a strong force is applied to the binder resin, the film is likely to peel off completely, which increases the risk of seizure. The upper limit is 1 because if there is too much metal soap relative to the solvent, the film itself will lose its integrity, and even a slight load will significantly increase the risk of the film cracking and being exposed to the environment. Furthermore, this concentration can be said to be the limit for maintaining the metal soap in a fine size without clumping.

[0150] "About types of metal soaps and alkaline soaps" In this disclosure, the metal soap and alkaline soap are assumed to be the following: That is, the metal soap and alkaline soap are composed of one or a combination of two or more soaps made from compounds of fatty acids of Group A and metal elements of Group B below. Group A (stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid) B group (Na, K, Mg, Ca, Zn)

[0151] In this disclosure, the metal soap is defined as being composed of one or more metal salts of group B, namely, magnesium salts, calcium salts, and zinc salts of fatty acids of group A. The metal salt of the alkali soap is composed of either or both of the sodium salts and potassium salts of group B. Other alkali metal salts are commercially available, but these were excluded because they are not used for purposes such as dissolving in water and using for cleaning.

[0152] "Amount of chemical to apply and drying time" As mentioned above, rapid drying enhancement is achieved by simultaneously achieving multiple factors. Specifically, the aforementioned volatile lower alcohols, ammonia, and primary amines are added to the solvent in appropriate amounts, while ensuring that the flash point is not too low. These volatilities are then utilized to promote the evaporation of the aqueous solvent, reducing the size of the metal soap particles and dispersing them uniformly without clumping. Furthermore, the viscosity of the agent is adjusted to 1000 mPa·sec or less to prevent the agent from being applied too thickly.

[0153] Furthermore, to ensure rapid drying, the coating amount was actually 0.1 g / mm, assuming the above conditions. 2For rapid drying, it is preferable to apply the coating evenly to the following conditions. Under these conditions, when left in the air at room temperature (15°C-30°C, for example 24°C), it can be expected to dry within 30 minutes. Furthermore, when drying with air blowing at a speed of 3 mm / sec or more, rapid drying is expected, with drying within 5 minutes at room temperature. The amount of coating is, for example, 0.2 to 0.05 g / mm 2 is the preferred range. If you apply it thicker than this, the drying time will tend to be slower and some of it will drip. In addition, there are cases where only the surface layer of that part does not dry. 2 Turning off the heat tends to speed up drying, but this can cause concerns about corrosion resistance.

[0154] "Film properties: film thickness, pencil hardness" In the present disclosure, when the agent has dried and become a solid lubricating coating, it is preferable that the film thickness be in the range of 1 μm to 100 μm and that the pencil hardness be soft, being H or less. Ideally, a uniform film thickness of approximately 10 μm to 50 μm is sufficient. However, when applying a coating agent with the above-mentioned viscosity, the low viscosity means that the paint that cannot form a film tends to drip and move, no matter how much drying is performed. In structures with threads, such as oil well pipe threads, the tendency for the coating agent to accumulate in the valleys of the threads, especially at the 6 o'clock position on a clock, cannot be denied. Furthermore, the surface tension of the coating agent tends to thin the corners of the thread structure. Therefore, to achieve both lubrication and corrosion resistance, the coating thickness is preferably within the above range. If the thinnest point is less than 1 μm, there is a high risk of seizure. Furthermore, if the coating thickness exceeds 100 μm, it tends to be scraped off during lubrication, and the resulting peeled pieces and powdery material can cause seizure. There is also a risk of the coating peeling off completely and seizing.

[0155] Here, the film thickness refers to the film thickness at the stage when the agent has dried and become a solid lubricating coating, as described above. The film thickness can be determined, for example, by cutting the thread longitudinally at four locations around the circumference (e.g., four locations spaced 90 degrees apart) and observing each cross section under a microscope. This observation identifies the film thickness at the thickest and thinnest parts of the coating. Then, it is confirmed that each film thickness is within the above-mentioned range. If the tendency of the film thickness distribution is known from past measurement results, the film thickness can be estimated as follows: That is, if the chemical application and drying method is the same, it is also possible to estimate the maximum and minimum film thickness values ​​for the entire threaded portion by measuring the film thickness at a predetermined specific location with an electromagnetic film thickness meter.

[0156] The hardness of the solid lubricating coating is preferably a pencil hardness of H or less. The solid lubricant coating of the present disclosure is intentionally made soft to achieve lubrication properties, assuming that it will wear away slightly when hit hard. Also, if the pencil hardness exceeds H and it is too hard, it may peel off completely, increasing the risk of seizure. The film hardness is measured by pencil hardness. The measurement method is specified in JIS K 5600-5-4 (1999). The JIS standard states that this standard is a translation of "ISO / DIS 15184, Paints and varnishes - Determination of film hardness by pencil test." The pencil hardness test method of the present disclosure is evaluated based on the JIS standard. In other words, the evaluation targets are 6B, B, HB, F, H, and 9H, and hardness of 9H or higher is evaluated as ≦6B and ≧9H, respectively.

[0157] "When oil country tubular goods that make up a threaded joint are coated on both sides, when they are coated on one side, and when they are coated on one side but there is a different type of solid lubricant coating on the opposing side." The present disclosure encompasses both cases in which the solid lubricating coating of the present disclosure, which is composed of the agent of the present disclosure, is applied to both sides of the surface to be lubricated, and cases in which it is applied to only one side and nothing is applied to the other side. When the solid lubricating coating of the present disclosure is formed on only one of the components, it is preferable that the pencil hardness of the solid lubricating coating of the present disclosure be softer than that of a different type of lubricating coating on the opposing surface. The solid lubricating coating of the present disclosure is designed to be a soft film. This is because the lubricating properties are achieved with the expectation that slight abrasion will occur during lubrication, and this effect cannot be achieved if the solid lubricating coating itself is hard.

[0158] "Method for evaluating the corrosion resistance of solid lubricant coatings" In this disclosure, corrosion resistance evaluation is performed on a structure with a thread structure, such as an oil well pipe thread, by tightening and loosening a protector used to protect the thread, and then removing the protector, and then spraying the solid lubricant coating with salt water. The evaluation was based on the criteria that the appearance of red rust all over the surface was deemed NG. In essence, corrosion resistance was evaluated by first inflicting possible damage on the film and then performing an evaluation with salt water spray. The salt spray conditions were in accordance with JIS K 5600-7-1, using 5% NaCl neutral salt spray conditions (35°C, humidity 98-99%, spray 1-2 mL / Hr / 80 cm). 2 , pH 6.5-7.2) and based on evaluation at 8 hours.

[0159] Here, the metal surfaces of metal parts covered by this disclosure include, for example, lathe-machined or machined surfaces, polished surfaces, etc. Note that for the corrosion resistance evaluation, areas with remaining mill scale were excluded. Depending on the roundness and eccentricity of the tubular structure, samples may have mill scale embedded in the thread structure. However, if mill scale is cleaned before forming a solid lubricating coating, water can penetrate into tiny defects, holes, and scratches in the mill scale. Furthermore, when a solid lubricating coating is formed on top of the mill scale, even if the solid lubricating coating is sound, rust spots may appear on the underlying steel. However, such rust spots are not rust on the solid lubricating coating and are therefore excluded from the evaluation.

[0160] "Lubrication evaluation method" The lubrication was evaluated under the most severe lubrication conditions among the environments in which the solid lubricant coating of the present disclosure is used, i.e., the tightening and loosening conditions of oil country pipe threads that are similar to those used in actual wells. However, evaluating the solid lubrication behavior of oil country pipe threads in actual wells or simulated wells is not realistic from the standpoint of cost and the time required to arrange experiments. Therefore, in the present disclosure, evaluation was performed using devices such as those shown in FIGS.

[0161] This solution involves attaching weights (1 to 3 full-length pins) to the upper end of the short pin to allow for load application. The screw is initially set in a state where the pin threads are exposed approximately halfway relative to the box screw, and then tightened with tongs. A weight is applied during tightening, but not during tightening, destabilizing the pin threads and simulating tightening conditions in an actual well. This allows the upper and lower limits of each parameter for lubrication characteristics to be set to values ​​consistent with actual conditions. This evaluation method is also referred to as "weight-tongs evaluation." The inventors have confirmed that this weight-tongs evaluation can adequately reproduce the evaluation of tightening and tightening in an actual well. The reason for using weight tongs for evaluation is as follows: if evaluation using horizontal power tongs with a short pin about 1 meter long or vertical power tongs with a simple short pin is relied upon, the "solid lubricant coating evaluation" that is the subject of this disclosure may be mistakenly evaluated as superior. In other words, the upper and lower limits of the parameters that define the invention would become meaningless.

[0162] Solid lubricant coatings can inevitably be damaged when tightening and loosening, and flaked or powdery debris does not always move in tandem with tightening and loosening. If they do not move in tandem, they can get stuck in the thread gap and cause seizure. However, evaluations using conventional short pins are less susceptible to damage, so there is a concern that something that is actually bad may be evaluated as good. On the other hand, with lubrication using conventional compounds, the compound is a viscous liquid, so it moves in tandem with tightening and loosening. For this reason, there is no significant discrepancy between the evaluation results using short pins and the evaluation in an actual well.

[0163] In past patent documents, there are occasional reports that lubrication tests based on solid lubricant coatings have shown that they can be tightened and untightened up to 15-20 times, even for large diameter sizes such as 9-5 / 8" and 13-3 / 8". However, with solid lubricant coatings, which have inferior lubrication properties compared to grease-like compounds, such a number of times is virtually impossible. These results are likely based on evaluations using horizontal or vertical power tongs using short pins, which are commonly seen in laboratories. If this is the case, then the value of the characteristic evaluation is possible, but in actual cases of tightening and untightening large-diameter OCTG using solid lubricant coatings in wells, it is rare to see a tightening and untightening cycle of 15 to 20 times. Based on the above considerations, the evaluation method in the examples described below was a weight-tongs test using the equipment shown in Figures 5 and 6. The conditions simulated are those of the tightening and untightening tests that occur in actual wells and simulated wells, and the lubricity of the solid lubricating coating is evaluated by simulating the tightening conditions seen in Figures 3 and 4(a).

[0164] What actually happens in actual wells is that because full-length pins (approximately 12 meters long) are used, it is impossible to set the pin perfectly straight during initial setting, and the pin is almost always inserted at an angle. Even when using a stubbing guide or compensator to set the full-length pin threads perfectly straight, they are never set at an extremely slight angle. It is virtually impossible to tighten the pin threads until they are hidden by the box screw. When the pin screw is inserted into the box screw and further tightened by hand, the threads partially touch each other. This prevents further advancement when five or more threads of the pin screw, or about half of the total threads, are exposed. Therefore, when initially tightening with tongs, it takes several turns until the load is applied—for example, about 6.3 turns in Figure 3—before the pin thread and box screw begin to mesh in the correct position. Like many other threaded structures, OCTG threads have a tapered structure, which ultimately allows the threads to mesh in a stable position. To exaggerate, the circled area in Figure 7 is severely damaged. Cracks, peeling, and other damage to the membrane are inevitable at a microscopic level. Specifically, because the pin thread 1a is set at a slight angle, the following occurs in relation to the thread portion 2a of the box screw 2. The locations where the pin thread contacts tend to be severely damaged: the tip of the pin thread 1a, near the center of the threads of the box screw thread portion 2a, and near the center of the pin thread 1a and near the entrance of the thread portion 2a of the box screw. "Near the center of the thread" refers to the area where the pin screw contacts the box screw when inserted. "Near the entrance of the thread portion 2a of the box screw" refers to the area near the entrance of the box screw 2a when inserted.

[0165] In Figure 3, irregular spikes of torque are observed several revolutions before the stable position is reached, i.e., before a steady torque is generated. This is directly related to damage to the solid lubricant coating due to uneven contact between the pin thread and the box thread. This fact is essential for evaluating the lubrication of solid lubricant coatings. Uneven contact between the threads inevitably causes the solid lubricant coating to wear away. These flaked pieces and debris do not necessarily move in conjunction with the tightening and loosening of the threads. If these debris become lodged in the thread gap, it becomes a major cause of seizure. This is due to the combination of rattle caused by the initial setting position of the pin thread and the weight of the actual length pin. This results in uneven, unbalanced loads contacting the pin thread and the box thread, which inevitably causes the solid lubricant coating to peel off or break into powder. The impact of these debris lodging in the thread gap and seizure was evaluated using a laboratory simulation method.

[0166] Figure 5 is an overall conceptual diagram of the test method, and Figure 6 is an enlarged view of the part involving the plumb bob 3. In the plumb bob tong test, a vertical power tong 4 is used. Then, the short screw 1 and box screw 2 are tightened using the threads of the pin thread portion 1a and the box thread portion 2a. In order to simulate a situation where the threads do not mesh, the initial temporary tightening position is set so that half of the total number of threads of the pin thread portion 1a are exposed from the box screw 2. This is one of the causes of play. Tightening with the power tong 4 begins from this state. At this time, attach plumb bob 3 to the side opposite the tightening screw of pin 1. The weight of plumb bob 3 is calculated based on the actual pin's outer diameter and thickness, with the load equivalent to one to three actual pins. For a 9-5 / 8" 53.5#, one pin weighs approximately 1 ton (2,200 lbs), and three pins connected together weigh approximately 3 tons (6,600 lbs). The equivalent of one pin is intended for use in an onshore well, and the equivalent of three pins is intended for use in tightening an offshore well.

[0167] The weight 3 in Figure 5 has a spool 13 welded to the weight body 3A at an axially symmetrical position, as shown in Figure 6. The spool 13 is inserted from above the pin 1, attaching the weight to the top end of the pin 1. Through holes 1d and 13a are pre-drilled in the pin 1 and the spool 13. A piercing rod 12 is inserted and set into the through holes 1d and 13a to integrate the weight 3 and pin 1. A swivel-type hook 11 is welded to the center of the shaft at the top of the weight 3, and the weight is suspended from a ceiling-mounted suspension device 20 via a hanging chain 21. When tightening, the weight load is applied to the box screw, and the screw is tightened at 5 to 20 rpm until the torque is reached. The initial temporary tightening position and the high-speed tightening and loosening rotation serve as a simulation of play. Once the torque is reached, reduce the rotation speed to 0.5 to 2 rpm and tighten to the tightening position.

[0168] To simulate a tightening / retraction test in an actual well, the weight 3 may or may not be applied, especially during loosening. It is preferable not to apply the weight 3 during retraction. In the following example, the weight 3 is not applied during retraction. If retraction is performed with the weight applied, the weight acts as a "weight" or balancer when loosening from the tightened position, loosening the pin screw as if it were rising straight up. This prevents the pin from rattling, and damage to the solid lubricant coating is not caused during retraction. Even under conditions where the load is not set to zero, the load is lifted and the test is performed. Even under conditions where the load is not set to zero, loosening the load allows for testing under conditions where rattling is more severe and more likely to damage the solid lubricant coating. The rotational speed during backtightening is such that when the torque is high, loosening begins at a speed of 0.5 to 2 rpm, and when the torque reaches about 1 / 10 of the tightening torque value, loosening is increased to a high speed of 5 to 20 rpm. In this example, after backtightening is complete, the pin thread and box thread are separated from each other by backtightening, and the surfaces of each are air-blowed to remove any debris from the solid lubricant coating, the surfaces are checked, and then the tightening is continued again for evaluation.

[0169] Lubrication evaluation is judged using the following methods and criteria. According to ISO 13679, casing sizes are considered acceptable after three or more tightening / unfastening cycles, and tubing sizes are considered acceptable after ten or more tightening / unfastening cycles. However, when considering lubrication using a solid lubricant film, the number of M / B cycles tends to be lower than when using conventional lubrication with a grease-like compound. The reasons for this are as follows: With conventional methods using a grease-like compound, after each tightening / unfastening cycle, the grease-like compound on the surface is washed away with an organic solvent, the surface is inspected, and then a new grease-like compound is applied. This means that the main source of lubrication is resupplied. On the other hand, with lubrication using a solid lubricant film, the thread surface is cleaned with an air blower, but no lubricating components are added during the process. As a result, it cannot be denied that the number of tightening / unfastening cycles using a solid lubricant film tends to be lower.

[0170] Therefore, as the criteria for the number of tightening and loosening times in this disclosure, a casing size that was tightened and loosened three times or more was deemed to pass. A tubing size that was tightened and loosened five times or more was deemed to pass. Furthermore, a line was drawn between casing sizes of 7 inches or more and tubing sizes of less than 7 inches for judgment. In addition to the number of M / B times, once the casing is completely loosened after tightening and loosening, the pin is released to the top and the pin thread surface and box thread surface are observed after air blowing to directly visually confirm whether or not there is any seizure. Additionally, the torque turn chart was checked to see if there are any abnormalities.

[0171] The NG judgment was made as follows: If the screw did not loosen during the M / B number of tightening and loosening attempts, it was judged that seizure had occurred at that number of tightening and loosening attempts, and the number of tightening and loosening attempts was judged as the previous number of tightening and loosening attempts. For screws that were completely loosened and the surface could be observed, if slight seizure had occurred in the seal area, it was judged as NG on the spot. Then, the number of tightening and loosening attempts was judged to be the next number of tightening and loosening attempts, and the tightening test using weight tongs was completed on the spot. If there was very slight seizure in the threaded area, it was repaired and the test continued as is. The number of tightening and loosening attempts performed in this way was sorted into good and bad using the judgment criteria described above. [Example]

[0172] Hereinafter, examples according to the present disclosure will be described. (Example 1: How to mix metal soap and how to mix it evenly) In the study group of this Example 1, the conditions for the metal soap mixing method were selected based on how it was mixed into the liquid. The conditions for the metal soap mixing were investigated using the chemicals in the following mixing ratios. The solvent used was a mixture of water as the main component, industrial ethanol, and aqueous ammonia. The solid lubricant was a mixture of calcium stearate (metallic soap: particle size 8-10 μm or less) and sodium stearate (alkaline soap) in a weight ratio of 99:1. The binder resin used was a copolymer of vinyl acetate and methacrylic acid, with 10 parts by weight of methacrylic acid mixed with 100 parts by weight of vinyl acetate. The copolymer referred to here corresponds to 100% "polymer having an acrylate or methacrylate structure" as described in this disclosure.

[0173] The mixing ratio of each was such that the solvent (water) (measured by volume and converted to weight with a specific gravity of 1) was 3 times the total weight of the solid lubricant (metal soap + alkali soap) and binder resin. The mixing weight ratio of the solid lubricant was 0.1 times the weight of the binder resin. To carry out these blends, we prepared a mixture of water and monomers to create a copolymer of vinyl acetate and methacrylic acid. As shown below, we blended the metal soap with industrial ethanol, then added ammonia water to adjust the pH to 7-8. Finally, we blended sodium stearate and mixed it in. We considered ways to mix the metal soap into this basic chemical.

[0174] <Condition 1> Condition 1 is a case where calcium stearate was added directly to the base chemicals according to the above mixing ratio and stirred. Condition 1 is a case where no industrial ethanol was used. Under condition 1, the metal soaps were not mixed thoroughly, with some floating on the surface and clumping together. In other words, they were not mixed homogeneously. This result supports the conventional wisdom that metal soaps are insoluble in water.

[0175] <Condition 2> In condition 2, calcium stearate was added to the base chemicals according to the above mixing ratio and stirred. Then, industrial ethanol was added in a vol / vol ratio of 100% water to 20% industrial ethanol. In condition 2, the metal soaps did not mix well, and some of them floated to the surface and clumped together. In other words, they were not mixed well and homogeneously. Condition 2 shows that the metal soaps do not mix well even if ethanol is added later.

[0176] <Condition 3> Condition 3 is an example in which calcium stearate was stirred in a separate container with industrial ethanol in a ratio of 100 parts water to 20 parts industrial ethanol, i.e., until it was homogeneously mixed, and then added to the base chemical and stirred. Condition 3 can be considered an example of a nearly homogeneous mixture. Although calcium stearate is said to be insoluble in both water and alcohol, we have confirmed that in alcohol (ethanol), the particles of calcium stearate can be dispersed finely without forming lumps, as the particles associate with each other. Therefore, we have found that by first dissolving it in ethanol (alcohol), and then adding this state to the base agent and stirring it, it is possible to create a situation in which the metal soap is homogeneously dissolved.

[0177] <Condition 4> In condition 4, calcium stearate was thoroughly stirred in a separate container with industrial ethanol (1 part water to 1 part industrial ethanol) before being added to the base chemicals. In condition 4, 19 parts industrial ethanol was then added to the base chemicals and stirred. In condition 4, when the metallic soap calcium stearate was mixed with a small amount of ethanol to make it cloudy, the metallic soap did not mix well, and some of it floated to the surface and formed clumps. In other words, this is an example where it was mixed into the base chemical, but it was not mixed well and homogeneously.

[0178] <Condition 5> In condition 5, calcium stearate was thoroughly stirred in a separate container with 15 parts industrial ethanol to 100 parts water, and then added to the base chemicals. In condition 6, 5 parts industrial ethanol was then added to the base chemicals and stirred. In the system under condition 5, the metal soap calcium stearate was already homogeneously mixed with industrial ethanol at a ratio of 15:1. Therefore, even if more industrial ethanol was added, the mixture was almost homogeneously mixed.

[0179] The following was learned from these examples of conditions 1 to 5. First, prepare a suitable amount of lower alcohol, i.e., an amount that allows the metal soap to be mixed thoroughly, and then add the appropriate amount of metal soap to the base chemical and stir. In this case, the metal soap can be mixed into a solvent that is primarily water. Furthermore, we found that if the amount of metal soap is too large to be mixed uniformly with the volume of lower alcohol, adding additional industrial ethanol after adding it to the base chemical tends to prevent it from mixing.

[0180] In the following examples, the examples are further provided on the premise that the chemicals contain metal soaps uniformly mixed. (Example 2: Rapid drying property, coating amount, and drying method) In the study group of Example 2, the chemicals were applied to the structure of oil well pipe threads, and the quality was judged based on the drying state. The mixing ratio of alcohol to ammonia water, different types of alcohol, and sizes of metal soap were examined. The conditions of each of the following chemicals were systematically changed to investigate their rapid drying properties.

[0181] The solvent was composed of alcohol and ammonia water for 100 parts water, and the solid lubricant was composed of metal soap and alkaline soap. The binder resin was a copolymer made by mixing 100 parts by weight of acrylic acid with 6 parts by weight of polyvinyl alcohol as the monomer. Polyvinyl alcohol is, for example, poval, which is made by saponifying polyvinyl acetate polymerized with vinyl acetate monomer. The mixing ratios for each correspond to the contents of this study. For the solvent system, when the solvent (water) was taken as 100 (measured by volume and converted to weight with a specific gravity of 1), mixing conditions were prepared for industrial ethanol and ammonia water.

[0182] Additionally, we prepared samples in which the total weight of the solid lubricant (metal soap + alkali soap) and binder resin, the balance of the solvent blend, and the weight ratio of the metal soap and alkali soap in the solid lubricant coating were varied. Furthermore, we also prepared samples in which the size of the metal soap was varied. We then examined the drying conditions for each. The mixing method was to mix sodium stearate just before the last one and mix it in. Finally, ammonia water (approximately 28%) was mixed in at the end to adjust the pH to 6.5-8.5. The method used was the same as that identified in the study group in Example 1 above, that is, the method of mixing the metal soap with "lower alcohol (ethanol: Example 1)" in advance and then mixing it in. The industrial ethanol referred to here is high-purity ethanol. However, it refers to ethanol that contains methanol or isopropyl alcohol at a level that does not fall under the Liquor Tax Act.

[0183] The common test conditions were as follows: the oil well pipe screw material was carbon steel, L80 grade, size was 5.5" 23#, and the screw was JFEBEAR TM We prepared pin screws with short lengths of 700-1000mm and processed both ends. To apply the agent, we first dipped a regular paint brush (Japanese standard for brushes: No. 20, 50mm wide) into the agent. Then, we placed the short pin on two rollers that rotate at the same rate and applied the agent while rotating it at a speed of about 10-20 seconds per rotation (see Figure 8). The two rollers were two axially rotating rollers that came into contact with a 5.5" 23# pin thread at approximately the 5 o'clock and 7 o'clock positions. The brush 30 was placed in the longitudinal direction of the pipe 31, perpendicular to the rotation of the thread, and swept only once in one direction, so as not to coat the same part of the thread in the same position. The areas that were coated included the entire thread, the end face of the tip of the pin thread, about 10 mm inward, and up to about 30 to 50 mm of the non-threaded area at the end of the thread (runout). Both ends were evaluated as one set. Note that the brush would inevitably wrap around to paint about 10 mm inward. The non-threaded area of ​​about 30 to 50 mm would inevitably be coated because the brush would wrap around.

[0184] First, as an example of leaving to dry in the air, one side was painted and then left to dry. Then, as an example of leaving to dry in the air, the other side was painted while rotating in the same way, and while continuing to rotate, the hand dryer was set to the atmospheric air blowing mode with the two-stage airflow setting set to the lowest, for example 1 m / sec, and dried. The drying time was then recorded. After that, the rotation of the pipe was stopped, and the drying time for the stationary drying side was also recorded. When touched with the hand, it was judged to be dry if no fingerprints remained and it was not sticky.

[0185] Dryness was judged at the upper part of the pipe, from 8 o'clock to 4 o'clock on a clock. The same judgment position was used for the side that was left to dry. When a large amount was applied, the coating liquid accumulated at the 6 o'clock position when left to dry. However, since the coating had already hardened except for the very surface, this judgment standard was used based on the judgment that there was no problem with the drying of the paint. For static drying, if 30 minutes was not considered dry, it was recorded as more than 30 minutes. The indoor temperature on the day was 25-28°C, and remained at approximately that temperature during drying. The forced drying conditions were simple air blowing conditions, which are slower and more severe than hot air blowing conditions. However, if these drying conditions were OK, any forced drying conditions could be judged as acceptable, so this was meant to be an examination under the most severe conditions imaginable.

[0186] The application weight was calculated from the difference in brush weight. However, because the agent has low viscosity and high fluidity, it appeared as if semi-dried paint had accumulated at the 6 o'clock position, especially on the side that was left after application. Ultimately, some dripping occurred from the 6 o'clock position, but this amount was ignored and the application amount was calculated as the difference in brush weight before and after application. Furthermore, the viscosity of the liquid was approximately 850 mPa·sec, with some exceptions, and did not change significantly under any condition. The exceptions were when the solvent mixing ratio was increased, falling below 850 mPa·sec. Examples of low fluidity include No. 2-10 to 2-14 below. An example of an increase in the solvent mixing ratio would be when a thinly mixed agent with a water-based solvent was used.

[0187] In the following examples, we will discuss film weight but not film thickness. There was only one case in which film thickness was measured, and cross-sectional microscopy was performed on No. 2-5. The pin thread shape of an oil well pipe thread showed a root thickness of 20–50 μm and a crest thickness of approximately 20–40 μm. Furthermore, the stabbing flank (the vertical wall of the thread that contacts when tightening) and the load flank (the vertical wall of the thread that contacts when loosening) were 5–10 μm. The actual results indicated that variations in thickness occurred depending on the brush stroke, for example, at the joints of the brush stroke. The joints in the brush stroke are non-stationary sections, such as when the brush is re-dipped in the agent and re-applied, or when the brush is pressed hard to squeeze out the coating fluid when the flow rate is low. Therefore, in this study, the brush stroke was performed while the pipe itself was rotating. This was intended to ensure uniform coating. However, because the viscosity of the liquid itself is low, a film forms from the dry areas, but on the other hand, the paint that has not dried tends to accumulate in the undried areas due to rotation. In other words, the paint moving to the grooves of the thread roots appears to be the cause of this difference in film thickness. The characteristics were evaluated with this level of film thickness difference. However, when evaluating the drying itself, as long as the pipe is rotated, there is a high tendency for the paint to dry uniformly, so the completion of drying was determined by the drying time of the slowest part.

[0188] The details are shown in Tables 1 to 3. These are examples of investigations into drying time. Note that the lubrication characteristics of oil country pipe threads, as represented by the number of M / Bs, are not included in the evaluation and judgment in Tables 1 to 3. "*" in the tables means that the specification is not met. "**" means that the preferred range has been exceeded. The evaluation was made in accordance with the following criteria: Inventive Example (drying OK) / Inventive Example (Δ: drying time outside the preferred range) / Comparative Example.

[0189] The present invention example (drying OK) was determined to have a drying time within the appropriate range defined in claims 10 and 11 of the present application, and also to satisfy the ranges defined in claims 1 to 9. The inventive example (△: drying time outside the preferred range) is an example that includes conditions that are unacceptable in terms of drying time. In other words, it is outside the preferred range. However, it is within the scope of the invention as defined by this disclosure. However, no tightening / loosening test is shown. The comparative examples include those that are NG in terms of drying time or those that do not form a good solid coating and cannot be expected to pass the M / B number of times. Therefore, the tightening / untightening test itself is difficult, making them NG. Furthermore, they deviate from the scope of the invention as defined by this disclosure.

[0190] [Table 1]

[0191] [Table 2]

[0192] [Table 3]

[0193] No. 2-1 to No. 2-3 are examples that do not contain alkaline soap. At the same time, No. 2-1 is also an example that does not contain alcohol or ammonia water as a solvent. No. 2-1 examines the drying state of the binder resin (acrylic acid and vinyl alcohol copolymer) examined in the examples, slightly exceeding the limit for thick coating. This demonstrates the drying characteristics of this binder resin formulation. This corresponds to a comparative example. Specifically, the solvent is water alone, without alcohol or aqueous ammonia. Because it is water alone, calcium stearate, which is characterized by its water-repellent properties, may not be uniformly dispersed and dissolved even at the chemical stage. As a result, even when a solid coating is formed, much of the calcium stearate component is not incorporated into the film but remains on top of the film, making it unsuitable as a solid lubricating coating. This example also requires a long drying time, making it a comparative example.

[0194] In both No. 2-2 and No. 2-3, the volume ratio (Vol / Vol) of ethanol to water is 6:100. The former does not contain aqueous ammonia, while the latter contains aqueous ammonia at a ratio of 0.5. In both cases, the application amount is within the target range, and both the blown-drying and the standing-drying met the target values. In other words, they are examples of the present invention (successful drying). No. 2-3 has a slightly shorter drying time, which is an improvement. This suggests that the inclusion of aqueous ammonia may have contributed to the somewhat favorable progress in volatility.

[0195] No. 2-4 is an example of No. 2-3 to which a small amount of alkaline soap component has been added. Metal soap (calcium stearate) and alkaline soap (sodium stearate) are added in a weight ratio of 99:1. The drying time is comparable to that of No. 2-3, making it an example of the present invention. No. 2-5 is an example of the ammonia water of No. 2-4, but with the addition of the primary amine methylamine. It has the same level of drying performance as No. 2-4, and is an example of the present invention. The above-mentioned No. 2-4 and No. 2-6 to 2-9 are cases where the ratio of industrial ethanol was increased in the order of 6, 10, 25, 25, and 43 per 100 parts of water by volume. These cases also correspond to cases where the ammonia content was increased in the order of 0.5, 1.0, 1.0, no addition, and 2.0.

[0196] Generally speaking, the drying time was shorter for samples 2-4, 2-5, 2-7, 2-8, and 2-9, in that order, whether they were air-dried or left to dry. This example shows that the more industrial ethanol used, the faster the drying. All of these are examples of the present invention (they dried OK). Case No. 2-7 shows that drying can be enhanced without ammonia, simply by the volatilization capacity of industrial ethanol. From cases No. 2-4, 2-5, 2-6, and 2-8, it can be interpreted that ammonia has a positive effect on rapid drying. In addition, in the case of No. 2-9, the sum of alcohol and ammonia water is 45 parts by volume relative to the water volume, which means that there are no problems with drying up to this range.

[0197] Cases No. 2-10 to 2-15 are the results of examining the weight ratio of the solvent to the solid content (the weight of the solid lubricant component + the total weight of the binder resin). Note that the weight of the solvent refers to the weight change assuming that the volume of the solvent, which is made up of water, alcohol, and ammonia, has a specific gravity of 1. No. 2-10 to No. 2-11 are cases where the ratio of industrial ethanol to water volume is 25 parts, and No. 2-12 to No. 2-15 are cases where the ratio of industrial ethanol to solids is 40 parts. The former group is made up of cases where the weight ratio of solvent to solids is 0.7 and 30, respectively. The latter group is made up of cases where the weight ratio is 20, 50, 100, and 130, respectively.

[0198] When the weight ratio of solvent to solids is up to 100, the target drying time of this disclosure is met, and it is an example of the present invention (drying OK) (Nos. 2-11 to 2-14). On the other hand, in case No. 2-15, which is over 100 and is 130, the drying time during standing does not meet the target, and it is an example of the present invention (△: drying time outside the suitable range). This means that although the drying time standard is not met, the basic structure of this disclosure is satisfied. However, the lubrication behavior is not listed in Example 2.

[0199] Nos. 2-16 to 2-20 are the results of investigations when the alkaline soap content was increased. These are cases where the amount of solvent was higher (solvent weight ratio was 2.5) and the alcohol content was also high. The weight ratios of metal soap to alkaline soap were 99:1, 99:1, 95:5, 90:10, and 80:20, respectively. Furthermore, the application amounts differ between Nos. 2-16 and 2-17, with the former being 6g and the latter being 12g, and the latter being 0.1g / mm2, which was the target application amount. 2 This is also a case where the number slightly exceeded this.

[0200] No. 2-16 and 2-17 met the standard for air drying. However, when left to dry, the former met the standard, while the latter did not. The latter applied twice as much paint as the former, so it is presumed that the drying time standard was exceeded. The application amount was the specified value: 0.1 g / mm2 This suggests that if the drying time exceeds this range, the drying time may not meet the criteria for the preferred range, especially when left to dry. The former corresponds to an example of the present invention (drying OK), while the latter corresponds to an example of the present invention (△: drying time outside the preferred range). This is because, except for the preferred drying time, the range specified in this application is met.

[0201] No. 2-18 is an example of an alkaline soap content at the upper limit of the regulation value. Although the drying time is longer than No. 2-15, the target was met. This is an example of the present invention (drying OK). On the other hand, Nos. 2-19 and 2-20 exceeded the target, containing too much alkaline soap component (sodium stearate), increasing the viscosity of the solvent and making it difficult to apply evenly. Furthermore, even after application, the drying time took too long, failing to meet the target value. This shows that adding too much alkaline soap is not a good idea. In particular, No. 2-20 exceeded the standard for the preferred drying time range, and the viscosity increased too much, making it difficult to apply evenly. No. 2-20 had unevenness and dripping, resulting in very slow drying in some areas, making it impossible to accurately determine the drying time. Therefore, Nos. 2-19 and 2-20 are comparative examples.

[0202] Cases No. 2-21 to 2-26 are a series of studies on lower alcohols. No. 2-21 is a case study of methanol, No. 2-22 to 2-24 are cases of isopropyl alcohol, No. 2-25 is a case study of normal propyl alcohol, and No. 2-26 is a case study of isobutyl alcohol. Nos. 2-22 to 2-24 are the results of investigating the effect of the film thickness of the solid lubricating coating (solid lubricating coating).

[0203] Nos. 2-21 to 2-25 are examples of films with up to 3 carbon atoms. When using methanol, ethanol (Nos. 2-2 to 2-20), isopropyl alcohol, or normal propyl alcohol, the metal soap content is the specified amount. At the same time, the target film thickness is 0.1 g / mm 2If the following conditions are met, it indicates that the drying target can be met. Nos. 2-21 to 2-23 and 2-25 are examples of the present invention (successful drying). On the other hand, No. 2-24 is a case where the film thickness exceeded the target value when using isopropyl alcohol, but the drying time did not meet the target range. Since the basic structure of the present disclosure is satisfied (experimental data omitted), this case is an example of the present invention (△: drying time outside the preferred range).

[0204] No. 2-26 was an example of isobutyl alcohol with four carbon atoms. Prior to application, the metal soap did not mix well with the aqueous solvent during formulation, which is why it was designated a comparative example. As the number of carbon atoms increases, the ability to dissolve in water gradually deteriorates. From this, even if metal soap can be uniformly dispersed and dissolved in isobutyl alcohol, if this mixture is dispersed and mixed in water and considered as a paint, the following can be said. In other words, it is estimated that the dissolved isobutyl alcohol and metal soap did not mix well with the water-based solvent. Therefore, even before considering the drying time, a uniform coating film was not formed, so this was designated a comparative example.

[0205] Cases No. 2-27 to 2-33 are the results of investigating the effects of the type of metal soap and alkaline soap, and the particle size of the metal soap. No. 2-27 to 2-29 are cases of calcium stearate and sodium stearate. No. 2-30 is a case of zinc stearate and sodium oleate. No. 2-31 is a case of magnesium stearate and potassium stearate. No. 2-32 is a case of calcium montanate and sodium 12-hydroxystearate, and No. 2-33 is a case of calcium behenate and sodium laurate. The effects of fine particles of metal soap were also investigated.

[0206] In the case of Example No. 2-29, when the particle size of the metal soap is 25 μm, the drying time exceeds the specified range. However, in the other cases where the particle size is 10 μm or less, the drying time meets the preferred range and allows for rapid drying. In other words, although adding metal soap tends to enhance drying, keeping the particle size 10 μm or less tends to meet the drying time target. It was also found that the types of metal soap and alkaline soap can be applied without any particular problems within the scope of this disclosure.

[0207] No. 2-29 can be judged as an example of the present invention (Δ: drying time outside the preferred range), and Nos. 2-27 to 2-34 are examples of the present invention (drying OK). No. 2-29 is an example of the present invention (△: drying time outside the preferred range) for the following reason: the metal soap (calcium stearate) is 25 μm, and as mentioned above, there are often regions where the film thickness on the vertical wall portion, stabbing flank, and load flank of the OCTG thread is smaller than the particle size of the metal soap. For this reason, it is possible that the integrity of the film cannot be maintained at all times during lubrication, and that problems may arise with long-term rust prevention.

[0208] (Example 3: Influence of each condition on lubricity) The study group of this Example 3 explains the invention based on the results of investigating the lubrication behavior by applying a chemical to the structure of an oil country pipe thread, forming a film, and then conducting a weight-tongs test. The weight was applied in its entirety during tightening. On the other hand, when tightening back, the weight load was reduced to nearly zero, and the bolt was lifted by the overhead crane 20 shown in Figure 5, simulating wobble. Various combinations of conditions were systematically prepared for consideration, and the feasibility was judged based on the lubrication behavior, that is, the number of M / Bs. Reflecting the findings already made in Example 1, the metal soap component was dispersed and uniformly dissolved in a lower alcohol in advance to ensure homogeneous dispersion, and then used as a drug.

[0209] As already mentioned above, the criteria for judging the lubrication properties using weight tongs were that a casing size was judged to pass if it could be tightened and loosened three times or more. A tubing size was judged to pass if it could be tightened and loosened five times or more. Furthermore, judgment was made by drawing a line between casing sizes of 7 inches or more and tubing sizes of less than 7 inches. In thread test standards such as API-5C5, the standard for tubing-equivalent materials with conventional lubrication requirements using API-mod compounds is to achieve 10 or more M / B cycles. However, with solid lubricant coatings, the film itself inevitably wears away gradually, so the number of cycles tends to decrease. Therefore, in this application, the pass range is set at 5 or more cycles.

[0210] In addition to the number of M / B times, once the screw was completely loosened after tightening, the pin was released to the top. Then, the pin thread surface and box thread surface were observed after air blowing to directly visually confirm whether or not there was any seizure. In addition, the torque turn chart was checked to confirm whether there were any abnormalities. The judgment method was as follows: If the screw did not loosen during the tightening / loosening of the M / B number of times, it was judged that seizure had occurred at that tightening / loosening count, and the number of tightening / loosening was judged as the previous number of times.

[0211] For those that were completely loosened and the surface could be observed, if there was any seizure, even slight, in the seal area, it was judged as NG. Then, the number of times that the tightening and loosening was to be repeated was judged as the next time seizure would occur, and the number of times that it was tightened with the weight tongs was recorded on the spot, and the tightening and loosening test was completed. If there was very slight seizure in the thread area, rather than in the seal area, it was repaired and the test continued as is. The number of times that was tightened and loosened in this way was used to sort whether it was good or bad using the judgment criteria described above. The conditions and results are shown in Tables 4 to 12. The symbol "*" next to each parameter in the tables means that it is outside the specified range, and the symbol "**" means that it is outside the preferred range.

[0212] [Table 4]

[0213] Table 5

[0214] Table 6

[0215] Table 7

[0216] Table 8

[0217] Table 9

[0218] Table 10

[0219] Table 11

[0220] Table 12

[0221] The "solid lubricant coating A with a pencil hardness of 3H" frequently mentioned in the table is as follows: In the case of carbon steel, it is a manganese phosphate conversion coating, and in the case of stainless steel, it is a solid lubricant coating formed on top of a Cu-Sn electroplated coating (Sn: 45-47%) undercoat. In this case, the binder resin is a polyamide-imide film, the solid lubricant is PTFE, and trace amounts of MoS2 (1-3%) are dispersed uniformly, resulting in a structure that can be considered nearly uniform. The solid lubricant coating has a thickness of 50-80 μm. The film thickness is measured on the thread. It refers to the same solid lubricant coating, including the pencil hardness of 3H. The film thickness distribution of individual portions of the thread is as follows: The thread design of oil country pipe threads has an inverted hook structure. For this reason, even if a uniform film thickness is achieved by applying chemicals in an ingenious manner, the film thickness tends to be thinner on the vertical wall portions of the threads at the load flank and stabbing flank. However, by devising a method for forming the solid lubricating coating, it was possible to ensure that the film thickness on the vertical wall was more than half the measured film thickness on the threads.

[0222] No.3-1 to 3-12 are made of carbon steel P110 material, 7"38# JFELION TM The screw was treated with a styrene-acrylic acid copolymer (500 parts by weight of styrene for 100 parts by weight of acrylate). This example shows this treatment applied to the pin screw side. The box screw side was also treated with the above-mentioned "Solid Lubricant Coating A with pencil hardness of 3H." In this case, a manganese phosphate conversion coating was applied to the base. A tightening / loosening test was conducted using a 2-ton weight, equivalent to the tightening force when three screws are connected, to determine whether it was acceptable.

[0223] In the cases of No. 3-1 to 3-8, the solvent was composed of 15 parts industrial ethanol and 2 parts aqueous ammonia per 100 parts water by volume. The blending ratios were also the same, and the blending conditions were the same within the specified range. The test cases differed in the size of the metal soap, the presence or absence of alkaline soap, and the film thickness. No. 3-1 to 3-4 were cases in which the particle size of the metal soap (calcium stearate) was 5 μm, 1 μm, 10 μm (this example was the only one without alkaline soap), and 10 μm, respectively. No. 3-1, 2, and 4 showed good lubrication behavior with more than 10 M / B cycles using weighted tongs (topped at 10 cycles), and are examples of the present invention. No. 3-3 only had 3 M / B cycles, and is also an example of the present invention. However, the lubrication properties of No. 3-3 were inferior to those of No. 3-1, 2, and 4, which contained alkaline soap components. This indicates that the addition of alkaline soap is effective in improving lubrication.

[0224] In Nos. 3-5 to 3-8, the metal soap size was 25 μm. However, the thicknesses of the solid lubricant coatings were 20 μm, 50 μm, 100 μm, and 180 μm, respectively. Furthermore, the drying times for these cases were, respectively, 7 minutes of air drying, 23 minutes of air drying, 8 minutes of hot air drying, and 10 minutes of hot air drying. In Nos. 3-7 and 3-8, drying was performed using a hot air blower (output 1000 W). Generally speaking, they tend to be longer than No. 3-1 to 3-4. This change is thought to be due to the larger size of the solid lubricant film and the particle size of the metal soap. If the particle size of the metal soap is small and dispersed, the surface area increases and the number of drying points within the film increases. As a result, it can be expected that drying will be accelerated. However, in these cases, this cannot be expected due to the large size, and this can be explained by the fact that the volume required for drying increased due to the influence of the film thickness.

[0225] No. 3-5 is an example of a 20 μm film thickness, where the metallic soap size is large relative to the film thickness. These examples show that when the metallic soap is larger than the film thickness, there are areas where the film integrity is difficult to maintain, resulting in destruction and seizure in those areas. No. 3-6 (film thickness 50 μm) corresponds to an inventive example with six or seven M / B cycles. Nos. 3-7 and 3-8 are examples of an investigation into the effect of film thickness. While the former clears the M / B cycle requirement with a film thickness of 100 μm, the latter, with a film thickness of 180 μm, has some M / B cycles that do not meet the standard of three. This shows that lubrication performance can deteriorate when the film thickness exceeds 100 μm.

[0226] Nos. 3-9 and 10 are comparative examples where the drying method was changed. These will be explained in comparison with No. 3-1. No. 3-1 mentioned above is an example where the number of M / Bs was more than 10 (it was capped at 10). No. 3-9 is the same up to the point where one coat was applied with a brush while the pipe was rotating. However, in this example, only the pin thread pipe was rotated and allowed to dry in the air, and it dried in 15 minutes. In No. 3-10, after the spin coating, the rotation was stopped and the pipe was left to dry in a stationary state, and it took extra time to dry.

[0227] As mentioned above, the drying assessment was performed on the upper part of the pipe from the 8 o'clock to 4 o'clock positions. This assessment was possible because the lower part of the coating had already formed a film, which could be estimated by the drying from the 8 o'clock to 4 o'clock positions. Furthermore, in this case, the 5 o'clock to 7 o'clock positions, where the liquid pools were present, were also dry on the surface, but not completely dry in the center, so corrosion resistance was deemed acceptable. As shown in this example, the lubrication behavior was slightly inferior to that of No. 3-1 and 3-9, but still within the acceptable range. Therefore, the lubrication performance was considered to be excellent and this example can be considered an example of the present invention. This is because the agent had low viscosity, resulting in high fluidity. This appeared to be correlated with the fact that the paint, which was not completely dry at the end of application, moved along the threads (dripping). The 5 o'clock to 7 o'clock positions were dry on the surface, but this could be attributed to the influence of the paint not yet completely dry in the center, but still within the acceptable range.

[0228] Cases No. 3-11 and 3-12 are cases where the binder resin contained a binder resin component other than an acrylate or methacrylate. The cases No. 3-11 and 3-12 are cases where 11 parts by weight and 35 parts by weight of water-soluble phenolic resin were mixed, respectively, per 100 parts by weight of the binder resin component other than a methacrylate. The former are examples of the present invention, while the latter are comparative examples, in which the amount mixed exceeded the upper limit of the standard.

[0229] In terms of the weight percentage of binder resins other than acrylate or methacrylate based resins contained in the total binder resin, these are 90% and 74%, respectively (less than the standard 90%). The former meets the M / B count regulations and is an inventive example. The former is an example where the solvent / (solid lubricant + binder resin) mixing ratio is 1.8, the solid lubricant / binder resin weight ratio is 0.12, and the viscosity is 650 mPa·sec. The latter are examples where the values ​​are 1.8, 0.12, and 1300 mPa·sec, respectively. On the other hand, the latter was coated with a 25 μm thick solid lubricant coating, but did not dry completely. Even after waiting overnight after coating, the coating was still semi-wet, and a tightening / untightening test could not be performed. Therefore, it was determined to be a comparative example.

[0230] The examples of No. 3-13 to 3-17 are made of carbon steel Q125 material, 9-5 / 8" 53.5# JFELION TM The chemicals used for the screws were vinyl acetate-butyl acrylate and polyvinyl polymer (420:100:75). This example shows a case where this was applied to the pin thread side. The box thread side was also coated with the above-mentioned "Solid Lubricant Coating A with pencil hardness of 3H." A manganese phosphate conversion coating was then applied to the base under these conditions. A tightening / untightening test was conducted using a 3-ton weight, equivalent to the tightening force when three screws are connected, to determine whether or not the test would be successful. This example shows a study where the amount of lower alcohol (ethanol) added was increased to increase volatility and strengthen drying.

[0231] The solvents are 100 parts water to 35 parts industrial ethanol, 35 parts water to 35 parts ethanol, 45 parts water to 60 parts industrial ethanol, and the coating methods are spin coating / air drying, spin coating / air drying, static coating (hand coating) / static drying, spin coating / static drying, static coating (hand coating) / static drying. Only No. 3-17, which contained 60% lower alcohol, exceeding the standard limit of 45, did not meet the standard for the number of tightening and tightening times. When tightening and tightening tests were conducted using weight tongs, the results were 5, 1, and 2, which were passable, but the overall M / B number was poor. Therefore, it was selected as a comparative example. This suggests that the coating may dry too quickly, resulting in an inconsistent film thickness. Furthermore, since the flash point is 40°C, there is a risk of explosion or other accidents if it is applied at the wellhead, and this point also qualifies it as failing.

[0232] In the other cases, the number of M / B cycles met the pass standard. The reason why the number of M / B cycles in No. 3-13 was limited to the lower limit of 3 is presumably because the solid lubricant / binder resin ratio exceeded the preferred range of 1.0. This is presumably due to the slightly inferior film integrity in solid lubricant films containing a large amount of solid lubricant. Furthermore, in the cases examined in No. 3-15 to 17, the number of M / B cycles tended to be slightly lower in cases where the coating was applied by hand and / or left to dry (without airflow). This is presumably due to uneven film thickness caused by the wet agent gradually flowing down and forming a film at the 6 o'clock position during drying.

[0233] The examples of No. 3-18 to No. 3-34 are made of martensitic stainless steel HP2-13CR-110 (13Cr-5Ni-2Mo type), size: 9-5 / 8" 43.5# JFELION TM The agent used for the screws was ethylene-methacrylic acid copolymer resin. However, the ethylene in this case was a polymerized ethylene-methacrylic acid based on a random copolymer of ethylene oxide and propylene oxide, and this example was formed on the pin screw side. The box screw side was formed under conditions where a "solid lubricant coating A with a pencil hardness of 3H" was formed, with a Cu-Sn binary electroplated indicator film formed on top. A tightening / untightening test was conducted using a 2-ton weight to determine whether the test would be successful, and the applied weight was equivalent to the tightening force when connecting just under three wells in an actual well.

[0234] Nos. 3-19 to 3-22 and 3-24 to 33 were in the pass range for the number of times of tightening and loosening in the tightening and loosening test using weight tongs, and are examples of the present invention. Nos. 3-18, 23, and 3-34 are comparative examples. Examples No. 3-18 to No. 3-21 are examples investigating the lower limit of the lower alcohol content. No. 3-18 is an example of a purely water-based solvent with no added alcohol. It was dried with hot air at 100°C, and the drying time was not particularly long. However, the weight-tongs tightening and loosening test was only performed once, resulting in a failure, making it a comparative example. Because the solvent was water only, the metal soap, the main component of the solid lubricant, is water-repellent. This, in part, may be related to the inhomogeneity of the film quality even when the solid lubricant film is formed, due to the inability to disperse uniformly.

[0235] Nos. 3-19 to 21 are cases where the industrial ethanol is 0.5, 1, and 5, respectively. From No. 3-19 (industrial ethanol: 0.5), it can be confirmed that the M / B count is within the acceptable range. Nos. 3-22 to 3-24 are examples of tests that investigated the inclusion of a third solid lubricant other than metal soap and alkali soap, with graphite, graphite, and BN added, respectively. Nos. 3-22 and 3-24, which were adjusted within the specified range, had an acceptable M / B count and are examples of the present invention. No. 3-23 is an example in which a high content of the third solid lubricant (graphite in this case) was found, with the metal soap and alkali soap exceeding the specified weight percentage of the total solid lubricant. These examples were NG because they did not meet the acceptable criteria for M / B count and are comparative examples. In reality, the graphite formed a tape-like product extending over 20 mm along the thread groove, which caused seizure.

[0236] Cases No. 3-25 to No. 27 use the same solvent, binder resin, and solid lubricant, but the application and drying methods were changed to compare cases where the solid lubricant coating was completely dried with cases where some semi-dried areas remained. No. 3-25 is a case where the coating was applied by brush while the pipe was rotating, and then air-dried while continuing to rotate. The completely dried film passed the M / B test using a weight tong, and is an example of the present invention. Nos. 3-26 and 27 were created using the same process as No. 3-25 up to application, but the drying process was different. They were left to dry and formed a solid lubricant coating. No. 3-26 was completely dried, while No. 3-27 had some insufficient dry areas. Specifically, there were some areas of liquid paint between the 5 and 7 o'clock positions that had not completely dried. Furthermore, since the paint film formation (drying) begins with the outermost layer (the surface in contact with the atmosphere) and the surface that contacts the screw steel, in this case, a semi-dried area remained near the center of the film thickness. This example shows that the contact surface between the screw and the coating was also dry. Although the application and drying times were the same, there was some variation in the application method, which is presumably responsible for the effects. However, there were no problems with lubrication, and both are examples of the present invention.

[0237] The examples No. 3-28 to No. 3-32 compare the effects of the weight ratio of the solvent to the total weight of the solid lubricant and binder resin (calculated assuming the specific gravity of the solvent is 1) and the weight ratio of the solid lubricant to the binder resin. Both parameters were examined in the following order: 100 - 0.6, 150△ - 5.0△, 0.7 - 0.1, 0.5▽ - 0.08▽, and 0.6▽ - 1.1△. △ indicates exceeding the upper limit of the preferred range, and ▽ indicates reaching the lower limit of the preferred range. All conditions are examples of the invention. Those within the preferred range showed good M / B cycles, with No. 3-28 reaching 6 cycles and No. 3-30 reaching 10 cycles. However, those exceeding the preferred range only achieved lubrication performance of around 3 or 4 cycles.

[0238] Cases No. 3-33 and No. 3-34 are examples of solvents containing a solvent other than water and alcohol, such as DMSO (dimethyl sulfoxide). In the former case, DMSO is added in a volume of 6 to a base agent containing 14 parts industrial ethanol, assuming a volume of water of 100. Furthermore, these cases involve 95% water and lower alcohol by volume and 5% other solvents by volume relative to the total weight of the solvent, representing a study of the solvent composition limits of the present application. These cases involve the use of stable, non-volatile polar solvents, which can be dried in approximately 5 minutes with hot air drying. However, these cases do not dry within the specified 5 minutes with air drying at room temperature, and cannot be dried for 30 minutes even when left to dry. If a film can be formed, the lubrication level targeted by the present application can be achieved, making them examples of the present invention.

[0239] On the other hand, No. 3-34 is a case in which even more DMSO was added, containing a solvent with a high boiling point (approximately 190°C). Therefore, it did not dry or form a film when left to dry in the air or when blown with air (including hot air). It could form a film when heated at 200°C or higher. However, due to the low viscosity of the solvent, it did not form a film instantly during the baking process, and dripping occurred even during baking. Specifically, a thick film formed at the 6 o'clock position, filling the pin thread valleys in some places. In some places, further dripping occurred, leading to the formation of droplet-like film protrusions. As a result, the required number of tightening / untightening tests was not completed, resulting in seizure, making this a non-compliant sample and a comparative example. These considerations indicate that the solvent must be composed of at least 95% water and lower alcohol.

[0240] Cases No. 3-35 to 39 are made of carbon steel T95, size 5.5" 23# JFELION TMIn this example, the screw was treated with a mixture of diacetone acrylamide (DAAD: a type of acrylate) and a polymer of diphenylmethane diisocyanate (MDI: a urethane compound), with 40 parts by weight of MDI mixed with 100 parts by weight of the acrylate DAAD. The box screw was coated with a "solid lubricant coating A with a pencil hardness of 3H," with a Cu-Sn binary electroplated indicator film formed underneath. A tightening / untightening test was conducted using a 1-ton weight to determine whether the screw would fit, and the applied weight was equivalent to the tightening force when connecting just under three wells in an actual well.

[0241] Nos. 3-35 to 3-39 are examples in which solid lubricant coatings were formed using different coating and drying methods. The five examples are, in order, spin coating and spin-transfer air drying, spin coating and static drying, static hand coating and static drying, spin coating and spin-transfer air drying, and spin coating and static air drying. The weight-tong M / B counts were, in order, ≥ 10 times (10 times max), ≥ 10 times (10 times max), 9 times, 8 times, and 9 times. All passed and are examples of the present invention. Compared to Examples 3-1 to 3-34, the smaller diameter materials used resulted in a smaller tightening torque, indicating that the coating thickness unevenness due to static hand coating or static drying was not significantly affected. Examples No. 3-38 and 39 are examples in which a different type of metal soap was used, different from the calcium stearate and calcium / zinc stearate (mixture) used in Examples No. 3-1 to 3-37. The former uses zinc stearate, and the latter uses barium stearate. In both cases, the other requirements are within the specified range, and the M / B count is within the acceptable range, making them examples of the present invention.

[0242] Cases No. 3-40 to 43 are made of carbon steel T95, size 3.5" 9.2# JFEBEAR TMThis example uses a copolymer of acrylic acid and polyvinyl acetate as a chemical agent for screws. It also uses a chemical agent where 30 parts by weight of polyvinyl acetate is mixed with 100 parts by weight of acrylic acid. In this example, "Solid Lubricant Coating A with pencil hardness 3H" is used on box screws, and the base is coated with a manganese phosphate chemical conversion coating. Other examples include use on pin screws, a case where both thread surfaces are formed using only the chemical agent, and a case where only the manganese phosphate chemical conversion coating is used. A 500 kg weight was applied to conduct a tightening / untightening test to determine whether the test was successful, which corresponds to the weight applied when three pipes are connected in an actual well.

[0243] No. 3-40 is the same as the series of cases above, in that a solid lubricant coating was applied to the pin thread side, and "solid lubricant coating A with pencil hardness 3H" was formed on the box thread side. It is also an example of the present invention in which the number of M / Bs was ≥ 10 (up to 10 times). No. 3-41 is an example in which a solid lubricant coating was applied to the pin thread side, and the box thread only had a manganese phosphate coating and no "solid lubricant coating A with pencil hardness 3H," but it was able to be tightened and loosened three times, making it an example of the present invention. In No. 3-42, both sides of the threads were coated with the solid lubricant coating of this disclosure, and five tightening and loosening cycles were confirmed, which also constitutes an example of the invention. In No. 3-43, the box thread was coated with a solid lubricant coating, and "Solid Lubricant Coating A with a pencil hardness of 3H" was applied to the pin thread side, and the number of M / B cycles was ≥ 10 (up to 10 cycles), which also constitutes an example of the invention.

[0244] (Example 4) Corrosion study results The results are shown in Table 13. [Table 13]

[0245] In the corrosion resistance evaluations disclosed herein, a protector used to protect the thread structure of a structure with a thread structure, such as an oil well pipe thread, was tightened and then loosened, and then the protector was removed, and salt spray was applied to the solid lubricant coating. The evaluation was based on the criteria that the appearance of red rust over the entire surface was deemed NG. The salt spray evaluation was performed after inflicting possible damage on the film. Corrosion resistance was examined using some of the materials and conditions considered in Tables 1 to 12. The salt spray conditions were in accordance with JIS K 5600-7-1, using 5% NaCl neutral salt spray conditions (35°C, humidity 98-99%, spray 1-2 mL / Hr / 80 cm). 2 , pH 6.5-7.2) and based on evaluation at 8 hours.

[0246] Here, the metal surface of a metal part (oil country pipe thread surface) that is the subject of this disclosure includes, for example, lathe-machined or machined surfaces, polished surfaces, etc. Note that for the corrosion resistance evaluation, areas with remaining mill scale were excluded. Depending on the roundness and eccentricity of the tubular structure, samples may contain mill scale in the thread structure. However, if the mill scale is cleaned before forming a solid lubricant coating, the water-based agent may penetrate into tiny defects, holes, or scratches in the mill scale. For this reason, when a solid lubricant coating is formed on top of the mill scale, even if the solid lubricant coating is sound, rust spots may appear on the underlying steel. However, such rust spots are not rust on the solid lubricant coating and are therefore excluded from the evaluation.

[0247] The sample numbers in Table 13 indicate the drug composition based on the ingredients and composition used in Tables 1 to 12. The application method is different from that of the sample numbers in question; it was applied with a brush while rotating a pipe, and the drying method was rotation and air drying, resulting in complete drying. In addition, all materials were L80, 3.5"9.2#JFELION TMThis is an example where the pin threads (male threads) were aligned with those of the original. After complete drying, a protector made of HDPE resin (high density polyethylene) was used to tighten and loosen the screws once, and then a salt spray test was conducted. As a comparison material, a general-purpose thin steel SPCC material was used, and the pin threads were coated with the agents No. 3-1, 13, 17, 20, 38, and 42. However, the comparison SPCC material was not coated with rust preventative oil, and was not subjected to the equivalent of one tightening and loosening of the protector. The results clearly show that all of the materials coated with the agent of the present invention have excellent corrosion resistance.

[0248] (others) The present disclosure may also have the following configuration. (1) A chemical for forming a solid lubricating coating on a metal surface, The main components are a solid lubricant, a binder resin, and a solvent, the solvent contains water as a main component, and a lower alcohol having 3 or less carbon atoms is added to the water as an additive, and the volume of the additive is 0.5 to 45 per 100 of the volume of water in the solvent; 95% or more of the volume of the solvent is composed of the water and the additives; The solid lubricant contains a soap component containing at least a metal soap from among a metal soap and an alkali soap component, and the metal soap component accounts for 95% or more of the total weight of the metal soap and alkali soap components, the particle size of the metal soap does not exceed the film thickness of the solid lubricating coating, The binder resin is composed of a water-soluble or water-dispersible polymer or copolymer, and the polymer or copolymer having an acrylate or methacrylate structure accounts for 90% or more of the total weight of the binder resin. (2) The additive further contains at least one of aqueous ammonia and a primary amine. (3) The lower alcohol is one or more lower alcohols selected from methanol, ethanol, isopropyl alcohol, normal propyl alcohol, and industrial ethanol, and the volume of the lower alcohol is 0.5 or more per 100 parts by volume of water in the solvent. (4) The metal soap and alkaline soap components constituting the solid lubricant include one or more soaps that are compounds consisting of a fatty acid selected from Group A below and a metal element selected from Group B below, The weight of the metal soap is 95% or more of the total weight of the metal soap and alkaline soap. Group A: stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid B group: Na, K, Mg, Ca, Zn (5) The particle size of the metal soap is 10 μm or less. (6) The water-soluble or water-dispersible polymer constituting the binder resin is a polymer composed of one or more monomers selected from the following (1) to (4), and the copolymer is a copolymer composed of two or more monomers selected from the following (1) to (4): (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Monomers containing acrylates, methacrylates, and their respective derivatives, as well as monomers containing alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and their respective derivatives. (3) Monomer grafted onto (1) and (2) above (4) Monomers of either or both of vinyl compounds and urethane compounds (7) The flash point of the agent is above 60°C or it is flame retardant. (8) If the specific gravity of the solvent is 1 and the volume of the solvent is converted to weight, The weight of the solvent is 0.7 to 100 times the total weight of the solid lubricant and the binder resin, The weight of the solid lubricant is 0.1 to 1.0 times the weight of the binder resin. (9) The viscosity of the drug is 1000 mPa·sec or less. (10) Coating amount for metal surface: 0.1 g / mm 2 When applied as described below, it dries quickly within 30 minutes when left to dry in a windless atmosphere at room temperature. (11) Coating amount for metal surface: 0.1 g / mm 2 When applied as described below, it dries quickly within 5 minutes when dried in an air environment at room temperature with air blowing at a speed of 1 m / sec or more. (12) A method for producing a reagent for forming a solid lubricating coating according to the present disclosure, comprising: The metal soap is prepared by dispersing and clouding the metal soap in a lower alcohol and then pouring it into the water solvent. (13) A method for applying the agent for forming a solid lubricating coating of the present disclosure to a surface of a tubular part, comprising: The agent is applied while the tubular element is rotated about its axis. (14) An oil well tubular good having a lubricating coating formed on a thread portion, the lubricating coating having a solid lubricating coating, The solid lubricant coating has a solid lubricant dispersed in a binder resin, The solid lubricant contains a soap component containing at least a metal soap from among a metal soap and an alkali soap component, and the metal soap component accounts for 95% or more of the total weight of the metal soap and alkali soap components, the particle size of the metal soap does not exceed the film thickness of the solid lubricating coating, The binder resin is composed of a water-soluble or water-dispersible polymer or copolymer, and the polymer or copolymer having an acrylate or methacrylate structure accounts for 90% or more of the total weight of the binder resin. (15) The metal soap and alkali soap components constituting the solid lubricant include one or more soaps that are compounds consisting of a fatty acid selected from Group A below and a metal element selected from Group B below, The weight of the metal soap is 95% or more of the total weight of the metal soap and alkaline soap. Group A: stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid B group: Na, K, Mg, Ca, Zn (16) The particle size of the metal soap is 10 μm or less. (17) The water-soluble or water-dispersible polymer constituting the binder resin is a polymer composed of one or more monomers selected from the following (1) to (4), and the copolymer is a copolymer composed of two or more monomers selected from the following (1) to (4): (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Monomers containing acrylates, methacrylates, and their respective derivatives, as well as monomers containing alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and their respective derivatives. (3) Monomer grafted onto (1) and (2) above (4) Monomers of either or both of vinyl compounds and urethane compounds (18) The solid lubricating coating has a thickness of 1 μm or more and 100 μm or less, and is soft, with a pencil hardness of H or less. (19) An oil well pipe threaded joint in which a box having a female thread and a pin having a male thread are connected, At least one of the oil country tubular goods of the box and the pin is made of the oil country tubular goods on which the solid lubricating coating of the present disclosure is formed. (20) An oil well pipe threaded joint in which a box having a female thread and a pin having a male thread are connected, one of the oil country tubular goods of the box and the pin is made of the oil country tubular goods on which the solid lubricant coating of the present disclosure is formed, On the other hand, a coating having a higher hardness than the solid lubricating coating is formed on the thread portion of the oil country tubular good.

[0249] The entire contents of Japanese Patent Application No. 2022-134375 (filed August 25, 2022), from which this application claims priority, are incorporated herein by reference. While the present invention has been described with reference to a limited number of embodiments, the scope of the invention is not limited thereto, and modifications of each embodiment based on the above disclosure would be obvious to those skilled in the art. [Explanation of symbols]

[0250] 1 pin 1a Threaded part 2 boxes 2a Threaded part

Claims

1. An oil country tubular good having a lubricating coating formed on a thread portion, the lubricating coating having a solid lubricating coating, The solid lubricant coating has a solid lubricant dispersed in a binder resin, The solid lubricant contains a soap component containing at least a metal soap from among a metal soap and an alkali soap component, and the metal soap component accounts for 95% or more of the total weight of the metal soap and alkali soap components, the particle size of the metal soap does not exceed the film thickness of the solid lubricating coating, The binder resin is made of a water-soluble or water-dispersible polymer, and 90% or more of the total weight of the binder resin is a polymer having an acrylate or methacrylate structure. Oil country tubing.

2. The metal soap and alkaline soap components constituting the solid lubricant include one or more soaps that are compounds comprising a fatty acid selected from Group A below and a metal element selected from Group B below, The weight of the metal soap is 95% or more of the total weight of the metal soap and the alkaline soap.

2. An oil country tubular good according to claim 1. Group A: stearic acid, behenic acid, lauric acid, 12-hydroxystearic acid, oleic acid, montanic acid Group B: Na, K, Mg, Ca, Zn

3. The particle size of the metal soap is 10 μm or less.

2. An oil country tubular good according to claim 1.

4. The water-soluble or water-dispersible polymer constituting the binder resin is a polymer composed of one or more monomers selected from the following (1) to (4):

2. An oil country tubular good according to claim 1. (1) Monomers based on acrylates, methacrylates, and their respective derivatives (2) Monomers containing acrylate, methacrylate, and their respective derivatives, as well as alkyl esters, vinyl esters, styrene esters, carboxylic acid esters, and monomers containing their respective derivatives. (3) Monomers grafted onto the above (1) and (2) (4) Monomers of either or both of vinyl compounds and urethane compounds

5. the solid lubricating coating has a thickness of 1 μm or more and 100 μm or less and is soft, with a pencil hardness of H or less; 2. An oil country tubular good according to claim 1.

6. An oil well pipe threaded joint in which a box having a female thread and a pin having a male thread are connected, At least one of the box and the pin is made of the oil well tubular good according to any one of claims 1 to 5. Oil well pipe threaded joints.

7. An oil well pipe threaded joint in which a box having a female thread and a pin having a male thread are connected, The oil well tubular goods of one of the box and the pin is made of the oil well tubular goods according to any one of claims 1 to 5, a coating having a higher hardness than the solid lubricating coating is formed on the thread portion of the other oil country tubular good; Oil well pipe threaded joints.

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