Agent for forming solid lubricating coating film, tubular products for oil fields and threaded joint for tubular products for oil fields.

Abstract

Agent for forming a solid lubricating coating film, tubular products for oilfields and threaded joints for tubular products for oilfields. It is possible to provide a solid lubricating coating film capable of imparting excellent seizing resistance as well as lubricity to a connection for tubular products for oilfields, even when a solid lubricating coating film is adopted for lubrication.An agent for forming a solid lubricating coating film on a thread portion of tubular products for oilfields, wherein a binder resin contains a prepolymer and a curing agent, the prepolymer being formed of one or more epoxy resins, 70 parts by weight or more of the prepolymer being contained in relation to 100 parts by weight of the binder resin, the epoxy resin constituting the prepolymer having an epoxy equivalent of 100 or more and 500 or less, the solid lubricant containing boron nitride (bn) in an amount of 80% by weight or more, bn having an average particle size of 10 µm or less, and the total weight of the solid lubricant being 0.1 times or more and twice or less the total weight of the binder resin.

Description

1 / 86 “AGENT FOR FORMING SOLID LUBRICANT COATING FILM, TUBULAR PRODUCTS FOR OIL FIELDS AND THREADED JOINT FOR TUBULAR PRODUCTS FOR OIL FIELDS” Technical Field

[001] This disclosure is a technology relating to the lubrication and seizing resistance of tubular products for oilfields and a threaded joint for tubular products for oilfields. This disclosure is a technology relating to tubular products for oilfields and a threaded joint for tubular products for oilfields in each of which a solid lubricant coating film is formed on a surface (including a metallic sealing surface) of a threaded portion instead of a wet lubricant compound. In this descriptive report, a clamping surface of a threaded portion includes a metallic sealing surface.

[002] In this document, solid lubricant coating film means a coating film including a binder resin as a matrix component, a solid lubricant dispersed and distributed in the binder resin, and an additive added as needed. Furthermore, this disclosure aims to provide seizing resistance while improving lubrication by a solid lubricant coating film that achieves lubrication of a connection for tubular products for oilfields.

[003] Furthermore, in this descriptive report, a phenomenon described by the terms “lubricity” and “high lubricity” means a lubricious phenomenon with low friction in a broad sense. Additionally, high lubricity means that the number of times assembly / disassembly can be performed (also referred to as the number of times M / B) is a specific number of times or more in a strict sense. For example, the seizing resistance of a threaded joint for products Petition 870230105138, dated 11 / 29 / 2023, page 12 / 116 2 / 86 tubular pipes for oilfields are described in the API 5C5 standard. The API 5C5 standard requires that the assembly be able to be performed up to three times in a casing size. Additionally, it requires that the assembly be able to be performed up to ten times in a pipe size.

[004] Note that in this descriptive report, a tube having a female thread may be collectively referred to as a housing. That is, a coupling is also described as a housing type. Background of the Technique

[005] In a threaded joint for tubular products for oilfields, for the lubrication of a threaded portion, conventionally, a clamping surface (sealing surface) (hereinafter also simply referred to as “clamping surface”) which is a surface of a threaded portion of at least one male thread and one female thread is surface treated with a chemical conversion coating film of Mn phosphate or electroplating using Cu or similar to form a coating film. After that, a lubricating compound containing Pb, Zn or similar is applied over the coating film to obtain lubrication.

[006] Note that in this descriptive report, when a coating film is formed on a clamping surface (sealing surface) of a threaded portion, the coating film is also referred to as a clamping surface.

[007] On the other hand, in recent years, non-wet lubrication technology using “dry / dope-free” methods has attracted attention. “Dry / dope-free” means that the film itself is not a viscous liquid similar to API-mod compounds and that the film itself does not contain a harmful heavy metal. As such, “dry / dope-free” lubrication involves the technology of forming a solid lubricating coating film on a clamping surface to achieve lubrication. The present disclosure is the technology Petition 870230105138, dated 11 / 29 / 2023, page 13 / 116 3 / 86 related to "dry / dope-free" lubrication.

[008] Previous PTLs disclose inventions relating to various solid lubricating coating films. The solid lubricating coating film includes a lubricating component that acts for lubrication and a solid film as a matrix component that holds the lubricating component in the film. Solid film means a film that is neither viscous nor liquid, and also means completing the lubrication at the time of assembly / disassembly of the connection by itself. A conventional Mn phosphate film or galvanized Cu film is itself a solid film. However, since lubrication is assumed to be achieved by applying a greasy compound, conventional Mn phosphate film and galvanized Cu film are not included in the solid lubricating coating film. In the present disclosure, lubrication is achieved as a solid film, and an organic resin film is considered as the solid film.Therefore, in the following description, the solid film is also referred to as a binding resin.

[009] A conventional lubricating coating film used in a threaded joint for tubular products for oilfields is described in, for example, PTLs 1 to 9.

[010] In the field of a connection for tubular products for oilfields, BN is widely exemplified in many PTLs as one of the candidates for a solid lubricant. For example, PTLs 1 and 2 exemplify BN as a solid lubricant present in a solid lubricant coating film.

[011] Furthermore, an epoxy resin is exemplified in previous PTLs. However, there are few PTLs that clearly define an epoxy resin and define a chemical composition of the epoxy resin. In addition, there are many PTLs that appear to specify the technology, but fail to specify it completely.

[012] The definition of epoxy resin is very broad. Epoxy resin is generally a generic term for a thermosetting resin formed by crosslinking and bonding. Petition 870230105138, dated 11 / 29 / 2023, page 14 / 116 4 / 86 of a chemical substance having an epoxy group as a prepolymer (precursor of epoxy resin) and a curing agent between them. However, academically, commercially, and in the description of PTLs, the term epoxy resin can refer to a chemical substance that has an epoxy group of a prepolymer or an epoxy resin that can be generated by the copolymerization of the prepolymer and a curing agent. However, in most cases, they are used interchangeably. In previous PTLs, the term “epoxy resin” generally refers to the latter. In summary, the previous PTLs only describe that epoxy resin is widely used (see PTLs 3 to 8).

[013] Note that in the following description, when the present disclosure is described, an epoxy resin agent as a source material (prepolymer) for the formation of an epoxy resin film is referred to as “prepolymer” or “epoxy resin in a strict sense”. Furthermore, an epoxy resin (film) finally obtained by polymerization of a prepolymer and a curing agent is referred to as an “epoxy resin coating film” for the sake of distinction.

[014] PTLs 3 to 9 will be described next.

[015] PTL 3 discloses an invention for forming a solid lubricating coating film on a Cu-Sn-Zn electroplating base. PTL 3 utilizes a resin selected from one or two epoxy resins and a polyamide-imide resin as a binder resin for the solid lubricating coating film.

[016] PTLs 4 to 6 exemplify an epoxy resin as a component of a solid lubricating coating film having excellent heat resistance and excellent lubricity. PTLs 4 to 6 do not clearly reveal up to what degree of temperature the epoxy resin is heat resistant, and it is difficult to understand a characteristic of the epoxy resin used.

[017] PTL 7 clearly describes that a mixed-type epoxy of two liquids Petition 870230105138, dated 11 / 29 / 2023, p. 15 / 116 5 / 86 is formed on a Zr-based electroplating base. However, the two-liquid mixed-type epoxy is not innovative, and as described above, epoxy resin is formed by a curing agent in a strict sense as a prepolymer. The two-liquid mixed type simply means a type in which two liquids are mixed on-site. Since even a single-liquid type contains a prepolymer and a curing agent, the two-liquid mixed type itself is not new.

[018] PTL 8 discloses an invention in which a silicon acrylic resin is formed into an ultraviolet curable resin. PTL 8 exemplifies an acrylic acid-modified epoxy resin as one of the candidates and describes an acrylic acid-modified epoxy resin in which a backbone of the main chain is formed from an epoxy resin and a terminal of the backbone of the main chain is acryloylated.

[019] PTL 9 discloses a photocurable acrylic resin coating film. PTL 9 describes a photocurable (meth)acrylate resin, specifies a film obtained by copolymerization of (meth)acrylate monomers based on a trigger, such as a photopolymerization initiator, and exemplifies an epoxy as well as a polyester, a polyether, and a polyurethane as a main chain structure forming an acrylate side chain between the candidates.

[020] Furthermore, although not a case of evaluating a solid lubricant coating film, NPL 1 describes, as a vertical hydraulic wrench assembly test method using a short pin, a method for performing assembly / disassembly in a state where a 5 kN weight (510 kg weight) is constantly loaded onto a surface of the upper end of the short pin. However, NPL 1 performs the evaluation using a conventional greasy compound as a means to determine whether an innovative connection design is acceptable or not. List of Citations Patent Literature Petition 870230105138, dated 11 / 29 / 2023, page 16 / 116 6 / 86

[021] PTL 1: JP 2017-110686 A1

[022] PTL 2: WO 2017-110685 A

[023] PTL 3: JP 2018-216497 A1

[024] PTL 4: JP 2015-501906 A

[025] PTL 5: JP 2015-198557 A1

[026] PTL 6: JP 2017-110685 A1

[027] PTL 7: JP 2017-71844 A

[028] PTL 8: JP 2013-183634 A1

[029] PTL 9: JP 2011-12251 A Non-Patent Literature

[030] NPL 1: Tsuru et al., Journal of Japan Petroleum Institute, Vol. 61, No. 6 (1996), pages 527-536. Summary of the Invention Technical Problem

[031] The lubrication of a connection for tubular products for oilfields targeted by this disclosure is in a special sliding situation.

[032] That is, in a location (real well), a pin having an actual length of about 8 m or more and less than 15 m is mounted and dismounted in a box placed below. At this moment, although the pin is mounted and dismounted using a hydraulic wrench in a state to be lifted by a crane, a full load of the pin can be applied to the box connection. That is, lubrication is performed in a state of high applied load.

[033] At this moment, the pin is not necessarily assembled and disassembled in an ideal state. That is, at the time of assembly, the pin connection is inserted into the housing connection or manually adjusted to a slightly tightened state. However, the pin is not positioned vertically and immobile in Petition 870230105138, dated 11 / 29 / 2023, page 17 / 116 7 / 86 in relation to the housing connection. Furthermore, the pin does not lie straight while being bent in an oblique direction, i.e., in a state of ascent without curvature. That is, one side of the upper end (a side of the tip opposite a mounting side) of the pin bends slightly according to the elastic modulus (Young's modulus) of a material and the actual length of the pin, while a lower portion of the pin is constrained by the housing connection. In particular, in the case of a pin having a length of 8 m or more, when viewed from below, the pin appears to bend when placed straight in the housing. From this state, the pin is assembled and disassembled. Therefore, the housing connection and the pin connection are never assembled and disassembled in a state where a load is applied homogeneously and symmetrically to the housing connection and the pin connection. For this reason, assembly / disassembly is performed in a state where parts of the thread emerge locally and collide strongly with each other.In other words, lubrication is performed under an unbalanced load state. Furthermore, a portion where parts of the thread emerge locally and collide strongly with each other changes depending on the assembly / disassembly.

[034] In conventional lubrication technology using a greasy compound, the compound moves after assembly / disassembly. For this reason, a lubricant (lubricating compound) works to converge assembly / disassembly in a favorable direction even when there is a slight change in lubrication conditions and the like. Therefore, in an evaluation test (also referred to as a laboratory test) of assembling / disassembling a threaded joint, it is possible to understand a lubrication situation of a full-size pin by evaluating it using a short pin without relying on the evaluation using the full-size pin.

[035] However, according to an examination by the inventor, in the lubrication technology of a connection for tubular products for oil fields using Petition 870230105138, dated 11 / 29 / 2023, page 18 / 116 8 / 86 A solid lubricant coating film, the solid lubricant coating film is inevitably scraped to some extent. It is necessary to devise a solution so that a thread clearance does not become obstructed with scrapings of the solid lubricant coating film. At this point, a byproduct formed from the scraped solid lubricant coating film does not necessarily move along with and after assembly / disassembly.

[036] The above is what occurs in a real well, and is a point quite different between the case of lubrication using the solid lubricant coating film and the case of lubrication using the lubricant compound.

[037] When a solid lubricant coating film is evaluated in a laboratory test, in evaluation using a short pin as in the case of lubrication using the lubricant compound, it is not necessarily possible to simulate the influence of a large load and an unbalanced load for the above reason. In evaluation using a short pin shorter than a pin used in a real well situation, it was found that a solid lubricant coating film is less likely to be scraped, and it is not possible to create a situation where a seizure behavior in the real well can be simulated.

[038] As described above, in conventional evaluation using a short pin, a byproduct formed from shavings of the solid lubricant coating film causes clogging and seizing, or the byproduct is compressed against a clamping surface again. As a result, it is not possible to simulate, for example, a situation in which an effect such as that of a lubricant coating film is maintained. That is, in conventional evaluation simply using a short pin, the evaluation of the solid lubricant coating film is inevitably vague, and when a physical property parameter of the solid lubricant coating film is determined, a region that should be unacceptable is erroneously evaluated as being a suitable range. Petition 870230105138, dated 11 / 29 / 2023, page 19 / 116 9 / 86

[039] For this reason, the inventors discovered that, in reality, a suitable range is often described in the description of past conventional literature based on the vague assessment above.

[040] The inventors then discovered that it is necessary to specify a group of parameters related to a solid lubricating coating film by performing the evaluation in a situation similar to that in which a connection for tubular products for oilfields is exposed during assembly / disassembly in a real well, i.e., on the premise that the assembly / disassembly is performed with a large load and an unbalanced load. For this purpose, the inventors discovered that it is necessary to adjust each definition after ensuring lubricity and clarify the meanings of the definitions of the upper and lower limits of a parameter according to the conditions of use in the real well. That is, the present inventor discovered that it is important to specify upper and lower limits of a parameter in the evaluation of a situation in accordance with the real well.

[041] In this document, as described above, in the evaluation of a lubrication behavior to be confirmed in the lubrication of a connection for tubular products for oilfields, conventionally, an assembly / disassembly behavior with a hydraulic wrench using a short pin and the number of assembly / disassembly times are often evaluated.

[042] At this point, when a greasy compound is used as a lubricant, the compound also moves along with the assembly / disassembly. For this reason, when lubrication is evaluated, there is no particular problem even if the lubrication is evaluated with a horizontal hydraulic wrench or a vertical hydraulic wrench using a short pin, and lubrication behavior can be assessed. That is, the conventional greasy compound can be evaluated even by performing a laboratory test using a Petition 870230105138, dated 11 / 29 / 2023, page 20 / 116 10 / 86 short pin, including a thread design, whether a base coat, such as a chemically treated or galvanized coat, is acceptable, and comparison and evaluation of the compound itself.

[043] However, there is a problem in evaluating the lubrication of the solid lubricant coating film as described above. That is, in evaluating it by a laboratory test simply using a short pin, the behavior in a real well is not simulated, and the lubrication evaluation is too vague. For this reason, there is a problem that even in a case where the evaluation using a short pin is “acceptable” in the conventional laboratory test, it does not necessarily mean that the evaluation is “acceptable” in the assembly / disassembly in a real well.

[044] Furthermore, since the lubrication of the connection for tubular products for oilfields differs from other lubrication behaviors in some respects, there is a problem that a definition with an evaluation based on other lubrication conditions cannot be applied.

[045] In general, regarding lubrication behavior between two objects rubbing against each other, a situation is assumed where one object is fixed and the other object moves. Lubrication is considered to begin from a state where the moving object is in close contact with the fixed object. Even when both objects move, lubrication usually begins from a state where both objects are in contact with each other.

[046] However, lubrication of the connection for tubular products for oilfields begins from a state where a pin connection (male thread) has vibration in relation to a housing connection (female thread) due to connection clearance at an early stage of assembly. Therefore, the connection is not always in stable contact with each other until the threads are engaged to some extent. That is, in the lubrication of the connection for tubular products for oilfields, a case where the threads strongly impact each other Petition 870230105138, dated 11 / 29 / 2023, page 21 / 116 11 / 86 others and a case where the threads hardly touch each other are unevenly distributed, and there is great concern that the lubricating coating film will be damaged when the threads strongly touch each other. Furthermore, in lubrication after the threads are engaged, the threads slide under the influence of a lubrication situation in place.

[047] In particular, in a situation where there is “vibration” until the threads are engaged with each other, in the conventional method using a greasy compound, the compound moves together with the assembly of the connection in an initial assembly stage and a final disassembly stage when the connection has vibration. Therefore, the influence on vibration is small. However, in the case of a solid lubricant coating film, the solid lubricant coating film is directly affected by an unbalanced load derived from vibration, and the solid lubricant coating film is easily damaged, which is different from the conventional method using a greasy compound.

[048] Furthermore, in a real well, there is an influence from the application of the total weight of a pin connection to a housing connection at the time of assembly / disassembly. Additionally, since there is vibration as described above, a load is not uniformly applied, and the pin tends to rotate eccentrically until the threads are engaged with each other. For this reason, the solid lubricant coating film needs to be a film that allows the lubrication to withstand a large applied load as an unbalanced load. A film that is completely removed or a film that is almost completely destroyed and lost cannot withstand the large load. A real well is frequently operated with oilfield tubular products having a length of about 12 to 16 m. For example, oilfield tubular products having a length of about 12 m (about 40 ft) and an outside diameter of 9-5 / 8” have a load weight of about one ton.On an offshore platform, Petition 870230105138, dated 11 / 29 / 2023, page 22 / 116 12 / 86 three pre-connected pin fittings are frequently assembled and used. Therefore, when tubular products for oilfields having an outside diameter of 9-5 / 8” are used, a serious situation occurs where a load of approximately three tons is applied to one side of the box.

[049] In lubricating the connection for tubular products for oilfields, it is necessary to assume a lubrication that can withstand this large load and an unbalanced load. As a result of several studies, the inventors discovered that what is important is to design a solid lubricant and a binding resin taking into account how to suppress damage to a solid lubricant coating film in a situation of a large load and in a situation where there is “vibration” until the threads are engaged with each other.

[050] However, in previous literature, it is difficult to say that a solid lubricant coating film is designed based on such a point of view.

[051] In this document, the inventors discovered that the above discovery is unique to a solid lubricating coating film.

[052] In conventional lubrication where a greasy compound is applied, the viscous liquid greasy compound also moves along with assembly / disassembly. Therefore, a large part of the influence of a large load or an unbalanced load is relieved. For this reason, lubrication behavior can be evaluated without particular problem even if the lubrication behavior is evaluated with a horizontal hydraulic wrench using a short pin or evaluated with a vertical hydraulic wrench using a short pin with reference to previous literature.

[053] However, in a case of lubrication behavior of a connection for tubular products for oilfields using a solid lubricant coating film as in the present disclosure, the solid lubricant coating film is damaged and peeled off or, inevitably, the film of Petition 870230105138, dated 11 / 29 / 2023, page 23 / 116 13 / 86 Solid lubricant coating is gradually and finely scraped off even during assembly until the threads are engaged, or during assembly after the threads are engaged. The scraped-off shavings do not necessarily move along with the assembly / disassembly, unlike the greasy compound. It has been found that the release of a byproduct (shavings) derived from the scraped-off solid lubricant coating film in a gap between a pin connection and a housing connection greatly affects lubrication. That is, if the gap is obstructed by the shavings, the shavings can directly lead to seizure. However, there is also a case where the shavings are compressed with a large load to reconstitute a film, and the film adheres to one of the threads again to improve lubrication.

[054] Then, the inventors discovered that, in the evaluation using a short pin in a laboratory test, neither a situation of a large load nor a situation of an unbalanced load that occurs in a real well can be simulated. That is, in the evaluation simply using a short pin, the amount of formation of a secondary product itself derived from the solid lubricant coating film is small. For this reason, lubrication behavior is often erroneously considered acceptable, and it is often found that a solid lubricant coating film design is not good only when the solid lubricant coating film is applied to a real well.

[055] Furthermore, in a laboratory test, it is not possible to simulate what actually occurs in a well without intentionally creating a situation where there is “vibration” until the threads are engaged with each other. However, it is not realistic to perform a test every time in a real well or a simulated well (a test location where an assembly / disassembly test is performed by making a pin of a certain size stand upright) using a full-size pin. That is, the cost of the experiment is enormous, which is unrealistic. For example, the latter requires Petition 870230105138, dated 11 / 29 / 2023, p. 24 / 116 14 / 86 a rental cost of around ten million yen or more per day and, in a solid lubrication test, the maximum number of assembly / disassembly times is estimated at 20 to 30 times, which requires enormous costs.

[056] In previous literature, most evaluations of a solid lubricant coating film do not take this into account. That is, the evaluation of thread lubrication is not particularly clearly described, and there are many cases of application of a horizontal hydraulic wrench frequently used in a laboratory test and a vertical hydraulic wrench simply using a short pin. In this conventional evaluation, since the influence of a large load and an unbalanced load is eliminated, basically, most evaluation results are good. Therefore, specifying adequate upper and lower limits of lubrication using a solid lubricant coating film in these evaluation methods does not mean an adequate range in the true sense.As described above, even the conditions selected in the evaluation of a short pin in conventional laboratory testing include a condition under which lubrication is not good in a real well and do not specify the technology.

[057] In this document, NPL 1 describes that a weight load of 510 kg is continuously applied to the upper end of a pin at all times, both during the assembly and disassembly of the connection, although this is not an examination of the lubrication behavior of a solid lubricant coating film. The application of a weight load of 510 kg may be intended to apply a weight corresponding to a full-size pin of 7”. As described above, in the evaluation of a solid lubricant coating film, it is important to simulate a large load and an unbalanced load, which occurs in a real well. This is because a secondary phenomenon caused by a byproduct derived from a solid lubricant coating film greatly affects lubrication. Petition 870230105138, dated 11 / 29 / 2023, page 25 / 116 15 / 86

[058] However, when a method disclosed in NPL 1 is applied to a laboratory test, there are two problems.

[059] First, a load corresponding to one to three full-size pins connected in a real well is applied to the real well, but the application of a weight of 510 kg corresponds only to a specific case where the pins are light. That is, a large load is not necessarily simulated depending on the pin size.

[060] Secondly, an unbalanced load cannot be simulated. As can be determined from Figure 5 and similar figures in NPL 1, particularly in the case of a premium joint, since there is no rotation before assembly, NPL 1 intends to test lubrication performed from a state where an initial assembly position (starting point of assembly) by manually tightening is in a state where the threads are engaged with each other. Furthermore, there is the following problem when disassembly is continued in a state where a weight load is applied even at the moment of disassembly, although this is not easily found.

[061] In other words, at the moment of disassembly, conversely, the weight acts as a balancer, and the connection is loosened directly from an assembled position without vibration. Therefore, the pin does not oscillate, and the occurrence of seizure at the moment of disassembly, which occurs in a real well, cannot be properly simulated. For this reason, depending on a situation, a situation may occur where it is misinterpreted that a lubrication characteristic is good. Therefore, it was also discovered that a condition parameter related to a solid lubricant coating film needs to be proven to have an excellent lubrication characteristic by performing a simulation that considers a lubrication state where the threads are not sufficiently engaged with each other and lubrication after the threads are sufficiently engaged with each other.

[062] In this document, as described above, in the field targeted by this Petition 870230105138, dated 11 / 29 / 2023, page 26 / 116 16 / 86 disclosure, BN is widely exemplified in many PTLs as one of the candidates for a solid lubricant. For example, PTLs 1 and 2 exemplify BN as a solid lubricant present in a solid lubricant coating film. However, it is not necessarily possible to maintain lubrication simply by defining BN in a broad sense from the point of view of whether the lubricity that can support lubrication behavior in a real well can be ensured as described above.

[063] Furthermore, the previous PTLs exemplify the use of an epoxy resin as a binder resin, but there are very few PTLs that can clearly define the binder resin according to the quality of the epoxy resin.

[064] PTLs 3 to 8 refer to a mixture of a prepolymer and a curing agent as an epoxy resin, or refer to an epoxy resin coating film formed from the prepolymer and the curing agent as an epoxy resin and merely exemplify epoxy resin as one of the candidate materials. Furthermore, the definition of epoxy resin is broad, and what is specified by epoxy resin is unclear.

[065] In this document, an epoxy group is a three-membered ring having oxygen of oxycyclopropane (oxirane), and is subjected to a crosslinking reaction with an appropriate curing agent selected in order to become a resin. This means that the three-membered ring is opened and polymerized. In short, the epoxy group is not present in a state where the epoxy group has become the epoxy resin, and is in a final form of polyether (including RO-R'), polyester (including R-COO-R'), polyhydroxyether (including -OH group and ether group), polyhydroxylamine (including -OH group and amine group), or similar.

[066] The characteristics of a film also assume the characteristics of the epoxy resin in a strict sense and the characteristics of the curing agent. Therefore, even if the epoxy resin in a broad sense does not specify any technology. Petition 870230105138, dated 11 / 29 / 2023, page 27 / 116 17 / 86 The characteristics of epoxy resin coating films are also determined by a combination of an agent of "epoxy resin in a strict sense" as a prepolymer and a curing agent, and even if only the epoxy resin agent in a strict sense is mentioned, the characteristics of the epoxy resin coating film are not specified. With reference to previous PTLs, it may be interpreted that any epoxy group can be widely applied, but in fact this is not necessarily the case. In most cases, the high lubricity as targeted by this disclosure cannot be ensured. In order to achieve the objective, it is necessary to select an epoxy resin coating film that excels in high lubricity in a final form.

[067] Furthermore, in the previous PTLs, an expression that an epoxy resin (which possibly means an epoxy resin coating film as a final film formed from an epoxy resin and a curing agent) is contained in an amount of oo% is also ambiguous. As described above, in a combination of an epoxy resin in a strict sense and a curing agent, when the epoxy resin is represented by A and the curing agent is represented by B, the polymerization is carried out as ABABA ···. It is an approximate mixing rule of epoxy resin that the mixture is carried out by combining the equivalent of an epoxy group of the epoxy resin in a strict sense with the equivalent of an amine when the curing agent is an amine-based agent or the active hydrogen equivalent when the curing agent is another curing agent including an amine.Therefore, even an expression of the weight occupied by the epoxy resin film expresses a numerical value that varies considerably depending on the selection of the prepolymer and the curing agent. By simply limiting the expression to containing the epoxy resin in an amount of 00%, the epoxy resin cannot be specified and the technology is not specified.

[068] In other words, a simple expression of an epoxy resin expresses the use of Petition 870230105138, dated 11 / 29 / 2023, page 28 / 116 18 / 86 an epoxy resin agent as a source material (prepolymer), and a polymer having a completely different structure is obtained depending on the selection of a curing agent. Therefore, unless the physical properties of an “epoxy resin” as a finally cured object are specified, the physical properties of an agent containing an epoxy group of a prepolymer are specified, a curing agent is specified, or a range of parameters specifying them secondarily is clearly specified, the technology is not specified.

[069] PTL 3 selects a resin selected from one or two of an epoxy resin and a polyamide-imide resin as formed on a Cu-Sn-Zn electroplating base. It is unclear what epoxy resin is referred to here. That is, a low-lubricity epoxy resin is broadly included.

[070] PTLs 4 to 7 merely exemplify an epoxy resin for a solid lubricating coating film, and it is also difficult to specify this epoxy resin.

[071] PTL 8 discloses an invention in which a silicon acrylic resin is formed into an ultraviolet curable resin. This is a case where an acrylic acid-modified epoxy resin is exemplified as one of the candidates among organic and inorganic resins for a binder resin of the ultraviolet curable resin. Furthermore, a backbone of the main chain is formed from an epoxy resin and a terminal of the backbone of the main chain is acryloylated. PTL 8 merely exemplifies the acrylic acid-modified epoxy resin, and does not specify other information, such as a curing agent of the epoxy resin coating film or the characteristics thereof.

[072] However, PTL 9 describes a photocurable acrylic resin coating film. PTL 9 specifies a film obtained by copolymerizing a photocurable (meth)acrylate resin with a group of (meth)acrylate monomers with a trigger, such as a photopolymerization initiator. PTL 9 exemplifies, as a Petition 870230105138, dated 11 / 29 / 2023, page 29 / 116 Candidate 19 / 86, an epoxy along with a polyester, a polyether, and a polyurethane as a main chain structure forming an acrylate side chain. This invention expresses an acrylate (corresponding to the prepolymer of the present disclosure) and a polymer (corresponding to the curing agent of the present disclosure) using a resin-per-hundred unit (PHR) system, and can accurately express the ratio and weight of an epoxy resin when a main chain structure is formed from the epoxy resin. The description of PTL 9 is clearer than the definitions in PTLs 3 to 7. However, since the present disclosure does not intend a photopolymerizing resin, but a heat-formed (curing) film, PTL 9 differs in technology from the present disclosure.

[073] The present invention was made in view of the above points, and an objective of the present invention is to provide a solid lubricating coating film capable of imparting excellent resistance to seizing as well as lubricity to a connection for tubular products for oilfields even when the solid lubricating coating film is adopted for lubrication. Solution to the Problem

[074] Unlike a situation where a lubrication material has been conventionally selected based on the vague assessment above, the present inventor targets tubular products for oilfields and a threaded joint for tubular products for oilfields having excellent lubrication and rust prevention characteristics, and an agent for manufacturing the tubular products for oilfields and the threaded joint for tubular products for oilfields. The present inventor targets a composition obtained by adding BN as a solid lubrication component in an appropriate ratio to a binder resin containing mainly an epoxy resin and appropriately adding another additive to it. These films are formed by specifying a parameter so as to be able to withstand severe lubrication conditions, such as those Petition 870230105138, dated 11 / 29 / 2023, page 30 / 116 20 / 86 performed in the lubrication of a real connection for tubular products for oil fields, to which a large load and an unbalanced load are applied as described above.

[075] That is, one aspect of the present invention is an agent for forming a solid lubricating coating film on a threaded portion of tubular products for oilfields, wherein a solid lubricant is dispersed in a binder resin, the binder resin contains a prepolymer and a curing agent, the prepolymer is formed from one or more epoxy resins, 70 parts by weight or more of the prepolymer are contained in relation to 100 parts by weight of the binder resin, the epoxy resin constituting the prepolymer has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, BN has an average particle size of 10 μm or less, and the total weight of the solid lubricant is 0.1 times or more and two times or less the total weight of the binder resin.

[076] Another aspect of the present invention is tubular products for oilfields having a lubricating coating film including a solid lubricating coating film in a threaded portion, wherein the solid lubricating coating film is formed by dispersing a solid lubricant in a binder resin, the binder resin contains an epoxy resin cured with a curing agent, 70 parts by weight or more of the epoxy resin are contained in relation to 100 parts by weight of the binder resin, the epoxy resin has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, BN has an average particle size of 10 μm or less, and the total weight of the solid lubricant is 0.1 times or more and two times or less the total weight of the binder resin. Advantageous Effects of the Invention

[077] One aspect of the present invention specifies comprehensively Petition 870230105138, dated 11 / 29 / 2023, p. 31 / 116 21 / 86 elements (physical property parameters) of a binder resin (main component: epoxy resin) and a solid lubricant (main component: BN) that constitutes a solid lubricating coating film with reference to evaluation by a recently developed laboratory test capable of reproducing behavior in a real well. As a result, one aspect of the present invention can provide an agent capable of forming a solid lubricating coating film (lubricating coating film) capable of imparting lubricity equal to or superior to that of a greasy compound for lubrication that has been conventionally used, and a lubrication and seizing resistance characteristic comparable to a grease-preventive anti-rust compound for storage or a rust-preventive material in oil even when the solid lubricating coating film is adopted for lubrication.

[078] For example, one aspect of the present invention may provide a threaded joint for tubular products for oilfields having lubricity and resistance to seizing during assembly, which considers a condition corresponding to a real well that may occur in a real well environment. Note that the condition corresponding to a real well is a situation in which a pin weight is applied to a casing from above, a situation in which a load is applied obliquely due to a deviation from the center of the shaft, a situation in which a load is often applied locally rather than uniformly, or similar. Brief Description of the Drawings

[079] Figure 1 is a diagram illustrating tubular products for oilfields and a threaded joint for tubular products for oilfields;

[080] a Figure 2A is a diagram of a setup chart in a real well, and Figure 2B is a diagram illustrating a defined initial position at that moment;

[081] Figure 3A is a diagram of an assembly chart in a test of Petition 870230105138, dated 11 / 29 / 2023, page 32 / 116 22 / 86 conventional laboratory, and Figure 3B is a diagram illustrating a defined initial position at that moment;

[082] Figures 4A and 4B are schematic diagrams of an assembly chart, wherein Figure 4A illustrates a case of a real well, and Figure 4B illustrates a case of a conventional laboratory test;

[083] a Figure 5 is a diagram to explain a new laboratory test (hydraulic wrench test with heavy pendulum);

[084] a Figure 6 is a diagram that illustrates a definite example of a weighted pendulum in the new laboratory test (hydraulic wrench test with weighted pendulum); and

[085] Figures 7A and 7B are diagrams that illustrate a coating film structure. Description of the Modalities

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

[087] Conventionally, for lubrication and rust prevention purposes during storage, and in order to achieve both objectives, lubrication for assembly / disassembly and long-term external storage (rust prevention) have been achieved using different types of greasy compounds or the same type of greasy compound.

[088] On the other hand, in a threaded structure of the present embodiment, an epoxy resin coating film whose parameter is appropriately specified is used as a binder resin for one or both of a portion where a surface metal of the male thread and a surface metal of the female thread of a connecting material are in contact with each other or a part thereof. A solid lubricant coating film is adopted in which BN as a solid lubricant whose parameter is appropriately specified is dispersed. As a result, the Petition 870230105138, dated 11 / 29 / 2023, page 33 / 116 23 / 86 This model aims to improve lubrication and provide resistance to seizing.

[089] In addition, an agent for the formation of the solid lubricating coating film is also targeted. Furthermore, a film structure suitable for lubricating a connection for tubular products for oilfields, including a lubricating coating film obtained by combining a coating film of the present embodiment and a base layer and film hardness on the other side of a non-forming side, is also targeted. Furthermore, the present embodiment can be applied to a range where the lubricating coating film can be widely used for improving lubrication and preventing rust on a metallic material as another form of use.

[090] The inventors studied the problems described above. As a result, the above problems can be solved by mixing an agent, forming a solid lubricating coating film of a connection for tubular products for oilfields, a method for confirming the formation of the solid lubricating coating film, and the like.

[091] The solid lubricating coating film of the present embodiment is obtained by studying in which an epoxy resin cured with a curing agent is used as a main component of a binder resin and boron nitride (BN) is used as a main component of a solid lubricant. (Settings)

[092] The present embodiment is an invention relating to a coating film structure formed on a clamping surface of a threaded portion of tubular products for oilfields in tubular products for oilfields and a threaded joint for tubular products for oilfields used for actual oil / gas, and a structure having the coating film structure as a lubricating coating film. The present embodiment is characterized by a lubricating coating film including a film of Petition 870230105138, dated 11 / 29 / 2023, page 34 / 116 24 / 86 solid lubricating coating formed on the threaded portion of the tubular products for oilfields, and the threaded structure itself of the tubular products for oilfields and the threaded joint of the tubular products for oilfields are not particularly limited. As the threaded structure of the tubular products for oilfields and the threaded joint of the tubular products for oilfields, it is only necessary to adopt a known or innovative threaded structure. <Produtos tubulares para campos petrolíferos e junta roscada para produtos tubulares para campos petrolíferos>

[093] Tubular products for oil fields include, for example, a housing 2, such as a coupling, and a pin 1 as illustrated in Figure 1.

[094] As illustrated in Figure 1, the threaded joint for tubular products for oilfields includes housing 2, such as a coupling having a female thread 2a and pin 1 having a male thread 1a. A lubricating coating film including a solid lubricating coating film is formed on a contact surface (clamping surface 10) of a threaded portion in at least one of housing 2 and pin 1. <agente>

[095] Next, an agent for the formation of the solid lubricant coating film in the present embodiment will be described.

[096] The agent of the present embodiment is formed by dispersing a solid lubricant in a binder resin as a matrix component.

[097] The agent contains a binding resin, a solid lubricant and a solvent component.

[098] The binder resin contains a prepolymer and a curing agent.

[099] The prepolymer is formed from one or more epoxy resins. The prepolymer is contained in an amount of 70 parts by weight or more relative to Petition 870230105138, dated 11 / 29 / 2023, page 35 / 116 25 / 86 to 100 parts by weight of the binder resin.

[0100] The epoxy resin that constitutes the prepolymer has an epoxy equivalent of 100 or more and 500 or less.

[0101] The epoxy resin that constitutes the prepolymer preferably has a glass transition temperature Tg of 100 °C or higher.

[0102] The solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more. The BN has an average particle size of 10 μm or less.

[0103] The total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the binder resin.

[0104] The solvent component is preferably contained in an amount of 30 parts by weight or more and 80 parts by weight or less in relation to 100 parts by weight of a sum of the total weight of the solid lubricant and the total weight of the binder resin excluding the curing agent.

[0105] A cure accelerator may be contained in the agent in an amount of 0 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of the total weight of the epoxy resin that constitutes the prepolymer.

[0106] The curing agent is a curing agent for curing an epoxy resin, and is formed by an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent, or a latent curing agent.

[0107] At present, the epoxy resin that constitutes the prepolymer preferably has more than two epoxy groups (polyfunctional epoxy resin). The epoxy resin that constitutes the prepolymer preferably has six or fewer epoxy groups. The epoxy resin that constitutes the prepolymer more preferably has four or fewer epoxy groups.

[0108] The agent having the above composition preferably has a viscosity of 20 mPa*s or more and 2,000 mPa*s or less.

[0109] The agent of the present embodiment is applied to a clamping surface Petition 870230105138, dated 11 / 29 / 2023, p. 36 / 116 26 / 86 of the thread and dried to form a solid lubricating coating film 10A (see Figure 7A). <filme de revestimento lubrificante incluindo filme de revestimento lubrificante sólido 10A>

[0110] The 10A solid lubricant coating film is formed by dispersing a solid lubricant in a binder resin as a matrix component.

[0111] The binder resin contains a prepolymer and a curing agent, and the prepolymer is polymerized with the curing agent and cured.

[0112] The prepolymer is formed from one or more epoxy resins. The prepolymer is contained in an amount of 70 parts by weight or more in relation to 100 parts by weight of the binder resin.

[0113] The epoxy resin that constitutes the prepolymer has an epoxy equivalent of 100 or more and 500 or less.

[0114] The epoxy resin that constitutes the prepolymer preferably has a glass transition temperature Tg of 100 °C or higher.

[0115] The solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more. BN has an average particle size of 10 μm or less.

[0116] The total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the binder resin.

[0117] The curing agent is a curing agent for curing an epoxy resin, and is formed by an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent, or a latent curing agent.

[0118] Currently, the epoxy resin that constitutes the prepolymer preferably has more than two epoxy groups (polyfunctional epoxy resin). The epoxy resin that constitutes the prepolymer preferably has six or fewer epoxy groups. The epoxy resin that constitutes the prepolymer more preferably has four or Petition 870230105138, dated 11 / 29 / 2023, p. 37 / 116 27 / 86 fewer epoxy groups.

[0119] The solid lubricating coating film 10A of the present embodiment has a hardness of, for example, 3H or more.

[0120] The 10A solid lubricant coating film has a thickness of, for example, 10 μm or more and 150 μm or less.

[0121] The lubricating coating film of the present embodiment may have a base layer 10B between a clamping surface of a threaded portion and the solid lubricating coating film 10A (see Figure 7B). The base layer 10B is formed by, for example, a chemically converted treated layer or a galvanized layer.

[0122] The lubricating coating film described above is formed on a clamping surface of a threaded portion of at least one of the housing and the pin. <Determinação de cada definição>

[0123] The inventors discovered that what is important to solve the above problems is to control the following four ((a) to (d)) and related matters within appropriate ranges. (a) Develop a new suitable laboratory test that simulates assembly / disassembly in a real well, specifying the upper and lower limits of each parameter for a solid lubricant coating film by a method of the new laboratory test, and specifying an appropriate range for the same. (b) Specify an ideal BN range with reference to the evaluation by the laboratory test in (a). (c) Specify an ideal range of a physical property value of an epoxy resin using the definition in (b). (d) Specify further appropriate ranges related to the same. Petition 870230105138, dated 11 / 29 / 2023, page 38 / 116 28 / 86

[0124] In this document, the appropriate method for simulating assembly / disassembly in a real well is a method for simulating assembly behavior that occurs when a connection for tubular products for oilfields is assembled in a real well. Using this, the upper and lower limits of a parameter in the present embodiment are confirmed, and an appropriate range is determined.

[0125] A lubrication state of a connection for tubular products for oilfields is divided into two phases in each of a laboratory test and a real well. Phase 1 is the lubrication at the moment of assembly / disassembly in a state where the threads are not engaged with each other, and phase 2 is the lubrication at the moment of assembly / disassembly in a state where the threads are engaged with each other. Phase 1 corresponds to, for example, a region (x) in a torque rotation graph of Figures 4A and 4B. Phase 2 corresponds to, for example, regions (y) and (z) in Figures 4A and 4B.

[0126] The first (phase 1) is eliminated if the connection is tightened to a point where the threads are engaged by manually tightening or similar means at the moment of starting the assembly of the connection (example: Figures 3A and 3B). However, in many real wells, simply inserting a pin into a housing for adjustment is defined as an initial assembly position. Alternatively, after that, assembling the connection only by several rotations to fix the connection only loosely so that cross-threading does not occur is defined as an initial assembly position. That is, in many real wells, it is common to start assembly / disassembly from a situation where the threads are not engaged with each other (example: Figures 2A and 2B). Note that cross-threading refers to a situation where the connection is assembled with threads at different levels or slides to the original thread positions on the way to being closed.

[0127] In phase 1, a hydraulic wrench performs assembly / disassembly of Petition 870230105138, dated 11 / 29 / 2023, page 39 / 116 29 / 86 at a high speed of 5 to 20 rpm. However, when the connection is continuously assembled, the threads begin to engage with each other, and the phase changes to phase 2. This change causes the torque to increase slightly, and from then on, the assembly is carried out slowly at a speed of approximately 0.5 to 2.0 rpm. To loosen, a procedure reversed to the assembly is performed.

[0128] These procedures are similarly performed when a conventional greasy compound is used as lubrication or when a solid lubricating coating film is formed as lubrication, as in the present embodiment. As a condition for adjusting a connection in an initial position, a behavior to create vibration is important. As an adjustment position, it is important that about one to three or more threads are exposed relative to a housing connection when initially assembling a pin connection when a joint behavior is considered. <Figuras 2A e 2B>

[0129] Figures 2A and 2B are examples where a real well is simulated as such. That is, Figures 2A and 2B are assembly graphs (torque turning graph) when an assembly test is performed using a real length pin of 40 feet (« 12 m) as a pin and using a solid lubricant coating film for lubrication.

[0130] The test conditions in Figure 2A will be described.

[0131] As an example, such as the solid lubricant coating film, a film obtained by dispersing MoS2 as a solid lubricant in a polyamideimide (PAI) binder resin is used.

[0132] Figures 2A and 2B are examples of a simulation of a situation frequently encountered in a real oil / gas field. That is, this is an example where the assembly is started from a situation where the threads are not sufficiently engaged with each other, as illustrated in Figure 2B. Petition 870230105138, dated 11 / 29 / 2023, page 40 / 116 30 / 86 as a defined starting position at the moment of initiating the assembly of the connection. That is, as illustrated in Figure 2B, this is an example where assembly is initiated from a state where approximately half of the pin connection is exposed at the moment of starting the initial assembly. The state where the threads are not engaged is not caused by intentional interruption in manual tightening. When attempting to adjust the pin connection to a housing connection by manually tightening, the pin connection inevitably stops halfway. This means that the connection can no longer be tightened manually. A long, heavy, actual length pin is not exactly vertical with respect to the housing connection, unlike in a theoretical case. When the pin is viewed from below, it is very common for the pin to be slightly inclined and can no longer be tightened manually.

[0133] The pin used is a 9-5 / 8”53.5#Q125 JFELIONTM connection, and is approximately over 40 feet long. Figure 2A is a graph of when a joint is assembled while the pin is suspended by a crane that hangs the entire length of the pin on a platform. It can be observed that the torque rotation graph example in Figure 2A is a situation that frequently occurs in a real well.

[0134] What is noteworthy in Figure 2A is a region before a point where torque increases continuously (rotation number is 0 at approximately 6.3 rotations: corresponding to phase 1). In this region, the torque should not rest in principle, but in fact, as illustrated in Figure 2A, it can be confirmed that a pin-shaped torque tends to rest frequently in an irregular manner. This suggests that the pin connection is in local and irregular contact with the housing connection during rotation. This is a situation that occurs in the actual assembly.

[0135] This means that the destruction or peeling of a solid lubricant coating film is inevitable to some extent depending on the design or optimization of the solid lubricant coating film. Petition 870230105138, dated 11 / 29 / 2023, page 41 / 116 31 / 86

[0136] In this document, what is noteworthy is that the graph in Figure 2A does not intentionally create a worse state as a condition, but is a torque turning graph for a very common sample with a solid lubricant coating film. <Figuras 3A e 3B>

[0137] Figure 3A is a torque rotation graph when the same solid lubricant coating film from Figures 2A and 2B is used and the assembly is performed with a vertical hydraulic wrench.

[0138] In Figures 3A and 3B, a pin having the same outer diameter, thickness and connection type as Figures 2A and 2B is adopted, but a short pin having a length of about 1 m is adopted as the pin.

[0139] Figure 3A is an assembly graph (torque rotation graph) when assembly is initiated from a state where the threads are sufficiently engaged with each other. That is, Figure 3A is an assembly graph (torque rotation graph) when approximately one to three pin threads are exposed at the moment of starting the initial assembly as illustrated in Figure 3B.

[0140] The condition in Figure 3A is also a condition frequently used during assembly in a conventional laboratory test, and is a case where a connection is adjusted until the threads are engaged with each other by manually tightening and then the assembly test is performed.

[0141] In Figure 3A, it is necessary to pay attention to a point where the unit of the horizontal axis is different from that in Figures 2A and 2B.

[0142] In Figure 3A, the assembly by a hydraulic wrench goes from a state where manual tightening is performed to a state where the threads are engaged with each other and, thus, a spike-shaped torque as observed in Figure 2A is not observed. That is, it was found that it can be understood that the examination of a lubrication characteristic of the coating film Petition 870230105138, dated 11 / 29 / 2023, page 42 / 116 32 / 86 solid lubricant only in phase 2 without going through phase 1 corresponds to the conventional laboratory test.

[0143] As can be seen from Figures 3A and 3B, in the conventional laboratory test, the destruction of the solid lubricant coating film, which frequently occurs in phase 1, does not occur, and the assembly takes place from a state where the threads are sufficiently engaged with each other, i.e., from a region where the thread surfaces begin to come into contact with each other. <Figuras 4A e 4B>

[0144] Figures 4A and 4B illustrate Figures 2A and 3A in a state where Figures 2A and 3A can be easily compared with each other.

[0145] Figure 4A is the case of Figures 2A and 2B, and Figure 4B is the case of Figure 3.

[0146] According to the inventor's study, which considers use in a real well, for an ideal solid lubricant coating film, the solid lubricant coating film is preferably not destroyed in the region of (x) in Figure 4A, and concerns about destruction and peeling are preferably minimized. Alternatively, a spike may stand up slightly. Furthermore, it is preferable to design the solid lubricant coating film so that a byproduct derived from the destroyed or peeled solid lubricant coating film does not obstruct a thread clearance in an assembly / disassembly process even in a situation where the solid lubricant coating film is damaged and, conversely, adheres well to the threads to aid in lubrication.

[0147] For this purpose, it is important to control the quality of the solid lubricating coating film so that it is hard to a predetermined hardness or higher. As an example of how to assess hardness, one can consider pencil hardness, which is a hardness index based on scratch resistance. However, when a Petition 870230105138, dated 11 / 29 / 2023, page 43 / 116 33 / 86 lubricating coating film is formed, it is preferable to suppress the viscosity of an agent for the solid lubricating coating film to such a low degree that spray coating or brush coating can be performed, and be able to apply the agent without unevenness in film thickness. Furthermore, during a heating step (during a curing step), the constituent components of the solid lubricating coating film are preferably formed into a single, smooth film with surface tension by a liquid-rubber behavior.

[0148] Furthermore, in a method of evaluating the laboratory test study of the present embodiment, it is preferable to perform the evaluation by a new laboratory test having the following conditions (1) to (6) for the purpose of simulating an assembly / disassembly behavior in a real well. Note that an example of the configuration of the real laboratory test apparatus will be described later. (1) A weighted pendulum having a weight corresponding to 1 to 3 full-size pegs is placed on an upper portion of a short peg. (2) As initial positions of the short pin connection and a housing connection are defined, about half of the pin threads are defined, for example, half of the pin threads are exposed, i.e., the short pin connection is weakly fixed, and an assembly / disassembly test is initiated. (3) Starting from the state of "(2)", the assembly is initiated at high speed rotation of 15 rpm, and the assembly continues until a torque of a predetermined value or more is detected. (4) When the torque increases, the rotation is temporarily stopped, and the assembly is carried out by low-speed rotation of 1 rpm (assembly is completed). (5) Disassembly is carried out in a reverse step. (6) When the short pin connection is completely removed, a Petition 870230105138, dated 11 / 29 / 2023, page 44 / 116 34 / 86 The threaded surface of the pin and a connection surface of the housing are observed (the air-blown part is observed depending on the situation) to determine whether an abnormal event, such as seizure, has occurred or not. If there is no problem, "(2)" and the subsequent steps are repeated.

[0149] If slight seizing occurs in a threaded portion (seizing in a sealed portion is NG regardless of the degree of seizing), the threaded portion is repaired and, if necessary, a solid repair lubricant is applied to the threaded portion, and "(2)" and subsequent steps are repeated.

[0150] In the present embodiment, a lubrication characteristic of the solid lubricant coating film was recently evaluated based on this evaluation method, and suitable conditions for the solid lubricant coating film were selected (see Examples).

[0151] In this document, it is acknowledged that the conventional laboratory test targets lubrication after the threads are engaged with each other (situations in the (y) region and in the (z) region in Figures 4A and 4B) as determined from the results of many assembly / disassembly tests (laboratory tests) in the previous literature. The conventional laboratory test is considered superior and inferior in lubrication characteristics based on lubrication after the threads are engaged with each other, i.e., a state where the solid lubricant coating film is satisfactorily in a state where the state in the (x) region, i.e., a situation where the torque increases in a spike shape, is not considered.In other words, the conventional laboratory test looks like the conventional laboratory test performing the assembly / disassembly from a position where the connection was sufficiently adjusted by manually tightening to a portion where the threads were engaged together in the evaluation using a short pin and a horizontal hydraulic wrench or a vertical hydraulic wrench. In PTLs where the number of times of. Petition 870230105138, dated 11 / 29 / 2023, page 45 / 116 35 / 86 assembly / disassembly is clearly described; there is a description that the number of assembly / disassembly times can be 10 for a small diameter size when assembling in a real well. However, in both the evaluation with a short pin and the evaluation in a real well, if the defined initial position (initial assembly position) starts from a position where the threads are sufficiently engaged with each other, the number of assembly / disassembly times seems to be a feasible number.

[0152] However, in previous literature, it is sometimes described that the number of assembly / disassembly times can be up to 15 to 20 by assembly / disassembly based on a solid lubricant coating film for a large diameter size of 9-5 / 8” or 13-3 / 8”. However, in assembly / disassembly in a real well, i.e., when a full-size pin has its own weight and the assembly / disassembly is performed from a state where the threads are not engaged with each other, it seems that this number is almost impossible in the case of a large diameter using a solid lubricant coating film.

[0153] It is evident that simulating a real assembly / disassembly situation is important to evaluate the lubricity of the solid lubricant coating film. In a situation where there is vibration until the threads are engaged with each other, it is necessary to perform the evaluation based on a state where the solid lubricant coating film is peeled off or damaged. In the present embodiment, several definitions are made with reference to the results of a new laboratory test that can be evaluated considering such conditions.

[0154] The conditions for the solid lubricant coating film of the present embodiment are defined with reference to the results of the new laboratory test on the premise that the solid lubricant coating film is a solid lubricant coating film in which BN is a major component of a Petition 870230105138, dated 11 / 29 / 2023, page 46 / 116 36 / 86 solid lubricant is dispersed in a binder resin containing an epoxy resin film as a main component.

[0155] Furthermore, each definition will be described in detail. <Composição básica de filme de revestimento lubrificante sólido, espessura do filme e estrutura do filme>

[0156] In the present embodiment, the solid lubricant coating film is formed by dispersing a solid lubricant containing mainly BN in a coating film cured with epoxy resin. In particular, it is preferable to obtain a pencil hardness of 3H or more.

[0157] In this embodiment, BN is selected as a main component of the solid lubricant in order to obtain a film capable of achieving high lubrication, and to obtain a film capable of maintaining high lubrication even at high temperatures. That is, during assembly / disassembly, a pin connection and a housing connection do not rub against each other in any way to generate frictional heat. BN is selected in order to maintain sufficient lubrication even at this time.

[0158] In the present embodiment, an epoxy resin coating film is selected as the binder resin. The epoxy resin coating film is selected because it is easy to handle and cheaper than other agents. Furthermore, the epoxy resin coating film is selected because it is a well-balanced material, and it facilitates obtaining a hard, targeted film by the present embodiment or a film having excellent heat resistance by selecting an appropriate "epoxy resin agent in a strict sense" and curing agent. In addition, the epoxy resin coating film is selected because it has many excellent advantages; for example, it is excellent in adhesion / bonding, it can Petition 870230105138, dated 11 / 29 / 2023, page 47 / 116 37 / 86 can be formed without a base layer (film treated by chemical conversion of Mn phosphate, galvanized film or similar), and does not shrink significantly during curing.

[0159] Regarding the thickness of the coating film, it is necessary to form a film having at least a thickness of 10 μm in order to maintain lubrication and seizing resistance characteristics. An upper limit for film thickness is defined as 150 μm, although it is difficult to state the upper limit unconditionally because the clearance between a housing connection and a pin connection varies depending on the type and design of a connection for tubular products for oilfields.

[0160] In this document, since many connections for tubular products for oilfields are designed so that an upper limit of a thread clearance is about 100 to 200 μm, the upper limit of the film thickness is specified as 150 μm or less. The film thickness is more preferably 10 to 50 μm. There may be a clearance of 100 to 200 μm between a thread and a root of a male thread and a female thread as described above. However, a clearance between a thread and a flank in a male thread and a female thread and a clearance between a fillet and a flank changes between the assembly moment and the disassembly moment. When the clearance is narrow, the film is in substantially close contact. Therefore, the film thickness is preferably small, and the film thickness is preferably 10 to 50 μm.

[0161] However, film thickness refers to the thickness of the film in a formed state as before the first assembly. At the time of assembly / disassembly, in reality, the binder resin is somewhat scraped off, and the applied film thickness at room temperature actually results in a thin film due to film crushing. Therefore, even if there is a thickness equal to or greater than a considered clearance on a threaded surface, a problem such as Petition 870230105138, dated 11 / 29 / 2023, page 48 / 116 38 / 86 The flu does not occur for this reason.

[0162] Epoxy resin can be formed directly onto a threaded surface, or a base layer can be formed between the threaded surface and the epoxy resin. Examples of base layers include a chemically converted layer with Mn phosphate and a metal-coated layer including a Cu-coated layer. Although there are various opinions and it is difficult to say that this is theoretically determined, an OH group in the epoxy resin can form a film having strong adhesion by hydrogen bonding or similar with a metallic surface. The OH group above is an OH group in the epoxy resin film, such as polyhydroxyether or polyhydroxylamine. For this reason, even when there is no treated layer on the surface as a base or even when there is a treated layer on the surface (an anchoring effect or similar can be expected in some cases), it is considered that there are few adhesion problems. <Lubrificante sólido>

[0163] The present embodiment targets one in which a solid lubricant containing boron nitride (BN) as a main component is dispersed in a binder resin. [Solid lubricant]

[0164] A range of BN as a solid lubricant having a notable lubrication-enhancing effect was clarified using the novel laboratory test method above. That is, by studying various lubricating coating films in which BN is dispersed in an epoxy resin as a binder resin using the novel laboratory test method above, the range of BN having a notable lubrication-enhancing effect was clarified.

[0165] In this document, a highly lubricated state cannot necessarily be created using boron nitride (BN) as the solid lubricant. Petition 870230105138, dated 11 / 29 / 2023, page 49 / 116 39 / 86

[0166] As for BN, it has been found that when a BN-based component system containing BN in an amount of 80% or more relative to the total weight of the solid lubricant as a denominator is used, and BN having an average particle size of 0.1 to 10 μm is selected, a remarkable effect is obtained.

[0167] The BN size is preferably as small as possible. However, since a lower limit of average particle size of commercially available BN is 0.1 μm, a lower limit of BN is defined as 0.1 μm. An upper limit has been determined experimentally, and it has been confirmed that excellent lubricity is exhibited down to 10 μm.

[0168] In the case of a lubricant formed by overlapping in a sheet-like shape, or when an average particle size is greater than 10 μm, a strong crystalline structure of a two-dimensional surface, such as BN, achieves lubrication in such a way that a sheet-like structure slides. At this point, adjacent sheet-like structures extend so as to overlap each other. As a result, a white ribbon-like byproduct is formed. Then, since the byproduct is formed to be thicker, there is a high tendency for a thread clearance to be obstructed by the byproduct and, therefore, a concern that seizure will increase. In general, the smaller the average particle size, the less overlap there will be, and the formation of the white ribbon-like byproduct can be suppressed. Therefore, it is considered that high lubrication can be obtained.

[0169] From this, containing BN in an amount of 80% or more in relation to the total weight of the solid lubricant as a denominator, and BN having an average particle size of 10 μm or less are defined as constituent elements of the present invention.

[0170] The meanings of these definitions are as follows. A highly lubricated state cannot necessarily be created with boron nitride (BN) Petition 870230105138, dated 11 / 29 / 2023, page 50 / 116 40 / 86 in a broad sense. This means that high ideal and noticeable lubricity can be expected when BN is used in this range so that the BN dispersed in the epoxy resin as the binder resin in the present embodiment in a connection environment for tubular products for oilfields achieves high lubricity.

[0171] In this document, BN has a strong crystalline structure in a two-dimensional sheet surface direction like MoS2 and graphite, and the two-dimensional sheet surfaces are connected to each other by a weak intermolecular force in the Z-axis direction. When a force is applied to BN, the sheet surfaces slide against each other to achieve lubrication.

[0172] In this embodiment, the expression that the BN content is 80% or more means that BN is a major component of the solid lubricant. The BN content is specified as 80% or more to mean that even if another solid lubricant is contained in a ratio of 20% or less, there is no negative influence on a BN-based design.

[0173] In this embodiment, the more BN as a material constituting the solid lubricant, the better. Since lubricity can be deteriorated due to the mixing of other components, the BN content is defined as 80% or more as a handling range of BN as a major component. The BN content is preferably 90% or more.

[0174] The smaller the average particle size of BN, the better. Note that the average particle size is a parameter that means a particle size at an integrated value of 50% in a particle size distribution obtained by a laser diffraction / scattering method or similar.

[0175] The upper limit of the average particle size of BN is defined as 10 μm because when the average particle size of BN is greater than 10 μm, there is great concern that the binder resin film may be destroyed and completely peeled off due to the large particle size of BN. That is, Petition 870230105138, dated 11 / 29 / 2023, p. 51 / 116 41 / 86 What is peeled off from the solid lubricant coating film is compressed during assembly / disassembly to form a secondary product. However, when each BN having a sheet-shaped structure is deformed so as to slide on a sheet surface, BNs having sheet-shaped structures close to each other overlap each other and, finally, a strong white ribbon-shaped secondary product is formed. Then, since the secondary product is formed to be thicker, the secondary product cannot move after assembly / disassembly, and the concern about seizing increases. In general, the smaller the average particle size of BN, the less overlap occurs, and the formation of the white ribbon-shaped secondary product can be suppressed. As a result, it is considered that high lubrication can be obtained.Currently, since a lower limit for the average particle size of commercially available BN is 0.1 μm, a lower limit for BN is considered to be around 0.1 μm. However, the present embodiment also includes BN having an average particle size of 0.1 μm or less obtained through technological development.

[0176] Furthermore, as industrial types of BN, there are flaked BN and particulate BN. In the present embodiment, either type can be used. Granulated BN is preferably used.

[0177] A solid lubricant other than BN may be mixed under the condition that its content is 20% or less, as described above. Any other type of solid lubricant may be used, and examples thereof include polytetrafluoroethylene (PTFE: Teflon (registered trademark)), graphite, fluorographite, MoS2, WS2, melamine cyanurate (MCA), mica, and talc. An oil-based substance may be mixed as a type of solid lubricant under the condition that its content as the solid lubricant is 20% or less. For example, carnauba wax, perfluoropolyether oil (PFPE), chlorotrifluoroethylene oil (CTFE). Petition 870230105138, dated 11 / 29 / 2023, p. 52 / 116 42 / 86 (low chlorotrifluoroethylene polymer) or similar materials may be mixed. BN lubrication can be maintained or improved. <Resina epóxi que constitui a resina aglutinante>

[0178] In the present embodiment, an epoxy resin film is selected as the binder resin.

[0179] In the present embodiment, a material containing an epoxy resin in an amount of 70 parts by weight or more in relation to 100 parts by weight of a total quantity of a resin, excluding the epoxy resin that constitutes the binder resin and the epoxy resin as the prepolymer, is selected. In addition, as the epoxy resin, an epoxy resin having an epoxy equivalent of 100 or more and 500 or less is selected.

[0180] Furthermore, in the present embodiment, the solid lubricating coating film is preferably a hard film. In order to achieve this, a curing agent is selected and the design is carried out in such a way as to obtain an epoxy resin coating film having a strong three-dimensional network structure. For example, an epoxy resin as the prepolymer having more than two epoxy groups (polyfunctional epoxy), a curing agent having more than two functional groups, or an epoxy resin having more than two epoxy groups and a curing agent having more than two functional groups are selected. This makes it possible to form a three-dimensionally copolymerized film and confer heat resistance.

[0181] The term "heat resistance" as used in this document means that even when slight seizing occurs during assembly of the connection, a portion where strong friction occurs can generate heat, and the epoxy resin is prevented from being destroyed by the heat generation.

[0182] The epoxy equivalent is selected to be in a range of 100 to 500 because the film is hardened by increasing the crosslinking density. This also means increasing the concentration of epoxy groups, which is accomplished by Petition 870230105138, dated 11 / 29 / 2023, page 53 / 116 43 / 86 mode to suppress the epoxy equivalent to a low value, in other words.

[0183] In this document, when the epoxy equivalent exceeds 500, the film quality is inevitably soft. Furthermore, it is difficult to impart heat resistance, which may be exhibited during assembly / disassembly. The lower limit value of the epoxy equivalent is defined as 100 because the lower limit value is specified as an approximate limit value for a distributed epoxy resin. When an epoxy material having a lower epoxy equivalent is formed, the epoxy equivalent is not limited to 100, and the selection of an epoxy material having a lower epoxy equivalent is included in this embodiment.

[0184] Epoxy resin as used in this document means an epoxy resin as a coating film obtained by copolymerizing an "epoxy resin in a strict sense" as a prepolymer with a curing agent. Epoxy resin is selected because epoxy resin has excellent advantages, for example, epoxy resin is excellent in adhesion / bonding, water resistance / moisture resistance and heat resistance, and does not shrink significantly during curing. In addition, epoxy resin is selected because epoxy resin is a well-balanced material, for example, epoxy resin is easily handled and cheaper than other agents.

[0185] In particular, among the binder resins, the present embodiment targets a hard film, selects an appropriate curing agent and selects a hard epoxy resin coating film having a pencil hardness of 3H or more. The binder resin is a matrix that holds a BN-based solid lubricant, and forms a major component of the solid lubricant coating film along with BN.

[0186] One reason why a hard epoxy resin film is favorable for lubricity (assembly / disassembly characteristic) is as follows.

[0187] In the lubrication of a connection for tubular products for oilfields using solid lubricant coating film, when vibration occurs until the threads are engaged with each other, the coating film Petition 870230105138, dated 11 / 29 / 2023, page 54 / 116 44 / 86 solid lubricant tends to be quite damaged. However, the solid lubricant coating film tends to withstand the damage. Even after the threads are engaged, the connection is assembled while the weight of a normal connection for oilfield pipe products having a length of about 8 to 12 m is applied to the threads. For this reason, a structure in which lubrication is maintained while the solid lubricant coating film is slightly scraped can inevitably be obtained. Therefore, if the pencil hardness is not adjusted to 3H or more, the solid lubricant coating film will be extensively damaged, and there is a real situation where the solid lubricant coating film can only withstand zero to several assembly / disassembly times.

[0188] Based on the above, in the present embodiment, the "epoxy resin in a strict sense" is contained in an amount of 70 parts by weight or more in the binder resin-forming agent relative to 100 parts by weight of a group sum of "epoxy resin in a strict sense" excluding the weight of a curing agent component and a lubricant component as another component, which makes the epoxy resin a major component. Furthermore, an epoxy resin having an epoxy equivalent of 100 or more and 500 or less is selected. This is to increase the number of crosslinking points (increased crosslinking density) to form a strong coating film.

[0189] Even if the "epoxy resin in a strict sense" as the prepolymer has two epoxy groups, a three-dimensional structure can be formed. However, as a more preferable approach, a polyfunctional epoxy resin having more than two epoxy groups is preferable. The meaning of "polyfunctional" epoxy is that the number of epoxy groups in a molecule is greater than two, on average. This means that the number of epoxy groups is greater than that of a "normal epoxy resin" containing two epoxy groups. Since the polyfunctional epoxy can be further three-dimensionally crosslinked in a reaction with the curing agent, the film quality can Petition 870230105138, dated 11 / 29 / 2023, pp. 55 / 116 45 / 86 can be hardened (the hardness of the pencil can also be hardened) because the cross-linked network is reinforced when (co)polymerized.

[0190] At the same time, polyfunctional epoxy has a higher glass transition temperature (Tg) and therefore has excellent heat resistance. Note that a polyfunctional epoxy preferably has a Tg greater than 100 °C as a suitable range in order to have excellent heat resistance. The number of epoxy groups in a molecule is preferably 2 or more to 6 or less, and more suitablely more than 2 and 4 or less. This is to suppress peeling and prevent complete destruction due to hardening of the solid lubricating coating film at an early assembly stage and a final disassembly stage. At the early assembly stage and the final disassembly stage, the threads are not engaged with each other, i.e., there is vibration, and the solid lubricating coating film is easily destroyed.There is significant concern that an epoxy resin having more than six epoxy groups may cause steric hindrance in a reaction between the epoxy group and the curing agent. In this case, copolymerization between the epoxy resin and the curing agent may take a long time, and there is a possibility that a hard film may not necessarily be obtained. Therefore, an epoxy resin having six or fewer epoxy groups is used. However, even when a bifunctional epoxy resin and a curing agent having more than two functional groups are used, a three-dimensional network structure is formed, and therefore, the quality of the cured film can be achieved. When the epoxy resin and the curing agent are both polyfunctional, a harder three-dimensional network is formed, which is preferable.

[0191] An epoxy equivalent of 100 or more and 500 or less is specified as a suitable range. The epoxy equivalent is a value obtained by dividing the molecular weight of an epoxy resin in a strict sense as a prepolymer by the number of epoxy groups. The epoxy equivalent can be considered as a molecular weight linked and restricted to a crosslinking point. The epoxy equivalent is Petition 870230105138, dated 11 / 29 / 2023, pp. 56 / 116 46 / 86 is specified in the range above because the lower the epoxy equivalent, the higher the crosslinking density and the greater the hardness.

[0192] The prepolymer is exemplified. Examples of a bifunctional epoxy resin as a prepolymer include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a bisphenol C type epoxy resin. Examples of a polyfunctional epoxy resin having more than two functional groups include a phenol novolac type compound, a cresol novolac type epoxy compound, an aliphatic epoxy compound, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, a polyfunctional phenol type epoxy resin compound, and groups derived from them. These can be used alone or in combination.

[0193] In the present embodiment, the "epoxy resin in a strict sense" is contained in an amount of 70 parts by weight or more in the binder resin-forming agent relative to 100 parts by weight of a group sum of "epoxy resin in a strict sense" excluding the weight of a curing agent component and a lubricant component as another component. That is, this makes the epoxy resin a major component. As a more preferable range, it is desirable that the multifunctional epoxy resin be contained in an amount of 70 parts by weight or more relative to 100 parts by weight of the total weight of the "epoxy resin in a strict sense".

[0194] The preceding expression "epoxy resin is contained in an amount of 70 parts by weight or more" is as follows. The present embodiment targets a hard film having a pencil hardness of 3H or more as described above. However, when a hard film is selected with an epoxy resin, brittleness often occurs in conjunction. Therefore, the expression "epoxy resin is contained in an amount of 70 parts by weight or more" means that another binder resin component may be contained on the condition that the content of the other binder resin component is less than 30 parts by weight. In order to obtain Petition 870230105138, dated 11 / 29 / 2023, page 57 / 116 47 / 86 For a hard film, it is preferable to reinforce a three-dimensional network structure. Therefore, the content of the polyfunctional epoxy resin (having more than two epoxy groups) is specified as 70 parts by weight or more. A thermoplastic resin may be selected as another binder resin component under the condition that the content of the thermoplastic resin is less than 30 parts by weight in order to prevent the binder resin formed from the epoxy resin from becoming too hard and brittle.

[0195] The epoxy resin coating film as a final material formed by (co)polymerization between the prepolymer and the curing agent is inevitably brittle when adjusted to be hard. In order to avoid this brittleness, a suitable agent is prepared as an agent for a monopolimeric epoxy resin. Alternatively, a resin obtained by introducing a strong backbone, such as a benzene ring or a molecular chain into a main chain of an epoxy resin, can be used. At this point, in some cases, a flexible chain can be introduced by rubber modification, fluorene modification, urethane modification or similar modification of the epoxy resin itself. This is intended to improve hardness by introducing a point to reduce internal stress in the epoxy resin coating film. Alternatively, the adjustment can be achieved by introducing a thermoplastic polymer in an amount of less than 30 parts by weight.This is intended to improve hardness through a cavitation effect or similar by introducing a thermoplastic polymer into the epoxy resin coating film. The thermoplastic polymer, as used in this document, is not particularly limited. The thermoplastic polymer is permitted to contain, for example, polyacetal (POM), polycarbonate (PC), polyphenylene sulfide (PPS), or polytetrafluoroethylene (PTFE) (Teflon (registered trademark)).

[0196] Note that the amount of epoxy resin mixture by weight is expressed in parts by weight rather than % by weight or similar for the following reason. Basically, in each agent for epoxy resin such as the prepolymer, a Petition 870230105138, dated 11 / 29 / 2023, pp. 58 / 116 48 / 86 active hydrogen reacts with an epoxy group. Note that when the curing agent is an amine, one active hydrogen corresponds to almost one amine equivalent. Therefore, a mixing ratio by weight is determined by the epoxy equivalent of each prepolymer and the active hydrogen equivalent of the curing agent. Therefore, the number of combinations between the epoxy resin and the curing agent is infinite. On the other hand, the mixing quantity by weight of the epoxy resin is proportional to the amount of epoxy resin after curing. For this reason, the mixing ratio is not clear unless the expression is made using the mixing quantity by weight of the epoxy resin as the prepolymer. Therefore, the mixing quantity by weight of the epoxy resin is defined using parts by weight.

[0197] However, in the case of a latent curing agent, the curing agent itself is unnecessary in the true sense. For example, this is a case where the epoxy resin itself as the prepolymer is self-polymerized by a catalytic anionic polymerization reaction of the latent curing agent. Examples of latent curing agents include imidazole, a tertiary amine, dicyandiamide, and fast-curing, low-temperature polymercaptan. When these latent curing agents are used, polymerization is not necessarily carried out at a 1:1 ratio. However, in the present descriptive report, the definition is made using the weight parts of the epoxy resin as the prepolymer as a parameter to specify the characteristics of the epoxy resin.

[0198] In this document, it is preferable to form a coating film by applying an agent with a brush or by mechanically applying an agent at room temperature. Therefore, the agent needs to be liquid within a room temperature range. Furthermore, for convenience, the agent is preferably a single-liquid type rather than a two-liquid type. Additionally, the agent is preferably heat-treated and thus copolymerized to form a film without immediately solidifying after being applied to the surface of a thread. Petition 870230105138, dated 11 / 29 / 2023, page 59 / 116 49 / 86

[0199] If the agent viscosity is too low, the agent drips along a thread immediately after the agent is applied to a threaded portion. In the case of a female thread, there is a great concern that the agent may accumulate and remain at the six o'clock position, and the film thickness may only increase in that portion. Also in the case of a male thread, the agent droplets may fall at the six o'clock position and it may be difficult for the agent to be homogeneous in a state prior to heat treatment. However, when the agent viscosity is too high, the agent cannot be applied by brush. Furthermore, spray application is not suitable because clogging and similar problems occur. Therefore, a preferable range of agent viscosity is 200 cps or more and 900 cps or less (0.2 Pa*s or more and 0.9 Pa*s or less).However, even when the viscosity of the agent itself is elevated beyond this range, an agent having a decreased viscosity by adding a reactive diluent is included in the present embodiment. <Agente de cura para resina epóxi>

[0200] In the present embodiment, the curing agent means an agent that contributes to a crosslinking reaction between crosslinking groups of the "epoxy resin in a narrow sense" as the prepolymer.

[0201] The curing agent is not particularly limited, and any curing agent generally known as an epoxy resin curing agent may be used. The curing agent is not particularly specified, provided that the hard epoxy resin coating film described above having a pencil hardness greater than 3H is obtained by selecting the epoxy resin in a restricted sense and selecting the curing agent.

[0202] Examples of curing agents include, as an amine-based curing agent, an aliphatic amine, a polyether amine, an alicyclic amine, and an aromatic amine. An epoxy resin formed with these curing agents is polyhydroxyamine. Petition 870230105138, dated 11 / 29 / 2023, pp. 60-116 50 / 86 Examples of an acid anhydride-based curing agent include dodecenyl succinic anhydride, polyadipic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, and phthalic anhydride. An epoxy resin formed with these curing agents is polyester. Examples of a phenol-based curing agent include a dihydroxyphenyl-based curing agent, and an epoxy resin formed with these curing agents is polyhydroxyether. Examples of a latent curing agent include an amine-based curing agent, such as a tertiary amine or an aromatic amine, imidazole, and a halogenated boroamine complex, and examples of an epoxy resin include polyether.

[0203] The amount of curing agent excluding the latent curing agent is based on mixing an amount defined by the active hydrogen equivalent of each curing agent with the epoxy equivalent of the epoxy agent in a restricted sense. Note that when the curing agent is an amine, the active hydrogen equivalent of each curing agent corresponds to almost one amine equivalent. However, since the amount of latent curing agent to be added changes along with the reaction rate, it is only necessary to determine the appropriate mixing amount each time.

[0204] In the present embodiment, basically, a hard coating film having a pencil hardness of 3H or more is formed. Therefore, it is preferable to use a thermosetting curing agent without using a curing agent that cures a resin at room temperature. With the first curing agent, the coating film has a low glass transition temperature Tg, and has a soft film quality. With the latter curing agent, the coating film has a high glass transition temperature Tg, and is often excellent in heat resistance and mechanical strength. <Acelerador de cura para resina epóxi>

[0205] A curing accelerator can be used in a reaction between the resin Petition 870230105138, dated 11 / 29 / 2023, pp. 61 / 116 51 / 86 epoxy in a restricted sense and the curing agent.

[0206] Although there is an exception, when the healing agent is an aromatic amine, a healing reaction proceeds when the healing agent is heated, but in many healing agents, the reaction does not proceed even when the healing agents are heated. In this case, a healing accelerator can be used.

[0207] When an acid anhydride-based curing agent, a phenol-based curing agent, or a dicyandiamide-based latent curing agent is selected as the curing agent, curing cannot be achieved in most cases unless a curing accelerator is used.

[0208] Examples of curing accelerators include a tertiary amine and tertiary amines, such as diazabicycloundecene (DBU) or diazabicyclononene (DBN), an imidazole-based agent, phosphine, and a triphenylphosphine (TPP), such as a phosphonium salt. The amount of curing accelerator added is, for example, 0.01 to 10 parts by weight relative to 100 parts by weight of the epoxy resin in a narrow sense (the epoxy resin that constitutes the prepolymer). However, it is necessary to adjust the amount added according to the situation. The amount added is desirably 0.1 to 3 parts by weight. <Outros aditivos>

[0209] In the present embodiment, the coating film is formed by dispersing a solid lubricant mainly containing BN in a cured epoxy resin film. However, it is preferable to obtain a hard film (pencil hardness of 3H or more). Therefore, a primary objective is to obtain a hard epoxy resin coating film. In addition, a glass fiber or a carbon fiber can be added to harden the film quality. Furthermore, the resin composition of the present embodiment may also contain a surfactant, an emulsifier, an elasticity-reducing agent, a diluent, an antifoaming agent, an ion-retaining agent, and the like. Petition 870230105138, dated 11 / 29 / 2023, pp. 62 / 116 52 / 86<Método para analisar a dureza do filme>

[0210] In the present embodiment, the pencil hardness of a hard film is evaluated. Specifically, the pencil hardness is measured by a method specified in JIS K 5600-5-4 (1999). It is clearly described in the JIS standard that this standard is a translation of the standard "ISO / DIS 15184, Paints and varnishes - Determination of film hardness by pencil test". However, the pencil hardness test method itself is evaluated based on the definition of the JIS standard. The film hardness is evaluated with the pencil hardness because this is an evaluation of "scratching" with a pencil, and it is a method for evaluating the film hardness caused by "scratching," which is similar to the behavior in which the solid lubricating coating film is peeled off on a male and female thread of a connection for tubular products for oil-producing regions.Rockwell, Vickers, Shore, and Knoop, which are indentation-based film hardness measurement methods sometimes used on coating films or similar, are not suitable for thin coating films and affect a base layer. Therefore, pencil hardness is used in the present embodiment. <Superfície na qual o filme de revestimento lubrificante sólido é formado>

[0211] The solid lubricating coating film of the present embodiment is used where the coating film is formed on one or both coupling sides (female thread side) and one pin side (male thread side) in a connection for tubular products for oilfields. Alternatively, the solid lubricating coating film of the present embodiment is preferably used where the solid lubricating coating film of the present embodiment is formed on one of the coupling sides (female thread side) and the pin side (male thread side), and a softer film that is of a different type of coating film is formed on the other side.

[0212] In the latter case, the hardness of the pencil of the different type of soft film Petition 870230105138, dated 11 / 29 / 2023, pp. 63 / 116 53 / 86 formed on the side where the coating film of the present embodiment is not formed is more preferably 4B or less. Since the epoxy resin coating film of the present embodiment is a hard film having a pencil hardness of 3H or more, the hardness of the film type different from soft film brings with it a preferable lubrication characteristic by having a film structure with a different hardness.

[0213] The first is a method of use that utilizes the lubrication characteristic of the solid lubricant coating film originally intended by the present embodiment. The latter is a method for further improving the lubrication characteristic.

[0214] It can be expected that the lubrication characteristic will be further improved by making the hardness of one of the films harder or softer than that of the film of the present embodiment and by having the films facing each other, instead of having the films having a good lubrication characteristic facing each other to obtain lubrication. In a situation (phase 1) where a spike-shaped torque increases at the moment of assembly / disassembly in a vibration situation until the threads are engaged with each other as indicated in Figures 2A and 2B, it can be expected that the soft coating film will deform to decrease the surface pressure. Furthermore, with the hard coating film of the present embodiment containing mainly BN and an epoxy resin coating film, high lubrication can be expected throughout the assembly / disassembly region of the connection. <Método para fabricar filme de revestimento lubrificante sólido>

[0215] A film can be formed by applying an agent all at once to a desired thickness to be formed and forming a film by burning or similar means.

[0216] Preferably, instead of performing the main burn many times by one method to form a film a plurality of times, it is preferable to perform a Petition 870230105138, dated 11 / 29 / 2023, pp. 64 / 116 54 / 86 Temporary heat treatment (temporary drying) is performed one or more times at a temperature lower than the main firing temperature, followed by the main firing to form a film. In this case, the thickness of the solid lubricant coating film per application is set to 50 μm or less, the temporary drying step is interposed between applications, and a coating film is formed on the formed and temporarily dried coating film. These steps are performed in two or more stages, including the initial film formation, and in the final film formation, temporary drying is not performed and a main drying step is carried out. Examples of the main drying step include firing, infrared irradiation, ultraviolet irradiation, drying media such as hot air, leaving the film in the atmosphere, and natural drying. The final total thickness of the coating film to be formed is preferably set to 10 to 150 μm.Temporary drying refers, for example, to drying in which only a portion (e.g., 30% to 70%) of a solvent is removed.

[0217] In the present embodiment, a film is formed with an agent based on a solution obtained by dissolving a solid lubricant containing mainly BN and a binder resin containing mainly an epoxy resin in a solvent. The agent is preferably a highly viscous agent containing a large amount of film components relative to a solvent. In this case, when a film is formed at once, due to the influence of surface tension along a connection to the structure of petroleum pipeline products, a liquid tends to be pulled to have a small thickness in a corner portion of a thread, and the liquid tends to accumulate in a corner portion of the base. Therefore, it is preferable to perform the burning several times.

[0218] However, when the primary firing is performed multiple times, the adhesion between the films can be weak and the films tend to peel off easily. Therefore, it is preferable to perform the temporary firing in a Petition 870230105138, dated 11 / 29 / 2023, pp. 65 / 116 55 / 86 state in which a portion of the solvent components is expelled, repeat the application and temporary burning again, forming a film while performing the temporary burning until the required film thickness is obtained, and then perform the main burning. This is because it works effectively for film quality uniformity and film thickness uniformity. Furthermore, it is less likely that a hole penetrating the entire film will form when applying the agent multiple times, from the point of view of corrosion resistance. This is also effective.

[0219] Furthermore, it is preferable to perform the primary firing by two-stage heat treatment in order to strengthen the cross-linked structure of the epoxy resin. A complete cross-linked structure can be expected to be formed by performing a primary cure treatment at a Tg temperature or lower to gel the agent and then performing a secondary cure at a Tg temperature or higher.

[0220] Note that the detailed description of the solid lubricant containing BN as a main component, the binder resin containing an epoxy resin as a main component, and other additives refer to the present embodiment, and the method for simulating real well conditions as an evaluation method will be clarified, as well as its suitable ranges. The present embodiment can be used not only for a solid lubricant coating film formed on a threaded joint for oilfield tubular products, but also for an agent for the formation of the coating film and lubrication of something other than the connection for oilfield tubular products. The description will then focus on a box connection (female thread side) and a pin connection (male thread side). However, it is considered that a Threaded & Coupled (T&C) type joint and an integral type joint of oilfield tubular products are included. Petition 870230105138, dated 11 / 29 / 2023, pp. 66 / 116 56 / 86 <Método de teste para simular condições reais de teste de poço (novo teste de laboratório)>

[0221] In the present embodiment, as described with reference to Figures 2A to 4B, the phenomenon caused by the lubrication of the connection for tubular products for oil fields is considered in two stages, that is, before the threads are engaged with each other (phase 1) and after the threads are sufficiently engaged with each other (phase 2). Then, considering assembly / disassembly (lubrication) in the first stage (phase 1), the thread lubrication is comprehensively evaluated, including lubrication in the second stage (phase 2).

[0222] If this assessment is not carried out, although acceptable in the assessment of a laboratory test, problems may frequently occur in a real well. In a real well, a large load and an unbalanced load are applied before the threads are engaged with each other. Therefore, the solid lubricant coating film is damaged or peeled off. In a severe case, the film may be completely peeled off. Based on this, the upper and lower limits of a suitable range of a parameter of the present embodiment are selected.

[0223] As described above, in the case of solid lubricant coating film, damage to the coating film cannot be avoided by assembly or similar means until the threads are engaged. Then, a byproduct is formed based on the peeled film. If a thread clearance is obstructed with this byproduct, seizure will occur. Therefore, if the lubrication assessment is not performed under conditions conforming to a real well, there is a concern that even a solid lubricant coating film that is actually at an unacceptable level may be erroneously judged acceptable. When the assessment is based on such a loose assessment, limiting a parameter related to the solid lubricant coating film with upper and lower limits and selecting an appropriate range is meaningless. Petition 870230105138, dated 11 / 29 / 2023, pp. 67 / 116 57 / 86

[0224] In other words, it is impossible to specify the solid lubricant coating film precisely unless it is considered whether a byproduct formed by damage or peeling of the solid lubricant coating film, i.e., a "byproduct" to be rebuilt, affects lubrication. In the present embodiment, the evaluation is carried out by a new laboratory test considering such findings.

[0225] Note that if evaluation with a horizontal hydraulic wrench using a short pin or evaluation with a vertical hydraulic wrench using a short pin (evaluation by a conventional laboratory test) is reliable, there is no point in evaluating the solid lubricant coating film. In previous PTLs, it is sometimes described that the number of assembly / disassembly times can be 15 to 20, even for a large diameter size of 9-5 / 8” or 13-3 / 8” in a lubrication test based on a solid lubricant coating film. That is, even with a solid lubricant coating film, the result is not inferior to that of a greasy compound, but the number of times is substantially impossible with a solid lubricant coating film. In a solid lubricant coating film, the solid lubricant coating film, which primarily causes lubrication, is inevitably scraped off.However, in the case of the greasy compound, a surface is cleaned and the compound is reapplied each time the assembly / disassembly is performed, and therefore a heavy metal, such as Pb or Zn, which primarily causes lubrication, is supplied each time. Therefore, in the case of a large diameter with a solid lubricating coating film during assembly / disassembly in a real well, a level of 15 to 20 times is almost impossible. Furthermore, regarding the lubrication of the solid lubricating coating film, the expression that the number of assembly / disassembly times can be around 15 to 20 is considered a case where the thread lubrication is evaluated only in phase 2 after the threads are sufficiently engaged with each other without going through phase 1, in which the threads are not. Petition 870230105138, dated 11 / 29 / 2023, pp. 68 / 116 58 / 86 are engaged with each other. That is, the evaluation is considered to be based on a horizontal or vertical hydraulic wrench using a short pin, which is frequently observed in a conventional laboratory test.

[0226] In the present embodiment, a test is performed with a device configuration illustrated in Figure 5 based on the conditions of the new laboratory test above.

[0227] The new laboratory test is based on evaluation under conditions that may reach a high load condition during assembly and an unbalanced load condition during assembly / disassembly. In the new laboratory test, for example, in a step where a high load corresponding to a full-size pin is applied and the connection is assembled, vibration until the threads are engaged is considered. Furthermore, in a step of disassembling the connection, the fact that the threads are disengaged from each other and vibration occurs is considered.

[0228] In the new laboratory test, a vertical hydraulic wrench 4 is used. A short pin 1 is adopted as a test pin. However, it is possible to apply a load to an upper portion of the pin 1 by a heavy pendulum 3 and to remove the load.

[0229] Short pin 1 and box connection 2 are assembled by a threaded pin portion 1a and a threaded box portion 2a.

[0230] At this point, in order to simulate a situation where the threads are not engaged with each other, an initial temporary mounting position is defined so that half of the total number of pin threads 1a is exposed from the box connection 2 (see Figure 2B). This is one of the causes of vibration. Assembly is started from this state.

[0231] During assembly, the weighted pendulum 3 is attached to one upper end of pin 1, which is the opposite end to the connection of Petition 870230105138, dated 11 / 29 / 2023, pp. 69 / 116 59 / 86 box connection assembly 2.

[0232] The weight of the heavy pendulum 3 is calculated based on a full-size pin having an outer diameter and wall thickness such that it is a load corresponding to one to three full-size pins. In the case of a pin having a size of 9-5 / 8” 53.5#, the weight of the heavy pendulum 3 is about one ton (2,200 lb) of load for one pin, or about three tons (6,600 lb) when the weight corresponds to three connected pins.

[0233] As illustrated in Figure 6, the heavy pendulum 3 illustrated in Figure 5 includes a heavy pendulum body 3A and an insertion rod 13. The insertion rod 13 is attached to a lower surface of the heavy pendulum body 3A by welding and is arranged at an axisymmetric position of the heavy pendulum 3. By inserting the insertion rod 13 into pin 1 in a loosely inserted state, the heavy pendulum is attached to the pin. Reference number 1c denotes an inner diameter surface of pin 1.

[0234] In the insertion rod 13 and pin 1, holes 1d and 13a that penetrate pin 1 and insertion rod 13 when the weighted pendulum 3 is attached as described above are formed in advance. Then, as illustrated in Figure 6, by inserting a penetrating rod 12 into holes 1d and 13a, the weighted pendulum 3 and pin 1 are integrated.

[0235] A swivel-type hook 11 is attached to an axial central position of an upper portion of the heavy pendulum 3 by welding, and the heavy pendulum 3 is suspended from a ceiling suspension device 20 by means of a suspension chain 21. As a result, the magnitude of the heavy pendulum load on the pin can be adjusted by adjusting the elevation level of the heavy pendulum by the suspension device 20.

[0236] During assembly, the suspension chain 21 is disassembled, a heavy pendulum load is applied to the housing connection, and the connection is assembled. Petition 870230105138, dated 11 / 29 / 2023, pp. 70 / 116 60 / 86 between 5 and 20 rpm until the torque increases (phase 1). This is a vibration simulation. When the torque increases, the rotation speed is reduced to 0.5 to 2 rpm, and the assembly is carried out until a mounting position is reached (phase 2).

[0237] However, when loosening (disassembly), the heavy pendulum 3 is lifted by the suspension device 20, and the disassembly is carried out in a state where the load on the heavy pendulum 3 is not applied. As for the rotation speed, when the torque increases, the disassembly is initiated at a rotation speed of 0.5 to 2 rpm, and when the torque reaches about 1 / 10 of the assembly torque value, the disassembly is carried out at a high rotation speed of 5 to 20 rpm.

[0238] In this document, a condition closer to a real well environment is obtained when a load from the heavy pendulum 3 is not applied at the time of disassembly. This is a finding based on an experimental fact that the evaluation of a lubrication characteristic is better in the case of applying the load from the heavy pendulum 3 than in the case of not applying the load. That is, as a result of actual observation of the experiment, the inventors found that when disassembly is performed in a state where the heavy pendulum is applied, the heavy pendulum acts as a balancer, and the pin is released directly from the assembly completion position without vibration.However, the inventors discovered that when the weighted pendulum is reduced, that is, when a test is performed by lifting a load so as to reduce the load on the weighted pendulum to zero, the test can be carried out under a condition where the pin vibration is severe and the solid lubricant coating film is likely to be damaged in a situation where the load is reduced and the joint is loosened, including a case where the load is not completely zero.

[0239] In the new laboratory test under the above conditions, it is possible to simulate a situation in which a secondary product derived from a derived component Petition 870230105138, dated 11 / 29 / 2023, pp. 71 / 116 61 / 86 of solid lubricant coating film that is released into a thread clearance due to inevitable stripping or similar does not move after assembly / disassembly and obstructs a specific location causing seizure, or a situation where the coating film itself is completely stripped. As a result, the upper and lower limits of a parameter related to the solid lubricant coating film can be specified as those in accordance with the actual well conditions. After completion of disassembly, the evaluation was performed by separating the pin connection and the housing connection from each other, and removing fragments and similar byproducts of the solid lubricant coating film on the thread surfaces by air blowing, then checking the surfaces, and continuing the assembly again.

[0240] This embodiment specifies components and the like in order to obtain a lubrication characteristic that can withstand an environment that may occur in a real well. Furthermore, the upper and lower limits are specified by conducting confirmation under conditions in accordance with the assembly / disassembly conditions in a real well.

[0241] The new laboratory test under the above conditions is then also referred to as a heavy pendulum hydraulic key test.

[0242] In the present embodiment, as described with reference to Figures 2A to 4B, it is important to divide a phenomenon that occurs in the lubrication of a connection for tubular products for oilfields into two phases for consideration, and to evaluate the thread lubrication in consideration of assembly / disassembly (lubrication) at an early stage. If this evaluation is not performed, although acceptable in the evaluation of a laboratory test, problems can frequently occur in a real well. In a real well, there is assembly / disassembly focusing primarily on lubrication in a state where there is vibration before the threads are engaged, and assembly / disassembly focusing Petition 870230105138, dated 11 / 29 / 2023, pp. 72 / 116 62 / 86 primarily in lubrication after the threads are sufficiently engaged with each other. In a real well, the weight of a full-size pin or the weight of three full-size pins connected depending on the situation, is applied to a female thread on a receiving side. A pin is not ideally mounted vertically and straight. In reality, a pin connection is bent in an elastic region, tends to be slightly bent, and is necessarily mounted eccentrically by vibration at an initial assembly stage and a final disassembly stage. In the horizontal and vertical hydraulic wrenches above, using a short pin, the solid lubricant coating film needs to withstand a situation where a torque is not stable until the threads are engaged with each other and sometimes a spike-shaped torque builds up, as illustrated in (x) of Figure 4A. (Others)

[0243] This disclosure may also have the following configurations. (1) An agent for forming a solid lubricating coating film on a threaded portion of tubular products for oilfields, wherein a solid lubricant is dispersed in a binder resin, the binder resin contains a prepolymer and a curing agent, the prepolymer is formed of one or more epoxy resins, 70 parts by weight or more of the prepolymer are contained in relation to 100 parts by weight of the binder resin, the epoxy resin constituting the prepolymer has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, BN has an average particle size of 10 μm or less, and the total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the binder resin. (2) The agent includes a solvent component in an amount of 30 parts by weight or more and 80 parts by weight or less in relation to 100 parts by weight of a sum of the total weight of the solid lubricant and the total weight of the resin. Petition 870230105138, dated 11 / 29 / 2023, pp. 73 / 116 63 / 86 binder excluding the curing agent. (3) The agent includes a healing accelerator in an amount of 0 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of a total weight of the agent. (4) The epoxy resin that constitutes the prepolymer has more than two epoxy groups (polyfunctional epoxy resin). (5) The epoxy resin that constitutes the prepolymer has six or fewer epoxy groups. (6) The epoxy resin that constitutes the prepolymer has four or fewer epoxy groups. (7) The curing agent is a curing agent for curing an epoxy resin, and is formed from an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent or a latent curing agent. (8) The epoxy resin that constitutes the prepolymer has a glass transition temperature Tg of 100 °C or more. (9) The agent has a viscosity of 20 mPa*s or more and 2,000 mPa*s or less. (10) Tubular products for oilfields having a lubricating coating film including a solid lubricating coating film in a threaded portion, wherein the solid lubricating coating film is formed by dispersing a solid lubricant in a binder resin, the binder resin contains an epoxy resin cured with a curing agent, 70 parts by weight or more of the epoxy resin is contained in relation to 100 parts by weight of the binder resin, the epoxy resin has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, BN has an average particle size of 10 μm or less, and the total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the resin. Petition 870230105138, dated 11 / 29 / 2023, pp. 74 / 116 64 / 86 binder. (11) Epoxy resin has more than two epoxy groups (polyfunctional epoxy resin). (12) Epoxy resin has six or fewer epoxy groups. (13) Epoxy resin has four or fewer epoxy groups. (14) The curing agent is a curing agent for curing an epoxy resin, and is formed from an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent or a latent curing agent. (15) Epoxy resin has a glass transition temperature Tg of 100 °C or higher. (16) The solid lubricating coating film has a pencil hardness of 3H or more. (17) The solid lubricating coating film has a thickness of 10 μm or more and 150 μm or less. (18) The lubricating coating film is formed on a clamping surface of a threaded portion of at least one of the housing and the pin. (19) The lubricating coating film has a base layer between a clamping surface of the threaded portion and the solid lubricating coating film, and the base layer is formed of a chemically converted treated layer or a galvanized layer. (20) A threaded joint for oilfield tubular products connecting a housing having a female thread and a pin having a male thread, wherein the oilfield tubular products of at least one of the housing and the pin are made up of the oilfield tubular products having the lubricating coating film of the present disclosure. Examples

[0244] The following examples based on this modality will be described. Petition 870230105138, dated 11 / 29 / 2023, pp. 75 / 116 65 / 86<Critérios de aceitação>

[0245] First, an acceptance criterion for lubrication behavior based on the number of assembly / disassembly times will be described.

[0246] In the judgment criteria, regarding the size of the casing, those that could be assembled and broken three or more times were judged acceptable, and those that could be assembled and broken five times were judged better. Regarding the size of the piping, those that could be assembled and broken five or more times were judged acceptable, and those that could be assembled and broken ten or more times were judged better. The casing size is specified according to the ISO 13679 definition. Meanwhile, regarding the piping, those that could be assembled and broken five or more times were considered acceptable, which is a criterion lower than the ISO 13679 definition.

[0247] It is clear that the M / B ratio tends to be worse than lubrication using a conventional greasy compound because of the solid lubricant coating film. This is also being recognized in the oil and gas industry.

[0248] As described above, the ISO 13679 definition may be a simple objective if an assembly / disassembly test is performed simply using a short pin from a state where the threads are engaged with each other. However, in the present embodiment, the evaluation was performed by a "heavy pendulum hydraulic wrench test (new laboratory test)", in order to simulate a condition in which a large load and an unbalanced load are applied and vibration in which the threads are not engaged with each other, which is close to a condition that may actually occur in a well.

[0249] In the following description, 9-5 / 8”53.5#, 9-5 / 8”43.5# and 7”29# are used. In many cases, once a size is used to which the coating is Petition 870230105138, dated 11 / 29 / 2023, pp. 76 / 116 66 / 86 applied, those that could be assembled and disassembled three or more times are deemed acceptable, and those that could be assembled and disassembled five times are deemed better, as described above.

[0250] As a condition in which a three-pin connected load is applied, in a 9-5 / 8”53.5# case study, a test was performed using a three-ton weighted pendulum. In 9-5 / 8”43.5# and 7”29#, the study was performed using 2.5-ton and one-ton weighted pendulums, respectively.

[0251] Regarding the initial mounting position, the assembly was performed from a state where the connection was made only up to a position where half of the total number of pin threads was exposed from the housing connection, i.e., the threads were not intertwined. That is, the assembly was performed using the device illustrated in Figures 5 and 6. The test was performed in a state where a load was applied at the time of assembly and no load was applied at the time of disassembly.

[0252] If the test is performed under a load-bearing condition by a heavy pendulum at the moment of disassembly, when a pin in which a short pin and a heavy pendulum are integrated is used, the short pin integrated with the heavy pendulum rises directly from a mounting position different from a full-size pin in a real well. As the heavy pendulum acts as a balancer, no vibration occurs. As the full-size pin bends slightly due to its long length, as the threads gradually move and do not mesh with each other, vibration occurs and there is a great tendency to destroy the solid lubricant coating film. Therefore, in the evaluation of lubrication using a hydraulic wrench with a heavy pendulum, the test was performed without load application at the moment of disassembly, and the vibration that occurs in conjunction with a situation where the threads are not engaged with each other was simulated.Furthermore, not applying a load does not necessarily mean that the charge is zero. O. Petition 870230105138, dated 11 / 29 / 2023, pp. 77 / 116 Test 67 / 86 was performed by lifting the heavy pendulum with an overhead crane or similar, so that the load of the heavy pendulum was not applied. Note that the test to confirm the number of assembly / disassembly times using the hydraulic wrench with the heavy pendulum was performed two or more times. Regardless of whether the number of assembly / disassembly times in each test was achieved or not, the acceptance criteria were compared and evaluated based on how many times the acceptance criteria were achieved in relation to the number of tests to determine if the parameter was acceptable. Example 1

[0253] Next, Example 1 based on the present embodiment will be described with reference to the Tables.

[0254] In this example, primarily, a lubricating coating film including a solid lubricating coating film is formed on a clamping surface 10 of a threaded joint for tubular products for oilfields, and whether the lubricating coating film including the solid lubricating coating film is acceptable or not is evaluated. In this Example, an assembly / disassembly test was performed under the conditions presented in Tables 1 to 4, and it was evaluated whether the lubricating coating film was acceptable or not. [Table a 1] Steel type OD (inch a) WT (LPF ) Connection type Side where the coating film is formed Base film and base treatment Viscosity of the epoxy resin chemical agent (mPa.s at room temperature) % ​​by weight of solid lubricant BN (relative to the total weight of solid lubricant) Average particle size of BN (pm) Other solid lubricant Chemical agent as epoxy resin Number of epoxy groups Epoxy equivalent 1 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG connection MnPhos 200 100% 20 None Cresol / novol type epoxy resin ac 6 200 PIN connection - - - - - - - - 2 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG connection MnPhos 200 100% 20 None Cresol / Novol type epoxy resin AC 6 200 PIN connection Sandblasted - - - Metallic soap Coating material - - Petition 870230105138, dated 11 / 29 / 2023, pp. 78 / 116 68 / 86 Fluoride-based Acrylate-based 3 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG Connection MnPhos 200 100% 5 None Cresol / novol type epoxy resin ac 6 200 PIN Connection Sandblasted - - - Metallic soap Fluoride-based coating material Acrylate-based - - 4 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG Connection MnPhos 200 100% 5 None Cresol / novol type epoxy resin ac 6 200 PIN Connection Sandblasted - - - Metallic soap Fluoride-based coating material Acrylate-based - - 5 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG Connection MnPhos 200 100% 5 None Resin Cresol / Nomol type epoxy AC 6 200 PIN connection Sandblasted - - Metallic soap Fluorine-based acrylate-based coating material - - 6 Q12 5 9-5 / 8 53.5 # JFELIONT M CPLG MnPhos connection - - Metallic soap Fluorine-based acrylate-based coating material - - PIN connection Sandblasted 200 100% 5 None Cresol / Nomol type epoxy resin AC 6 200 7 C11 0 9-5 / 8 53.5 # JFELIONT M CPLG MnPhos connection 2.200* 100% 5 None Trisphenol methane type epoxy resin 3 165 PIN connection Sandblasted - - - Metallic soap Fluorine-based coating material Acrylate-based - - 8 C11 0 9-5 / 8 53.5 # JFELIONT M CPLG connection MnPhos 100% 10 None Trisphenol methane type epoxy resin 3 170 PIN connection Sandblasted - - - Aluminum powder Aqueous acrylate - - 9 C11 0 9-5 / 8 53.5 # JFELIONT M CPLG connection MnPhos 180 100% 10 None Trisphenol methane type epoxy resin 3 170 PIN connection MnPhos 180 100% 10 None Trisphenol methane type epoxy resin 3 170 1 0 C11 0 9-5 / 8 53.5 # JFELIONT M Connection CPLG MnPhos 180 100% 10 None Trisphenol methane type epoxy resin 3 170 PIN connection Sandblasted - - - - - - -. Petition 870230105138, dated 11 / 29 / 2023, pp. 79 / 116 69 / 86 [Table 2] Name of curing agent Functional group equivalent to the curing agent Other additive 0 Tg of epoxy resin film (°C) pbr in relation to 100 parts by weight of the total weight of epoxy resin curing aid (pbr) Curing aid Solvent Mixing ratio of solvent (parts by weight) in relation to 100 parts by weight of solid lubricant + prepolymer 0 Firing temperature Firing pattern Thickness of solid lubricant film (pm) Hardness of solid lubricant film pencil Number of times of assembly / disassembly m Remarks 1 Phenol / novol-based curing agent 195 None 200 2 TPP Triphenylphosphine Toluene / methyl ethyl ketone (MEK) / dimethyl cellulose (DME) 70 160°C 2h + 180°C x 4h 45 3H Horizontal hydraulic wrench £5 times £5 times Comparative reference case - - - - - HFE - - - - 2 Phenol / novol-based curing agent ac 195 None 200 2 TPP Triphenylphosphine Toluene / ME K / DME 50 160°C x 2h + 180°C x 4h 45 3H Hydraulic wrench with 3-ton heavy pendulum(Vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) 2 times 1 time 3 times Comparative example - - - - - HFE - Left in the atmosphere and dry 10-15 £6B 3 Phenol / novol based curing agent ac 195 None 200 2 TPP Triphenylphosphine Toluene / ME K / DME 30 160°C x 2h + 180°C x 4h 45 3H Hydraulic wrench with 3-ton heavy pendulum (Vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) 5 times 5 times 5 times Inventive example - - - - - HFE - Left in the atmosphere and dry 10-15 £6B Petition 870230105138, dated 11 / 29 / 2023, pp. 80-116 70 / 86 S) 4 Phenol / novol-based curing agent ac 195 None 200 2 TPP Triphenylphosphine Toluene / ME K / DME 30 160°C x 2h + 180°C x 4h 45 3H T Simulated well test using full-size PIN (three Range-3 size pins are connected S) times 25 times 25 times Inventive example - - - - - HFE - Left in the atmosphere and dry 10-15 S6B 5 Phenol / novol-based curing agent ac 195 None 200 2 TPP Triphenylphosphine Toluene / ME K / DME 30 160°C x 2h + 180°C x 4h 8* 3H Hydraulic wrench with 3-ton heavy pendulum (vertical hydraulic wrench to which the weight corresponding to the three vertical pins is applied) connected S) 3 times 1 time 1 time Comparative example - - - - - HFE - Left in the atmosphere and dry 10-15 S6B 6 - - - - - HFE - Left in the atmosphere and dry 10-15 £ 6B Simple vertical hydraulic wrench 3 times 4 times 4 times Inventive example Phenol / novol based curing agent ac 195 None 200 2 Toluene / ME K / DME 30 160°C x 2h + 180°C x 4h 10 3H 7 Modified cyclic polyamine at 40% ePolyamide iodine at 60% 95 - 110 - - Example of two-liquid type Epoxy resin side: none Curing agent side: MEK - Left in the atmosphere and dry 20 3B* 3-ton heavy pendulum hydraulic wrench (vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) Solidifies rapidly, in the form of a water syrup, and is applied with difficulty 2 times 1 time 3 times Comparative example - - - - - HFE - Left in the atmosphere and dry 30 6B 8 Diethylenetriamine-based curing agent 125 None 150 - - Propylene glycol monomethyl ether 80 Left in the atmosphere for five days 55 3H 3-ton heavy pendulum hydraulic wrench (hydraulic wrench 8 times £ 10 times 10 times Example inventive - - - - - Water - Drying with blowing 10~15 4B Petition 870230105138, dated 11 / 29 / 2023, pp. 81 / 116 71 / 86 Vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) 9 Curing agent based on diethylenetriamine 125 None 150 - - Propylene glycol monomethyl ether 60 Left in the atmosphere for five days 55 3H Hydraulic wrench with 3-ton heavy pendulum (vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) 4 times 3 times 3 times Inventive example Curing agent based on diethylenetriamine 125 None 150 - - Propylene glycol monomethyl ether 60 Left in the atmosphere for five days 55 3H 1 0 Curing agent based on diethylenetriamine 125 None 150 - - Propylene glycol monomethyl ether 60 Left in the atmosphere for five days 55 3H Wrench Hydraulic wrench with a 3-ton heavy pendulum (vertical hydraulic wrench to which the weight corresponding to the three connected vertical pins is applied) 4 times 3 times 3 times Inventive example - - - - - - - - - - [Table 3] Steel type OD (inch) WT (LPF) Connection type Side where the coating film is formed Base film and base treatment Epoxy resin chemical agent viscosity (mPa.s at room temperature) % ​​by weight of solid lubricant BN (relative to the total weight of solid lubricant) Average particle size of BN (pm) Other solid lubricant Chemical agent as epoxy resin Number of epoxy groups Epoxy equivalent 1 1 C11 0 9-5 / 8 53.5 # JFELION™ CPLG connection MnPhos 800 100% 5 None Tetrakisphenol ethane type epoxy resin 4 165 PIN connection Sandblasted - - - - - - - 1 C11 9-5 / 8” 53.5 JFELION MnPhos connection 800 100% 5 None Epoxy resin 4 165 Petition 870230105138, dated 11 / 29 / 2023, pp. 82 / 116 72 / 86 2 0 # --- Tetraquisphenol ethane type CPLG PIN connection Sandblasted - - - - - - - 1 3 C11 0 9-5 / 8 53.5 # JFELION TM CPLG connection MnPhos 750 * _ * _ - Tetraquisphenol ethane type epoxy resin 4 165 PIN connection Sandblasted - - - Metallic soap Fluorine-based acrylate-based coating material - - 1 4 C11 0 7 29# JFELION TM CPLG connection MnPhos 250 85% 3 15% PTFE Glycidyl ester type epoxy resin 3 190 PIN connection Sandblasted - - - Metallic soap Fluorine-based acrylate-based coating material - - 1 5 Q12 5 9-5 / 8 43.5 # JFELION TM CPLG MnPhos 3500* Connection (Epoxy resin viscosity as prepolymer) 100% 5 None Polyglycidyl ether-based resin and polyglycidyl ether-based resin are mixed 1:1 510* (epoxy resin) PIN Connection Sandblasted - - - - - - - 1 6 Q12 5 9-5 / 8 43,5 # JFELION TM MnPhos 25* 100% 5 None Cyclohexanedimethanol diglycidyl ether 2 135 PIN connection Sandblasted - - - Metallic soap Acrylate-based fluorine-based coating material - -, [Table 4] Name of the agent Functional group equivalent Other additive Tg of the PBR film in relation to 100 parts by weight of the weight Solvent Auxiliary Mixing ratio of solvent (parts by weight) in Burning temperature Film thickness lubrication Film pencil hardness Number of times of assembly / disassembly Observation of curing agent relative to the curing agent epoxy resin (°C) total epoxy resin curing in relation to 100 parts by weight Burning standard solid lubricant (Mm) solid lubricant m lubrication auxiliary actions of solid lubricant (PBR) + pre- Petition 870230105138, dated 11 / 29 / 2023, pp. 83 / 116 73 / 86 Polymer 0 1 1 Phenol / Novolac-based curing agent 200 None 206 1 TPP Triphenylphosphine Ethylene glycol tert-butyl ether 40 160°C x 2h + 180°C x 6h 30 6H Hydraulic wrench with 3-ton heavy pendulum (vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) 7 times 8 times 6 times Inventive example - - - - - - - - - - 1 2 Phenol / Novolac-based curing agent 200 None 206 1 TPP Triphenylphosphine Ethylene glycol tert-butyl ether 75 160°C x 2h + 180°C x 6h 30 6H Hydraulic wrench with 3-ton heavy pendulum (vertical hydraulic wrench to which the weight corresponding to the three vertical pins connected S is applied) three vertical pins connected S) 9 times 6 times 7 times Inventive example - - - - - - - - - 1 3 Phenol / Novolac-based curing agent 200 None 206 1 TPP Triphenylphosphine Ethylene glycol tert-butyl ether 75 160°C x 2h + 180°C x 6h 45 6H Hydraulic wrench with 3-ton heavy pendulum (vertical hydraulic wrench to which the corresponding weight is applied)tooth to the three vertical pins connected S) 2 times 1 time 2 times Comparative example - - - - HFC - Left in the atmosphere and dry 10-15 £6B 1 4 - - - 185 5 1,2,4- Triazole Dioxyalkylene ether 35 80°C x 1h + 180°C x 1h 50 4H Hydraulic wrench with heavy pendulum of 1 ton (vertical hydraulic wrench to which is applied the 3 times 4 times 4 times Inventive example - - - - - HFE - Left in the atmosphere and dry 10-15 £6B Petition 870230105138, dated 11 / 29 / 2023, pp. 84 / 116 74 / 86 (weight corresponding to the three vertical pins connected S) Example Chemical solvent agent The wrench was of the hydraulic type in the form of two liquid pastes in the form of a pendulum and was applied with heavy solvent 1 5 Phthalic anhydride 297 None 160 2 DMP-30: 2,4,6tris(dimethylaminomethyl)phenol of epoxy resin: diethyl acetamide Solvent 40 165°C x 1h + 180°C x 2h paste, applied with difficulty care of 4H 2.5 tons (vertical hydraulic wrench to which it is difficult care, but two were tested Inventive example of Destina applied the example agent of the 40 weight s in curing: pm corresponding that the no tooth to the chemical curing agent three vertical pins could be connected S) applied.- - - - - - - - - - 3 times 3 times Smooth Chemical agent Dicyansia mida 10 in relation to 100 of chemical agent None 95* 4 Imidazole (Not used) Curing aid is mixed when 60 120°C20 + 150°C10 applied with difficulty Dripping occurs Intended for 50 pm 3H Hydraulic wrench with was very smooth due to its viscosity similar to that of edible oil, epoxy resin epoxy resin is cured heavy pendulum of 2.5 tons (hydraulic wrench Comparative example 1 6 - - - - - HFE - Left in the atmosphere and dry 10~15 μm £ 6B vertical to which the weight corresponding to the three vertical pins connected is applied) dried quickly, was applied smoothly with difficulty and it couldn't be applied thickly. 2 times 1 time 3 times.

[0255] In the Tables, Nos. 1 to 4 are results of a test performed using one type of steel: Q 125 high-strength carbon steel material, one connection size: 9-5 / 8”53.5#, and one JFELION™ connection.

[0256] In Nos 1 to 4, a solid lubricating coating film was formed. Petition 870230105138, dated 11 / 29 / 2023, pp. 85 / 116 75 / 86 in a coupling side connection forming an epoxy resin containing primarily BN. Additionally, Nos. 1 to 4 are examples where one side of the pin was sandblasted and left as is, or a soft, rust-resistant lubricating paint was formed on the pin side.

[0257] As the epoxy resin, a cresol / novolac type epoxy resin having six epoxy groups and an epoxy equivalent of 200 was used. As the curing agent, a phenol / novolac-based curing agent having a functional group equivalent to the curing agent, i.e., an active hydrogen equivalent of 195, was used. As the curing aid, triphenylphosphine (TPP) was used, and 2 parts by weight (2 pbr) of the curing aid were mixed in relation to 100 parts by weight of a total weight of epoxy resin and curing agent to proceed with the curing. The heat treatment was carried out at 160 °C for two hours + at 180 °C for four hours. Note that the epoxy resin had a pencil hardness of 3H as a film hardness.

[0258] Note that in the Tables the coupling connection is represented by a CPLG connection and the pin connection is represented by a Pin connection.

[0259] No. 1 is an example where the BN size of the solid lubricant is 20 μm, which exceeds the specified size of 10 μm, and the film thickness is 45 μm. No. 1 is an example where an assembly / disassembly test of a connection for oilfield tubular products was performed with a horizontal hydraulic wrench. Because the pin weight is not applied to the coupling and axial adjustment is performed, No. 1 is an ideal condition in which the assembly is performed in a symmetrical position. No. 1 is an example where the assembly / disassembly test can be performed without any particular problem. However, although the BN was out of standard, the number of assembly / disassembly times of five or more was achieved because the test evaluation was a loose condition compared to the assembly / disassembly condition in a real well. Petition 870230105138, dated 11 / 29 / 2023, pp. 86 / 116 76 / 86

[0260] Meanwhile, No. 2 is a case where an acrylate-based fluorine coating material was applied to one side of a pin connection under the same coupling film conditions as No. 1. No. 2 is the result of the assembly / disassembly test under a condition where a heavy pendulum of a three-ton load was applied with a vertical hydraulic wrench, as illustrated in Figure 5, i.e., the condition of the new laboratory examination. As described at the beginning of the Examples, assembly / disassembly was performed by applying a load at the time of assembly and removing the load at the time of disassembly (including loosening the load). Note that the three-ton load simulates three real-length pins connected.

[0261] No No 2, the number of assembly / disassembly times was less than the required number of times. In a real well, the weight of a pin is applied to a coupling connection, the pin is not placed in a symmetrical and straight position relative to the center of the coupling, but is adjusted so that the pin axis bends. Furthermore, as there is a "clearance" before the threads are engaged with each other, a large load and an unbalanced load are applied to the coupling connection. Under such a condition close to a real well, when the average particle size of BN of the solid lubricant exceeds the upper limit of 10 μm, the number of assembly / disassembly times does not meet the standard.

[0262] No. 3 is an example where the average particle size of BN in the solid lubricant coating film on the coupling side has been altered compared to No. 2. Specifically, No. 3 is an example where the average particle size of BN is 5 μm within the standard range. Other parameters are also adjusted within the scope of this disclosure. In No. 3, the number of assembly / disassembly times also meets the standard in a heavy pendulum hydraulic wrench test. It was indicated that sufficient lubrication can be maintained even in a real well. Petition 870230105138, dated 11 / 29 / 2023, pp. 87 / 116 77 / 86

[0263] No. 4 is a case where the same conditions as No. 3 were used, except that the assembly test was performed in a simulated well. No. 4 was designed so as not to apply an impact on the side of the housing connection when a pin connection was set with a drill guide using three full-length pins connected. Furthermore, No. 4 was designed to prevent the pin connection from oscillating more than necessary using a compensator. This is the result of simulating a situation in a real well. No. 4 exhibits good lubricity and had the same result as the No. 3 case. This result indicates that the heavy pendulum hydraulic wrench test implementing the new laboratory test method can simulate the situation in the real well.

[0264] No. 5 is a case where the film thickness is 8 μm, which is less than the lower limit value of 10 μm, compared to Nos. 3 and 4. No. 5 is a case where assembly / disassembly was difficult and was judged to be NG.

[0265] No. 6 is a case where a film under the conditions of Nos. 1 to 5 was formed not on the coupling connection side, but on the short pin side with a film thickness of 10 μm. A simply vertical hydraulic wrench was used and, structurally, a heavy pendulum was not applied to the top of the coupling. It was found that even when a coating film ratio between the coupling connection and the pin connection is reversed, a sufficient number of assembly / disassembly cycles is guaranteed within the standard of the present disclosure.

[0266] In Nos. 3 and 6, it is clear that good lubrication behavior is exhibited in the case where a BN-based epoxy resin coating film is formed on the mating side and a soft coating material is applied on the pin side and, conversely, in the case where a BN-based epoxy resin coating film is formed on the pin side and a soft coating material is applied on the mating side. Petition 870230105138, dated 11 / 29 / 2023, pp. 88 / 116 78 / 86

[0267] No. 7 is a case where a test was performed using a type of steel: acid-resistant carbon steel C 110, a connection size: 95 / 8”53.5#, and a JFELION™ connection. A solid lubricating coating film was formed on the coupling side connection by forming an epoxy resin containing primarily BN. No. 7 is an example where one side of the pin was sandblasted and a soft, rust-resistant lubricating paint was formed on the sandblasted surface. Only this example of the solid lubricating coating film on the coupling side connection is a mixed type of two liquids. As the epoxy resin, a bisphenol A type epoxy resin with four epoxy groups and an epoxy equivalent of 220 was used. A modified alicyclic polyamine and a polyamidoamine, which are curing agents, were dissolved in a solvent in a weight ratio of 4:6. The functional group equivalent of the curing agent as a whole, i.e., the active hydrogen equivalent was 95.Therefore, the mixture was prepared in such a way that the reaction occurred while the bisphenol A epoxy resin had an epoxy equivalent of 185. This is a flexible case where the film hardness is 3B, which is below the standard lower limit. Furthermore, due to the two-liquid type, as the mixing progressed, the mixture tended to solidify rapidly, resulting in a watery syrup consistency and targeting a film thickness of 50 μm. However, it was difficult to determine if the film was homogeneous. This is a case (Comparative Example) where the number of assembly / disassembly cycles was not good.

[0268] Nos. 8 to 10 are cases where a test was performed using a type of steel: acid-resistant carbon steel C 110, a connection size: 95 / 8”53.5#, and a JFELION™ connection. A solid lubricating coating film was formed on one side of the coupling connection using an epoxy resin containing primarily BN. Nos. 8 to 10 are examples where one side of the pin was sandblasted and a soft, rust-resistant lubricating paint was formed on the sandblasted surface. As for the epoxy resin, a trisphenol methane type epoxy resin having three Petition 870230105138, dated 11 / 29 / 2023, pp. 89 / 116 79 / 86 epoxy groups and an epoxy equivalent of 185. In Nos. 8 to 10, as the curing agent, a diethylenetriamine-based curing agent having a functional group equivalent, i.e., an active hydrogen equivalent of 125, was used; curing was performed without a lubricating aid, and a glass transition temperature Tg of 150 °C. Nos. 8 to 10 are examples where the film thickness was 55 μm and the pencil hardness was 3H. No. 8 is a case where an epoxy resin coating film was formed on the coupling connection side, and a mild, anti-rust lubricating paint was applied to the pin side, and the number of assembly / disassembly times was equal to or greater than the specified number of times.

[0269] No. 9 is a case where an epoxy resin coating film has formed not only on the coupling connection side but also on the pin connection side, and this case is also a case where the number of assembly / disassembly times was equal to or greater than the specified number of times.

[0270] When Nos. 8 and 9 are compared to each other, No. 8 is better in the number of assembly / disassembly times. It is indicated that lubrication is better when one connection on one side has a hard coating film of 3H or higher epoxy resin containing BN as specified in the invention and the other connection has a soft film.

[0271] No. 10 is a case where the pin side did not have a film and was only sandblasted. It is clear that the BN as a solid lubricant is contained within a range specified by the present embodiment, and the epoxy resin coating film has an excellent lubrication characteristic.

[0272] Nos. 11 to 13 are cases where a test was performed using a type of steel: acid-resistant carbon steel C 110, a connection size: 9-5 / 8”53.5#, and a JFELION™ connection. A solid lubricant coating film was formed on a coupling side connection forming an epoxy resin altering the condition of the solid lubricant BN. Nos. 11 to 13 are examples where Petition 870230105138, dated 11 / 29 / 2023, pp. 90 / 116 80 / 86 One side of the pin was sandblasted, and a soft, rust-resistant lubricating paint was formed on the sandblasted surface. A tetraquisphenol ethane epoxy resin with four epoxy groups and an epoxy equivalent of 165 was used as the epoxy resin. A phenol / novolac-based curing agent with a functional group equivalent, i.e., an active hydrogen equivalent of 206, was used as the curing agent. This is a case where triphenylphosphine (TPP) was used as the curing aid. This is a case where an epoxy resin was formed on a coupling-side connection, altering the condition of the solid lubricant BN.

[0273] Nos. 11 and 12 are examples where the pin side was only sandblasted. No. 13 is a case where an acrylate-based coating material F containing a metallic soap was applied. A difference between Nos. 11 and 12 is the film thickness and solvent mixing ratio, but both Nos. 11 and 12 are cases where lubrication is good.

[0274] No. 13 is a case where BN was not added and is an example where the number of assembly / disassembly times does not meet the acceptance criterion because a solid lubricant was not included.

[0275] No. 14 is a case where a test was performed using a type of steel: acid-resistant carbon steel C 110, a connection size: 7”29# and a JFELION™ connection. A solid lubricating coating film was formed on the coupling side connection by forming an epoxy resin under a condition where the solid lubricant BN was contained in an amount of 85% and PTFE as another solid lubricant was contained in an amount of 15%. No. 14 is an example where one side of the pin was sandblasted and a soft, rust-preventive lubricating paint was formed on the sandblasted surface. As the epoxy resin, a glycidyl ester type epoxy resin with three epoxy groups and an epoxy equivalent of 190 was used. This is an example of a self-polymerizing type epoxy resin coating film, in which 5 parts by weight of 1,2,4 were added. Petition 870230105138, dated 11 / 29 / 2023, pp. 91 / 116 81 / 86 triazole in relation to 100 parts by weight of a total weight of solid lubricant and weight of epoxy resin as prepolymer to form a self-polymerizing type epoxy catalyst. In No. 14, lubrication can be considered acceptable in a coating film formed within a mixed parameter within the standard of the present disclosure.

[0276] Nos. 15 and 16 are cases where the agent viscosity is outside a suitable range. Nos. 15 and 16 are cases where a test was performed using a type of steel: acid-resistant carbon steel C 110 material, a connection size: 9-5 / 8”43.5#, and a JFELION™ connection. An epoxy resin coating film containing BN was formed on one mating side. In No. 15, one side of the pin was sandblasted and left as is. In No. 16, one side of the pin was sandblasted and a fluorine-based acrylate resin was applied to the pin side.

[0277] In No. 15, as the epoxy resin, a mixture of a polyglycerol polyglycidyl ether-based resin and a polyglycerol polyglycidyl ether-based resin in a 1:1 ratio was used. Phthalic anhydride was used as the curing agent. As the curing aid, DMP-30, i.e., 2,4,6-tris(dimethylaminomethyl)phenol, was added in an amount of 5 parts by weight to 100 parts by weight of the sum of the total weight of the lubricant solid and the total weight of the epoxy resin. This is a case where the viscosity of the epoxy resin is 3500 mPa*s, which is significantly higher than the standard upper limit. Given that the viscosity is very high, there is the disadvantage of it being difficult to apply the epoxy resin well and homogeneously in a paste form. However, the number of assembly / disassembly cycles was three times for each of the two examples in which epoxy resin could be applied. Therefore, this example is considered to be an example of the present invention.

[0278] No. 16 is a case in which cyclohexanedimethanol diglycidyl ether was used as the epoxy resin, and dicyandiamide was used as the agent. Petition 870230105138, dated 11 / 29 / 2023, pp. 92-116 82 / 86 curing agent and imidazole were used as the curing aid. This is a case where the viscosity of the epoxy resin is 25 mPa*s, which is significantly lower than the standard lower limit. In No. 16, the epoxy resin had a viscosity similar to that of an edible oil, and there was a tendency that even when the epoxy resin was applied, the epoxy resin did not remain there and accumulated at the six o'clock position. Even when an attempt was made to apply the epoxy resin while the tube was rotating, the epoxy resin accumulated at the six o'clock position before being burned, and as a result, the film had a thin thickness of 25 µm and could not be a homogeneous film. Therefore, it can be determined that the lubrication was not good. Furthermore, this is a case where the Tg of the epoxy resin film is also outside the appropriate range.Therefore, the assembly / disassembly test was attempted three times, but in No. 16 the results were two times, once, and three times, which cannot be considered excellent. No. 16 corresponds to the Comparative Example. Example 2

[0279] Example 2 is the evaluation of corrosion resistance by a salt spray test.

[0280] Among the cases illustrated in Example 1, Nos. 3, 8, 11 and 14 under the connection to the carbon steel base for tubular product conditions in oil-producing regions were chosen, and saltwater spraying was carried out on them.

[0281] As a material, a coupling sample was recently formed for this saltwater spray test.

[0282] The test was carried out using a thin sheet of normal general mild steel / cold rolled hard sheet (SPCC) with a thickness of 0.8 mm as a Comparative Example (condition A).

[0283] In the connection for petroleum tubular materials, both ends of a coupling connection were assembled and disassembled once. Petition 870230105138, dated 11 / 29 / 2023, pp. 93 / 116 83 / 86 times with a protector. Then, salt water was sprayed on the samples that were left as they were (Nos. 3-2, 8-2, 11-2 and 14-2) and on the samples to which the protector was again attached and which were mounted (corresponding to the second composition: Nos. 3-3, 8-3, 11-3 and 14-3). From there, a corrosion test was carried out under a condition in which the samples were observed side by side, i.e., side by side in a state in which the samples were not standing.

[0284] Like the pin connection, a sample containing only one thread was used, and the threaded side was assembled and disassembled once with a protector. An imide tape was fixed on the outside where the protector was not fixed again to prevent water from entering the pipe.

[0285] The detailed conditions are as follows.

[0286] The conditions of the solid lubricant coating films of Nos. 3-2 and 3-3, 8-2 and 8-3, 11-2 and 11-3 and 14-2 and 14-3 correspond to the conditions of Nos. 3, 8, 11 and 14 of Example 1, respectively. <Condições de pulverização de água salgada>

[0287] The saltwater spraying conditions are as follows.

[0288] Spraying conditions: JIS K 5600-7-1

[0289] Saltwater concentration: 5 ± 0.5 % by weight

[0290] Temperature: 35 °C

[0291] Humidity: 98 to 99 %

[0292] Spraying quantity: 1-2 mL / h / 80 cm2

[0293] pH: 6.5 to 7.2

[0294] Time: 24 hours

[0295] The importance of this test method is as follows. A connection for petroleum pipeline products is shipped after one end of it is fitted with a protector and is usually stored in a yard near a well. Therefore, a state where saltwater is sprayed onto a connection is a Petition 870230105138, dated 11 / 29 / 2023, pp. 94 / 116 84 / 86 environment close to real-world usage conditions. The condition where the protector is not attached means a more serious condition when the protector is removed. The case of the SPCC thin sheet is a case where assembly / disassembly is not performed with a protector, in which the corrosion resistance of the film itself is observed by the way the connection is made.

[0296] The results are presented in Table 5. [Table 5] N2 Steel type OD Weight Connection type Solid lubricant film condition Treatment before saltwater spraying Example of situation in saltwater spraying Corrosion result Observations A SPCC 75 mm x 150 mm x tO.8 mm (Thin steel sheet) Solid lubricant film on the film side of the coupling thread of Example 1-N23 None (Entire back surface: imide tape) (With imide tape 10 mm from the end surface on the evaluation side) Placed obliquely (Assembly in a comb-shaped jig made of vinyl chloride) Not corroded Comparative reference example 3-2 Q125 9- 5 / 8 53.5# CPLG JFELION™ Solid lubricant film on the film side of the coupling thread of Example 1-N23 Assembly / Disassembly were performed with a protector once The protector was attached to the sample again and the sample was placed horizontally (meaning the sample was not positioned) Not corroded Inventive example 3-3 Q125 9-5 / 8 53.5# CPLG JFELION™ FilmSolid lubricant on the film side of the coupling screw of Example 1-N23. Assembly / Disassembly were performed with the protector once. The protector was attached horizontally to the saltwater spray device (meaning the sample was not position-affected). Not corroded. Inventive Example 8-2 C110 9- 5 / 8 53.5# CPLG JFELION™ Solid lubricant film on the film side of the coupling screw of Example 1-N28. Assembly / Disassembly were performed with the protector once. The protector was attached to the sample again and the sample was placed horizontally (meaning the sample was not position-affected). Not corroded. Inventive Example 8-3 C110 9- 5 / 8 53.5# CPLG JFELION™ Solid lubricant film on the film side of the coupling screw of Example 1-N28. Assembly / Disassembly were performed with the protector once. The protector was attached to the sample and the sample was placed horizontally (meaning the sample was not position-affected). Not corroded. corroded ExampleInventive Example 11- 2 C110 9- 5 / 8 53.5# CPLG JFELION™ Solid lubricant film on the film side of the coupling thread of Example 1-N211 Assembly / Disassembly were performed with the protector once The protector was attached to the sample again and the sample was placed horizontally (meaning the sample was not position-affected) Not corroded Inventive Example 11- 3 C110 9- 5 / 8 53.5# CPLG JFELION™ Solid lubricant film on the film side of the coupling thread of Example 1-N211 Assembly / Disassembly were performed with the protector once The protector was attached to the sample and the sample was placed horizontally (meaning the sample was not position-affected) Not corroded Inventive Example 14- 2 C110 7 29# CPLG JFELION™ Solid lubricant film on the film side of the coupling thread of Example 1-N214 Assembly / Disassembly were performed with a protector once the protector was attached to the sample and the sample was placed horizontally (meaning the sample was not(caused by position) Not corroded Inventive Example 14- 3 C110 7” 29# CPLG JFELION™ Solid lubricant film on the film side of the coupling thread of Example 1-No. 14 Assembly / Disassembly were performed with the protector once the protector was attached to the sample and the sample was placed horizontally (meaning the sample was not caused by position) Not corroded Inventive Example Petition 870230105138, dated 11 / 29 / 2023, pp. 95 / 116 85 / 86

[0297] As can be seen in Table 5, it was found that none of Nos. 32, 3-3, 8-2, 8-3, 11-2, 11-3, 14-2 and 14-3, including No. A as a Comparative Example, are corroded by saltwater spray and have sufficient corrosion resistance.

[0298] It is estimated that this occurs because these samples have a hard 3H film quality, these samples are not fatally damaged even when mounted and dismounted with a protector, and BN itself is water repellent and does not draw water.

[0299] In this document, the entire content of Japanese Patent Application No. 2021-91463 (filed on May 31, 2021), the priority of which is claimed by this application, is incorporated herein by reference. In this document, the description has been made with reference to a limited number of embodiments, but the scope of the rights is not limited to them, and the modifications of each embodiment based on the above disclosure are obvious to those skilled in the art. List of Reference Signs

[0300] 1 Test pin

[0301] 1a Male thread

[0302] 1c Inner diameter surface

[0303] 1d Through hole

[0304] 2 Box (coupling)

[0305] 2a Female thread

[0306] 3 Heavy pendulum

[0307] 4 Hydraulic wrench

[0308] 10 Solid lubricant coating film

[0309] 10B Base layer

[0310] 11 Hook fitting (swivel type)

[0311] 12 Penetrating rod

[0312] 13 Insertion rod Petition 870230105138, dated 11 / 29 / 2023, pp. 96-116 86 / 86

[0313] 20 Lifting device (crane)

[0314] 21 Chain (Sling) Petition 870230105138, dated 11 / 29 / 2023, pp. 97-116< / agente>

Claims

1 / 4 CLAIMS 1. An agent for forming a solid lubricating coating film on a threaded portion of tubular products for oilfields, CHARACTERIZED in that a solid lubricant is dispersed in a binder resin, the binder resin contains a prepolymer and a curing agent, the prepolymer is formed of one or more epoxy resins, and 70 parts by weight or more of the prepolymer are contained in relation to 100 parts by weight of the binder resin, the epoxy resin constituting the prepolymer has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, and BN has an average particle size of 10 μm or less, and the total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the binder resin,where the average particle size is a parameter that means a particle size at an integrated value of 50% in a particle size distribution obtained by a laser diffraction / scattering method.

2. Agent for forming a solid lubricating coating film, according to claim 1, the agent CHARACTERIZED in that it comprises a solvent component in an amount of 30 parts by weight or more and 80 parts by weight or less in relation to 100 parts by weight of a sum of the total weight of the solid lubricant and the total weight of the binder resin excluding the curing agent.

3. Agent for forming a solid lubricating coating film, according to claim 1 or 2, the agent CHARACTERIZED in that Petition 870260062771, dated 06 / 26 / 2026, page 11 / 19 2 / 4 comprises a cure accelerator in an amount of 0 parts by weight or more and 10 parts by weight or less in relation to 100 parts by weight of a total weight of the epoxy resin that constitutes the prepolymer.

4. Agent for forming a solid lubricating coating film, according to any one of claims 1 to 3, CHARACTERIZED in that the epoxy resin constituting the prepolymer has more than two epoxy groups (polyfunctional epoxy resin).

5. Agent for forming a solid lubricating coating film, according to claim 4, CHARACTERIZED in that the epoxy resin constituting the prepolymer has six or fewer epoxy groups.

6. Agent for forming a solid lubricating coating film, according to claim 4, CHARACTERIZED in that the epoxy resin constituting the prepolymer has four or fewer epoxy groups.

7. Agent for forming a solid lubricating coating film, according to any one of claims 1 to 6, CHARACTERIZED in that the curing agent is a curing agent for curing an epoxy resin, and is formed from an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent, or a latent curing agent.

8. Agent for forming a solid lubricating coating film, according to claim 7, CHARACTERIZED in that the epoxy resin constituting the prepolymer has a glass transition temperature Tg of 100 °C or higher.

9. Tubular products for oilfields having a lubricating coating film including a solid lubricating coating film in Petition 870260062771, dated 06 / 26 / 2026, page 1. 12 / 19 3 / 4 threaded portion, CHARACTERIZED in that the solid lubricant coating film is formed by dispersing a solid lubricant in a binder resin, the binder resin contains an epoxy resin cured with a curing agent, and 70 parts by weight or more of the epoxy resin is contained in relation to 100 parts by weight of the binder resin, the epoxy resin has an epoxy equivalent of 100 or more and 500 or less, the solid lubricant contains boron nitride (BN) in an amount of 80% by weight or more, and BN has an average particle size of 10 μm or less, the total weight of the solid lubricant is 0.1 times or more and twice or less the total weight of the binder resin, and the solid lubricant coating film has a thickness of 10 μm or more and 150 μm or less,where the average particle size is a parameter that means a particle size at an integrated value of 50% in a particle size distribution obtained by a laser diffraction / scattering method.

10. Tubular products for oil fields, according to claim 9, CHARACTERIZED in that the epoxy resin has more than two epoxy groups (polyfunctional epoxy resin).

11. Tubular products for oil fields, according to claim 10, CHARACTERIZED in that the epoxy resin has six or fewer epoxy groups.

12. Tubular products for oil fields, according to claim 10, CHARACTERIZED in that the epoxy resin has four or fewer epoxy groups.

13. Tubular products for oil fields, according to any of claims 9 to 12, CHARACTERIZED in that the curing agent is a curing agent for curing an epoxy resin, and is formed of an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent or a latent curing agent.

14. Tubular products for oil fields, according to claim 13, CHARACTERIZED in that the epoxy resin has a glass transition temperature Tg of 100 °C or higher.

15. Tubular products for oil fields, according to any one of claims 9 to 14, CHARACTERIZED in that the solid lubricating coating film has a pencil hardness of 3H or more.

16. Tubular products for oil fields, according to any one of claims 9 to 15, CHARACTERIZED in that: the lubricating coating film has a base layer between a surface of the threaded portion and the solid lubricating coating film, and the base layer is formed of a chemically converted treated layer or a galvanized layer.

17. Threaded joint for oilfield tubular products connecting a housing having a female thread and a pin having a male thread, CHARACTERIZED in that the oilfield tubular products of at least one of the housing and the pin are constituted by the oilfield tubular products having the lubricating coating film as defined in any one of claims 9 to 16. Petition 870260062771, dated 06 / 26 / 2026, p. 14 / 19

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