Reagents, oil well pipes and oil well pipe threaded joints

Abstract

A solid lubricating film is used to achieve the same or better burn prevention (galling resistance) as the doping / complexing method of the prior art for the lubricating properties during tightening and loosening of an oil well pipe. An agent for forming a solid lubricating film on a fastening surface of a threaded portion, wherein a solid lubricant is dispersed in a binder resin as a base component, the main component of the solid lubricant being melamine cyanurate having an average particle diameter of 0.1 μm or more and 10.0 μm or less, the binder resin containing an alkyd resin and nitrocellulose, the alkyd resin and nitrocellulose accounting for 85% or more by weight of the total weight of the binder resin components, the total weight of the solid lubricant being 10 parts by weight or more and 100 parts by weight or less relative to 100 parts by weight of the total weight of the binder resin.

Description

Technical Field

[0001] This invention relates to a technology for the lubrication and corrosion resistance of oil well pipe threaded joints. Specifically, it relates to a film structure in which a solid lubricating film is formed on the fastening surface (including the metal sealing surface) of the threaded portion, replacing a wet lubricating compound, and to a technology for oil well pipe threaded joints. In this specification, the fastening surface, which is the threaded portion, includes the metal sealing surface.

[0002] Here, a solid lubricating film refers to a film composed of a binder resin as a matrix component, a solid lubricant dispersed and distributed in the binder resin, and additives added as needed. The present invention aims to improve lubrication by providing a solid lubricating film for lubricating oil well pipe threads, and also to provide corrosion resistance.

[0003] Furthermore, in this specification, phenomena described using terms such as "lubricity" and "high lubricity" broadly refer to the phenomenon of easy sliding with low friction. In a narrower sense, high lubricity refers to the ability to perform a specified number of tightening / loosening cycles (also referred to as tightening / loosening cycles). For example, the burn resistance (resistance to burns) of oil well pipe thread joints is described in API 5C5. In API 5C5, for casing sizes, up to 3 tightening cycles are required. For pipe sizes, up to 10 tightening cycles are required.

[0004] It should be noted that in this specification, pipes with internal threads are sometimes collectively referred to as sleeves. That is, connectors are also referred to as a type of sleeve. Background Technology

[0005] In oil well pipe threaded joints, for the lubrication of the threaded portion, conventionally a coating is formed by surface treatment of the fastening surface (sealing surface) (hereinafter also simply referred to as "fastening surface") of the threaded portion of at least one of the external and internal threaded sides using a chemical conversion treatment film of Mn phosphate or electroplating of Cu, etc. Then, a lubricating compound containing Pb, Zn, etc. is coated on the coating to achieve lubrication.

[0006] It should be noted that, in this specification, when a film is formed on the fastening surface (sealing surface) of the threaded portion, the film itself is referred to as the fastening surface.

[0007] In contrast, in recent years, non-wet lubrication technologies based on "dry / undoped" lubrication have attracted attention. "Dry / undoped" means that the film itself is not a viscous liquid like API-mod compounds and does not contain harmful heavy metals. As such "dry / undoped" lubrication, there are techniques that seek lubrication by forming a solid lubricating film on the fastened surfaces. This invention relates to lubrication technology under this "dry / undoped" condition.

[0008] Here, in the past patent literature, there are inventions regarding various solid lubricating films. The solid lubricating film is composed of a lubricant component responsible for lubrication and a solid film as a base component that holds the lubricant component in the film. The solid film refers to a film that does not have tackiness, is not a liquid film, and itself also has the meaning of completing lubrication when tightening of a thread is loosened. The Mn phosphate film and the electroplated Cu film since the past are solid films. However, since lubrication is sought as a premise by coating a grease-like compound, they are not included in the solid lubricating film. In the present invention, lubrication is achieved in the form of a solid film, and an organic resin film is envisaged as the solid film. Therefore, in the following description, the solid film is also described as an adhesive resin.

[0009] In the present invention, a hard film in which the main component of the solid lubricant is set to MCA and the adhesive resin component is composed of an alkyd resin and cellulose and its derivatives is utilized. The cellulose and its derivatives are particularly utilized as nitrocellulose in the present invention. In addition, among commercially available paint groups, there is a group called lacquer, and as the mainstream of the group called lacquer, there is a paint classification composed of an alkyd resin and nitrocellulose. These paint classification substances cannot be said to be particularly excellent in lubrication. They are generally used as general-purpose paints and paints for quick drying in interest fields such as plastic models. In order to prevent rust and for decoration, they are optimized, and properties related to lubrication are not necessarily particularly guaranteed. Therefore, in order to lubricate them, the selection of a lubricant and the optimization of the component content range are also required while the optimization of the component combination of the alkyd resin and nitrocellulose is optimized. However, although there is no completely matching patent literature, past literature related to alkyd resins, nitrocellulose, and the like as individual components is disclosed.

[0010] Here, as patent literature that lists MCA as a solid lubricant, for example, there are patent literatures 1 to 4. In patent literatures 1 to 3, MCA is exemplified as one of the candidate groups of solid lubricant powders for oil well pipe threads. In addition, in patent literature 4, the use of MCA is shown as one of the necessities for a solid lubricating film for an oil well pipe.

[0011] In addition, regarding the alkyd resin, it is described in patent literature 5. In patent literature 5, a surface layer in which inorganic silica particles are dispersed is proposed as a treatment that replaces the conventional chromate treatment on a wide range of metal material surfaces. Furthermore, in patent literature 5, an alkyd resin is exemplified as one of the candidate groups as a resin that adheres silica.

[0012] In Patent Literature 6, a case where nitrocellulose is provided is described, and as an example of a carbohydrate that can be mixed into a lubricating film, cellulose is exemplified as one of the candidate groups. Also, in Patent Literature 6, a substance made of cellulose, an acrylic resin, a vinyl chloride resin, a polyvinyl butyral, a rubber, a fluororesin, or the like, alone or in a mixture, is exemplified as a material for making a film that holds a lubricating powder.

[0013] In Patent Literature 7, nitrocellulose is also exemplified. In Patent Literature 7, a liquid lubricating layer is present on the lower layer, and a solid lubricating film is formed thereon. Also, as a binder resin of the solid lubricating film, nitrocellulose is exemplified as one of the candidate groups. In Patent Literature 7, natural drying is a prerequisite in order to form an upper layer while protecting the liquid lubricating film of the lower layer. Also, nitrocellulose is exemplified as one of the candidate groups of the binder resin of the upper layer made by natural drying.

[0014] In addition, although not an example of evaluation of a solid lubricating film, in Non-Patent Literature 1, a fastening test method based on a vertical power tongs using a short pin is described. In Non-Patent Literature 1, a method is described in which, regardless of the outer diameter and the wall thickness of the oil well pipe to be evaluated, a state in which a weight of 5 kN (510 kg) is always loaded is implemented, regardless of whether it is at the time of fastening or at the time of loosening. In Non-Patent Literature 1, as the pin, 7”29#, 7”35# are described, and if the length of the pin is set to be close to the actual length of Range-3 of 40 feet (≈12 m), the pin load is about 520 kg or about 630 kg. Therefore, it is considered that the weight of one amount of the evaluation size is applied, regardless of whether it is at the time of fastening or at the time of loosening. In addition, if judged from the torque rotation diagram, it is known that since fastening is completed in an amount of half a turn (see Non-Patent Literature 1, FIG. 1), the initial set position of the coupling of the pin before the fastening is about to start is almost completely started from a state in which the threads are engaged with each other. Figure 5 In addition, although not an example of evaluation of a solid lubricating film, in Non-Patent Literature 1, a fastening test method based on a vertical power tongs using a short pin is described. In Non-Patent Literature 1, a method is described in which, regardless of the outer diameter and the wall thickness of the oil well pipe to be evaluated, a state in which a weight of 5 kN (510 kg) is always loaded is implemented, regardless of whether it is at the time of fastening or at the time of loosening. In Non-Patent Literature 1, as the pin, 7”29#, 7”35# are described, and if the length of the pin is set to be close to the actual length of Range-3 of 40 feet (≈12 m), the pin load is about 520 kg or about 630 kg. Therefore, it is considered that the weight of one amount of the evaluation size is applied, regardless of whether it is at the time of fastening or at the time of loosening. In addition, if judged from the torque rotation diagram, it is known that since fastening is completed in an amount of half a turn (see Non-Patent Literature 1, FIG. 1), the initial set position of the coupling of the pin before the fastening is about to start is almost completely started from a state in which the threads are engaged with each other.

[0015] Prior Art Documents

[0016] Patent Literature

[0017] Patent Literature 1: International Publication No. 2018 / 216416

[0018] Patent Literature 2: Japanese Patent Application Publication No. 2008-069883

[0019] Patent Literature 3: Japanese Patent Application Publication No. 2008-537062

[0020] Patent Literature 4: International Publication No. 2014 / 024755

[0021] Patent Literature 5: International Publication No. 2009 / 057754

[0022] Patent Literature 6: Japanese Patent Application Laid-Open No. 2017-110685

[0023] Patent Literature 7: Japanese Patent Application Laid-Open No. 2004-053013

[0024] Non-Patent Literature

[0025] Non-Patent Literature 1: Tsunoda et al., Journal of the Society of Oil Technologists, Vol. 61, No. 6 (1996) pp. 527-536 Figure 1 ) SUMMARY

[0026] PROBLEMS TO BE SOLVED BY THE INVENTION

[0027] The inventors have studied solid lubricating films in view of the materials of the solid lubricating films described in the above-mentioned patent literatures and the like. Specifically, the inventors have studied the lubricity of a film structure in which the amount of MCA (melamine cyanurate) used as a solid lubricant is optimized, on the basis of adjustment of the hardness of the binder resin by optimizing the blending ratio of cellulose and its derivatives to alkyd resin, in order to further improve lubricity. Further, the inventors have studied whether or not corrosion resistance can also be maintained. In this study, cellulose and its derivatives were studied with nitrocellulose as the center. However, in the past patent literatures, there is no example in which this combination is used for improvement of lubricity and improvement of corrosion resistance. That is, in the past patent literatures, although the conditions are different, each of the constituent elements is only individually specified as an appropriate range.

[0028] In the patent literatures 1 to 4, the use of MCA as a solid lubricant is described. However, MCA is only one of the candidates listed as a solid lubricant. In the patent literatures 1 to 3, alkyd resin is not specified as a binder resin for holding a solid lubricant. At this time, even if alkyd resin is widely understood as polyester resin, polyester resin is not listed as a candidate for a binder resin. In the patent literature 4, it is a film containing semi-solid to viscous oil and the like compared to a hard resin film, and thus is different from the application mode of the present application. Furthermore, in the patent literatures 1 to 4, only MCA is exemplified, and it is not shown in detail that a specific size range, a specific concentration range, and the like are appropriate.

[0029] In addition, in Patent Literature 5, there is an example in which the binder resin uses an alkyd resin. However, Patent Literature 5 is not an example applied to oil well pipe threads, but widely takes a metal material as an object. Furthermore, in Patent Literature 5, the alkyd resin is not the main body. In the context of the invention in which the silica particle is used as the rust-preventive coating, in the candidate group of the coating film in which the silica particle is used as the binder for fixation, only the possibility of the alkyd resin as one of the binders is listed. In particular, this does not match the field targeted in the present invention.

[0030] Regarding the nitrocellulose, it is described in Patent Literatures 6 and 7. In Patent Literature 6, as an example of the additive contained in the lubricating film, a carbohydrate is exemplified. Furthermore, as an example in which the film quality of the carbide changes to the high viscosity side at high temperatures, an example is exemplified.

[0031] In the present invention, the nitrocellulose is used as the binder resin, and in contrast, Patent Literature 7 is an application example based on a different idea from the use of the nitrocellulose-based as the binder resin. That is, it is an application example of the solid layer in the lubricating film structure of the double-layer structure of the liquid layer and the solid layer.

[0032] In Patent Literature 7, in order to retain the solid lubricant, as a resin that is cured in the room temperature region, the nitrocellulose is exemplified as one of the candidate groups. However, the polymerization with the alkyd resin as in the present invention is not assumed.

[0033] As described above, in any of the patent literatures, there is no description of the solid lubricating film based on the nitrocellulose and the alkyd resin for the purpose of balancing the lubrication and the corrosion prevention. Originally, for the lubricating film using the cellulose and the cellulose derivative or the nitrocellulose, the film of these monomers is brittle. Therefore, it is not used for the lubrication use. It is necessary to optimize the most optimal, the appropriate amount of the addition of the solid lubricant, and the balance of the binder resin and the solid lubricant. That is, in the case of simply mixing only with these constituent elements, it is difficult to achieve the expected lubrication. It is necessary to additionally add an appropriate additive material while explicitly indicating the detailed conditions of each constituent element. However, regarding this point, none of the patent literatures describes it.

[0034] In addition, the lubrication of the oil well pipe thread targeted in the present invention is in a special sliding condition.

[0035] That is, in the field (actual well), the pin having an actual length of about 8 m or more and less than about 15 m is fastened / loosened with respect to the sleeve provided below. At this time, the pin is in a condition in which, although it is fastened / loosened using a power tong in a state of being lifted by a crane, the entire load of the pin can be applied to the sleeve thread. That is, it becomes lubrication in a large load application state.

[0036] In addition, at this time, the pin is not necessarily fastened and loosened in an ideal state. That is, at the time of fastening, the pin thread is inserted into the box thread, or is set in a state of being slightly manually tightened. However, the pin is not set upright without moving with respect to the box thread. In addition, the pin is not set in a state of being straight (without being bent) with one side being inclined. That is, the lower portion of the pin is restrained by the box thread, and depending on the modulus of elasticity (Young's modulus) possessed by the material and the actual pin length, the upper end side (the opposite side of the fastening side, the front end side) becomes a state of being slightly bent. In particular, in the case of a pin of a length of 8 m or more, when viewed from below, the pin is set straight in the box, and looks like a curve. From such a state, the pin is fastened and loosened. Therefore, the box thread and the pin thread are not fastened and loosened in a state of being uniformly and symmetrically loaded. Therefore, a situation (lubrication in a state of an asymmetric load) in which fastening and loosening are performed in a state in which a portion of the thread surfaces locally collide strongly is caused. In addition, the portion that locally collides strongly also changes depending on fastening and loosening.

[0037] In the lubrication technology using the conventional grease-like compound, the compound moves following at the time of fastening and loosening. Therefore, even if there is some variation in lubrication conditions or the like, the lubricant (lubricating compound) functions in such a way that fastening and loosening converge in a good direction. Therefore, in the evaluation test (also referred to as a laboratory test) of the fastening and loosening of the threaded joint, it is possible to grasp the lubrication condition of the actual size pin by using the evaluation of the short pin without depending on the evaluation using the actual size pin.

[0038] On the other hand, according to the investigation by the inventor, in the lubrication technology of the oil well pipe thread using the solid lubricating film, the solid lubricating film is inevitably ground to some extent. Moreover, it is necessary to somehow prevent the grinding chips from clogging the thread gap. In addition, at this time, the secondary formation from the ground solid lubricating film does not necessarily always move following in conjunction with fastening and loosening.

[0039] This is a point that is greatly different from the case of using the wet lubricating compound, which occurs in an actual well.

[0040] Moreover, in the oil well pipe threaded joint, the following insight was obtained: the lubrication technology of the oil well pipe thread using the solid lubricating film cannot be evaluated by the same evaluation as the conventional lubrication technology using the grease-like compound, and becomes a loose evaluation. That is, in the conventional patent literature, the evaluation of the fastening and loosening of the oil well pipe threaded joint is mostly an evaluation using the lubrication using the wet lubricating compound even if it is an evaluation of the solid lubricating film, and therefore, the insight that the conditions (suitable range of components, etc.) of the solid lubricating film lubrication described in the past patent literature cannot be directly adopted was obtained.

[0041] That is, in the case where the solid lubricating film is evaluated by a laboratory test, in the evaluation using a short pin as in the case of lubrication using a lubricating compound, due to the reasons as described above, it is not necessarily possible to simulate the effects of large load / uneven load. In the evaluation using a short pin shorter than the actual conditions in the well, it is known that the solid lubricating film is not easily ground, and it is not possible to form conditions that can simulate the actual behavior of burning (burning) in the well.

[0042] Thus, in the conventional evaluation using a short pin, the secondary product formed by the grinding chips of the solid lubricating film is clogged and burned, or the secondary product is pressed again on the fastening surface, and it is not possible to simulate the conditions such as the effect of maintaining the lubricating film. That is, in the conventional evaluation using only a short pin, the evaluation of the solid lubricating film is somehow relaxed, and there is a problem that an area that is inherently unqualified is erroneously evaluated as a suitable range when deciding the physical property parameters of the solid lubricating film.

[0043] For such reasons, the inventors have reached the following insight: in the records of the conventional prior art documents, the actual situation is that the suitable range is recorded based on the relaxed evaluation as described above.

[0044] As described above, it is reached the following insight: as the specificity of the lubrication of the oil well pipe thread, the following (1), (2) need to be considered.

[0045] (1) At the initial stage of fastening of the thread and at the late stage of loosening of the thread, there is play (play) in the structure.

[0046] (2) The lubrication / friction in the state where a large weight is applied from the upper part is targeted.

[0047] That is, it is necessary to be in the same conditions as the actual well pipe thread in the well is exposed to fastening loosening. That is, it is necessary to perform the provision of the parameter set related to the solid lubricating film on the premise that the fastening loosening is performed under large load / uneven load. It is reached the following insight: it is necessary to complete the invention on the basis of the clear meaning of guaranteeing lubricity and providing upper and lower limits of the parameters that follow such actual use conditions.

[0048] Thus, it is important to set the upper and lower limits of the parameters in accordance with the actual conditions of the well. With respect to the lubrication behavior to be confirmed in the lubrication of the oil well pipe thread, in the past, the tightening and loosening behavior using a power tongs with a short pin, the number of tightening and loosening, has been used as an evaluation target. With the past grease-like compound, the compound also moves in conjunction with the tightening and loosening. Thus, in evaluating the lubrication, there is no particular problem whether the evaluation is performed using a horizontal tongs with a short pin or a vertical tongs, and the lubrication behavior can be evaluated. That is, with the past grease-like compound, the evaluation can be performed using a short pin, including the design of the thread, the presence or absence of a base layer such as chemical conversion treatment or plating, and comparative evaluation of the compound itself.

[0049] On the other hand, in the case of lubrication of the solid lubricating film, this is not the case. In the evaluation using a short pin, the simulation of the actual well does not occur, and a rather loose evaluation of the lubrication occurs. The evaluation of "not qualified" using a short pin coincides with "not qualified" in the tightening and loosening in the actual well. However, on the other hand, the evaluation of "qualified" using a short pin does not necessarily mean "qualified" in the tightening and loosening in the actual well. The evaluation of "qualified" using a short pin becomes an evaluation that also includes "not qualified" in the tightening and loosening in the actual well, and this becomes a problem.

[0050] In addition, the lubrication of the oil well pipe thread has a point that is different from other lubrication behaviors, and thus there is a problem that the provisions made based on the evaluation performed under other lubrication conditions cannot be applied.

[0051] In general, if the lubrication behavior between two objects that rub against each other is mentioned, a situation in which one is fixed and the other moves is assumed. Also, with respect to the moving object, it is assumed that the lubrication starts from a state in which the object is in close contact with the fixed object. Even in the case where both objects move, the lubrication often starts from a state in which they are in close contact with each other.

[0052] On the other hand, in the lubrication of the oil well pipe thread, at the initial stage of tightening, the pin thread (external thread) starts from a state in which there is a thread play amount with respect to the sleeve thread (internal thread). Thus, before the threads are engaged with each other to a certain extent, the threads do not always stably contact each other. That is, in the lubrication of the oil well pipe thread, the cases where the threads strongly collide with each other and the cases where the threads hardly collide with each other are not uniform. In addition, when the threads strongly collide with each other, there is a high concern that the lubrication film is damaged. Furthermore, in the lubrication after the threads are engaged, the sliding is affected by the lubrication conditions on the spot.

[0053] In particular, in the case of the solid lubricating film, in the "loose" state before the threads are engaged, there is a problem that the solid lubricating film is easily damaged by the bias load from the loose.

[0054] In particular, in the case of the lubricating coating film composed of cellulose and cellulose derivatives, or nitrocellulose and alkyd resin, which is the object of the present application, the brittleness inherent to the binder resin becomes a key. Under the use conditions in an actual well, particularly in the state of looseness before the engagement of the thread, the film peels off without fail or the film breaks. In this phenomenon, in order not to occur a case where lubrication cannot be ensured, it is necessary to design a solid lubricating coating film.

[0055] In addition, in an actual well, at the time of tightening and loosening, there is an influence caused by the total weight of the pin thread being applied to the box thread. In addition, since there is looseness as described above, this load is not uniformly applied, and before the engagement of the thread, there is a tendency that the pin rotates eccentrically. Therefore, the solid lubricating coating film must be a film that is tolerable to a large load applied as an eccentric load. In the case of a film that peels off without fail, or a film that almost disappears by being broken, it is not possible to cope with. In an actual well, oil well pipes are mostly used at about 12 m to about 16 m. For example, an oil well pipe of a length of about 12 m (about 40 feet) is about 1 t of load of dead weight in the case of an outer diameter of 9-5 / 8". In a marine drilling rig, mostly, a pin thread connected in advance by three is used. Therefore, if an oil well pipe of an outer diameter of 9-5 / 8" is used, it becomes a severe condition of about 3 tons of load applied to the box side.

[0056] In the lubrication of an oil well pipe thread, it is necessary to assume lubrication tolerable to such a large load and an eccentric load. Moreover, the inventors have conducted various studies, and as a result, obtained the following insight: it is important to research a solid lubricant and a binder resin, taking into consideration how to suppress the damage of a solid lubricating coating film under the condition of a large load and the condition of looseness before the engagement of the thread.

[0057] On the other hand, in the past patent literatures, it is difficult to say that the solid lubricating film is designed based on such a viewpoint. For example, in Patent Literature 1, the fastening is performed by hand tightening until the threads are engaged at the initial stage of fastening, and thus, it is not considered that the looseness is clear. In addition, the fastening to the portion where the threads are engaged with each other is indirectly shown as a laboratory evaluation using a short pin. In an actual well, the fastening is not like this to the engagement of the threads. The actual size pin thread is almost impossible to be set in an ideal upright state. The pin is fastened somewhat bent. Thus, almost all of the hand fastening is ended at a position where the pin thread tooth is not completely received in the coupling. In Patent Literature 2, Patent Literature 3, Patent Literature 4, and Patent Literature 6, it is performed at a fastening speed of 10 rpm. In Patent Literature 7, as a test which simulates the operation in the actual pipe, it is described that the fastening test is performed at a fastening speed of 20 rpm, and the fastening and loosening test is performed. None of them discloses the information to the initial fastening position. However, since it is not particularly clearly described that the fastening is performed in the actual well, it is presumed that the result is the laboratory using the short pin. In addition, in the instruction manual of the thread provided by the applicant of these patent literatures, it is taught that the fastening is performed at 1 rpm or less at the time of tightening. Thus, it is presumed that the fastening and loosening test in these patent literatures is the laboratory test. Since it is not particularly clearly described that the fastening is started using a power tong at the beginning, when the threads of the pin and the sleeve are set by the hand fastening, it does not seem to intentionally start the fastening from the portion having the looseness.

[0058] Here, in the method of applying the grease-like compound, the viscous liquid-like grease-like compound is also moved in conjunction with the fastening and loosening. Thus, the portion where the influence of the large load and the eccentric load is considerable is mitigated. Thus, whether the evaluation is performed using the short pin using the horizontal tong or using the vertical tong, the lubricating behavior can be evaluated without a particular problem.

[0059] On the contrary, in the case of the lubricating behavior of the oil well pipe thread using the solid lubricating film, the solid lubricating film which is comparable to the viscous liquid-like grease-like compound is damaged and peeled off at the fastening before the engagement of the threads and at the fastening after the engagement. Or, the solid lubricating film is inevitably thinned gradually. The debris of the peeled off solid lubricating film is not necessarily moved in conjunction with the fastening and loosening unlike the grease-like compound. The influence of the secondary product from the thinned solid lubricating film released to the gap between the pin thread and the sleeve thread has a great influence on the lubrication. If the thread gap is occluded, it directly leads to the burn. Or, by pressing the secondary product with a large load, it is moved in conjunction with the fastening and loosening contrary. Sometimes the secondary product is pressed and reconstituted, and is attached again in the form of a film to either of the threads, thereby improving the lubrication.

[0060] In the past, it was not possible to simulate the large load and the eccentric load that occur in actual wells using short pins. Therefore, in the past laboratory tests, the secondary products from the solid lubricating film were small, and the lubricating behavior was often erroneously determined to be acceptable. Therefore, the design of the solid lubricating film was often not good until the pipe was applied to an actual well. Moreover, it was not possible to simulate the actual conditions in the well if the condition in which "looseness" exists before the thread engagement is not intentionally created.

[0061] On the other hand, it is not realistic to perform a test each time using an actual size pin in an actual well or a simulated well (a test field in which an actual size pin is erected to perform a tightening and loosening test). The test cost becomes enormous, and it is not realistic. The latter costs a rental fee of about 10 million yen or more per day, and in a solid lubricating test, if the diameter is small, it is estimated that the maximum number of times is 10 to 20 times of tightening and loosening, and a large cost is incurred to perform such a test.

[0062] In the past patent literature, such a consideration is almost not made in the evaluation of the solid lubricating film. Moreover, in the lubricating evaluation of the thread, there is no particular indication, and the application examples of a horizontal clamp that is often present in a laboratory and a vertical clamp using a short pin are mostly used. If evaluation is performed using them, it becomes evaluation in which the influence of the above-mentioned large load / eccentric load is excluded, and therefore, basically, almost all of them show good results. Therefore, in these evaluation methods, even if appropriate upper and lower limits are defined, it does not mean an appropriate range in the true sense.

[0063] Even the conditions selected by the short pin evaluation in a laboratory include cases in which the lubrication in an actual well cannot be said to be good, and it cannot be said that the technology is determined.

[0064] Here, although it is not an investigation of the lubricating behavior of the solid lubricating film, in Non-Patent Literature 1, a load of 510 kg is continuously applied at all times during the tightening and loosening of the thread. This can mean that a weight equivalent to one of an actual size pin of a 7" size is applied. As described above, in the evaluation of the solid lubricating film, it is important to simulate the large load and the eccentric load that occur in an actual well. This is because the secondary phenomena caused by the secondary products from the solid lubricating film have a large influence on the lubrication. However, in Non-Patent Literature 1, it is difficult to say that the large load is certainly simulated depending on the size.

[0065] In addition, in Non-Patent Literature 1, it is not possible to simulate the eccentric load. If it is determined according to Non-Patent Literature 1 Figure 1 and the like, there is no one rotation until the tightening in the case of a premium joint. Therefore, there is a problem in that the initial tightening position (the tightening start point) based on the manual tightening is intended to test the lubrication that is performed from the state in which the threads engage with each other.

[0066] Here, although it is difficult to notice, if the above load is continued at the time of loosening, there is a problem as follows. That is, it is understood that, although it is a pitfall in laboratory evaluation, the weight becomes a balancer at the time of loosening and the thread is loosened straight from the initial fastening position without being loosened. Therefore, the pin does not rotate and the burn generation at the time of loosening in the actual well cannot be properly simulated. Depending on the situation, there can be a misunderstanding that the condition is good in lubricating properties. Therefore, regarding the condition parameters related to the film of the solid lubricating film, it is necessary to take the lubrication state of the state where the thread is not sufficiently engaged and the lubrication after the engagement into the field of view to simulate and prove that the lubricating properties are excellent.

[0067] For the lubrication of the oil well pipe thread using the solid lubricating film, it is necessary to achieve lubrication equivalent to the lubrication level that can be achieved by the conventional composite by specifying the binder resin and the solid lubricant as an additive in the binder resin and optimizing it. However, the evaluation of the conventional solid lubricating film does not become the evaluation under the condition generated in the actual well as described above. That is, it is necessary to specify the appropriate range of the solid lubricating film by a test method that reflects the points as described above. However, there has been no such laboratory test in the past.

[0068] The present application is completed focusing on the points as described above, and aims to achieve burn prevention (seizure resistance) equivalent to or higher than the method of the prior art doped composite with respect to the lubricating properties at the time of fastening and loosening of the oil well pipe using the solid lubricating film.

[0069] Method for solving the problem

[0070] The present application forms a solid lubricating film in which MCA (melamine cyanurate) is specified as the main component of the solid lubricant and the binder resin composed of nitrocellulose and alkyd resin is specified as the main body, which has not been focused on in the past.

[0071] In addition, in view of the problems as described above, the inventors conducted research, and as a result, it was understood that the above problems can be solved by the formulation of the reagent, the development of the solid lubricating film of the oil well pipe thread, the method of confirming it, and the like.

[0072] It was understood that the important points are the following four points and the condition control of the related matters related thereto in the appropriate range.

[0073] (a) The upper and lower limits of each parameter are specified by an appropriate test method that confirms the fastening in the actual well or simulates the fastening and loosening of the actual well, and the appropriate range thereof is clarified;

[0074] (b) The optimal range of MCA (melamine cyanurate) of the main solid lubricant is specified using the above (a);

[0075] (c) using the above (b), defining the optimum range of the main nitrocellulose and alkyd resin;

[0076] (d) and defining other additives, plasticizers, solvents, etc.

[0077] Based on the above insights, to solve the problem, one mode of the present application is an agent for forming a solid lubricating coating on a threaded portion of an oil well pipe, the gist of which is that a solid lubricant is dispersed with respect to a binder resin, the main component of the above-mentioned solid lubricant is melamine cyanurate, the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less, as the above-mentioned binder resin, an alkyd resin and a nitrocellulose are contained, the alkyd resin and the nitrocellulose are contained in 85% by weight or more of the total weight of the binder resin components, and the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight with respect to 100 parts by weight of the total weight of the binder resin.

[0078] In addition, a mode of the present application is an oil well pipe in which a lubricating coating having a solid lubricating coating is formed on a threaded portion, the gist of which is that a lubricating coating having a solid lubricating coating is formed on a fastening surface of a threaded portion of a member of at least one of the above-mentioned sleeve and the above-mentioned pin, the above-mentioned solid lubricating coating is constituted by dispersing a solid lubricant with respect to a binder resin, the main component of the above-mentioned solid lubricant is melamine cyanurate, the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less, as the above-mentioned binder resin, an alkyd resin and a nitrocellulose are contained, the alkyd resin and the nitrocellulose are contained in 85% by weight or more of the total weight of the binder resin components, and the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the total weight of the binder resin.

[0079] Effects of the Invention

[0080] According to the mode of the present application, it is possible to provide a solid lubricating coating which employs MCA as a solid lubricant and which can impart good lubricity and corrosion resistance to the threaded portion of an oil well pipe.

[0081] For example, according to the mode of the present application, it is possible to obtain an oil well pipe threaded joint which has lubricity at the time of fastening and corrosion resistance, taking into consideration conditions equivalent to actual wells which can occur in actual well environments. Note that the conditions equivalent to actual wells refer to conditions such as a situation in which the sleeve is subjected to the weight of the pin from above, a situation in which the load is applied obliquely due to axial misalignment, a situation in which the load is applied unevenly and locally, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0082] Figure 1is a drawing showing an oil well pipe and an oil well pipe threaded joint.

[0083] Figure 2 is a drawing of a tightening chart in an actual well and a drawing (b) showing an initial set position at that time.

[0084] Figure 3 is a drawing of a tightening chart in a conventional laboratory test and a drawing (b) showing an initial set position at that time.

[0085] Figure 4 is a tightening chart schematic drawing, (a) is a case of an actual well, and (b) is a case of a conventional laboratory test.

[0086] Figure 5 is a drawing explaining a new laboratory test (dead load tong test).

[0087] Figure 6 is a drawing showing a set example of a dead load in a new laboratory test (dead load tong test).

[0088] Figure 7 is a drawing illustrating a coating structure. DETAILED DESCRIPTION

[0089] Next, an embodiment of the present application will be described with reference to the drawings.

[0090] Here, the inventors have repeatedly conducted research, and as a result, have found that the lubrication condition of the tightening and loosening of a solid lubricating coating is divided into two stages, and the conditions occurring in each stage need to be considered.

[0091] <Concerning Figure 2 >

[0092] Figure 2 (a) is an example of a torque reversal chart occurring in an actual well.

[0093] Figure 2 The condition of (a) is a torque reversal chart (tightening chart) when a tightening test is performed using a pin of an actual length of 40 feet (≈12 m) simulating an actual well. In actual oil / gas fields, the tightening is often started from a condition where the threads are not sufficiently engaged with each other. In view of this condition, in Figure 2 (a), the initial set position is as shown in Figure 2 (b). Note that, as the pin, a 9-5 / 8" 53.5# Q125 JFE LION TM thread was used. In addition, from the viewpoint of simulating an actual well, a pin of a length of about 40 feet or more (a pin of a length of Range-3) was used.

[0094] Furthermore,Figure 2 (a) is a graph when a vertical tong is fastened while being hoisted by a crane hoisted from above the rig in the form of the full length of the pin.

[0095] This Figure 2 (a) can be considered as a situation that often occurs in actual wells. The torque rotation graph is explained by dividing it into two stages. The region where fastening is released in a state where the threads of the sleeve and the pin are not fully engaged is set as "Stage 1". The region where the torque starts to rise and the torque increases with fastening while the threads are stably engaged with each other is set as "Stage 2".

[0096] Figure 2 In (a), it should be noted that, before the point at which the torque continuously increases (Stage 2), the torque should not rise in principle. However, in actuality, in Stage 1, a tendency that the torque irregularly and frequently rises in a spike shape can be observed. Figure 2 (a) in the region where the rotational speed is 6.3 rpm or less: Stage 1), the torque should not rise in principle. However, in actuality, in Stage 1, a tendency that the torque irregularly and frequently rises in a spike shape can be observed.

[0097] This implies that, in the region of Stage 1, the pin threads are irregularly and locally in contact with the sleeve threads while rotating. This is a situation that occurs in fastening in actual wells.

[0098] Moreover, in Stage 1, the design, optimization by the solid lubricating film means that the solid lubricating film is destroyed, peeled off to some extent cannot be avoided. Here, it is emphasized that, Figure 2 (a) is not intentionally formed in the worst state, but is a torque rotation graph of a very ordinary sample with a solid lubricating film.

[0099] Regarding Figure 3 >

[0100] On the other hand, Figure 3 (a) is a torque rotation graph in the case where fastening is performed using the same solid lubricating film as in Figure 2 (a) and using a vertical power tong.

[0101] Figure 3 In (a), the same outer diameter, wall thickness, and thread type as in Figure 2 (a) are adopted, but a short pin of about 1 m in length is adopted as the pin. In this case, a situation in which a load of 100 kg corresponding to the weight of the short pin is applied to the sleeve threads occurs.

[0102] In addition, Figure 3 (a) is a fastening-time graph (torque rotation graph) when fastening is started from a state in which the threads are sufficiently engaged with each other. That is, as shown in Figure 3 (b), it is a fastening-time graph (torque rotation graph) when the exposure of the pin threads is about 1 to 3 threads at the start of initial fastening.

[0103] ThisFigure 3 The condition of (a) is also a condition often used at the time of fastening in the past laboratory test, and is a case where the setting to the thread engagement is performed by hand fastening. In summary, compared with the case of Figure 2 , it becomes a case where the load is small (there is no influence of large load), and there is no initial rotation of the thread (there is no influence of bias load).

[0104] Figure 3 In (a), attention is paid to the fact that the unit of the horizontal axis is different from that of Figure 2 (a).

[0105] Figure 3 In (a), the state from the state where the setting to the thread engagement is performed by hand fastening, and therefore, the peak-shaped torque as seen in Figure 2 (a) is not observed.

[0106] From Figure 3 , it is known that in the past laboratory test, the position where the fastening by hand fastening is fastened to the thread engagement with each other is often taken as the initial position of the fastening by the power wrench. Therefore, the behavior of stage 1 before the threads are engaged with each other is not observed. Therefore, in the past laboratory test, it becomes a test where the fastening relaxation is evaluated only in the region of stage 2 after the engagement, under the condition where the destruction of the solid lubricating film which should be generated before the thread engagement does not occur (under the condition where stage 1 is not present).

[0107] Regarding Figure 4

[0108] Figure 4 (a) and Figure 2 (a) are graphs illustrated in a state where they are easily compared. Figure 3

[0109] (a) is an example of Figure 4 (a), Figure 2 (b) is an example of Figure 4 (a). Figure 3 According to the research of the inventor, if the use in the actual well is considered, the ideal solid lubricating film is preferably a film where the solid lubricating film is not destroyed, and the worry of the destruction or peeling is minimized in the region of (x) of

[0110] (a). Or, the peak can be slightly raised. This is a condition where damage is brought to the solid lubricating film. In this case, it is preferable that the secondary product from the solid lubricating film which is destroyed or peeled off does not clog the thread gap during the fastening relaxation, but rather, is well attached to the thread, and lubrication is assisted. Figure 4

[0111] ​​In this regard, many past documents have considered, when judged from the results of the tightening-loosening test, the lubrication after the thread engagement (b) Figure 4 (b), Figure 3 (a)) as the object. The lubrication after the thread engagement, i.e., the lubrication characteristics of the solid lubricating film itself was considered to be superior or inferior. Therefore, it was inferred that, using a short pin, using a horizontal tong, a vertical tong, and after the portion to be thread-engaged was set by manual tightening, tightening-loosening was performed. Note that, in the patent document in which the number of times of tightening-loosening was explicitly described, there was a description that, in the actual well tightening, if it was a small-diameter size, 10 times could be performed. In both the evaluation of the short pin and the evaluation of the actual well, this was the number of times that seemed possible. On the other hand, in the case of a large-diameter size such as 9-5 / 8" or 13-3 / 8", there were scattered descriptions that, in the tightening-loosening based on the solid lubricating film, the number of times of tightening-loosening could be performed up to 15-20 times. However, this was almost impossible in the case of the actual well tightening and the use of the solid lubricating film for a large diameter.

[0112] In addition, in the case of a large-diameter size of the oil well pipe thread, the tightening torque value is probably higher, and the play (looseness) of the sleeve thread and the pin thread is more. Accordingly, before the thread is sufficiently engaged, the solid lubricating film is inevitably damaged and peeled to some extent. In addition, at the beginning of the test, at the stage of setting the pin thread to the sleeve thread, since the weight of the pin is heavy, the operation is very difficult. Therefore, unintentional collision of the pin thread and the sleeve thread also occurs at a certain frequency, which also damages and peels the solid lubricating film.

[0113] Furthermore, the present embodiment focuses on the actual well tightening-loosening situation, designs a new laboratory test, and also refers to the evaluation based on the new laboratory test.

[0114] Here, a suitable method for simulating the tightening and loosening of the actual well is a method for simulating the tightening behavior that occurs when the oil well pipe thread is tightened in the actual well. Using this method, the upper and lower limits of the parameters of the present application are confirmed, and the appropriate range is determined. The evaluation of the lubrication of the oil well pipe thread needs to be determined by assuming what occurs in the actual well. For this reason, the evaluation can be performed only by simulating what occurs in the actual well, or the evaluation can be performed using an actual length pin. The tightening and loosening of the oil well pipe thread can be considered in two stages. The pin thread is inserted into the box thread, and is directly rotated, or is rotated by hand to a certain extent to engage the threads. However, there are a procedure from when the threads do not completely engage each other to when the torque rises, i.e., when the threads are sufficiently engaged, and a procedure after the threads are engaged. The former is a condition that does not exist much in consideration of the usual friction / slip. The latter is generally a condition that is commonly assumed if it is referred to as friction. In the case of the former, the tightening and loosening is performed at 5 to 25 rpm, and after the torque rises, the tightening and loosening is performed at a low speed of rotation of only from less than 1 rpm to at most about 3 rpm. In the actual well, since the pin is provided suspended from above, it becomes a condition in which the maximum is the weight of the pin applied to the box thread. This is referred to as a large load. In addition, if the pin performs the tightening and loosening standing up as viewed from a distance, in reality, since there is play in the threads, the tightening and loosening is performed eccentrically before the threads sufficiently engage each other. This is referred to as an eccentric load. In particular, in the region where the threads are not engaged, the solid lubricating film is easily damaged, and a portion peels off. Therefore, in order to prevent this peeled piece from clogging the gap of the threads, or from burning, the solid lubricating film itself is designed by the solid lubricant, the adhesive resin, and other specifications.

[0115] For each of the above-described elements, an appropriate range is specified. Furthermore, the film evaluation evaluates the lubrication based on the play and the large load application conditions according to what occurs in the actual well, and determines the lubrication, thereby completing the present application.

[0116] (Construction)

[0117] The present embodiment is an invention relating to a film structure formed on a tightening surface in an oil well pipe thread used in an actual oil / gas, and a threaded joint having the film structure as a lubricating film. In the present embodiment, the lubricating film having the solid lubricating film formed on the tightening surface of the threaded joint has a feature, and the threaded structure of the threaded joint itself is not particularly limited. The threaded structure of the threaded joint can adopt a known or new threaded structure.

[0118] <Oil well pipe and oil well pipe threaded joint>

[0119] The oil well pipe is constituted by a box 2, a pin 1, and the like, as shown in Figure 1 ​

[0120] As shown in Figure 1 Fig. 1, an oil well pipe threaded joint is composed of a pin 1 having an external thread 1a and a box 2 having an internal thread 2a. Moreover, a contact surface (fastening surface 10) of a threaded portion in a member of at least one of the pin 1 and the box 2 is formed with a lubricating film having a solid lubricating film.

[0121] The following description is made with the center of a box thread (internal thread side) and a pin thread (external thread side). It also includes a joint of a T&C (thread & coupling) method and a joint of an integral method of an oil well pipe.

[0122] <Reagent>

[0123] Hereinafter, a reagent for forming a solid lubricating film in the present embodiment is described.

[0124] The reagent of the present embodiment is composed by dispersing one or two or more solid lubricants in a binder resin as a base component.

[0125] The main component of the solid lubricant is melamine cyanurate, and the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less. The main component of the solid lubricant means, for example, 80% by weight or more, preferably 90% by weight or more of the total weight of the solid lubricant is melamine cyanurate.

[0126] When the total weight of the binder resin is set to 100 parts by weight, the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less.

[0127] As the binder resin, an alkyd resin and nitrocellulose are contained. The alkyd resin and the nitrocellulose are contained in 85% by weight or more of the total weight of the binder resin components.

[0128] The weight of the nitrocellulose is preferably 0.5 times or more and 3 times or less of the weight of the alkyd resin.

[0129] The solvent contained in the reagent contains one or two or more materials selected from the group consisting of solvent oil, aromatic, alcohol, ester solvent, and ketone solvent. The aromatic is, for example, solvent oil, or toluene, xylene, naphtha, benzene, or the like. The alcohol is, for example, ethanol, propanol, isopropanol, butanol, or the like. The ester solvent is, for example, butyl acetate, methyl acetate, isobutyl acetate, or the like. The ketone solvent is, for example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, or the like.

[0130] The weight of the solvent is, for example, 20% or more and 80% or less of the total weight of the total weight of the solid lubricant and the total weight of the binder resin.

[0131] The oil length of the alkyd resin is, for example, 10 to 60.

[0132] In addition, the agent can contain a plasticizer. The plasticizer is set, for example, to one or two or more materials selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP).

[0133] In the case of containing a plasticizer, for example, 10 parts by weight or more and 20 parts by weight or less of a plasticizer are contained with respect to 100 parts by weight of the weight of the nitrocellulose.

[0134] <Coating structure of oil well pipe thread>

[0135] Hereinafter, the coating structure of the oil well pipe thread in the present embodiment will be described.

[0136] A lubricating coating having a solid lubricating coating is formed on the fastening surface of the threaded portion of the member of at least one of the sleeve and the pin. The solid lubricating coating is constituted by dispersing a solid lubricant with respect to a binder resin as a base component.

[0137] The main component of the solid lubricant is melamine cyanurate, and the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less.

[0138] As the binder resin, an alkyd resin and a nitrocellulose are contained. The alkyd resin and the nitrocellulose are contained in 85% by weight or more of the total weight of the binder resin components.

[0139] The total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the total weight of the above binder resin, and the thickness of the above solid lubricating coating is 10 μm or more and 150 μm or less.

[0140] The lubricating coating can have a base layer 10B( Figure 7 (b)) between the fastening surface and the solid lubricating coating.

[0141] The base layer 10B contains, for example, a Mn phosphate chemical conversion treatment film, a zinc phosphate chemical conversion treatment film, or an electroplated film containing one or more metals selected from the group consisting of Cu, Sn, and Zn.

[0142] The solid lubricating coating has, for example, a hardness of 2B or more in terms of pencil hardness.

[0143] <Oil well pipe thread joint>

[0144] A lubricating coating having the above solid lubricating coating is formed on the fastening surface of the threaded portion of the member of at least one of the sleeve and the pin.

[0145] Alternatively, a lubricating film having the above-mentioned solid lubricating film is formed on the fastening surface of the threaded portion of the component of one of the sleeve and the pin. On the other hand, a second solid lubricating film, which is softer than the above-mentioned solid lubricating film, is formed on the fastening surface of the threaded portion of the component of the other of the sleeve and the pin.

[0146] The second solid lubricating film is constituted, for example, by dispersing a second solid lubricant with respect to a second binder resin as a base component. The second binder resin contains a fluorine-containing organic compound as a main component. The second solid lubricant component contains one or two or more compounds of a material using a fatty acid selected from the following Group X and a material of a metal element selected from the following Group Y.

[0147] • Group X: stearic acid, isostearic acid, behenic acid, lauric acid, 12-hydroxystearic acid

[0148] • Group Y: Li, Na, Mg, Al, Ca, Zn, Ba

[0149] As for the solvent possessed by the reagent for forming the second solid lubricating film, for example, a fluorine-containing solvent of the following Group Z accounts for 90% or more in the weight of the solvent component.

[0150] • Group Z: HFC, HFE, HFO

[0151] The second solid lubricating film preferably has a pencil hardness of 3B or less.

[0152] Here, the inventors simply selected MCA as a solid lubricant and a binder resin composed of nitrocellulose and an alkyd resin as a binder resin, and tried to make a solid lubricating film with them as main components. In this case, if the fastening and loosening test is actually performed, burned and unburned ones are mixed, becoming a situation that was completely unexpected. That is, with reference to the disclosed invention group, simply combining materials cannot achieve the lubrication achieved by the conventional lubricating compound. Therefore, even if the past invention is used for analogy, it is not necessarily possible to reproduce good lubrication.

[0153] Moreover, in the present embodiment, the test was performed by an evaluation method capable of evaluating in conditions equivalent to actual wells, which will be described later. Also, with reference to the test results, for the solid lubricating film, a solid lubricating film in which the burn prevention property is further improved and which can also withstand use in actual wells, and a suitable range of each reagent covering a range extending to the reagents and oil well pipe threaded joints or metal materials were found, thereby completing the present invention.

[0154] Further, detailed description will be given.

[0155] <Basic constitution and film thickness of solid lubricating film>

[0156] The solid lubricating coating of the present embodiment is formed by dispersing a solid lubricant having MCA (melamine cyanurate) as a main component in a binder resin composed of an alkyd resin and nitrocellulose. The combination is preferably derived from a large number of experiments based on new laboratory tests of a new design.

[0157] MCA is selected as the main component in the solid lubricant for the following reasons. That is, because MCA is excellent as a lubricant that provides high lubrication, and even in the presence of some burning and local high temperatures, high lubrication can be maintained. At the time of fastening and loosening, friction heat is sometimes generated by the mutual friction of the pin threads and the box threads, and at this time, lubrication is sufficiently maintained.

[0158] The binder resin composed of an alkyd resin and nitrocellulose is selected for the following reasons. The selection of the alkyd resin and nitrocellulose is a level development of so-called technology from paint coating. Paint coating has the following characteristics: if an alkyd resin of an appropriate oil degree is selected, curing can be performed even without heat treatment at normal temperature and pressure. Therefore, film formation can be made simple, and overcoating is also possible. Furthermore, because paint coating does not have a particular problem even if the above-mentioned MCA is mixed in.

[0159] The binder resin preferably provides a film that is as hard as possible. A hardness of about HB to about 2H on the pencil hardness scale is preferred. In addition, the binder resin does not peel off little by little like that, and in order to not produce peeling that leaves a large portion (peeling without leaving a trace), brittleness needs to be overcome.

[0160] Regarding the film thickness of the solid lubricating coating, film formation of 10 μm is required at a minimum. If the film thickness is 10 μm or more, lubrication properties can be maintained, and corrosion resistance can be maintained. Regarding the upper limit of the film thickness, the clearance of the box threads and the pin threads differs depending on the type and design of the oil well pipe threads, and therefore, it cannot be generalized. In the present embodiment, for example, 150 μm is set as the upper limit. The clearance of the thread teeth of many oil well pipe threads is designed with 100 to 200 μm as a target, and therefore, 150 μm is specified as the upper limit. More preferably, the film thickness is preferably 10 to 50 μm.

[0161] Here, the clearance of the tooth groove of the external thread and the internal thread can be 100 to 200 μm as described above. However, the clearance between the penetration tooth flanks of the external thread and the internal thread and the clearance between the load tooth flanks vary at the time of tightening and loosening. When the clearance narrows, a substantially close state is obtained. Therefore, the smaller the film thickness, the better, and a range of 10 μm to 50 μm is preferable. However, these film thicknesses are film thicknesses in the As-formed state before the first tightening. At the time of tightening and loosening, there are cases where the adhesive resin is slightly shaved off and the film thickness coated at room temperature is actually crushed to become a thinned film in the actual state, and therefore, even if the thickness is above the clearance assumed in the actual well, it becomes a reason, and a problem of occurrence of a burn does not arise.

[0162] <Concerning the solid lubricant>

[0163] One or two or more kinds of solid lubricants are contained. Of the solid lubricants, melamine cyanurate (MCA) is contained at 80% by weight or more. The average particle diameter of the melamine cyanurate is 0.1 to 10.0 μm.

[0164] In the present embodiment, the solid lubricant having MCA as the main component is dispersed in the adhesive resin. Furthermore, the fact that MCA accounts for 80% when the total weight of the solid lubricant is the denominator and the average particle diameter of MCA is 0.1 μm or more and 10.0 μm or less is the constitutional element of the present application. These provisions cannot form a high lubricating state at any time in a widely generalized MCA. Therefore, this means that, in the use environment of the oil well pipe thread and in order to achieve high lubricity, the MCA dispersed in the epoxy resin used as the adhesive resin in the present application is optimally used in this range, and a significantly high lubricity can be expected.

[0165] The average particle diameter of MCA is preferably finer. Note that the average particle diameter is a parameter meaning the particle diameter at which the cumulative value in the particle size distribution obtained by a laser diffraction scattering method or the like is 50%.

[0166] As a more preferable range, the average particle diameter of MCA is preferably 2 μm or less. In the case where MCA having an average particle diameter of 2 μm or less is selected, there are rare cases where a coarse MCA of about 10 μm to about 20 μm is sometimes contained. The more preferable range is prescribed in order to eliminate the concern that a burn is generated due to the mixing of a coarse MCA.

[0167] The fact that MCA is 80% by weight or more of the solid lubricant means that MCA is the mainstream of the solid lubricant. In addition, when the total weight of the solid lubricant is the total parameter, even if other solid lubricants are contained at less than about 20%, it is defined in the sense that no bad influence is generated in the design of MCA as the main component.

[0168] In the present application, the more the proportion of MCA in the solid lubricant, the better. Since the lubricity is sometimes deteriorated by mixing other components in MCA, the range of treatment with MCA as the main component is set to 80% or more. As other solid lubricants that can be mixed in a range of less than 20% and can be envisaged, for example, BN of the same white tone, PTFE excellent in lubricity, etc. can be considered. In addition, as other solid lubricants, graphite, fluorinated graphite, MoS2, WS2, mica, talc, etc. can also be exemplified.

[0169] In addition, an oily substance can also be mixed in as one solid lubricant. For example, carnauba wax, PFPE oil (perfluoropolyether), CTFE oil (oligomer of trifluorochloroethylene), etc. can be mixed in. By mixing in an oily substance, the lubricity of MCA can be maintained or improved.

[0170] <Adhesive Resin Component>

[0171] As the adhesive resin component, an alkyd resin and nitrocellulose are contained, and the combination contains 85% by weight or more of the total weight of the adhesive resin component. It is preferable that the proportion of nitrocellulose be 0.5 times or more and 3 times or less of the weight of the alkyd resin.

[0172] In addition, it is preferable that the oil length of the alkyd resin be 10 to 60.

[0173] As the plasticizer, for example, one or two or more phthalates can be mixed in. In this case, it is preferable that, when the weight of the nitrocellulose is set to 100 parts by weight, 10 parts by weight or more and 20 parts by weight or less of the phthalate can be contained. Note that, as candidates for the phthalate, dibutyl phthalate (DBP), dimethyl phthalate (DMP), diethyl phthalate (DEP) can be exemplified.

[0174] In the present embodiment, as a constituent component of the adhesive resin, a so-called nitrocellulose lacquer is used. The nitrocellulose lacquer is a substance in which nitrocellulose and an alkyd resin are dissolved in a quick-drying solvent with compatibility. If this nitrocellulose lacquer is applied, the solvent is scattered on the surface of the application, and a hard film can be obtained. The film formed by the nitrocellulose lacquer is a hard film, but is accompanied by brittleness, so it is necessary to have a certain degree of flexibility.

[0175] By adding the alkyd resin, the film quality is improved. In this case, the alkyd resin is set to 0.5 times or more and 3 times or less of the weight of the nitrocellulose component. When it is less than 0.5 times, the brittleness characteristics are significantly improved. Moreover, at the time of tightening and loosening of the threaded connection of the oil well pipe, peeling off all at once is likely to occur, and as a result, the tendency to burn is high. When it exceeds 3 times, small cracks are likely to occur in the film of the adhesive resin.

[0176] In the present embodiment, it is assumed that the agent is dried by nature after being applied to form a film as the main use condition. Therefore, the oil length of the alkyd resin is preferably 10 or more and less than 60. When it is less than 10, heat treatment is required for film formation. When it exceeds 60, the viscosity is too high, and it can become lumpy during brushing and spraying, and uniform application can not be possible. In addition, when the oil length is large, it directly leads to a decrease in the strength of the alkyd resin, and thus is not preferable.

[0177] In addition, as described above, although the nitrocellulose is hard, it is accompanied by brittleness. Therefore, the alkyd resin is mixed to make a resin film. Furthermore, in order to overcome the brittleness, as a plasticizer, one or two or more phthalates are preferably mixed. When the weight of the nitrocellulose is set to 100 parts by weight, the plasticizer can be contained in 10 parts by weight or more and 20 parts by weight or less. Even if it is contained to such an extent, it is possible to minimize the cracks on the surface.

[0178] On the other hand, the nitrocellulose has a weak property against ultraviolet rays. Therefore, it is preferable not to directly irradiate sunlight to the surface with the solid lubricating film. Therefore, it is preferable to form the solid lubricating film on the sleeve thread side. In the case where the solid lubricating film of the present embodiment is applied to the pin thread side, it is recommended to use it in a state with a protector.

[0179] In addition, in order to prevent ultraviolet rays, regardless of the case, a trace amount of an agent having ultraviolet absorption ability of hydroxybenzophenone is allowed to be added in 5 parts by weight or less when the weight of the nitrocellulose is set to 100 parts by weight.

[0180] Furthermore, an additive for adjusting the dryness and liquid viscosity of the entire agent and adjusting the hardness when becoming the solid lubricating film, and a solvent that does not remain in the solid lubricating film after drying can be contained.

[0181] <About Solvent>

[0182] The agent contains a solvent.

[0183] The solvent, for example, includes one or two or more of solvent oil, or toluene, xylene, naphtha, benzene, ethanol, propanol, isopropanol, butanol, or the like.

[0184] In the present embodiment, the quick-drying property of the agent to be applied is intended. Therefore, it is preferable to dissolve the film components (nitrocellulose, alkyd resin, MCA, or the like) in an organic solvent having high volatility. The quick-drying property here means the property that the film is cured in about 5 minutes of natural placement. Depending on the case, a blast or the like can also be used in combination at the time of film formation.

[0185] The weight of the solvent is preferably 20% or more and 80% or less relative to the total weight of the adhesive resin made of nitrocellulose and alkyd resin as main components and the total weight of the solid lubricant made of MCA as main components. This is because, when it exceeds 80%, the reagent itself is too thin to be coated, and also, it is too time-consuming to dry. Thus, it is difficult to use. In addition, when it is less than 20%, the viscosity of the liquid excessively increases, and it is difficult to uniformly coat.

[0186] <Combination ratio of solid lubricant and adhesive resin>

[0187] When the total weight of the adhesive resin is set to 100 parts by weight, the total weight of the solid lubricant is set to 10 parts by weight or more and 100 parts by weight or less. When the total weight of the adhesive resin made of nitrocellulose and alkyd resin as main components is set to 100 parts by weight, the solid lubricant made of MCA as main components needs to be specified as described above.

[0188] When the solid lubricant is less than 10 parts by weight, the lubricant is too small to achieve proper lubrication, and burn occurs too early. In contrast, when the solid lubricant exceeds 100 parts by weight, the solid lubricant is too much. That is, the amount of the solid lubricant embedded in the adhesive resin made of nitrocellulose and alkyd resin is too much, and thus the adhesive resin itself becomes brittle. Also, the peeling of the coating film increases more than necessary at the time of fastening, and the risk of burn increases. Thus, it is necessary to adjust to the above range.

[0189] <Film hardness of solid lubricating coating film>

[0190] The above solid lubricating coating film preferably has a hardness of 2B or more in terms of pencil hardness. In the case where the behavior of the solid lubricating coating film in the actual well is assumed, there is a tendency that damage to the solid lubricating coating film easily occurs at the time of the behavior before the thread engagement, that is, at the time of the fastening of the oil well pipe thread in the state where there is looseness. However, by making the film quality hard, the damage is minimized. Specifically, by making the film hard to 2B or more, the solid lubricating coating film is not ground.

[0191] In the present embodiment, the solid lubricating coating film is made hard. Thereby, in order not to be destroyed without a trace at the time of fastening, the film maintains lubrication as a film quality that is not brittle. Thus, it is sufficient to adjust the hardness of the adhesive resin to be a hard film of 2B or more with nitrocellulose and alkyd resin as main components. As described above, the adjustment of the hardness can be achieved by the ratio of nitrocellulose to alkyd resin, the particle size and concentration of MCA.

[0192] The pencil hardness evaluation was determined by the method specified in JIS K 5600-5-4 (1999). This standard is translated into "ISO / DIS 15184, Paints and varnishes - Determination of film hardness by pencil test" standard, which is clearly described in the JIS standard. However, the pencil hardness test method itself is evaluated based on the specification in the JIS standard. In addition, the reason for evaluating the film hardness with pencil hardness is that the pencil hardness test method is an evaluation using "scratches" of a pencil, which is a similar behavior to the peeling of the solid lubricating film in the external and internal threads of the oil well pipe threads, and is a film hardness evaluation method due to "scratches". As for the film hardness measurement methods due to indentation, Rockwell hardness, Vickers hardness, Shore hardness, and Knoop hardness, which are sometimes used in a coated film or the like, the coated film is thin, and is affected by the substrate, and thus pencil hardness is used in the present application.

[0193] <Other provisions>

[0194] The solid lubricating film 10A can be formed directly on the base steel material (fastening surface) (refer to Figure 7 (a)).

[0195] Alternatively, the base layer 10B can be formed as in Figure 7 (b), and then the solid lubricating film is formed. In the case where the base layer is present, the adhesion of the solid lubricating film can be improved.

[0196] As the base layer 10B, for example, a Mn phosphate chemical conversion treatment film, a zinc phosphate chemical conversion treatment film, and a plating film containing at least one or more of Cu, Sn, and Zn can be exemplified.

[0197] <Only one side of the above solid lubricating film is formed on the opposite one of the fastening surfaces>

[0198] The above solid lubricating film can be formed on both the pin thread and the box thread of the oil well pipe thread, or can be formed on only one of them.

[0199] In the case where the above solid lubricating film is formed on only one side, the fastening surface of the thread of the other can be left as machined, or can be a shot blasted surface. Alternatively, a soft second solid lubricating film can be formed on the fastening surface of the thread of the other.

[0200] [Second solid lubricating film]

[0201] The second solid lubricating film is constituted, for example, by dispersing a second solid lubricant with respect to a second binder resin as a base component.

[0202] The second binder resin contains a fluorine-containing organic compound as a main component.

[0203] The second solid lubricant component contains one or more compounds using a material selected from the group X of fatty acids and a material selected from the group Y of metal elements.

[0204] • Group X: stearic acid, isostearic acid, behenic acid, lauric acid, 12-hydroxystearic acid

[0205] • Group Y: Li, Na, Mg, Al, Ca, Zn, Ba

[0206] In the solvent of the reagent for forming the second solid lubricating film, for example, a fluorine-containing solvent of the group Z described below accounts for 90% or more of the weight of the solvent component.

[0207] • Group Z: HFC, HFE, HFO

[0208] The second solid lubricating film is preferably soft with a pencil hardness of 3B or less. The above-mentioned solid lubricating film is hard with a pencil hardness of 2B or more, and in contrast, the second solid lubricating film is preferably softer than the above-mentioned solid lubricating film because of the following reasons. That is, compared to the contact of hard objects with each other, the contact of a hard-soft film enables more preferable friction. Specifically, this is because, since it is expected that the solid lubricant is gradually exposed and supplied while grinding the soft film, low friction is easily achieved.

[0209] <Method for evaluating lubricating properties>

[0210] From the viewpoint of achieving lubricating properties that can withstand the environment that can occur in actual wells, the present embodiment specifies each material. In addition, when specifying the upper and lower limits, confirmation (test) is performed under conditions that conform to the tightening and loosening conditions in actual wells and a decision is made.

[0211] In a method based on a horizontal and vertical power tong using a short pin, as in a usual laboratory test, the tightening and loosening conditions do not follow realistic conditions, and in the case of a solid lubricating film, become lenient conditions. Therefore, it is meaningless to specify the upper and lower limits of each material by evaluation by a usual laboratory test. As long as it is not a very severe condition, the number of times of tightening and loosening is determined to be acceptable. In the present invention, a new laboratory test that can simulate the conditions in actual wells is designed, and evaluation is performed under conditions in accordance with actual wells by the new laboratory test. The new laboratory test is also referred to as a heavy tong test.

[0212] <Method for simulating actual well test conditions (new laboratory test (heavy tong test))

[0213] In the present embodiment, as used in the heavy tong test, a test jig 1 as shown in FIG. 1 is used. Figures 2 to 4As explained, the phenomenon caused by lubrication of the oil well pipe thread is divided into two stages, before the thread is engaged (stage 1) and after the thread is engaged (stage 2). Then, a method of comprehensively evaluating thread lubrication is considered, including lubrication in the second stage (stage 2) on the basis of the fastening and loosening (lubrication) in the initial stage (stage 1).

[0214] If this evaluation is not performed, the failure can occur more frequently in actual wells, although it is OK in the evaluation of the laboratory test. In actual wells, a large load and an eccentric load are applied before the threads engage with each other. Therefore, sometimes the solid lubricating film is damaged, or peeled off, or in a severe case, peeled off without leaving a trace. On this basis, for the parameters of the present embodiment, the upper and lower limits of the appropriate range are selected.

[0215] As described above, in the case of the solid lubricating film, the film is inevitably damaged by the fastening or the like before the thread is engaged. Then, a secondary product is formed on the basis of the peeled-off substance. If this secondary product is clogged in the thread gap, burnout can occur. Therefore, if the lubrication evaluation is not performed under conditions conforming to actual wells, the solid lubricating film that is actually a substandard level can be erroneously determined to be a standard. In the case of such a loose evaluation, the limitation of the upper and lower limits of the parameters related to the solid lubricating film, the selection of the appropriate range become meaningless.

[0216] That is, if it is not considered whether the secondary product, that is, the reconstituted "secondary product" formed on the basis of the damage and the peeling of the solid lubricating film, affects lubrication, it cannot be an accurate solid lubricating film. In the present embodiment, an evaluation based on a new laboratory test considering such an insight is performed.

[0217] Note that if the evaluation using a horizontal power tongs using a short pin, the evaluation using a vertical power tongs using a short pin (evaluation based on the past laboratory test) is relied on, it is meaningless in the evaluation of the solid lubricating film. In the past patent literature, in the lubrication test based on the solid lubricating film, for large diameter sizes such as 9-5 / 8", 13-3 / 8", there are also scattered expressions that the number of times of fastening and loosening is performed to 15-20 times. This is a result of the degree that the lubrication is slightly worse compared to the grease-like compound, but for the solid lubricating film, such a number of times is essentially impossible. It is considered that these are the results obtained based on the evaluation using a short pin using a horizontal or vertical power tongs, which is common in the past laboratory test. In the fastening and loosening in actual wells, in the case of a large diameter using a solid lubricating film, the case of 15-20 times is rare.

[0218] In the present embodiment, based on the conditions of the above new laboratory test, byFigure 5 The apparatus shown was used for testing.

[0219] In the new laboratory tests, the evaluation was based on conditions that allowed for both large loads during tightening and off-center loads during loosening. For example, a large load equivalent to that of an actual-sized pin was considered, and loosening before the threads engaged was taken into account during the thread tightening process. Furthermore, during the thread loosening process, the loosening that occurred due to the threads disengaging from each other was reflected.

[0220] In the new laboratory tests, a vertical power clamp 4 was used. Additionally, a short pin 1 was used as the test pin. However, it was possible to apply and unload a load based on a counterweight 3 onto the upper part of this pin 1.

[0221] Furthermore, the short thread 1 and the sleeve thread 2 are fastened by the pin thread portion 1a and the sleeve thread portion 2a.

[0222] At this point, to simulate a situation where the threads are not engaged, the initial temporary fastening position is set so that pin thread 1a appears to expose half of the total number of threads from sleeve thread 2 (refer to...). Figure 2 (b)). This is one of the causes of loosening. Tighten from this state.

[0223] When tightening, a counterweight 3 is pre-installed at the upper end of pin 1 on the side opposite to the tightening thread of sleeve thread 2.

[0224] The weight of counterweight 3 is set to be equivalent to the load of 1 to 3 actual-sized pins, and the weight is calculated based on the actual-sized pins with the outer diameter and wall thickness of the pins. If it is 9-5 / 8” 53.5#, then one pin is approximately 1 t load (2200Lb), and if it is equivalent to 3 pins connected together, then it is approximately 3 tons (6600Lb).

[0225] like Figure 6 As shown, Figure 5 The illustrated weight 3 consists of a weight body 3A and an insert rod 13. The insert rod 13 is welded to the lower surface of the weight body 3A and is positioned in an axisymmetric position on the weight 3. The weight is mounted on the pin 1 by inserting the insert rod 13 into the pin in a sliding position. The symbol 1c represents the inner diameter surface of the pin 1.

[0226] When the counterweight 3 is pre-installed on the insertion rod 13 and pin 1 as described above, holes 1d and 13a are pre-drilled to pass through the pin 1 and the insertion rod 13. Then, as... Figure 6 As shown, the weight 3 and the pin 1 are integrated by inserting the through rod 12 into the holes 1d and 13a.

[0227] In the shaft center position of the upper portion of the weight 3, a hook 11 of a free lock (swivel) type is tightly attached by welding, and is formed into a structure of a suspension device 20 suspended from the ceiling via a hoisting chain 21. Thus, by adjusting the hoisting of the weight by the suspension device 20, the magnitude of the load of the weight to the pin can be adjusted.

[0228] Further, at the time of tightening, the hoisting chain 21 is set to a state of being slackened, the weight load is applied to the sleeve thread, and tightening is performed at 5 to 20 rpm until the torque rises (stage 1). This becomes a simulation of loosening. If the torque rises, the rotation speed is lowered to 0.5 to 2 rpm, and tightening is performed until the tightening position (stage 2).

[0229] On the other hand, at the time of loosening (relaxation), the weight 3 is hoisted by the suspension device 20, and relaxation is performed in a state where the load of the weight 3 is not applied. With respect to the rotation speed, at the time of torque rise, the rotation speed is started to be loosened at 0.5 to 2 rpm, and if the torque reaches about 1 / 10 of the tightening torque value, it is loosened at a high speed of 5 to 20 rpm.

[0230] Here, in the case where the load is not applied at the time of loosening, a condition close to the environment of an actual well is obtained. This is based on an experimental fact, and is based on the insight of data in which the evaluation of the lubricating property is good in the case where the load of the weight 3 is applied compared to the case where it is not applied. That is, the inventors actually tried experiments to observe, and as a result, the following insight was obtained: when loosening in a state where the weight is applied, the weight becomes a balancer, and the pin is loosened straight from the tightening end position without loosening. On the other hand, a case where the weight is lightened, that is, a case where the load is hoisted for the purpose of making the weight load zero, is assumed. In this case, including the case where the load is not completely zero, in the case where the load is lightened and the threaded joint is loosened, it is possible to perform an experiment in a condition where the loosening is intense and the tendency to cause damage to the solid lubricating film is strong.

[0231] In a new laboratory experiment based on the above condition, it is possible to simulate a condition in which a secondary product of a component from the solid lubricating film released to the threaded gap due to inevitable peeling and the like does not move following the tightening and relaxation and is clogged in a certain portion to cause scorching. Alternatively, it is possible to simulate other conditions in which the film itself is peeled off without leaving a trace. As a result, it is possible to define the upper and lower limits of the parameters related to the solid lubricating film as parameters that conform to the actual well conditions. After the relaxation is ended, the pin thread and the sleeve thread are separated, the fragments and the like of the solid lubricating film present on the surface are scattered by blowing, the surface is inspected, and tightening is continued again, and evaluation is performed by such a method.

[0232] In the present embodiment, in order to realize lubrication properties that can withstand the environment that can occur in an actual well, the components and the like are specified. In addition, when the upper and lower limits are specified, confirmation is made under conditions that conform to the tightening and loosening conditions in an actual well, and a decision is made.

[0233] (EFFECT)

[0234] In the present embodiment, in the field of lubrication using a solid lubricant film for an oil well pipe thread, high lubricity and corrosion resistance that can withstand tightening in an actual well can be realized at the same time. At this time, the present embodiment realizes high lubricity and corrosion resistance at the same time on the premise that the main component of the solid lubricant is MCA, and the main component of the binder resin component is nitrocellulose and alkyd resin.

[0235] The solid lubricant film of the present embodiment can realize lubrication properties and corrosion resistance that match those of the grease-like compound for lubrication, the rust-preventive grease-like compound for storage, and the oil-like rust-preventive material that have been used in the past.

[0236] In addition, in the present embodiment, by further specifying the molecular weight for the binder resin and the solid lubricant that constitute the solid lubricant film, lubrication performance at the time of tightening that matches that of the oil well pipe thread in the past can be obtained without using the compound in the past.

[0237] In the present embodiment, for example, an oil well pipe thread joint having lubrication performance at the time of tightening that takes into account conditions equivalent to those of an actual well that can occur in an actual well environment can be obtained. Note that the conditions equivalent to those of an actual well refer to conditions such as a situation in which a sleeve is subjected to a pin weight (large load) from above, a load is applied obliquely (eccentric load) due to axial misalignment, and a load is applied unevenly and locally, and the like.

[0238] Furthermore, not only is the application to lubrication of an oil well pipe thread, but also the application to a metal material can be expanded. In addition, not only a film, but also a reagent for producing a film can be targeted.

[0239] (OTHER)

[0240] The present application can also be configured as follows.

[0241] (1) An agent for forming a solid lubricating coating film on a threaded portion of an oil well pipe, wherein a solid lubricant, the main component of which is melamine cyanurate having an average particle diameter of 0.1 μm or more and 10.0 μm or less, is dispersed in a binder resin, and the binder resin contains an alkyd resin and nitrocellulose, the alkyd resin and nitrocellulose being contained in an amount of 85% by weight or more of the total weight of the binder resin components, and the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the total weight of the binder resin.

[0242] (2) The weight of the nitrocellulose is 0.5 times or more and 3 times or less of the weight of the alkyd resin.

[0243] (3) A solvent is contained, the solvent including one or two or more materials selected from the group consisting of solvent oil, aromatic solvents, alcohol solvents, ester solvents, and ketone solvents, and the weight of the solvent is 20% or more and 80% or less of the total weight of the total weight of the total weight of the solid lubricant and the total weight of the binder resin.

[0244] (4) The oil length of the alkyd resin is 10 to 60.

[0245] (5) One or two or more materials selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP) are contained as plasticizers, and when the weight of the nitrocellulose is taken as 100 parts by weight, 10 parts by weight or more and 20 parts by weight or less of the plasticizer is contained.

[0246] (6) An oil well pipe having a lubricating coating film having a solid lubricating coating film formed on a threaded portion of at least one of a pin and a box, the solid lubricating coating film being formed by dispersing a solid lubricant in a binder resin, the main component of the solid lubricant being melamine cyanurate having an average particle diameter of 0.1 μm or more and 10.0 μm or less, the binder resin containing an alkyd resin and nitrocellulose, the alkyd resin and nitrocellulose being contained in an amount of 85% by weight or more of the total weight of the binder resin components, and the total weight of the solid lubricant being 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the total weight of the binder resin, and the thickness of the solid lubricating coating film (including the binder resin, the solid lubricant, and other additives) being 10 μm or more and 150 μm or less.

[0247] (7) The lubricating film has a base layer between the fastening surface of the threaded portion and the solid lubricating film, and the base layer contains a Mn phosphate chemical conversion treatment film, a zinc phosphate chemical conversion treatment film, or an electroplated film containing one or more metals selected from Cu, Sn, and Zn.

[0248] (8) The solid lubricating film has a hardness of 2B or more in pencil hardness.

[0249] (9) An oil well pipe threaded joint in which a sleeve having an internal thread and a pin having an external thread are connected, wherein the oil well pipe of at least one of the sleeve and the pin is composed of the oil well pipe of the present application having the lubricating film.

[0250] (10) A lubricating film having the solid lubricating film is formed on the fastening surface of the threaded portion of one of the sleeve and the pin, and a second solid lubricating film softer than the solid lubricating film is formed on the fastening surface of the threaded portion of the other of the sleeve and the pin.

[0251] (11) The second solid lubricating film is composed by dispersing a second solid lubricant with respect to a second binder resin, the second binder resin contains a fluorine-containing organic compound as a main component, and the second solid lubricant contains one or more than two kinds of compounds of a material using a fatty acid selected from Group X below and a material of a metal element selected from Group Y below.

[0252] • Group X: stearic acid, isostearic acid, behenic acid, lauric acid, 12-hydroxystearic acid

[0253] • Group Y: Li, Na, Mg, Al, Ca, Zn, Ba

[0254] (12) The second solid lubricating film has a pencil hardness of 3B or less.

[0255] Example

[0256] Next, an example based on the present embodiment will be described.

[0257] First, the qualification criteria for the lubrication behavior based on the number of fastening and loosening is described. The qualification criteria is as follows. Regarding the casing size, 3 or more fastening and loosening is set as qualified, and 5 times of determination is more excellent. Regarding the tubing size, 5 or more is determined as qualified, and 10 or more is evaluated as more excellent. The provision of the casing size is in accordance with the provision of ISO 13679. On the other hand, for the tubing, 5 or more which is lower than the provision of ISO 13679 is regarded as qualified. This is because, since it is a solid lubricating film, the tendency of the number of fastening and loosening to deteriorate is obvious compared with the conventional lubrication using a grease-like compound, and this is gradually recognized in the oil and gas industry. As described above, if the fastening and loosening test is performed from the start of the thread engagement using only the short pin, the provision of ISO 13679 is a simple target, but, in the present application, in order to simulate the condition in which the large load and the eccentric load are applied and the condition in which the thread is not engaged and the looseness exists as a condition close to the condition that can occur in the actual well, the evaluation is performed by a new laboratory test (heavy weight wrench test), and thus the criteria is set.

[0258] The load application using the heavy weight wrench is set to 1 ton load of 9-5 / 8" actual size pin 1 amount, and is performed using the heavy weight 1 ton load. Then, the heavy weight is installed at the upper portion of the pin thread, and the test is performed.

[0259] The initial fastening position is fastened to a position at which it seems that half of the total number of pin threads is exposed from the sleeve thread, that is, the fastening is performed from the state in which the threads are not engaged with each other.

[0260] That is, the present embodiment is performed by the device shown in Figure 5 , Figure 6 .

[0261] In addition, at the time of fastening, the load of the heavy weight is applied. On the other hand, at the time of loosening, the test is performed in a state in which the load of the heavy weight is not applied. If the test is performed using the load at the time of loosening, in the case in which the pin in which the short pin and the heavy weight are integrated is used, the short pin integrated with the heavy weight is straightly raised from the fastening position unlike the actual size pin of the actual well. The heavy weight becomes a balancer, and thus the looseness is not generated. For the pin used in the actual well, since it is long, the tendency to be subtly bent is high. Thus, the pin is gradually exposed, the looseness is caused as the threads are not engaged, and the tendency to damage the solid lubricating film is high.

[0262] Therefore, in the lubrication evaluation using the heavy weight wrench, at the time of loosening, the tightening and loosening are performed without applying a load, and when the condition that the thread teeth become disengaged is approached, loosening caused by linkage is simulated. In addition, the fact that no load is applied does not necessarily mean that the load is zero. The test is performed by lifting the heavy weight by a bridge crane or the like, and no load is applied. Note that the test for confirming the number of times of tightening and loosening using the heavy weight wrench is performed two or more times. Furthermore, the comparative evaluation is performed in terms of whether or not the number of times reaches the qualified criterion and what the number of times is with respect to the number of test points, and whether or not the parameters are judged.

[0263] (Example 1)

[0264] In Example 1, the lubrication characteristic evaluation using the heavy weight wrench is described.

[0265] The conditions and evaluation results of each example are described in Tables 1 to 4. Note that the solid lubricating film is also referred to as a coating film. In addition, the second solid lubricating film is also referred to as a coating film of a soft film.

[0266]

[0267]

[0268]

[0269]

[0270] In Nos. 1 to 10, a material Q125 of a carbon steel high strength grade was used. In Nos. 11 to 15, a material C110 of a carbon steel acid resistant grade was used. In addition, all of the examples are cases in which the oil well pipe coupling thread and pin thread of a size of 9-5 / 8" 53.5# were used. In addition, the thread type was JFELION TM .

[0271] <No. 1 to 10>

[0272] [No. 1 to No. 4]

[0273] The examples of No. 1 to No. 4 are comparative evaluation results concerning the difference of the power wrenches on which the evaluation was performed. The examples of No. 1 to No. 3 are all cases in which the parameters of the material are in the appropriate range and the conditions are the same. However, only the conditions of tightening and loosening of the wrenches are different.

[0274] No. 1 uses a horizontal wrench, No. 2 uses a simple vertical wrench, and No. 3 uses a vertical wrench, but a test based on a new laboratory test with a heavy weight (hereinafter, also referred to as a heavy weight wrench test) is adopted. In addition, No. 4 corresponds to the result of a tightening and loosening test using a pipe of Range-3 (more than 12 m, about more than 40 feet) in a simulated well.

[0275] No. 1 is an example in which fastening and loosening is performed 10 or more times (stopped at 10 times). In No. 2, fastening and loosening is performed up to 7 times. In No. 3, 2 times are performed, and it is shown that fastening and loosening is performed 3 and 4 times. In addition, in No. 4, 3 times are performed, and it is shown that fastening is performed 3 times, 3 times, and 4 times.

[0276] In No. 1, the weight of the short pin thread is not applied to the coupler thread. At the same time, in No. 1, shaft adjustment is also performed, and therefore the bias load based on the loosening of the thread is not applied.

[0277] On the other hand, in No. 2, it becomes a test in a state in which the weight of the short pin 1 is applied to the coupler thread. Note that if it is the size of the present piece, the weight of about 100 kg is applied to the short pin of 1 m.

[0278] No. 3 is a simulation in a state in which 1 ton of the weight of the actual size pin 1 is applied. Also, in No. 3, as described above, fastening is started from a state in which the short pin is intentionally half-fastened in a manner in which about half of the pin thread is exposed with respect to the coupler thread from the setting position of the pin. As a result, it is a state in which loosening occurs in the actual well due to the fact that the threads do not engage with each other. That is, it becomes a fastening and loosening condition in which the solid lubricating film is simulated to be damaged.

[0279] No. 4 corresponds to a fastening and loosening condition in a condition similar to the fastening condition in the actual well.

[0280] No. 3, No. 4 belong to the present application example.

[0281] In No. 1, 2, the number of fastening and loosening exceeds the qualification line, but is a comparative reference example. No. 3, 4 belong to examples that can be called the present application example according to the results thereof.

[0282] No. 1, No. 2 mean that the actual well is approached, and evaluation is performed using a weight caliper, and if the upper and lower limits of the parameters prescribed in the present application are not specified, it becomes a loose evaluation. That is, in the methods used in various patent documents so far, the evaluation of the solid lubricating film becomes a loose evaluation. Therefore, in the past laboratory test, it is implied that the evaluation method is not appropriate. In addition, it also means that the condition in the actual well can be simulated by the test method of the weight caliper.

[0283] Here, as a reference experiment (not described in the table) not incorporated into this embodiment, the following well experiment, which has been widely performed since olden times, was also performed under the same tong conditions as No. 1 to No. 4. That is, a Mn phosphate film was formed on the coupler thread, and an API-mod grade compound such as BOL-72733 of Best-O-Life Co. was applied as a grease-like compound to the shot peened surface of the pin thread, and a fastening and loosening test was performed. In this case, the number of fastening and loosening times was confirmed to be 5 or more, and no differences were found. In these examples, the grease-like compound moved in conjunction with the fastening and loosening of the threads, and thus it was shown that the solid lubricating film was not affected by the conditions of the test method being evaluated (the tong conditions under which evaluation was performed) in the case of a solid lubricating film.

[0284] From this, it was shown that a test for proving the significance of the parameters of the solid lubricating film needs to be performed by an actual well or a simulated well test or a new laboratory test (deadweight tong test).

[0285] [No. 5 to No. 8]

[0286] No. 5 to No. 8 are examples in which comparison was performed under approximately the same conditions. This example was mainly used for research on changing the film thickness of the solid lubricating film, the presence or absence of shot peening, the presence or absence of a plasticizer, and the presence or absence of a different kind of solid lubricating film on the pin thread side.

[0287] No. 5 is an example in which the film thickness exceeds the upper limit of the present application, and is an example in which the parameters other than this are within the appropriate range. No. 5 is an example in which the film is too thick, and thus the thread gap is clogged by the substance from the damaged solid lubricating film during fastening and loosening, and thus burns prematurely.

[0288] No. 6 is an example in which the film thickness is within the appropriate range, and a plasticizer is further added. The pencil hardness of No. 5 is soft by one grade, but fastening and loosening can be performed as prescribed or more, and thus this is an example of the present application.

[0289] No. 7 is an example of the present application in which a solid lubricating film is formed on the coupler thread under the same conditions as No. 6, and a soft film is formed on the pin thread side. According to the present application, the solid lubricant that is the MCA main body is set, and the thread on which a film in which nitrocellulose and alkyd resin are blended within the range of the present application is formed is set, and thus it was shown that if a soft solid lubricating film is formed on the thread surface of the opposite object material side, the number of fastening and loosening times further increases, that is, the lubricating properties are improved.

[0290] No. 8 is an example in which the film thickness of the solid lubricating film is set to 150 μm, which is the upper limit, and is an example of the present application.

[0291] No. 5, the tightening and loosening was performed only less than 3 times, but in No. 8, the number of times of tightening and loosening was achieved to the qualification level. It was shown that the upper limit of the film thickness was 150 μm.

[0292] [No. 9, 10]

[0293] The case of No. 9 is a case where a solid lubricant composed of 80 wt% of MCA and 20 wt% of BN is used in the solid lubrication. In the case of No. 9, all the parameters are in the appropriate range, and it belongs to the inventive example.

[0294] The case of No. 10 is a case where the proportion of MCA in the solid lubricant is less than the prescribed range disclosed, and the average particle diameter of MCA is larger than the prescribed range disclosed. The case of No. 10 is a case where the other parameters are in the appropriate range but burn prematurely in the tightening and loosening test, and it belongs to the comparative example.

[0295] <No. 11 to 15>

[0296] No. 12 and No. 14 are adjusted in the appropriate range of the components, and they belong to the inventive examples.

[0297] On the other hand, No. 11, 13, and 15 belong to the comparative examples.

[0298] No. 11 is a case where 20% of melamine resin is added to the constituent elements of the nitrocellulose and the alkyd adhesive resin, and the nitrocellulose is more than the prescribed amount. This condition is one of the reasons, and No. 11 is a case where the film becomes brittle. In No. 11, there is only one case where the number of times of tightening and loosening exceeds 5 times, but the other two cases are less than 3 times, and they are the cases belonging to the comparative examples.

[0299] No. 13 is a case where the solid lubricant is less than the prescribed amount of the adhesive resin, and thus the lubrication cannot be maintained and burns.

[0300] On the contrary, No. 15 is a case where the solid lubricant is more than the prescribed range disclosed, and it is a case where the proportion of the nitrocellulose is also less than the prescribed amount, and the oiliness of the alkyd resin is larger than the prescribed amount. Furthermore, No. 15 is a case where the number of times of tightening and loosening cannot achieve the prescribed amount.

[0301] Compared with No. 11, 13, and 15, the number of times of tightening and loosening of No. 12 and No. 14, which are in the prescribed range of the parameters of the present invention, is more.

[0302] By comparing No. 1 to No. 15, it is shown that it is a necessary condition that the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less. In addition, it is shown that it is a necessary condition that the component weight of the "alkyd resin and nitrocellulose" of the binder resin is 85% by weight or more with respect to the total binder resin component weight. In addition, it is shown that it is a necessary condition that the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less when the total weight of the binder resin is set to 100 parts by weight. Furthermore, it is shown that it is a necessary condition that the thickness of the solid lubricating film is 10 μm or more and 150 μm or less.

[0303] (Example 2)

[0304] In the example of Example 1, a plurality of examples were selected to perform a salt spray test, and corrosion resistance was confirmed.

[0305] In the example shown in Example 1, a salt spray was performed by picking up the carbon steel-based oil well pipe thread conditions of No. 3, 6, and 14.

[0306] In order to perform this salt spray test, a new film was formed in the coupler sample.

[0307] In addition, as a comparative example, a thickness of 0.8 mm t of SPCC (thin steel sheet of a general mild steel, cold-rolled annealed sheet) was also used to perform (condition A).

[0308] The oil well pipe thread material was maintained in a state in which the protector was fastened and loosened once with respect to both ends of the coupler thread (No. 3-2, 6-2, 14-2) and the protector was installed again (equivalent to the second fastening: No. 3-3, 6-3, 14-3). Then, each sample was arranged horizontally. That is, the samples were arranged without being erected, and the salt spray test was performed, whereby the corrosion test was performed.

[0309] At this time, the pin thread was set to be a sample in which only the thread was present, and the protector was fastened and loosened once with respect to the side in which the thread was present. Outside the side in which the protector was not installed again, an imide tape was attached, and protection was performed so that water does not enter the inside of the pipe.

[0310] The detailed conditions are described below. That is, the conditions of the solid lubricating film of No. 3-2, 3-3, No. 6-2, 6-3, No. 14-2, and 14-3 are equivalent to those of No. 3, 6, and 14 of Example 1.

[0311] The significance of this test method is that oil well pipe threads are mostly shipped with protectors fastened to the end portions, and are directly stored in the field near the well. This is because it is an environment close to the actual use conditions. The condition without the protector installed refers to the more severe condition when the protector is removed. The case of SPCC sheet is a case where fastening and loosening are not performed using a protector, and the corrosion resistance of the film itself is observed in terms of thread shape.

[0312] <Brine spray conditions>

[0313] Spray conditions: JIS K 5600-7-1

[0314] Brine concentration: 5 ± 0.5% by weight

[0315] Temperature: 35°C

[0316] Humidity: 98-99%

[0317] Spray amount: 1-2 mL / hour / 80 cm 2

[0318] pH: 6.5-7.2

[0319] Time: 24 hours

[0320] The results are shown in Table 5.

[0321]

[0322] As can be seen from Table 5, No. 3-2, 3-3, No. 6-2, 6-3, No. 14-2, 14-3, including No. A of the comparative example, were not corroded in the brine spray, and had sufficient corrosion resistance.

[0323] The film quality was F or more and hard, and even if fastening and loosening were performed using a protector, it would not be fatally damaged. Also, it is presumed that the main components of MCA, nitrocellulose, and alkyd have water repellency, and water is not introduced.

[0324] Herein, the entire contents of Japanese Patent Application No. 2021-91464 (filed on May 31, 2021) from which priority is claimed are incorporated herein by reference as part of the present application. Herein, a limited number of embodiments are described by way of illustration, but the scope of the right is not limited thereto, and modifications based on the above-mentioned disclosed embodiments will be apparent to those skilled in the art.

[0325] Explanation of symbols

[0326] 1 pin

[0327] 1a external thread

[0328] 2 sleeve (coupler)

[0329] 2a internal thread

[0330] 3 weight

[0331] 3A weight body

[0332] 4 power tong

[0333] 10A solid lubricating coating

[0334] 10B base layer

[0335] 12 through rod

[0336] 13 insertion rod

[0337] 20 hoisting device (crane)

[0338] 21 chain (sling)

Claims

1. An agent for forming a solid lubricating coating film on a threaded portion of an oil well pipe, characterized by comprising: a solid lubricant dispersed in a binder resin, wherein 80% by weight or more of the total weight of the solid lubricant is melamine cyanurate having an average particle diameter of 0.1 μm or more and 10.0 μm or less, wherein the binder resin contains an alkyd resin and nitrocellulose, and the alkyd resin and the nitrocellulose are contained in an amount of 85% by weight or more of the total weight of the binder resin, and wherein the total weight of the solid lubricant is 10 to 100 parts by weight per 100 parts by weight of the total weight of the binder resin. The weight of the nitrocellulose is 0.5 to 3 times the weight of the alkyd resin.

3. The agent according to claim 1 or claim 2, characterized by further comprising a solvent, wherein the solvent contains one or two or more materials selected from the group consisting of solvent oil, aromatic solvents, alcohol solvents, ester solvents, and ketone solvents, and wherein the weight of the solvent is 20 to 80% of the total weight of the solid lubricant and the total weight of the binder resin. The oil length of the alkyd resin is 10 to 60. The oil length of the alkyd resin is 10 to 60.

2. The agent of claim 1, wherein 6. The agent according to claim 1 or claim 2, characterized by further comprising a plasticizer selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP), and wherein the plasticizer is contained in an amount of 10 to 20 parts by weight per 100 parts by weight of the nitrocellulose.

7. The agent according to claim 3, characterized by further comprising a plasticizer selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP), and wherein the plasticizer is contained in an amount of 10 to 20 parts by weight per 100 parts by weight of the nitrocellulose.

8. The agent according to claim 4, characterized by further comprising a plasticizer selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP), and wherein the plasticizer is contained in an amount of 10 to 20 parts by weight per 100 parts by weight of the nitrocellulose.

9. The agent according to claim 5, characterized by further comprising a plasticizer selected from the group consisting of dibutyl phthalate (DBP), dimethyl phthalate (DMP), and diethyl phthalate (DEP), and wherein the plasticizer is contained in an amount of 10 to 20 parts by weight per 100 parts by weight of the nitrocellulose.

10. An oil well pipe having a lubricating coating film having a solid lubricating coating film formed on a threaded portion, characterized by comprising: a solid lubricating coating film formed by dispersing a solid lubricant in a binder resin, wherein the solid lubricating coating film is formed by dispersing a solid lubricant in a binder resin, 4. The agent of claim 1 or claim 2, wherein ​ 5. The agent of claim 3, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 80% by weight or more of the total weight of the solid lubricant is melamine cyanurate, the average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less, as the binder resin, an alkyd resin and nitrocellulose are contained, the alkyd resin and nitrocellulose are contained in 85% by weight or more of the total weight of the binder resin components, the total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the total weight of the binder resin, the thickness of the solid lubricating film is 10 μm or more and 150 μm or less.

11. The oil well pipe according to claim 10, wherein the lubricating film has a base layer between the fastening surface of the threaded portion and the solid lubricating film, the base layer contains a Mn phosphate chemical conversion treatment film, a zinc phosphate chemical conversion treatment film, or an electroplated film containing one or more metals selected from Cu, Sn, and Zn.

12. The oil well pipe according to claim 10 or claim 11, characterized in that, the solid lubricating film has a hardness of 2B or more in terms of pencil hardness.

13. An oil well pipe threaded joint which is a threaded joint of an oil well pipe in which a pin having an external thread is connected to a box having an internal thread, characterized in that at least one of the box and the pin is made of the oil well pipe according to any one of claims 10 to 12.

14. The oil well pipe threaded joint according to claim 13, wherein a lubricating film provided with the solid lubricating film is formed on the threaded portion of one of the box and the pin, a second solid lubricating film softer than the solid lubricating film is formed on the threaded portion of the other of the box and the pin.

15. The oil well pipe threaded joint according to claim 14, wherein the second solid lubricating film is made by dispersing a second solid lubricant with respect to a second binder resin, the second binder resin contains a fluorine-containing organic compound as a main component, the second solid lubricant contains one or two or more compounds of a material using a fatty acid selected from Group X below and a material of a metal element selected from Group Y below, Group X: stearic acid, isostearic acid, behenic acid, lauric acid, 12-hydroxystearic acid; Group Y: Li, Na, Mg, Al, Ca, Zn, Ba.

16. A threaded joint for oil country tubular goods according to claim 14 or claim 15, characterized in that, the pencil hardness of the second solid lubricating film is 3B or less.

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