Oil well pipe with threaded joint, method for manufacturing oil well pipe connection using oil well pipe with threaded joint, and method for manufacturing oil well pipe with threaded joint

Abstract

Provided is a screw joint-equipped oil well pipe which is capable of suppressing shouldering torque, minimizing rusting on the pin contact surface, and attaining excellent seizure resistance without using compound grease. A screw joint-equipped oil well pipe according to the present disclosure is equipped with a pipe main body (10) which includes a first end section (10A) and a second end section (10B). The pipe main body (10) includes a pin (40) formed at the first end section (10A) and a box (50) formed at the second end section (10B). The pin contact surface (400) of the pin (40) is coated with light oil (80). The box contact surface (500) of the box (50) has a solid lubrication film (60) formed thereon.

Description

[Technical field]

[0001] The present disclosure relates to an oil country tubular good with a threaded joint, a method for manufacturing an oil country tubular good connection body using an oil country tubular good with a threaded joint, and a method for manufacturing an oil country tubular good with a threaded joint. [Background technology]

[0002] Oil well tubular goods with threaded joints are used for the mining of oil fields and natural gas fields (hereinafter, oil fields and natural gas fields are collectively referred to as "oil wells"). Specifically, at an oil well drilling site, a number of oil well tubular goods with threaded joints are connected to form an oil well tubular goods connected body depending on the depth of the oil well. An oil well tubular goods connected body is formed by screwing oil well tubular goods with threaded joints together. The oil well tubular goods connected body is pulled up for inspection or the like, unscrewed, and after inspection, screwed again and reused.

[0003] The oil country tubular good with a threaded joint includes a pin and a box. The pin has a pin contact surface including a male thread portion on the outer peripheral surface of the end of the oil country tubular good with a threaded joint. The box has a box contact surface including a female thread portion on the inner peripheral surface of the end of the oil country tubular good with a threaded joint.

[0004] The pin contact surface and the box contact surface are repeatedly subjected to strong friction when an oil country tubular good with a threaded joint is screwed in and out. If these parts do not have sufficient durability against friction, galling (irreparable seizure) will occur when the pipe is repeatedly screwed in and out. Therefore, oil country tubular good with a threaded joint is required to have sufficient durability against friction, i.e., excellent seizure resistance.

[0005] Conventionally, compound grease containing heavy metal powder, called dope, has been used to improve seizure resistance. The seizure resistance of oil country tubular goods with threaded joints can be improved by applying compound grease to the pin contact surface and / or box contact surface. However, the heavy metal powders such as Pb, Zn, and Cu contained in the compound grease may have an impact on the environment.

[0006] In addition, most of the compound grease applied to the pin contact surface and / or box contact surface during screw tightening (screw fastening) is discharged from the tips of the pin and box when screw tightening (screw fastening) is completed. Some of the compound grease is discharged from the tip of the pin onto the inner surface of the OCTG. If the compound grease discharged onto the inner surface of the OCTG accumulates on the inner surface of the OCTG, it may cause clogging of the fastened OCTG (OCTG connection). For these reasons, there is a need for the development of OCTG with threaded joints that have excellent seizure resistance even without the use of compound grease.

[0007] In a threaded joint for pipes proposed in International Publication No. 2009 / 072486 (Patent Document 1), a solid lubricating coating is formed on the contact surface of the box, and a solid rust-preventive coating (solid corrosion-resistant coating) made of an ultraviolet-curable resin is formed on the contact surface of the pin. This document claims that the solid lubricating coating can suppress the occurrence of seizure even when the screw is repeatedly tightened and unscrewed. Furthermore, since the solid rust-preventive coating is hard, it is claimed that the solid rust-preventive coating does not affect seizure resistance even when a pin with a solid rust-preventive coating is fastened to a box with a solid lubricating coating. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2009 / 072486 Summary of the Invention [Problem to be solved by the invention]

[0009] Incidentally, when screws start to interfere with each other during screw tightening (screw fastening), the torque during screw tightening rises sharply. The torque applied when screws interfere with each other is called "shouldering torque." If the shouldering torque during screw tightening is low, the force applied to the rotation during the screw tightening operation can be reduced, and the screw can be tightened smoothly.

[0010] In addition, after being manufactured in a manufacturing mill, the oil well pipe with a threaded joint is not directly transported to the oil well drilling site, but is transported to a local yard that is a relay point and temporarily stored in the local yard. In response to the demand for the oil well pipe with a threaded joint at the oil well drilling site, the oil well pipe with a threaded joint stored in the local yard is transported from the local yard to the oil well drilling site. Until being transported from the local yard to the oil well drilling site, the oil well pipe with a threaded joint is stored in the local yard for a long period of about six months to two years. In addition, the oil well pipe with a threaded joint transported to the oil well drilling site is not used immediately after transportation, but is stored at the oil well drilling site for a short period of about one week to one month before being used. At the oil well drilling site, the oil well pipe with a threaded joint is often stored outdoors. If rust occurs on the pin contact surface during storage, it may affect the adhesion at the time of fastening. Therefore, it is preferable to suppress the occurrence of rust on the pin contact surface of the oil well pipe with a threaded joint at least during the storage period at the oil well drilling site.

[0011] In Patent Document 1, a solid rust-preventive coating made of an ultraviolet curing resin is formed on the pin contact surface of an oil well tubular good with a threaded joint, and this solid rust-preventive coating can suppress the occurrence of rust on the pin contact surface. However, as described above, after the oil well tubular good with a threaded joint is shipped from the manufacturing mill, it is transported to the oil well drilling site via the local yard. During the transportation from the manufacturing mill to the local yard, during the transportation within the local yard, and during the transportation from the local yard to the oil well drilling site, the pin of the oil well tubular good with a threaded joint may come into contact with other oil well tubular good, etc., and the solid rust-preventive coating may be partially damaged. If the solid rust-preventive coating is damaged at the local yard or the oil well drilling site, it is difficult to repair the damaged solid rust-preventive coating. In order to repair the solid rust-preventive coating, a composition for forming an ultraviolet curing resin is prepared, and further, an ultraviolet irradiation device for curing the composition is required. Therefore, in order to repair the damaged solid rust-preventive coating, it is necessary to arrange an ultraviolet irradiation device at the local yard and / or the oil well drilling site. Furthermore, in order to repair the solid rust-preventive coating, it is necessary to remove the damaged solid rust-preventive coating entirely and then form a new solid rust-preventive coating. In this case, the burden of the repair work is large. Therefore, when the solid rust-preventive coating is partially damaged or peeled off due to some factor, it is preferable that the solid rust-preventive coating can be easily repaired. Hereinafter, in this specification, being easily repairable is referred to as "having excellent repairability."

[0012] An object of the present disclosure is to provide an oil country tubular good with a threaded joint which has excellent anti-seizure properties without the use of compound grease, can suppress the occurrence of rust on the pin contact surface, can keep shouldering torque low during screw tightening, and has excellent repairability.

[0013] Another object of the present disclosure is to provide a method for manufacturing an oil well pipe connection which can suppress the generation of rust on the pin contact surfaces even when stored outdoors at an on-site yard or an oil well drilling site, thereby obtaining excellent seizure resistance while suppressing the impact on the environment caused by using oil well pipes with threaded joints, and which can keep shouldering torque low during screw tightening, thereby providing excellent repairability. [Means for solving the problem]

[0014] The oil country tubular goods with a threaded joint according to the present disclosure are: An oil well pipe with a threaded joint that can be fastened to another oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: a pin that is formed at the first end portion and that is inserted into a box of the other oil well tubular good with a threaded joint at the time of fastening to be fastened to the box of the other oil well tubular good with a threaded joint; a box formed at the second end portion, into which a pin of the other oil well tubular good with a threaded joint is inserted and fastened to the pin of the other oil well tubular good with a threaded joint during the fastening; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer peripheral surface of the first end portion of the pipe body, the pin contact surface contacting the box of the other oil well tubular good with a threaded joint during the fastening; The pin contact surface is coated with light oil; The box includes: a box contact surface that includes at least a female thread portion formed on an inner peripheral surface of the second end portion of the pipe body and that comes into contact with the pin contact surface of the pin of the other oil well tubular good with a threaded joint during the fastening; a solid lubricant coating formed on the contact surface of the box; Includes.

[0015] The oil country tubular good with a threaded joint according to the present disclosure has: An oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Equipped with The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Includes.

[0016] A method for producing an oil well tubular good joint according to the present disclosure includes the steps of: A method for manufacturing an oil well tubular good joint in which a plurality of oil well tubular good joints with threaded joints are fastened together, comprising the steps of: The method includes a process for preparing oil well pipes with threaded joints, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; Anti-rust grease is applied to the pin contact surface, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Including, The method for producing the oil well tubular good joint further comprises the steps of: transporting the oil well tubular goods with the threaded joint to a local yard which is a place for temporarily storing the oil well tubular goods with the threaded joint; a step of temporarily storing the oil well tubular good with the threaded joint transported to the on-site yard at the on-site yard; before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where the oil well tubular goods connected body is to be formed, removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; transporting the oil well tubular good with a threaded joint having the light oil applied to the pin contact surface to the oil well drilling site; a step of fastening, at the oil well drilling site, an oil well tubular good with a threaded joint having said light oil applied to said pin contact surface, to another oil well tubular good with a threaded joint to form an oil well tubular good connected body; Equipped with.

[0017] The method for manufacturing an oil well tubular good with a threaded joint according to the present disclosure includes: A method for manufacturing an oil well tubular good with a threaded joint, comprising the steps of: The method includes a process of temporarily storing the transported oil well pipes with threaded joints at a local yard, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Including, The method for manufacturing the oil well tubular good with a threaded joint further comprises: removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint temporarily stored at the on-site yard before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where an oil well tubular goods connection is to be formed, and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; Equipped with. Effect of the Invention

[0018] The oil country tubular good with a threaded joint according to the present disclosure has excellent seizure resistance without the use of compound grease, can suppress the occurrence of rust on the pin contact surface, can keep the shouldering torque low when tightening the screws, and has excellent repairability.

[0019] The method for manufacturing an oil country tubular good joint according to the present disclosure can prevent the formation of rust on the pin contact surfaces even when the joint is stored outdoors at a local yard or an oil well drilling site, and can provide excellent seizure resistance while suppressing the environmental impact of using oil country tubular good with a threaded joint, and can keep the shouldering torque low during screw tightening, resulting in excellent repairability. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram (torque chart) showing the relationship between the rotation speed and torque of an oil country tubular good with a threaded joint when the oil country tubular good with a threaded joint is fastened. [Diagram 2] FIG. 2 shows the results of a torque measurement test using an oil country tubular good with a threaded joint in which a solid lubricant coating is formed on the box contact surface and light oil is applied to the pin contact surface (test numbers 1 and 2) and a conventional oil country tubular good with a threaded joint in which a solid lubricant coating is formed on the box contact surface and a solid rust inhibitor coating is formed on the pin contact surface (test number 3) in the embodiment. [Diagram 3] FIG. 3 is a configuration diagram showing an example of an oil country tubular good with a threaded joint 1 of the present embodiment. [Figure 4] 4 is a partial cross-sectional view showing a cross section (longitudinal cross section) along the longitudinal direction of the coupling of the oil country tubular good with a threaded joint shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view parallel to the longitudinal direction of the threaded joint oil country tubular good shown in FIG. 4, showing a portion in the vicinity of the pin. [Figure 6] FIG. 6 is a cross-sectional view parallel to the longitudinal direction of the threaded joint oil country tubular good shown in FIG. 4, showing a portion of the threaded joint oil country tubular good in the vicinity of the box. [Figure 7]FIG. 7 is a diagram showing an example of an oil country tubular good with a threaded joint, in which the pin includes a male thread portion but does not include a pin seal surface or a pin shoulder surface, and the box includes a female thread portion but does not include a box seal surface or a box shoulder surface. [Figure 8] FIG. 8 is a partial cross-sectional view of an oil country tubular good with an integral type threaded joint according to this embodiment. [Figure 9] FIG. 9 is a cross-sectional view parallel to the longitudinal direction of the threaded joint oil country tubular good shown in FIG. 4, showing a portion of the threaded joint oil country tubular good in the vicinity of the box. [Figure 10] FIG. 10 is a diagram showing an example of the configuration of a box for an oil country tubular good with a threaded joint according to this embodiment. [Figure 11] FIG. 11 is a cross-sectional view parallel to the longitudinal direction of the threaded joint oil country tubular good shown in FIG. 4, showing a portion in the vicinity of a pin. [Figure 12] FIG. 12 is a diagram showing an example of the configuration of a pin of an oil country tubular good with a threaded joint according to this embodiment. [Figure 13] FIG. 13 is a diagram illustrating the location where each step is performed in the method for producing an oil well tubular good connected body of the present embodiment. [Figure 14] FIG. 14 is a configuration diagram showing an example of an oil country tubular good with a threaded joint. [Figure 15] FIG. 15 is a configuration diagram showing an example of an oil country tubular good with a threaded joint different from that in FIG. [Figure 16] FIG. 16 is a vertical sectional view of the vicinity of the pin contact surface in FIGS. [Figure 17] FIG. 17 is a vertical sectional view of the vicinity of the pin contact surface in FIGS. 14 and 15, which is different from FIG. [Figure 18] FIG. 18 is a diagram showing the configuration of the pin protector attached to the pin. [Figure 19] FIG. 19 is a vertical cross-sectional view of the male thread portion and the female thread portion of the pin protector in the vicinity thereof with the pin protector attached to the pin. [Figure 20] FIG. 20 is a torque chart created based on the torque measurement test results in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the present embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0022] The present inventors have carried out various investigations into a threaded joint oil country tubular good that can provide excellent seizure resistance without using compound grease, can suppress the occurrence of rust on the pin contact surface, and can suppress shouldering torque. As a result, they have obtained the following findings.

[0023] [About shouldering torque] When oil well pipes with threaded joints are fastened to each other, the optimum torque for completing the fastening is determined in advance. FIG. 1 is a diagram (torque chart) showing the relationship between the rotation speed and torque of the oil well pipes with threaded joints when the oil well pipes with threaded joints are fastened. Referring to FIG. 1, when the oil well pipes with threaded joints are fastened, the torque increases gradually at first in proportion to the rotation speed. If the screw is further fastened, the shoulder surfaces come into contact with each other. The torque at this time is called shouldering torque Ts. If the screw is further fastened after the shouldering torque Ts is reached, the torque increases rapidly in proportion to the rotation speed. The recommended torque (fastening torque To) when fastening a threaded joint is set to a predetermined range higher than the shouldering torque Ts. When the torque reaches the fastening torque To, the fastening is completed. At the fastening torque To, the pin seal surface and the box seal surface interfere with each other with an appropriate surface pressure. In this case, the airtightness of the oil well pipe connection formed by fastening multiple oil well pipes with threaded joints is high.

[0024] In addition, depending on the configuration of the pin and the box, the oil well pipe with a threaded joint may not include a shoulder surface. Even in such a case, when the oil well pipe with a threaded joint is screwed, the torque increases rapidly when the threads mesh with the rotation of the screw. For example, an oil well pipe with a threaded joint having a wedge-type thread may not include a shoulder surface. When such an oil well pipe with a wedge-type threaded joint is screwed, the torque increases rapidly at the timing when the flank surfaces of the threaded parts come into contact with each other. In other words, the torque chart of an oil well pipe with a threaded joint having a wedge-type thread and no shoulder surface is also as shown in FIG. 1. The torque that increases rapidly when the oil well pipe with a threaded joint having a wedge-type thread is screwed is called a locked flank torque, not a shouldering torque. However, in this specification, the locked flank torque when the oil well pipe with a threaded joint having a wedge-type thread is screwed is also called a "shouldering torque".

[0025] In addition, when it is particularly important to avoid loosening of the threaded joint after fastening, the fastening torque To is set high. However, if the fastening torque To is too high, a part of the pin and / or box may yield and cause plastic deformation. The torque at this time is called the yield torque Ty. In addition, the higher the yield torque Ty, the higher the fastening torque To can be set.

[0026] The present inventors first investigated an oil country tubular good with a threaded joint in which shouldering torque is suppressed to a low level, and as a result, obtained the following findings.

[0027] Instead of forming a conventional solid anti-rust coating on the pin contact surface, light oil is applied to the pin contact surface. The light oil is liquid before being applied to the pin contact surface. An example of the light oil is the product name "WD-40". For example, the light oil contains 50 to 70% by mass of mineral spirits and 25% or less by mass of petroleum oil.

[0028] A solid lubricating coating is formed on the contact surface of the box, and light oil is applied to the contact surface of the pin instead of a solid anticorrosive coating. In this case, the shouldering torque Ts during screw tightening of an oil country tubular good with a threaded joint can be kept low.

[0029] Fig. 2 shows the results of a torque measurement test using oil country tubular goods with a threaded joint (test numbers 1 and 2) in which a solid lubricant coating is formed on the box contact surface and light oil is applied on the pin contact surface in an embodiment described later, and an oil country tubular goods with a conventional threaded joint (test number 3) in which a solid lubricant coating is formed on the box contact surface and a solid rust-preventive coating is formed on the pin contact surface. In Fig. 2, the shouldering torque Ts and yield torque Ty of each test number are shown, with the shouldering torque of test number 3 set as 100. In the bar graphs of each test number in Fig. 2, the top of the hatched portion indicates the shouldering torque Ts, and the top of the white portion indicates the yield torque Ty.

[0030] 2, in the OCTG with threaded joint (Test Nos. 1 and 2) in which a solid lubricant coating is formed on the box contact surface and light oil is applied on the pin contact surface, the shouldering torque Ts is kept low compared to the conventional OCTG with threaded joint (Test No. 3) in which a solid lubricant coating is formed on the box contact surface and a solid rust-proofing coating is formed on the pin contact surface. The yield torque Ty of Test Nos. 1 and 2 is not so different from that of Test No. 3.

[0031] Furthermore, in the case of an oil country tubular good with a threaded joint including a pin contact surface to which the above-mentioned light oil has been applied, the occurrence of rust on the pin contact surface can be suppressed even if the oil country tubular good with a threaded joint having a pin contact surface to which light oil has been applied can exhibit excellent corrosion resistance if it is temporarily stored (for about one week to one month) after being transported from a local yard to an oil well drilling site before being used at the oil well drilling site.

[0032] However, the storage period at the local yard, which is the relay point, is long, about six months to two years, so if OCTG with threaded joints is stored at the local yard for a long period of time, further rust prevention measures are required.

[0033] Therefore, in the method for manufacturing an oil well tubular good joint according to the present embodiment, the oil well tubular good with threaded joints, on whose pin contact surfaces anti-rust grease is applied, is stored in the field yard. The anti-rust grease is in a grease-like form. In other words, the anti-rust grease is in a semi-solid or paste-like form, and is different from liquid light oil. The anti-rust grease is, for example, a grease-like, highly viscous anti-rust composition under the trade names "RUST VETO AS EU" and "KENDEX", and is also called a storage dope.

[0034] The anti-rust grease can suppress the occurrence of rust on the pin contact surface even if the outdoor storage period is two years. Then, when the oil well pipe with the threaded joint is transported from the local yard to the oil well drilling site, the anti-rust grease applied to the pin contact surface of the oil well pipe with the threaded joint is removed at the local yard, and light oil is applied to the pin contact surface from which the anti-rust grease has been removed. Then, the oil well pipe with the threaded joint with the pin contact surface with the light oil applied thereto is transported to the oil well drilling site. In this case, as described above, the pin contact surface with the light oil applied thereto exhibits excellent corrosion resistance for about one month. Furthermore, when used (when screwing), the shouldering torque can be kept low compared to the oil well pipe with the threaded joint on which a solid anti-rust coating is formed. The light oil, which is a liquid, has a lower viscosity than the anti-rust grease. Therefore, even if the light oil is discharged from the pin contact surface to the inner surface of the oil well pipe by screwing, it is unlikely to accumulate on the inner surface, and clogging is unlikely to occur inside the oil well pipe (oil well pipe connection body) after screwing.

[0035] Furthermore, unlike a solid rust-preventive coating, light oil is a liquid and can be easily applied to the pin contact surface. Therefore, even if a part of the light oil applied to the pin contact surface is peeled off due to contact with another oil well tubular good with a threaded joint during transportation at an oil well drilling site, it can be easily repaired by applying light oil. In other words, a pin contact surface applied with light oil has better repairability than a pin contact surface on which a solid rust-preventive coating is formed.

[0036] The oil country tubular good with a threaded joint, the method for manufacturing the oil country tubular good with a threaded joint, and the method for manufacturing an oil country tubular good connection body, which have been completed based on the above findings, have the following configurations.

[0037] [1] An oil well pipe with a threaded joint that can be fastened to another oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: a pin that is formed at the first end portion and that is inserted into a box of the other oil well tubular good with a threaded joint at the time of fastening to be fastened to the box of the other oil well tubular good with a threaded joint; a box formed at the second end portion, into which a pin of the other oil well tubular good with a threaded joint is inserted and fastened to the pin of the other oil well tubular good with a threaded joint during the fastening; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer peripheral surface of the first end portion of the pipe body, the pin contact surface contacting the box of the other oil well tubular good with a threaded joint during the fastening; The pin contact surface is coated with light oil; The box includes: a box contact surface that includes at least a female thread portion formed on an inner peripheral surface of the second end portion of the pipe body and that comes into contact with the pin contact surface of the pin of the other oil well tubular good with a threaded joint during the fastening; a solid lubricant coating formed on the contact surface of the box; Including, Oil well pipe with threaded joint.

[0038] [2] An oil well pipe with a threaded joint according to [1], The pin contact surface further comprises: a pin seal surface formed on the outer circumferential surface of the first end portion on a tip side of the male thread portion; a pin shoulder surface provided at a tip of the first end; Including, The box contact surface further comprises: A box seal surface is formed on the inner circumferential surface of the first end portion on a tip side of the female thread portion; a box shoulder surface provided at a tip of the second end portion; Including, Oil well pipe with threaded joint.

[0039] [3] An oil well pipe with a threaded joint according to [1] or [2], The pin further comprises: a conversion coating formed on the pin contact surface; The light oil is applied onto the chemical conversion coating. Oil well pipe with threaded joint.

[0040] [4] An oil well pipe with a threaded joint according to [3], In the chemical composition of the oil well pipe with the threaded joint, the Cr content is 2.0% or less by mass%, Oil well pipe with threaded joint.

[0041] [5] An oil well pipe with a threaded joint according to any one of [1] to [4], The box further comprises: a plating coating formed on the box contact surface; the solid lubricating coating is formed on the plating coating, Oil well pipe with threaded joint.

[0042] [6] An oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Equipped with The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Including, Oil well pipe with threaded joint.

[0043] [7] An oil well pipe with a threaded joint according to [6], The pin contact surface further comprises: a pin seal surface formed on the outer circumferential surface of the first end portion on a tip side of the male thread portion; a pin shoulder surface provided at a tip of the first end; Including, The box contact surface further comprises: A box seal surface is formed on the inner circumferential surface of the first end portion on a tip side of the female thread portion; a box shoulder surface provided at a tip of the second end portion; Including, Oil well pipe with threaded joint.

[0044] [8] An oil well pipe with a threaded joint according to [6] or [7], The pin further comprises: a conversion coating formed on the pin contact surface; The anti-rust grease is applied onto the chemical conversion coating. Oil well pipe with threaded joint.

[0045] [9] [8] An oil well pipe with a threaded joint according to the present invention, In the chemical composition of the oil well pipe with the threaded joint, the Cr content is 2.0% or less by mass%, Oil well pipe with threaded joint.

[0046]

[10] An oil well pipe with a threaded joint according to any one of [6] to [9], The box further comprises: a plating coating formed on the box contact surface; the solid lubricating coating is formed on the plating coating, Oil well pipe with threaded joint.

[0047]

[11] [6] to

[10] , further comprising: a protector that is fastened to the pin, The protector comprises: A cylindrical portion having an internal thread formed on an inner circumferential surface thereof; A cover portion disposed at one end of the cylindrical portion; Including, A distance D1 between the thread of the male screw of the pin and the thread root of the female screw of the cylindrical portion of the protector is longer than a distance D2 between the thread root of the male screw of the pin and the thread of the female screw of the cylindrical portion of the protector, A thickness T1 of the anti-rust grease between the thread of the male screw of the pin and the thread root of the female screw of the cylindrical portion of the protector is thicker than a thickness T2 of the anti-rust grease between the thread root of the male screw of the pin and the thread of the female screw of the cylindrical portion of the protector. Oil well pipe with threaded joint.

[0048]

[12] A method for manufacturing an oil well tubular good joint in which a plurality of oil well tubular good joints with threaded joints are fastened together, comprising the steps of: The method includes a process for preparing oil well pipes with threaded joints, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; Anti-rust grease is applied to the pin contact surface, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Including, The method for producing the oil well tubular good joint further comprises the steps of: transporting the oil well tubular goods with the threaded joint to a local yard which is a place for temporarily storing the oil well tubular goods with the threaded joint; a step of temporarily storing the oil well tubular good with the threaded joint transported to the on-site yard at the on-site yard; before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where the oil well tubular goods connected body is to be formed, removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; transporting the oil well tubular good with a threaded joint having the light oil applied to the pin contact surface to the oil well drilling site; a step of fastening, at the oil well drilling site, an oil well tubular good with a threaded joint having said light oil applied to said pin contact surface, to another oil well tubular good with a threaded joint to form an oil well tubular good connected body; Equipped with A method for manufacturing an oil well tubular good joint.

[0049]

[13] A method for manufacturing an oil well tubular good with a threaded joint, comprising the steps of: The method includes a process of temporarily storing the transported oil well pipes with threaded joints at a local yard, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: A pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the tube body; a solid lubricant coating formed on the contact surface of the box; Including, The method for manufacturing the oil well tubular good with a threaded joint further comprises: removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint temporarily stored at the on-site yard before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where an oil well tubular goods connection is to be formed, and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; Equipped with A method for manufacturing oil country tubular goods with threaded joints.

[0050] Hereinafter, the oil country tubular good with a threaded joint, the method for manufacturing an oil country tubular good connected body using the oil country tubular good with a threaded joint, and the method for manufacturing the oil country tubular good with a threaded joint of the present embodiment will be described in detail.

[0051] [Configuration of OCTG with threaded joint 1] [When OCTG with threaded joint 1 is T&C type] Fig. 3 is a configuration diagram showing an example of an oil country tubular good with a threaded joint 1 of this embodiment. Fig. 3 is a configuration diagram of an oil country tubular good with a so-called T&C (Threaded and Coupled) threaded joint. Referring to Fig. 3, the oil country tubular good with a threaded joint 1 comprises a pipe main body 10.

[0052] The pipe body 10 extends in the longitudinal direction and has a circular cross section perpendicular to the longitudinal direction. The pipe body 10 includes a first end 10A and a second end 10B. The first end 10A is the end opposite to the second end 10B. In the T&C type oil country tubular good 1 with threaded joint shown in FIG. 3, the pipe body 10 includes a pin tube body 11 and a coupling 12. The coupling 12 is attached to one end of the pin tube body 11. More specifically, the coupling 12 is fastened to one end of the pin tube body 11 by a screw.

[0053] Figure 4 is a partial cross-sectional view showing a cross section (longitudinal cross section) along the longitudinal direction of the coupling 12 of the oil country tubular good with a threaded joint 1 shown in Figure 3. With reference to Figures 3 and 4, the pipe body 10 includes a pin 40 and a box 50. The pin 40 is formed at a first end 10A of the pipe body 10. When fastening, the pin 40 is inserted into a box 50 of another oil country tubular good with a threaded joint (not shown), and is fastened to the box 50 of the other oil country tubular good with a threaded joint by a screw.

[0054] The box 50 is formed at the second end 10B of the pipe body 10. During fastening, the pin 40 of another oil well tubular good with a threaded joint 100 is inserted into the box 50, and fastened to the pin 40 of the other oil well tubular good with a threaded joint 100 by screws.

[0055] [About the configuration of pin 40] Figure 5 is a cross-sectional view parallel to the longitudinal direction of the oil country tubular good with a threaded joint 1, showing a portion near the pin 40 of the oil country tubular good with a threaded joint 1 shown in Figure 4. The dashed line portion in Figure 5 shows the configuration of a box 50 of the oil country tubular good with another threaded joint when fastening to another oil country tubular good with a threaded joint 1. Referring to Figure 5, the pin 40 has a pin contact surface 400 on the outer circumferential surface of the first end 10A of the pipe body 10. The pin contact surface 400 comes into contact with the box 50 of the oil country tubular good with another threaded joint when fastening to the oil country tubular good with another threaded joint.

[0056] The pin contact surface 400 includes at least the male thread portion 41 formed on the outer circumferential surface of the first end portion 10A. The pin contact surface 400 may further include a pin seal surface 42 and a pin shoulder surface 43. In FIG. 5, the pin seal surface 42 is disposed on the outer circumferential surface of the first end portion 10A, closer to the tip side of the first end portion 10A than the male thread portion 41. That is, the pin seal surface 42 is disposed between the male thread portion 41 and the pin shoulder surface 43. The pin seal surface 42 is provided in a tapered shape. Specifically, the outer diameter of the pin seal surface 42 gradually decreases from the male thread portion 41 toward the pin shoulder surface 43 in the longitudinal direction of the first end portion 10A.

[0057] When fastening with another oil well tubular good with a threaded joint, the pin seal surface 42 comes into contact with a box seal surface 52 (described later) of a box 50 of the oil well tubular good with a threaded joint. More specifically, when fastening, the pin 40 is inserted into the box 50 of the oil well tubular good with a threaded joint, so that the pin seal surface 42 comes into contact with the box seal surface 52. Then, when the pin 40 is further screwed into the box 50 of the oil well tubular good with a threaded joint, the pin seal surface 42 comes into close contact with the box seal surface 52. As a result, when fastening, the pin seal surface 42 comes into close contact with the box seal surface 52 to form a seal based on metal-metal contact. Therefore, it is possible to improve the airtightness of the oil well tubular good with a threaded joint 1 fastened to each other.

[0058] In FIG. 5, the pin shoulder surface 43 is disposed on the tip surface of the first end 10A. That is, in the pin 40 shown in FIG. 5, the male threaded portion 41, the pin seal surface 42, and the pin shoulder surface 43 are disposed in this order from the center of the pipe body 10 toward the first end 10A. When fastening with another oil well tubular good with a threaded joint, the pin shoulder surface 43 faces and contacts a box shoulder surface 53 (described later) of a box 50 of the oil well tubular good with a threaded joint. More specifically, when fastening, the pin 40 is inserted into the box 50 of the oil well tubular good with a threaded joint, so that the pin shoulder surface 43 contacts the box shoulder surface 53. This allows fastening with a high fastening torque. Also, the positional relationship between the pin 40 and the box 50 in the fastened state can be stabilized.

[0059] It should be noted that the pin contact surface 400 of the pin 40 includes at least the male thread portion 41. In other words, the pin contact surface 400 may include the male thread portion 41, and not include the pin seal surface 42 and the pin shoulder surface 43. The pin contact surface 400 may include the male thread portion 41 and the pin shoulder surface 43, and not include the pin seal surface 42. The pin contact surface 400 may include the male thread portion 41 and the pin seal surface 42, and not include the pin shoulder surface 43.

[0060] [About the composition of Box 50] Fig. 6 is a cross-sectional view parallel to the longitudinal direction of the oil country tubular good with a threaded joint 1, showing a portion near the box 50 of the oil country tubular good with a threaded joint 1 shown in Fig. 4. The dashed line portion in Fig. 6 shows the configuration of the pin 40 of the oil country tubular good with another threaded joint when fastening to the oil country tubular good with another threaded joint. Referring to Fig. 6, the box 50 has a box contact surface 500 on the inner peripheral surface of the second end 10B of the pipe body 10. When fastening to the oil country tubular good with another threaded joint, the pin 40 of the oil country tubular good with another threaded joint is screwed into the box contact surface 500, and the box contact surface 500 comes into contact with the pin contact surface 400 of the pin 40.

[0061] The box contact surface 500 includes at least a female thread portion 51 formed on the inner circumferential surface of the second end portion 10B. During fastening, the female thread portion 51 meshes with the male thread portion 41 of the pin 40 of another oil country tubular good with a threaded joint.

[0062] The box contact surface 500 may further include a box seal surface 52 and a box shoulder surface 53. In FIG. 6, the box seal surface 52 is disposed on the inner circumferential surface of the second end portion 10B closer to the center of the pipe body 10 than the female thread portion 51. That is, the box seal surface 52 is disposed between the female thread portion 51 and the box shoulder surface 53. The box seal surface 52 is tapered. Specifically, the inner diameter of the box seal surface 52 gradually decreases from the female thread portion 51 toward the box shoulder surface 53 in the longitudinal direction of the second end portion 10B.

[0063] When fastening with another oil well tubular good with a threaded joint, the box seal surface 52 comes into contact with the pin seal surface 42 of the pin 40 of the oil well tubular good with a threaded joint. More specifically, when fastening, the pin 40 of the oil well tubular good with a threaded joint is screwed into the box 50, so that the box seal surface 52 comes into contact with the pin seal surface 42, and when further screwed, the box seal surface 52 comes into close contact with the pin seal surface 42. As a result, when fastening, the box seal surface 52 comes into close contact with the pin seal surface 42 to form a seal based on metal-metal contact. Therefore, it is possible to improve the airtightness of the oil well tubular good with a threaded joint 1 fastened to each other.

[0064] The box shoulder surface 53 is disposed closer to the center of the pipe body 10 than the box seal surface 52. That is, in the box 50, the box shoulder surface 53, the box seal surface 52, and the female threaded portion 51 are disposed in this order from the center of the pipe body 10 toward the second end 10B. The normal of the box shoulder surface 53 faces the longitudinal direction of the pipe body 10. When fastening with another oil well tubular good with a threaded joint, the box shoulder surface 53 faces and contacts the pin shoulder surface 43 of the pin 40 of the oil well tubular good with the other threaded joint. More specifically, when fastening, the pin 40 of the oil well tubular good with the other threaded joint is inserted into the box 50, so that the box shoulder surface 53 contacts the pin shoulder surface 43. This allows fastening with a high fastening torque. In addition, the positional relationship between the pin 40 and the box 50 in the fastened state can be stabilized.

[0065] The box contact surface 500 includes at least an internal thread portion 51. During fastening, the internal thread portion 51 of the box contact surface 500 of the box 50 corresponds to and contacts the external thread portion 41 of the pin contact surface 400 of the pin 40. The box seal surface 52 corresponds to and contacts the pin seal surface 42. The box shoulder surface 53 corresponds to and contacts the pin shoulder surface 43.

[0066] When the pin contact surface 400 includes the male threads 41 and does not include the pin seal surface 42 and the pin shoulder surface 43, the box contact surface 500 includes the female threads 51 and does not include the box seal surface 52 and the box shoulder surface 53. When the pin contact surface 400 includes the male threads 41 and the pin shoulder surface 43 and does not include the pin seal surface 42, the box contact surface 500 includes the female threads 51 and the box shoulder surface 53 and does not include the box seal surface 52. When the pin contact surface 400 includes the male threads 41 and the pin seal surface 42 and does not include the pin shoulder surface 43, the box contact surface 500 includes the female threads 51 and the box seal surface 52 and does not include the box shoulder surface 53.

[0067] The pin contact surface 400 may include a plurality of male thread portions 41, a plurality of pin seal surfaces 42, or a plurality of pin shoulder surfaces 43. For example, in the pin contact surface 400 of the pin 40, the pin shoulder surface 43, the pin seal surface 42, the male thread portion 41, the pin seal surface 42, the pin shoulder surface 43, the pin seal surface 42, and the male thread portion 41 may be arranged in this order from the tip of the first end portion 10A toward the center of the pipe body 10. In this case, in the box contact surface 500 of the box 50, the female thread portion 51, the box seal surface 52, the box shoulder surface 53, the box seal surface 52, the female thread portion 51, the box seal surface 52, and the box shoulder surface 53 are arranged in this order from the tip of the second end portion 10B toward the center of the pipe body 10.

[0068] 5 and 6 show a so-called premium joint in which the pin 40 includes the male thread portion 41, the pin seal surface 42, and the pin shoulder surface 43, and the box 50 includes the female thread portion 51, the box seal surface 52, and the box shoulder surface 53. However, as described above, the pin 40 may include the male thread portion 41 and not include the pin seal surface 42 and the pin shoulder surface 43. In this case, the box 50 includes the female thread portion 51, but not the box seal surface 52 and the box shoulder surface 53. FIG. 7 shows an example of an oil well tubular good with a threaded joint 1 in which the pin 40 includes the male thread portion 41, but not the pin seal surface 42 or the pin shoulder surface 43, and the box 50 includes the female thread portion 51, but not the box seal surface 52 or the box shoulder surface 53.

[0069] [When OCTG with threaded joint 1 is an integral type] 3 and 4 is a so-called T&C type oil well pipe with a threaded joint in which a pipe body 10 includes a pin pipe body 11 and a coupling 12. However, the oil well pipe with a threaded joint 1 of this embodiment may be an integral type instead of a T&C type.

[0070] FIG. 8 is a partial cross-sectional view of an oil country tubular good with an integral type threaded joint 1 according to this embodiment. Referring to FIG. 8, the oil country tubular good with an integral type threaded joint 1 comprises a pipe body 10. The pipe body 10 includes a first end 10A and a second end 10B. The first end 10A is disposed on the opposite side to the second end 10B. As described above, in the oil country tubular good with a T&C type threaded joint 1, the pipe body 10 comprises a pin pipe body 11 and a coupling 12. That is, in the oil country tubular good with a T&C type threaded joint 1, the pipe body 10 is configured by fastening two separate members (the pin pipe body 11 and the coupling 12). In contrast, in the oil country tubular good with an integral type threaded joint 1, the pipe body 10 is formed as a single unit.

[0071] The pin 40 is formed at a first end 10A of the pipe body 10. When fastening, the pin 40 is inserted into and screwed into a box 50 of another oil well tubular good with an integral type threaded joint 1, and fastened to the box 50 of the other oil well tubular good with an integral type threaded joint 1. The box 50 is formed at a second end 10B of the pipe body 10. When fastening, the pin 40 of another oil well tubular good with an integral type threaded joint 1 is inserted into and screwed into the box 50, and fastened to the pin 40 of the other oil well tubular good with an integral type threaded joint 1.

[0072] The configuration of the pin 40 of the oil well pipe with integral type threaded joint 1 is the same as the configuration of the pin 40 of the oil well pipe with T&C type threaded joint 1 shown in FIG. 5. Similarly, the configuration of the box 50 of the oil well pipe with integral type threaded joint 1 is the same as the configuration of the box 50 of the oil well pipe with T&C type threaded joint 1 shown in FIG. 6. In addition, in FIG. 8, in the pin 40, from the tip of the first end 10A toward the center of the pipe body 10, the pin shoulder surface, the pin seal surface, the male thread portion, the pin seal surface, the pin shoulder surface, the pin seal surface, and the male thread portion are arranged in this order. Therefore, in the box 50, from the tip of the second end 10B toward the center of the pipe body 10, the female thread portion, the box seal surface, the box shoulder surface, the box seal surface, the female thread portion, the box seal surface, and the box shoulder surface are arranged in this order. However, as in FIG. 5, the pin contact surface 400 of the pin 40 of the oil well pipe with integral type threaded joint may include at least the male thread portion 41. 6, the box contact surface 500 of the box 50 of the oil country tubular good with an integral type threaded joint may include at least the female thread portion 51.

[0073] The oil country tubular good with a threaded joint 1 of this embodiment may be of the T&C type or of the integral type.

[0074] [Oil well tubular good with threaded joint in which the male threaded portion 41 and the female threaded portion 51 are wedge threads] As shown in FIG. 7, the oil well pipe with threaded joint of this embodiment may not include a shoulder surface (pin shoulder surface 43, box shoulder surface 53). In this case, the male thread portion 41 and the female thread portion 51 may be wedge-type threads (double-tail tapered threads). When the male thread portion 41 and the female thread portion 51 are wedge-type threads, the thread width of the male thread portion 41 tapers in the direction of right-handed thread advance along the helix of the thread. The thread valley width of the female thread portion 51 opposite to the male thread portion 41 also tapers in the direction of right-handed thread advance along the helix of the thread. When the male thread portion 41 and the female thread portion 51 are wedge-type threads, both the load flank surface and the stab flank surface have negative angles, and the load flank surfaces and the stab flank surfaces contact each other. This allows the entire thread portions to fit tightly together, and a high make-up torque can be maintained. In addition, in the fastened state, the crest surface and the root surface of the thread of the threaded portions 41 and 51 come into contact with each other, thereby ensuring sealing performance. As described above, when the male threaded portion 41 and the female threaded portion 51 are wedge threads, the oil country tubular good with a threaded joint does not need to include a shoulder surface (pin shoulder surface 43, box shoulder surface 53).

[0075] [Configuration on box contact surface 500 of box 50] Referring to FIG. 9, the box 50 is provided with a solid lubricant coating 60 on the box contact surface 500 .

[0076] [Solid lubricant coating 60] The solid lubricant coating 60 enhances the lubricity of the pin 40 of the box 50 of the oil country tubular good with a threaded joint 1 during make-up. The solid lubricant coating 60 is a solid coating at room temperature (20°C±15°C). The solid lubricant coating 60 contains a binder and a lubricant additive. In addition to the binder and the lubricant additive, the solid lubricant coating 60 may contain a solvent and other components as necessary. Each component of the solid lubricant coating 60 (binder and lubricant additive) will be described in detail below.

[0077] [Binding agent] The binder binds the lubricant additive in the solid lubricant coating 60. In this embodiment, the binder contains one or more resins selected from the group consisting of organic resins, inorganic resins, and mixtures thereof. When an organic resin is used as the binder, the organic resin is one or more of a thermosetting resin and a thermoplastic resin. The thermosetting resin is, for example, one or more resins selected from the group consisting of an epoxy resin, a polyimide resin, a polycarbodiimide resin, a polyethersulfone resin, a polyetheretherketone resin, a polyurethane resin, a phenol resin, a furan resin, a urea resin, and an acrylic resin. The thermoplastic resin is, for example, one or more resins selected from the group consisting of a polyamideimide resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, and an ethylene vinyl acetate resin.

[0078] When an inorganic resin is used as a binder, the inorganic resin is, for example, polymetalloxane. Polymetalloxane refers to a polymer compound in which the main chain is made up of repeated metal-oxygen bonds. Preferably, the inorganic resin is at least one selected from the group consisting of polytitanoxane (Ti-O) and polysiloxane (Si-O). These inorganic resins are obtained by hydrolyzing and condensing a metal alkoxide. The alkoxy group of the metal alkoxide is, for example, a lower alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an isobutoxy group, a butoxy group, and a tert-butoxy group.

[0079] If the melting temperature of the binder is too high, it becomes difficult to apply the composition by the hot melt method. On the other hand, if the melting temperature of the binder is too low, the solid lubricant coating 60 softens in a high-temperature environment. In this case, the adhesion of the solid lubricant coating 60 to the box contact surface 500 decreases. Therefore, the binder preferably contains at least one resin selected from the group consisting of ethylene vinyl acetate resin and polyolefin resin having a melting temperature (or softening temperature) of 80 to 320°C. More preferably, the binder contains at least one resin selected from the group consisting of ethylene vinyl acetate resin and polyolefin resin having a melting temperature (or softening temperature) of 90 to 200°C.

[0080] The ethylene vinyl acetate resin is preferably a mixture of two or more ethylene vinyl acetate resins having different melting temperatures in order to prevent rapid softening due to temperature rise.Similarly, the polyolefin resin is preferably a mixture of two or more polyolefin resins having different melting temperatures.

[0081] The binder content in the solid lubricant coating 60 is preferably 50 to 80 mass %. If the binder content is 50 mass % or more, the adhesion of the solid lubricant coating 60 is further improved. If the binder content is 80 mass % or less, the lubricity of the solid lubricant coating 60 is maintained better.

[0082] The lower limit of the binder content in the solid lubricant coating 60 is more preferably 55 mass %, even more preferably 60 mass %, and even more preferably 65 mass %. The upper limit of the binder content in the solid lubricant coating 60 is more preferably 78 mass %, and even more preferably 75 mass %.

[0083] [Lubricant additives] The lubricant additive is a general term for additives having lubricity. The lubricant additive reduces the friction coefficient of the surface of the solid lubricant coating 60. The lubricant additives are broadly classified into the following four types. The lubricant additive contains at least one type selected from the group consisting of the following (1) to (4). (1) Those that exhibit lubricity due to having a specific slippery crystal structure, for example, a hexagonal layered crystal structure (for example, one or more selected from the group consisting of graphite, zinc oxide, and boron nitride), (2) Those that exhibit lubricity by having a reactive element in addition to a crystal structure (for example, one or more selected from the group consisting of molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, and bismuth sulfide), (3) Lubricating agents that exhibit lubricity due to chemical reactivity (e.g., thiosulfate compounds); (4) Materials that exhibit lubricity due to plastic or viscoplastic behavior under frictional stress (e.g., polyamide, polytetrafluoroethylene (PTFE))

[0084] Any of the lubricant additives (1) to (4) above can be used. A combination of two or more of the above (1) to (4) can also be used. In other words, the solid lubricant coating can contain one or more selected from the group consisting of graphite, zinc oxide, boron nitride, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, thiosulfate compounds, and polyamides.

[0085] The content of the lubricant additive in the solid lubricant coating 60 is preferably 10 to 25 mass %. If the content of the lubricant additive is 10 mass % or more, the shouldering torque can be further reduced. On the other hand, if the content of the lubricant additive is 25 mass % or less, the strength of the solid lubricant coating 60 is further increased. As a result, wear of the solid lubricant coating 60 can be suppressed.

[0086] The lower limit of the content of the lubricant additive in the solid lubricant coating 60 is more preferably 12 mass %, and even more preferably 15 mass %. The upper limit of the content of the lubricant additive in the solid lubricant coating 60 is more preferably 23 mass %, and even more preferably 20 mass %.

[0087] A solvent is used when it is necessary to dissolve or disperse the lubricant additive and the binder. There is no particular limitation on the solvent as long as it can disperse or dissolve the components contained in the solid lubricant coating 60. Examples of the solvent include water, alcohol, and an organic solvent. The solvent may contain a small amount of a surfactant. There is no particular limitation on the proportion of the solvent. The proportion of the solvent may be adjusted so that the composition has an appropriate viscosity depending on the application method. The proportion of the solvent is, for example, 40 to 60 mass % when the total of all components other than the solvent is taken as 100 mass %. The organic solvent is, for example, one or more of toluene and isopropyl alcohol. Most of the solvent volatilizes when the solid lubricant coating 60 is formed. However, for example, 1 mass % or less of the solvent may remain in the solid lubricant coating 60.

[0088] [Other components in Solid Lubricant Coating 60] In addition to the above components, the solid lubricating coating 60 may contain one or more selected from the group consisting of anti-rust additives, plasticizers, surfactants, colorants, antioxidants, and inorganic powders for adjusting the sliding properties. The inorganic powder may be, for example, one or more of titanium dioxide and bismuth oxide. The total content of the other components is, for example, 5% by mass or less. The solid lubricating coating 60 may also contain very small amounts of extreme pressure agents, liquid oils, and the like, of 2% by mass or less. The total content of the other components in the solid lubricating coating 60 is, for example, 10% by mass or less.

[0089] The thickness of the solid lubricating coating 60 is preferably 10 to 40 μm. If the thickness of the solid lubricating coating 60 is 10 μm or more, high lubricity can be obtained more stably. On the other hand, if the thickness of the solid lubricating coating 60 is 40 μm or less, the adhesion of the solid lubricating coating 60 becomes more stable. If the thickness of the solid lubricating coating 60 is 40 μm or less, the thread tolerance (clearance) of the sliding surface becomes wider, and the surface pressure during sliding decreases. Therefore, it is possible to prevent the tightening torque from becoming excessively high. Therefore, the thickness of the solid lubricating coating 60 is preferably 10 to 40 μm. A more preferable lower limit of the thickness of the solid lubricating coating 60 is 15 μm, and more preferably 20 μm. A more preferable upper limit of the thickness of the solid lubricating coating 60 is 35 μm, and more preferably 30 μm.

[0090] The thickness of the solid lubricant coating 60 is measured by the following method. A box 50 provided with the solid lubricant coating 60 is prepared. The box 50 is cut perpendicular to the axial direction (longitudinal direction) of the OCTG. The area of ​​the cross section including the solid lubricant coating 60 is observed under a microscope. The magnification of the microscope observation is 500 times. The thickness of the solid lubricant coating 60 is determined in any 10 fields of view. In each field of view, the thickness of the solid lubricant coating 60 is measured at any 3 points, and the average of the measurements is defined as the thickness of the solid lubricant coating 60 in that field of view. The average of the thicknesses of the solid lubricant coating 60 in the 10 fields of view is defined as the thickness of the solid lubricant coating 60 in the box 50 of the OCTG with a threaded joint.

[0091] [Regarding the plating film 70 formed on the box contact surface 500] The box 50 of the oil country tubular good with a threaded joint 1 of this embodiment may include a plated coating 70 on the box contact surface 500. In this case, the solid lubricant coating 60 is formed on the plated coating 70.

[0092] Fig. 10 is a diagram showing an example of the configuration of a box 50 of an oil country tubular good with a threaded joint 1 of the present embodiment. Referring to Fig. 10, the box 50 of the oil country tubular good with a threaded joint 1 includes a plated coating 70 and a solid lubricant coating 60 on a box contact surface 500. The plated coating 70 is formed on the box contact surface 500. The solid lubricant coating 60 is formed on the plated coating 70.

[0093] The type of the plating film 70 is not particularly limited. For example, the plating film 70 may be a Zn plating film, a Ni plating film, a Cu plating film, a Zn-Ni alloy plating film, a Zn-Co alloy plating film, a Ni-W alloy plating film, or a Cu-Sn-Zn alloy plating film. The plating film 70 may be formed by laminating a plurality of plating films. For example, a Ni plating film may be formed on the box contact surface 500, and a Zn-Ni plating film may be further laminated thereon.

[0094] When the plating film 70 is a Zn-Ni alloy plating film, the chemical composition of the Zn-Ni alloy plating film is, for example, 10-20 mass% Ni, and the balance Zn and impurities. When the plating film 70 is a Cu-Sn-Zn alloy plating film, the chemical composition of the Cu-Sn-Zn alloy plating film is, for example, 40-70 mass% Cu, 20-50 mass% Sn, 2-20 mass% Zn, and the balance impurities. When the plating film 70 is a Cu plating film, the chemical composition of the Cu plating film is, for example, Cu and impurities.

[0095] When the plated coating 70 is formed, a chemical conversion coating may be formed on the surface of the plated coating 70. In this case, the solid lubricant coating 60 is formed on the chemical conversion coating. Details of the chemical conversion coating will be described later.

[0096] [Configuration of the pin contact surface 400 of the pin 40] Referring to FIG. 11, the pin 40 includes a light oil 80 on the pin contact surface 400 .

[0097] [Light Oil 80] Light oil 80 is applied onto pin contact surface 400. Light oil 80 is a liquid composition. The chemical composition of light oil 80 contains, for example, 50 to 70% by mass of mineral spirits and 25% or less by mass of petroleum oil.

[0098] [Mineral spirits] Mineral spirits is a solvent equivalent to industrial gasoline No. 4 as specified in JIS K 2201 (1991). The preferred lower limit of the mineral spirits content is 52%, more preferably 54%, more preferably 56%, and even more preferably 58%. The preferred upper limit of the mineral spirits content is 68%, more preferably 66%, more preferably 64%, and even more preferably 62%.

[0099] [Petroleum oil] Petroleum oil is an oil obtained by refining crude oil. For example, petroleum oil is one or more selected from the group consisting of paraffin oil, naphthene oil, and aromatic oil. The preferred lower limit of the petroleum oil content is 2%, more preferably 4%, more preferably 6%, and more preferably 8%. The preferred upper limit of the petroleum oil content is 22%, more preferably 20%, more preferably 18%, and more preferably 16%.

[0100] [Anti-rust additives] In addition to mineral spirits and petroleum oil, light oil 80 may contain a rust-preventive additive. The rust-preventive additive is a general term for additives having corrosion resistance. The rust-preventive additive is, for example, one or more selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite, and calcium ion-exchanged silica. Preferably, the rust-preventive additive is one or more selected from the group consisting of calcium ion-exchanged silica and aluminum phosphite. Other examples of the rust-preventive additive include commercially available reactive water repellents.

[0101] The content of the rust-preventive additive in the light oil 80 is preferably 10% or less by mass. A preferred upper limit of the rust-preventive additive in the light oil 80 is 9%, and more preferably 8%. A preferred lower limit of the rust-preventive additive in the light oil 80 is 1%, and more preferably 2%, and more preferably 3%. The light oil 80 does not need to contain the above-mentioned rust-preventive additive. In other words, the chemical composition of the light oil 80 may contain mineral spirits and petroleum oil, with the remainder being impurities.

[0102] The light oil 80 does not substantially contain heavy metal powder. In other words, heavy metal powder is an impurity in the light oil 80. Heavy metal powder is, for example, powder (particle) of Pb, Cu, Zn, etc. Therefore, the oil well tubular good with threaded joint of this embodiment can be used even in offshore oil wells where the use of compound grease containing heavy metal powder is prohibited.

[0103] [Preferred Viscosity for Light Oil 80] The preferred viscosity of Light Oil 80 at 22° C. using Zahn cup #1 is 27.5±1 seconds, although the viscosity of Light Oil 80 is not limited thereto.

[0104] [A well-known example of Light Oil 80] An example of Light Oil 80 is the brand name "WD-40."

[0105] The light oil 80 is liquid and has a lower viscosity than anti-rust grease such as storage dope. Therefore, no special equipment is required when applying the light oil 80 to the pin contact surface 400. Therefore, the light oil has excellent repairability compared to a solid anti-rust coating. Furthermore, the light oil 80 is applied thinly onto the pin contact surface 400. Therefore, as described above, clogging of the inner surface of the screwed oil well tubular goods (oil well tubular goods connection body) that occurs with anti-rust grease hardly occurs.

[0106] [Regarding the chemical conversion coating 90 formed on the pin contact surface 400] The pin 40 of the oil country tubular good with a threaded joint 1 of this embodiment may further include a chemical conversion coating 90 on the pin contact surface 400. In this case, the light oil 80 is applied onto the chemical conversion coating 90.

[0107] Fig. 12 is a diagram showing an example of the configuration of the pin 40 of the oil country tubular good with a threaded joint 1 of this embodiment. With reference to Fig. 12, the pin 40 of the oil country tubular good with a threaded joint 1 has a chemical conversion coating 90 formed on a pin contact surface 400. Furthermore, light oil 80 is applied onto the chemical conversion coating 90.

[0108] The chemical conversion coating 90 is, for example, one or more selected from the group consisting of a phosphate chemical conversion coating, an oxalate chemical conversion coating, and a borate chemical conversion coating. Preferably, the chemical conversion coating 90 is a phosphate chemical conversion coating.

[0109] The chemical conversion coating 90 is porous. Therefore, if light oil 80 is formed on the chemical conversion coating 90, the adhesion (retention) of the light oil 80 on the pin contact surface 400 is increased. The thickness of the chemical conversion coating 90 is not particularly limited. The preferred thickness of the chemical conversion coating 90 is 5 to 40 μm. If the thickness of the chemical conversion coating 90 is 5 μm or more, the corrosion resistance is further increased. If the thickness of the chemical conversion coating is 40 μm or less, the retention of the light oil 80 is further stably increased.

[0110] The pin 40 may have the light oil 80 applied directly onto the pin contact surface 400 and may not include the chemical conversion coating 90. In particular, when the oil country tubular good with a threaded joint 1 is carbon steel with a low alloy content, more specifically, when the Cr content in the chemical composition of the base material of the oil country tubular good with a threaded joint 1 is 2.0% or less by mass, it is preferable that the pin 40 has the chemical conversion coating 90 formed on the pin contact surface 400 and the light oil 80 applied onto the chemical conversion coating 90. For example, when the Cr content in the chemical composition of the base material of the oil country tubular good with a threaded joint 1 is 2.0% or less, the corrosion resistance of the base material itself of the oil country tubular good with a threaded joint 1 is not very high. When the chemical composition of the base material of the oil country tubular good with a threaded joint 1 has a Cr content of 2.0% or less, if the pin 40 has a chemical conversion coating 90 formed on the pin contact surface 400 and further has light oil 80 applied onto the chemical conversion coating 90, the corrosion resistance of the pin contact surface 400 can be improved. In this case, the occurrence of rust on the pin contact surface 400 of the pin 40 can be more stably suppressed during the period (one week to one month) during which the pin is temporarily stored at the oil well drilling site.

[0111] In the chemical composition of the base material of the oil country tubular good with a threaded joint 1, when the Cr content is 2.0% or less, preferably, the pin contact surface 400 of the oil country tubular good with a threaded joint 1 is blasted, a chemical conversion coating 90 is formed on the blasted pin contact surface 400, and a light oil 80 is formed on the chemical conversion coating 90. Here, the blasting is a process in which a blasting device is used to collide a blasting material (abrasive) against the box contact surface 500. The blasting is, for example, a sandblasting process. In this case, the adhesion of the chemical conversion coating 90 to the pin contact surface 400 is further increased. Therefore, the adhesion of the light oil 80 to the pin contact surface 400 is further increased.

[0112] [For light oil 80 applied onto the blasted pin contact surface 400] When the base material of the oil country tubular good with a threaded joint 1 is, for example, stainless steel such as so-called 13Cr steel, the pin contact surface 400 of the oil country tubular good with a threaded joint 1 may be blasted, and the light oil 80 may be formed on the blasted pin contact surface 400. In this case, the adhesion of the light oil 80 to the pin contact surface 400 is increased due to the microscopic irregularities formed on the blasted pin contact surface 400.

[0113] [Base material for oil well pipe with threaded joint 1] The base material of the oil country tubular good with a threaded joint 1 is not limited to the carbon steel described above, and is not particularly limited. The base material may be, for example, carbon steel, stainless steel such as 13Cr steel, or alloy steel other than stainless steel. Among alloy steels, Ni alloys and duplex stainless steels containing alloy elements such as Cr, Ni, and Mo have high corrosion resistance. Therefore, if Ni alloys and duplex stainless steels are used as the base material, excellent corrosion resistance can be obtained in a corrosive environment containing hydrogen sulfide, carbon dioxide, and the like.

[0114] [Operation of the oil well tubular good 1 with threaded joint of this embodiment] In the oil country tubular good with a threaded joint 1 of this embodiment, the light oil 80 does not contain heavy metal powder. Furthermore, the light oil 80 does not require the use of a dedicated device, such as a hot melt device, which is necessary when forming a solid rust-proofing coating. The light oil 80 can be easily applied to the pin contact surface 400 by a spray, a brush, or the like. Therefore, immediately before the oil country tubular good with a threaded joint 1 is transported to an oil well drilling site, the rust-proof grease applied to the pin contact surface 400 is removed at the local yard, and then the light oil 80 can be easily applied to the pin contact surface 400. Furthermore, the corrosion resistance of the pin contact surface 400 of the pin 40 can be increased during the period (one week to one month) during which the oil country tubular good with a threaded joint 1 is temporarily stored at the oil well drilling site after being transported from the local yard, and the occurrence of rust on the pin contact surface 400 can be suppressed during the period until the oil country tubular good with a threaded joint 1 is actually used at the oil well drilling site. Furthermore, even if a part of the light oil 80 applied to the pin contact surface 400 is peeled off due to contact with another oil well tubular good with a threaded joint during transportation at an oil well drilling site, it can be easily repaired by applying light oil 80. In other words, the pin contact surface 400 applied with the light oil 80 has better repairability than the pin contact surface 400 on which a solid rust-proofing coating is formed.

[0115] Furthermore, the oil well pipe with threaded joint 1 of this embodiment, to which the light oil 80 is applied, can suppress the shouldering torque Ts low when it is fastened to another oil well pipe with threaded joint 1. As shown in FIG. 2, the oil well pipe with threaded joint (Test No. 1, 2) to which the light oil 80 is applied has a lower shouldering torque Ts than the oil well pipe with threaded joint (Test No. 3) to which a solid rust-proofing coating is formed. Note that, as shown in FIG. 2, the yield torque Ty of the oil well pipe with threaded joint (Test No. 1 and 2) to which the light oil 80 is applied is approximately the same as the yield torque Ty of the conventional oil well pipe with threaded joint (Test No. 3) to which a solid rust-proofing coating is formed. Therefore, the oil well pipe with threaded joint 1 of this embodiment can also be fastened with a high fastening torque To.

[0116] [Method for manufacturing an oil well tubular good joint using the oil well tubular good with a threaded joint 1 of this embodiment] In this specification, a structure in which a plurality of oil well tubular goods with threaded joints 1 are fastened together is referred to as an "oil well tubular goods connected body." The oil well tubular goods connected body may be a casing, a tubing, or a drill pipe. The oil well tubular goods connected body is manufactured (fastened) at the oil well drilling site. A method for manufacturing the oil well tubular goods connected body will be described below.

[0117] In this specification, the term "oil well drilling site" refers to the site where an oil well is drilled. The oil well drilling site may be on land or offshore, and a drilling rig is disposed at the oil well drilling site. A derrick is disposed at the drilling rig, and oil well tubular goods with threaded joints are connected in the derrick to manufacture an oil well tubular goods joint. When the oil well drilling site is offshore, a floating production storage and offloading (FPSO) facility may be disposed instead of the drilling rig.

[0118] 13 is a diagram showing a schematic diagram of the location of each step in the method for manufacturing an oil well pipe connected body of this embodiment. Referring to FIG. 13, the method for manufacturing an oil well pipe connected body of this embodiment includes a step of preparing an oil well pipe with a threaded joint (oil well pipe with threaded joint preparation step: S1), a step of transporting the oil well pipe with a threaded joint 1 to an on-site yard A2 (on-site yard transport step: S2), a step of temporarily storing the oil well pipe with a threaded joint 1 at the on-site yard A2 (on-site yard temporary storage step: S3), and a step of removing anti-rust grease and applying light oil 80 to the oil well pipe with a threaded joint 1 before transporting the oil well pipe with a threaded joint 1 from the on-site yard A2 to an oil well drilling site A3 (light oil The method includes a step of transporting the oil well pipe with the threaded joint 1 to which the light oil 80 has been applied from the local yard A2 to the oil well drilling site A3 (oil well drilling site transporting step: S5), a step of temporarily storing the oil well pipe with the threaded joint at the oil well drilling site A3 (oil well drilling site temporary storage step: S6), and a step of fastening the oil well pipe with the threaded joint 1 to another oil well pipe with a threaded joint using the oil well pipe with the threaded joint temporarily stored at the oil well drilling site A3 to form an oil well pipe connector (oil well pipe connector manufacturing step: S7).

[0119] Each of the manufacturing steps S1 to S7 is carried out at a different location. Specifically, the threaded joint oil well tubular goods preparation step S1 is carried out at a factory A1 (hereinafter referred to as manufacturing mill A1) that manufactures threaded joint oil well tubular goods. The local yard temporary storage step S3 and the light oil application step S4 are carried out at a local yard A2. The oil well drilling site temporary storage step S6 and the oil well tubular goods connected body manufacturing step S7 are carried out at the oil well drilling site A3.

[0120] The manufacturing mill A1, the local yard A2, and the oil well drilling site A3 are located in different locations. Usually, the manufacturing mill A1 is located far from the oil well drilling site A3 where the oil well drilling work is being carried out. Therefore, the oil well tubular goods with threaded joints manufactured at the manufacturing mill A1 are transported to the oil well drilling site A3 by land or sea. However, the oil well drilling site A3 often does not have a place to store all of the oil well tubular goods with threaded joints used in the oil well drilling work. For example, when the oil well drilling site A3 is an offshore drilling rig or FPSO, the number of oil well tubular goods with threaded joints that can be temporarily stored in the drilling rig or FPSO is limited.

[0121] Therefore, in a normal oil well drilling operation, an on-site yard A2 capable of temporarily storing a plurality of oil well tubular goods with threaded joints is prepared in a location close to the oil well drilling site A3. Therefore, in an oil well drilling operation, first, the oil well tubular goods with threaded joints manufactured in the manufacturing mill A1 are transported by land or sea to the on-site yard A2 (on-site yard transport step S2). Then, the oil well tubular goods with threaded joints are temporarily stored in the on-site yard A2. Then, just before the oil well tubular goods with threaded joints are used, the oil well tubular goods with threaded joints are transported from the on-site yard A2 to the oil well drilling site A3 (oil well drilling site transport step S5). In short, the on-site yard A2 is used as a temporary storage location for the oil well tubular goods with threaded joints.

[0122] As described above, in the oil well drilling work, the local yard A2 is usually installed as a relay point between the manufacturing mill A1 and the oil well drilling site A3. Naturally, the local yard A2 is installed closer to the oil well drilling site A3 than the manufacturing mill A1. In general, the oil well tubular goods with threaded joints transported from the manufacturing mill A1 are temporarily stored for a long period of time at the local yard A2. Specifically, the oil well tubular goods with threaded joints transported from the manufacturing mill A1 are temporarily stored for a long period of time, about six months to two years, at the local yard A2. Then, just before being used at the oil well drilling site A3, the oil well tubular goods with threaded joints are transported from the local yard A2 to the oil well drilling site A3. At the oil well drilling site A3, the oil well tubular goods with threaded joints are temporarily stored for a short period of time, about one week to one month, at the oil well drilling site A3 until they are used in an oil well tubular goods connected body, that is, until they are fastened to other oil well tubular goods with threaded joints to form an oil well tubular goods connected body.

[0123] As described above, in recent years, in order to prevent contamination of oil well drilling sites, it has become desirable to avoid the use of heavy metal powder in the manufacture of oil well tubular goods connectors. Therefore, solid lubricant coatings and solid rust-preventive coatings have been used instead of compound greases containing heavy metal powder.

[0124] However, when the oil well pipe with a threaded joint, which has a solid rust-preventive coating formed on the pin contact surface and a solid lubricating coating formed on the box contact surface, is transported from the manufacturing mill A1 to the local yard A2, and when it is transported from the local yard A2 to the oil well drilling site A3, the pins of the oil well pipe with a threaded joint may collide with each other or collide with facilities during transportation. The pin has a pin contact surface formed on the outer circumferential surface of the end of the pipe body. Therefore, the solid rust-preventive coating formed on the pin contact surface may be damaged or a part of the solid rust-preventive coating may be broken due to a collision during transportation. In addition, the male thread, the pin seal surface, and the pin shoulder surface on the pin contact surface may be damaged or broken due to a collision.

[0125] Typically, a pin contact surface preparation device is installed in the on-site yard A2 in case the pin contact surface is damaged during transportation. For example, if the pin contact surface is damaged due to a collision, the pin of the oil well pipe with the threaded joint is cut off. Then, using the pin contact surface preparation device, a thread is cut on the end of the cut oil well pipe to form a new pin contact surface.

[0126] As described above, when the pin contact surface is damaged, it is possible to regenerate the pin contact surface using the pin contact surface preparation device arranged in the on-site yard A2. However, it is difficult to regenerate the solid rust-preventive coating in the on-site yard A2. This is because the on-site yard A2 does not usually have a device for forming a solid rust-preventive coating (hereinafter referred to as a solid rust-preventive coating preparation device). If the solid rust-preventive coating preparation device is arranged in the on-site yard A2, it is possible to regenerate (form again) the solid rust-preventive coating. However, when the solid rust-preventive coating preparation device is arranged in the on-site yard A2, it is naturally costly to arrange the solid rust-preventive coating preparation device.

[0127] Therefore, in the manufacturing method of the oil well pipe joint of this embodiment, a solid lubricating coating is formed on the box contact surface, but the use of a solid anticorrosive coating on the pin contact surface is avoided. As described above, the storage period (six months to two years) of the oil well pipe with a threaded joint at the local yard A2 is much longer than the storage period (one week to one month) of the oil well pipe with a threaded joint at the oil well drilling site A3. The above-mentioned liquid light oil 80 can suppress the occurrence of rust on the pin contact surface 400 even if it is stored outdoors for a period of about one month. However, for a period of more than one month, the light oil 80 may not provide sufficient corrosion resistance. Therefore, if the oil well pipe with a threaded joint 1 having the light oil 80 applied on the pin contact surface 400 is manufactured at the manufacturing mill A1 and transported to the local yard A2, rust may occur on the pin contact surface 400 of the oil well pipe with a threaded joint 1 during storage at the local yard A2.

[0128] On the other hand, a method of forming anti-rust grease on the pin contact surface 400 instead of the light oil 80 is also conceivable. The anti-rust grease is a semi-solid or paste-like anti-rust composition. Examples of the anti-rust grease include the product names "RUST VETO AS EU" and "KENDEX". The anti-rust grease is also called storage dope. The anti-rust grease exhibits longer corrosion resistance than the light oil 80. Specifically, the anti-rust grease can suppress the occurrence of rust on the pin contact surface 400 even if the storage period outdoors is two years. Furthermore, even if the pin is regenerated due to a collision or the like, the anti-rust grease can be easily applied to the pin contact surface.

[0129] However, it is not preferable to use the oil well pipe with threaded joints on which the anti-rust grease is applied to the pin contact surface as it is in the oil well pipe connection at the oil well drilling site A3. This is because, as with one of the problems of the compound grease described above, the anti-rust grease can cause clogging inside the screwed oil well pipe (oil well pipe connection). Specifically, most of the anti-rust grease applied to the pin contact surface and / or the box contact surface during screwing (screw fastening) is discharged to the outside from the tip of the pin and the box when fastening is completed. A part of the anti-rust grease is discharged from the tip of the pin into the inside of the oil well pipe. The anti-rust grease has a high viscosity. Therefore, the anti-rust grease discharged inside (inner surface) of the oil well pipe accumulates on the inner surface. The accumulated anti-rust grease may cause clogging of the oil well pipe.

[0130] Therefore, in the manufacturing method of the oil well pipe joint of this embodiment, the anti-rust grease on the pin contact surface 400 is repainted with light oil 80 at the on-site yard A2. Specifically, the anti-rust grease is applied to the pin contact surface of the oil well pipe with a threaded joint manufactured at the manufacturing mill A1 (S1). Then, the oil well pipe with a threaded joint with the pin contact surface coated with the anti-rust grease is transported to the on-site yard A2 (S2). The oil well pipe with a threaded joint is temporarily stored at the on-site yard A2 (S3). In this case, the outdoor storage period at the on-site yard A2 is six months to two years. However, in the oil well pipe with a threaded joint, the anti-rust grease is applied to the pin contact surface. Therefore, it is possible to suppress the occurrence of rust on the pin contact surface of the oil well pipe with a threaded joint during outdoor storage at the on-site yard A2. Furthermore, if anti-rust grease is applied, even if part of the anti-rust grease peels off for some reason, it can be easily repaired by reapplying anti-rust grease to that part (excellent repairability).

[0131] Then, before the oil well tubular goods with a threaded joint are transported from the local yard A2 to the oil well drilling site A3, the anti-rust grease applied on the pin contact surface 400 is replaced with light oil 80 at the local yard A2 to manufacture the oil well tubular goods with a threaded joint 1 (S4). Specifically, the anti-rust grease on the pin contact surface of the oil well tubular goods with a threaded joint is removed at the local yard A2. The anti-rust grease is semi-solid or paste-like, so it can be easily removed. Then, the light oil 80 is applied to the pin contact surface 400 from which the anti-rust grease has been removed. The light oil 80 is liquid and has a lower viscosity than the anti-rust grease. Therefore, the light oil 80 can be easily applied to the pin contact surface 400. In other words, the light oil 80 also has excellent repairability.

[0132] The oil well pipe with a threaded joint 1 manufactured in the local yard A2 by the above steps is transported to the oil well drilling site A3 (S5). Then, the oil well pipe with a threaded joint 1 is temporarily stored in the oil well drilling site A3 (S6). The storage period of the oil well pipe with a threaded joint 1 in the oil well drilling site A3 is shorter than the storage period of the oil well pipe with a threaded joint (oil well pipe with a threaded joint having anti-rust grease applied to the pin contact surface 400) in the local yard A2, and is about one week to one month. Therefore, even light oil 80 shows sufficient corrosion resistance. As a result, the occurrence of rust on the pin contact surface 400 of the oil well pipe with a threaded joint 1 can be suppressed during the storage period in the oil well drilling site A3.

[0133] An oil well pipe connection is manufactured using the oil well pipe with a threaded joint 1 temporarily stored at the oil well drilling site A3 (S7). Specifically, the pin 40 of the oil well pipe with a threaded joint 1 is inserted into the box 50 of another oil well pipe with a threaded joint 1 and screwed in. At this time, the light oil 80 on the pin contact surface 400 reduces the shouldering torque Ts as described above, compared to a solid rust-proofing coating. Furthermore, by removing the rust-proofing grease and applying the light oil 80, when the oil well pipe with a threaded joint 1 is screwed in at the oil well drilling site A3, clogging due to the light oil 80 hardly occurs in the screwed oil well pipe.

[0134] As described above, in the manufacturing method of the oil well tubular goods connected body of this embodiment, the shouldering torque Ts can be reduced during the manufacturing of the oil well tubular goods connected body. Also, fastening at a high fastening torque To can be realized. Furthermore, the rust-preventive grease and the light oil 80 are excellent in repairability. Furthermore, since the oil well tubular goods with threaded joint 1 coated with the light oil 80 instead of the rust-preventive grease is used at the oil well drilling site A3, clogging caused by the light oil 80 hardly occurs inside the oil well tubular goods (oil well tubular goods connected body) after screw fastening. Furthermore, in the manufacturing method of the oil well tubular goods connected body of this embodiment, the oil well tubular goods with threaded joint 1 including the solid lubricant coating 60 is used in the box 50, so that the oil well tubular goods connected body has excellent seizure resistance. Hereinafter, each manufacturing step S1 to S7 in the manufacturing method of the oil well tubular goods connected body of this embodiment will be described in detail.

[0135] [Oil country pipe preparation process with threaded joints: S1] In the threaded joint oil country tubular good preparation step S1, a threaded joint oil country tubular good 200 coated with anti-rust grease is prepared. The threaded joint oil country tubular good 200 is produced, for example, in a production mill A1.

[0136] [Configuration of oil well pipe with threaded joint 200] FIG. 14 is a configuration diagram showing an example of an oil well pipe with a threaded joint 200. FIG. 15 is a configuration diagram showing an example of an oil well pipe with a threaded joint 200 different from that of FIG. 14. FIG. 14 shows an oil well pipe with a T&C type threaded joint. FIG. 15 shows an oil well pipe with an integral type threaded joint. With reference to FIGS. 14 and 15, compared to the oil well pipe with a threaded joint 1, the oil well pipe with a threaded joint 200 includes a pin 40A applied with anti-rust grease instead of the pin 40 applied with light oil 80. The other configurations of the oil well pipe with a threaded joint 200 are the same as those of the oil well pipe with a threaded joint 1.

[0137] Figure 16 is a longitudinal cross-sectional view of a portion near the pin contact surface 400 of the pin 40A in Figures 14 and 15. Here, the longitudinal cross-sectional view means a cross section parallel to the longitudinal direction of the oil country tubular good with a threaded joint 200. Referring to Figure 16, the pin 40A of the oil country tubular good with a threaded joint 200 has anti-rust grease 80A applied on the pin contact surface 400 instead of light oil 80.

[0138] [Anti-rust grease 80A] The anti-rust grease 80A is a semi-solid or paste-like anti-rust composition, and is different from the light oil 80, which is a relatively low-viscosity liquid. The anti-rust grease 80A is, for example, under the trade name "RUST VETO AS EU" or the trade name "KENDEX". The anti-rust grease 80A is also called a storage dope. The anti-rust grease 80A exhibits longer-term corrosion resistance than the light oil 80. Specifically, the anti-rust grease 80A can suppress the occurrence of rust on the pin contact surface 400 even when the anti-rust grease 80A is stored outdoors for two years.

[0139] Anti-rust grease 80A contains, for example, by mass %, 50-80% refined mineral oil, 2.5-10.0% metal soap, and 1.0-2.5% petroleum sulfonic acid and / or its salt. The metal soap is, for example, lithium 12-hydroxystearate. The petroleum sulfonate is, for example, one or more selected from the group consisting of sodium petroleum sulfonate, calcium petroleum sulfonate, barium petroleum sulfonate, etc.

[0140] Fig. 17 is a vertical cross-sectional view of a portion near the pin contact surface 400 of the pin 40A in Figs. 14 and 15, which is different from Fig. 16. Referring to Fig. 17, the pin 40A of the oil country tubular good with a threaded joint 200 may further include a chemical conversion coating 90 on the pin contact surface 400. In this case, in the pin 40A of the oil country tubular good with a threaded joint 1, the chemical conversion coating 90 is formed on the pin contact surface 400. Antirust grease 80A is applied on the chemical conversion coating 90.

[0141] The oil country tubular good with a threaded joint 200 having the above-mentioned configuration is manufactured in a manufacturing mill A1, for example, by the following method. An example of a manufacturing method for the oil country tubular good with a threaded joint 200 will be described below. However, the manufacturing method for the oil country tubular good with a threaded joint 200 is not limited to this manufacturing method. As long as the oil country tubular good with a threaded joint 200 having the above-mentioned configuration can be prepared, the manufacturing method for the oil country tubular good with a threaded joint 200 is not particularly limited.

[0142] The method for manufacturing the oil country tubular good with a threaded joint 200 includes a blank pipe preparation step, a solid lubricant coating formation step, and an anti-rust grease application step.

[0143] [Main pipe preparation process] First, a blank pipe with a threaded joint is prepared on which a solid lubricant coating 60 is not formed and anti-rust grease 80A is not applied. The blank pipe with a threaded joint comprises a pipe body 10. The pipe body 10 includes a first end 10A and a second end 10B. A pin 40A is formed at the first end 10A. A box 50 is formed at the second end 10B. The pin of the blank pipe with a threaded joint includes a pin contact surface 400. The box of the blank pipe with a threaded joint includes a box contact surface 500.

[0144] The mother pipe with a threaded joint is manufactured, for example, by the following method. A raw material is manufactured using molten steel. Specifically, a cast piece (slab, bloom, or billet) is manufactured using the molten steel by a continuous casting method. An ingot may be manufactured using the molten steel by an ingot casting method. If necessary, a steel piece (billet) may be manufactured by blooming the slab, bloom, or ingot. A raw material (slab, bloom, or billet) is manufactured by the above steps. A mother pipe is manufactured by hot working the prepared raw material. The hot working method may be piercing rolling by the Mannesmann method or hot extrusion. The mother pipe after hot working is subjected to a known quenching and a known tempering to adjust the strength of the mother pipe. A mother pipe is manufactured by the above steps. When the oil country tubular good with a threaded joint 200 is a T&C type, a mother pipe for the coupling 12 is also prepared. The manufacturing method of the mother pipe for the coupling 12 is the same as the manufacturing method of the mother pipe described above.

[0145] When the oil country tubular good with a threaded joint 200 is of the T&C type, threads are cut on the outer surfaces of both ends of the mother pipe for the pin tube body 11 to form pin contact surfaces 400. Furthermore, threads are cut on the inner surfaces of both ends of the mother pipe for the coupling 12 to form box contact surfaces 500. The pin at one end of the mother pipe for the pin tube body 11 is inserted and screwed into the box at one end of the mother pipe for the coupling 12. Through the above steps, a mother pipe with a threaded joint, including the pin tube body 11 and the coupling 12, is manufactured.

[0146] When the oil country tubular good with a threaded joint 200 is of an integral type, a thread cutting process is performed on the outer surface of a first end 10A of a blank pipe corresponding to the pipe body 10 to form a pin contact surface 400. Furthermore, a thread cutting process is performed on the outer surface of a second end 10B of the blank pipe corresponding to the pipe body 10 to form a box contact surface 500.

[0147] Through the above steps, a mother pipe with a threaded joint including a pin and a box is prepared.

[0148] [Solid lubricant film formation process] In the solid lubricant coating forming process, a solid lubricant coating 60 is formed on the box contact surface 500 of the box of the mother pipe with a threaded joint prepared in the mother pipe preparing process. The solid lubricant coating forming process includes an application process and a hardening process. The hardening process is carried out after the application process.

[0149] [Coating process] In the coating step, a composition for forming the solid lubricant coating 60 is coated on the box contact surface 500. The composition contains a resin and a solid lubricant powder. The composition, excluding the solvent, is the same as the resin composition of the solid lubricant coating 60 described above.

[0150] The composition may be of the solventless type or the solvent type. For example, the solventless type composition can be produced by heating the resin to a molten state, adding a solid lubricant powder, and kneading the mixture. The composition may be a powder mixture in which all components are mixed in powder form.

[0151] The solvent-type composition can be produced, for example, by dissolving or dispersing the resin and the solid lubricant powder in a solvent and mixing them. The solvent is, for example, water, alcohol, and an organic solvent. The solvent may contain a small amount of a surfactant. The ratio of the solvent is not particularly limited. The ratio of the solvent may be adjusted so that the composition has an appropriate viscosity depending on the application method. The ratio of the solvent is, for example, 40 to 60 mass % when the total of all components other than the solvent is 100 mass %.

[0152] The above-mentioned composition is applied onto the box contact surface 500 by a known method. When the composition is a solvent-free type, the composition can be applied by, for example, a hot melt method. In the hot melt method, the composition is heated to melt the resin and to make it in a low-viscosity fluid state. The fluidized composition is sprayed from a spray gun having a temperature retention function. The application method may be brush application or immersion, instead of spray application. The heating temperature of the composition is preferably 10 to 50°C higher than the melting point of the resin.

[0153] When the composition is a solvent type, the composition in a solution state is applied by spraying. In this case, the viscosity of the composition is adjusted so that it can be sprayed under an environment of normal temperature and pressure. The application method may be brushing or immersion instead of spraying.

[0154] [Curing process] In the curing step, the applied composition is cured to form the solid lubricant coating 60. When the composition is a solventless type, the composition applied to the box contact surface 500 is cooled, whereby the molten composition is cured to form the solid lubricant coating 60. The cooling method can be carried out by a well-known method. For example, the cooling method is air cooling and air cooling. When the composition is a solvent type, the composition applied to the box contact surface 500 is dried, whereby the composition is cured to form the solid lubricant coating 60. The drying method can be carried out by a well-known method. For example, the drying method is natural drying, low-temperature air drying, and vacuum drying. The composition may be cured by a heat curing treatment.

[0155] In the solid lubricant coating forming process, the above-mentioned coating and curing processes are carried out to form the solid lubricant coating 60 on the box contact surface 500 .

[0156] [Plating film formation process] When the box 50 of the oil country tubular good with a threaded joint 200 includes the plating coating 70 between the box contact surface 500 and the solid lubricant coating 60, the plating coating forming step may be performed after the preparation step and before the solid lubricant coating forming step. In other words, the plating coating forming step is an optional step. When the oil country tubular good with a threaded joint 200 does not include the plating coating 70, the plating coating forming step is not performed.

[0157] When the plating film forming step is performed, the plating film 70 is formed on the box contact surface 500 in the plating film forming step.

[0158] The plating film 70 can be formed by a known method. The plating film 70 may be formed by electrolytic plating or electroless plating. For example, when the plating film 70 made of a Zn-Ni alloy is formed by electrolytic plating, the plating bath contains zinc ions and nickel ions. The plating bath preferably contains 1 to 100 g / L of zinc ions and 1 to 50 g / L of nickel ions. The conditions for the electrolytic plating method are, for example, plating bath pH: 1 to 10, plating bath temperature: 60° C., and current density: 1 to 100 A / dm 2 and treatment time: 0.1 to 30 minutes. For example, when the plating film 70 made of a Cu-Sn-Zn alloy is formed by electrolytic plating, the plating bath contains 1 to 50 g / L of copper ions, 1 to 50 g / L of tin ions, and 1 to 50 g / L of zinc ions. The electrolytic plating conditions may be the same as those for forming the plating film 70 made of the Zn-Ni alloy. When the plating film 70 is a Cu plating film, it can be produced by a well-known method.

[0159] [Surface preparation process] In addition, in the manufacturing process of the oil country tubular good with a threaded joint 200, a surface treatment process may be provided after the preparation process and before the plating film forming process. In other words, when the plating film forming process is performed, the surface treatment process may be performed before the plating film forming process. The surface treatment process is, for example, pickling or blasting. The surface roughness of the box contact surface 500 of the mother pipe with a threaded joint can be adjusted by the surface treatment process. In this case, the adhesion of the plating film 70 to the box contact surface 500 is improved. The pickling and blasting processes are described below.

[0160] [Acid washing treatment] The pickling process is a process in which the box contact surface 500 is immersed in a strong acid solution such as sulfuric acid, hydrochloric acid, nitric acid, or hydrofluoric acid to roughen the box contact surface 500. This makes it possible to increase the surface roughness of the box contact surface 500.

[0161] [Blast processing] The blasting process is, for example, a process in which a blasting material (abrasive) is collided with the box contact surface 500 using a blasting device. The blasting process is, for example, a sandblasting process. The sandblasting process is a process in which a blasting material (abrasive) is mixed with compressed air and projected onto the box contact surface 500. The blasting material is, for example, a spherical shot material and an angular grid material. The sandblasting process can increase the surface roughness of the box contact surface 500. The sandblasting process can be performed by a well-known method. For example, air is compressed with a compressor, and the compressed air is mixed with the blasting material. The material of the blasting material is, for example, stainless steel, aluminum, ceramic, alumina, etc. The projection speed and other conditions of the sandblasting process can be set appropriately.

[0162] [Anti-rust grease application process] In the rust-preventive grease application step, rust-preventive grease 80A is applied onto the pin contact surface 400 of the mother pipe with a threaded joint prepared in the mother pipe preparation step.

[0163] The anti-rust grease application step is not particularly limited as long as it is possible to apply the anti-rust grease 80A onto the pin contact surface 400. For example, the anti-rust grease 80A may be applied by spraying, by brushing, or by other well-known methods.

[0164] [Chemical conversion film formation process] When the pin 40A of the oil country tubular good with a threaded joint 200 includes a chemical conversion coating 90 between the pin contact surface 400 and the anti-rust grease 80A, a chemical conversion coating forming step may be performed after the preparation step and before the anti-rust grease application step. In other words, the chemical conversion coating forming step is an optional step. When the oil country tubular good with a threaded joint 200 does not include the chemical conversion coating 90, the chemical conversion coating forming step is not performed.

[0165] When the chemical conversion coating forming step is carried out, a well-known chemical conversion is carried out in the chemical conversion coating forming step to form a chemical conversion coating 90 on the pin contact surface 400. The chemical conversion can be carried out by a well-known method. A general commercially available chemical conversion solution can be used as the treatment liquid. To promote the formation of the chemical conversion coating, surface conditioning may be carried out before the chemical conversion. The surface conditioning is a treatment in which the workpiece is immersed in an aqueous liquid for surface conditioning containing colloidal titanium or the like. After the chemical conversion, it is preferable to rinse with water or hot water and then dry.

[0166] The above manufacturing process makes it possible to manufacture the oil country tubular good with a threaded joint 200. Note that the oil country tubular good with a threaded joint 200 may be prepared by a method other than the above-mentioned method.

[0167] [Protector installation process] Preferably, a protector attachment step is carried out to attach a protector to the pin 40A and / or the box 50 of the oil country tubular good with a threaded joint 200. A protector may or may not be attached. When attached, the protector attached to the pin 40A (hereinafter referred to as the pin protector) is a cap that covers the pin contact surface 400 of the pin 40A. The protector attached to the box 50 (hereinafter referred to as the box protector) is a lid that covers the box contact surface 500 of the box 50.

[0168] The box protector is cylindrical, and has an external thread formed on its outer circumferential surface, which can be screwed into the internal thread 51 of the box 50. The box protector is made of, for example, a known resin.

[0169] FIG. 18 is a configuration diagram of the pin protector attached to the pin 40A. Referring to FIG. 18, the pin protector 600 is placed on the pin 40A and fastened. The pin protector 600 includes a tubular portion 601 and a cover portion 602. The tubular portion 601 has a female thread formed on its inner circumferential surface. The female thread faces the pin contact surface 400. The female thread of the tubular portion 601 corresponds to the male thread 41 of the pin contact surface 400. When the pin 40A is inserted into the pin protector 600, the female thread of the tubular portion 601 meshes with the male thread of the pin contact surface 400. As a result, the pin protector 600 is fastened to the pin 40A. At this time, the tubular portion 601 covers the pin contact surface 400.

[0170] Fig. 19 is a vertical cross-sectional view of the male threaded portion 41 and the vicinity of the female threaded portion 610 of the pin protector 600 when the pin protector 600 is attached to the pin 40A. With reference to Fig. 19, when the pin protector 600 is attached, the distance between the thread bottom 41B of the male threaded portion 41 of the pin 40A and the thread 610T of the female threaded portion 610 of the tubular portion 601 of the pin protector 600 is defined as D1. The distance between the thread bottom 610B of the female threaded portion 610 of the tubular portion 601 of the pin protector 600 and the thread 41T of the male threaded portion 41 of the pin 40A is defined as D2. In this case, the distance D1 is longer than the distance D2.

[0171] The anti-rust grease 80A applied on the pin contact surface 400 is filled in the gap between the female thread portion 610 of the pin protector 600 and the male thread portion 41 of the pin 40A when the pin protector 600 is attached to the pin 40A. Therefore, the thickness T1 of the anti-rust grease 80A between the thread bottom 41B of the male thread portion 41 of the pin 40A and the thread 610T of the female thread portion 610 of the cylindrical portion 601 of the pin protector 600 is thicker than the thickness T2 of the anti-rust grease 80A between the thread 41T of the male thread portion 41 of the pin 40A and the thread bottom 610B of the female thread portion of the cylindrical portion 601 of the pin protector 600.

[0172] When the pin 40 of the oil well pipe with a threaded joint 1 is screwed into the box 50 of another oil well pipe with a threaded joint 1 at the oil well drilling site A3 and fastened, the thread bottom 41B of the male thread portion 41 of the pin 40 of the oil well pipe with a threaded joint 1 comes into contact with the thread of the female thread portion 51 of the box 50 of the other oil well pipe with a threaded joint 1. Meanwhile, during fastening, a slight gap is formed between the thread 41T of the male thread portion 41 of the pin 40 of the oil well pipe with a threaded joint 1 and the thread bottom of the female thread portion 51 of the box 50 of the other oil well pipe with a threaded joint 1. Therefore, in the oil well pipe with a threaded joint 200, when the pin protector is attached, the rust-preventive grease 80A is formed thick in the thread bottom 41B region. In this case, it is possible to further suppress the occurrence of rust in the thread bottom 41B region of the male thread portion 41 of the pin 40A, which comes into contact with the female thread of the box during fastening.

[0173] [Local yard transportation process: S2] The oil well pipes with threaded joints 200 prepared in the oil well pipe with threaded joint preparation process S1 are transported to the local yard A2 by land or sea. A well-known method of transportation is sufficient. In the case of a land route, a plurality of oil well pipes with threaded joints 200 are transported by a large vehicle such as a truck. In the case of a sea route, a plurality of oil well pipes with threaded joints 200 are loaded onto a ship and transported.

[0174] [Local yard temporary storage process: S3] In the local yard temporary storage step S3, the multiple oil well pipes with threaded joints 200 transported to the local yard A2 are temporarily stored at the local yard A2. The storage period of the oil well pipes with threaded joints 200 at the local yard A2 is longer than the storage period of the oil well pipes with threaded joints 1 at the oil well drilling site A3. The storage period of the oil well pipes with threaded joints 200 at the local yard A2 is, for example, about six months to two years.

[0175] In the on-site yard transportation step S2, a plurality of oil well pipes with threaded joints 200 are transported. Therefore, during transportation, the pins 40A of the oil well pipes with threaded joints 200 may collide with each other, or the pins 40A of the oil well pipes with threaded joints 200 may collide with structures other than the oil well pipes with threaded joints 200. Due to collisions during transportation, the rust-preventive grease 80A formed on the pin contact surface 400 may be partially removed. However, as described above, the rust-preventive grease 80A can be easily repaired by applying it to the pin contact surface 400. Therefore, even if a portion of the rust-preventive grease 80A is removed during transportation, the rust-preventive grease 80A can be easily applied to the pin contact surface 400 at the on-site yard A2 to repair it, and excellent repairability can be obtained. Therefore, unlike the case of forming a solid rust-preventive coating, there is no need to provide dedicated equipment at the on-site yard A2.

[0176] In addition, during transportation, the male thread portion 41, the pin seal surface 42, and the pin shoulder surface 43 on the pin contact surface 400 may be damaged or broken due to collision. In this case, the damaged pin 40A of the oil country tubular good with a threaded joint 200 is cut off at the on-site yard A2. Then, using a pin contact surface preparation device arranged at the on-site yard A2, a thread cutting process is performed on the cut-off end of the pin 40A of the oil country tubular good with a threaded joint 200, thereby forming a new pin contact surface 400. Furthermore, the anti-rust grease 80A is applied onto the newly formed pin contact surface 400. This allows the anti-rust grease 80A to be easily regenerated, and excellent repairability is obtained.

[0177] At the on-site yard A2, the oil country tubular good with a threaded joint 200 is stored outdoors for a long period of time, about six months to two years. However, as described above, the anti-rust grease 80A exhibits excellent corrosion resistance. Therefore, it is possible to suppress the occurrence of rust on the pin contact surface 400 during storage at the on-site yard A2. In addition, a solid lubricant coating 60 is formed on the box contact surface 500 of the oil country tubular good with a threaded joint 200. The solid lubricant coating 60 also has an anti-rust effect. Therefore, it is possible to suppress the occurrence of rust on the box contact surface 500 during storage at the on-site yard A2.

[0178] [Light oil application process: S4] When the number of oil well pipes 1 with threaded joints stored at the oil well drilling site A3 becomes low, new oil well pipes 1 with threaded joints are supplied from the local yard A2 to the oil well drilling site A3. Before transporting the oil well pipes 1 with threaded joints from the local yard A2 to the oil well drilling site A3, the rust-preventive grease 80A of the oil well pipes 200 with threaded joints is removed and light oil 80 is applied at the local yard A2 to produce the oil well pipes 1 with threaded joints.

[0179] Specifically, first, at the on-site yard A2, the anti-rust grease 80A on the pin contact surface 400 of the oil country tubular good with a threaded joint 200 is removed. The anti-rust grease 80A is semi-solid or paste-like, and therefore can be easily removed. For example, the anti-rust grease 80A can be removed by high-pressure water. Light oil 80 is applied to the pin contact surface 400 from which the anti-rust grease 80A has been removed. Since the light oil 80 is a liquid, it can be easily applied to the pin contact surface 400. The light oil 80 may be applied by spraying, by brushing, or by other well-known methods to the pin contact surface 400.

[0180] By the above process, the anti-rust grease 80A can be easily replaced with the light oil 80 at the on-site yard A2. This makes it possible to suppress clogging caused by the anti-rust agent inside the oil well pipe (oil well pipe combination) after screw tightening. Furthermore, as described later, the oil well pipe with threaded joint 1 to which the light oil 80 is applied can reduce the shouldering torque Ts.

[0181] [Oil well drilling site transportation process: S5] In the oil well drilling site transportation step S5, the oil well pipes with threaded joints 1 manufactured at the local yard A2 are transported from the local yard A2 to the oil well drilling site A3. A well-known transportation method is sufficient. In the case of a land route, a plurality of oil well pipes with threaded joints 1 are transported by a large vehicle such as a truck. In the case of a sea route, a plurality of oil well pipes with threaded joints 1 are loaded onto a ship for transportation.

[0182] [Oil well drilling site temporary storage process: S6] In the oil well drilling site temporary storage step S6, the oil well pipe with a threaded joint 1 transported from the local yard A2 is temporarily stored. The storage period of the oil well pipe with a threaded joint 1 at the oil well drilling site A3 is significantly shorter than the storage period of the oil well pipe with a threaded joint 200 at the local yard A2. The storage period of the oil well pipe with a threaded joint 1 at the oil well drilling site A3 is, for example, one week to one month.

[0183] As described above, the storage period of the oil well tubular good 1 with threaded joint at the oil well drilling site A3 is short, so the light oil 80 applied to the pin contact surface 400 provides sufficient corrosion resistance.

[0184] In the oil well drilling site transportation step S5, the male thread portion 41, the pin seal surface 42, and the pin shoulder surface 43 on the pin contact surface 400 may be damaged or broken due to a collision during transportation from the local yard A2 to the oil well drilling site A3. In this case, the damaged oil well pipe with a threaded joint 1 is returned from the oil well drilling site A3 to the local yard A2. Then, in the local yard A2, the damaged pin 40A of the oil well pipe with a threaded joint 1 is cut off and thread cutting is performed to newly form the pin contact surface 400. Furthermore, light oil 80 is applied to the newly formed pin contact surface 400. This makes it easy to regenerate the oil well pipe with a threaded joint 1 to which the light oil 80 has been applied.

[0185] [Oil country tubular joint manufacturing process: S7] An oil well tubular good connected body is manufactured (S7) using the oil well tubular good 1 with a threaded joint that is temporarily stored at the oil well drilling site A3. Specifically, the pin 40 of the oil well tubular good 1 with a threaded joint is inserted into the box 50 of another oil well tubular good 1 with a threaded joint and screwed in. At this time, the light oil 80 on the pin contact surface 400 reduces the shouldering torque Ts.

[0186] By the above manufacturing process, an oil well pipe assembly formed by fastening a plurality of oil well pipes with threaded joints 1 can be manufactured at the oil well drilling site A3. In this manufacturing method, a solid rust-proof coating is not formed on the pin contact surface 400, and instead, the rust-proof grease 80A is applied to the pin contact surface 400 until immediately before use. As a result, even if the pin 40A is damaged, a new pin 40A can be manufactured and the rust-proof grease 80A can be easily applied (repaired), resulting in excellent repairability. Furthermore, the rust-proof grease 80A exhibits a long-term rust-proofing function. Therefore, it is possible to suppress the occurrence of rust on the pin contact surface of the oil well pipe with threaded joints 200 during storage at the local yard A2. Then, before transporting from the local yard A2 to the oil well drilling site A3, the rust-proof grease 80A is removed and light oil 80 is applied to the pin contact surface 400. As a result, it is possible to suppress the occurrence of clogging caused by the rust-proofing agent inside the oil well pipe (oil well pipe assembly) after screw fastening. Furthermore, by manufacturing an oil well pipe connection using an oil well pipe with a threaded joint 1 having light oil 80 applied to the pin contact surface 400, the shouldering torque Ts can be kept low when the oil well pipe with a threaded joint 1 is screwed into another oil well pipe with a threaded joint 1 to fasten them together. The fastening torque To can be maintained high. Furthermore, the solid lubricant coating formed on the box 50 provides excellent seizure resistance. EXAMPLES

[0187] Examples will be described below. However, the oil country tubular good with a threaded joint of the present embodiment is not limited to these examples. In the examples, % means mass % unless otherwise specified.

[0188] [Production of oil well pipes with threaded joints, test numbers 1 to 3] Oil well pipes with threaded joints were prepared for test numbers 1 to 3. As the oil well pipes with threaded joints, a T&C type oil well pipe threaded joint VAM21 (registered trademark) KW (outer diameter 250.83 mm (9.875 inches), wall thickness: 15.88 mm (0.625 inches)) manufactured by Nippon Steel Corporation was used. The steel type of the oil well pipes was carbon steel, equivalent to P110 in the API 5CT standard, with a C content of 0.2% and a Cr content of 1.0%.

[0189] [Regarding pin contact surfaces of test numbers 1 and 2] A zinc phosphate chemical conversion coating was formed on the pin contact surfaces of test numbers 1 and 2. Specifically, the pin contact surfaces were first subjected to mechanical grinding finishing. Then, a chemical conversion treatment was carried out by a well-known method using a commercially available zinc phosphate treatment solution to form a zinc phosphate chemical conversion coating.

[0190] In simulating the manufacturing method of oil well tubular connectors, anti-rust grease was first applied to the zinc phosphate conversion coating of test numbers 1 and 2. Specifically, a product name of "RUST VETO AS EU" was applied to the zinc phosphate conversion coating of test numbers 1 and 2. Two hours after the application of the anti-rust grease, the anti-rust grease was removed with high-pressure water. At this time, the zinc phosphate conversion coating on the pin contact surfaces of test numbers 1 and 2 remained.

[0191] After removing the rust-preventive grease, light oil was applied onto the zinc phosphate conversion coating. Specifically, product name "WD-40" was applied onto the zinc phosphate conversion coating of test numbers 1 and 2. WD-40 was sprayed from a position 500 mm away from the pin contact surface. During the spraying, the pin was rotated around its central axis to apply WD-40 to the entire pin contact surface. With the above configuration, oil country tubular goods with threaded joints of test numbers 1 and 2 were manufactured.

[0192] [Regarding the pin contact surface of test number 3] A zinc phosphate conversion coating was formed on the pin contact surface of test number 3 in the same manner as in test numbers 1 and 2. The conditions for producing the zinc phosphate conversion coating were the same as those for test numbers 1 and 2.

[0193] A solid anti-rust coating was formed on the zinc phosphate conversion coating. The composition for forming the solid anti-rust coating was mainly composed of an acrylic resin-based ultraviolet-curable resin. The applied composition for forming the solid anti-rust coating was irradiated with ultraviolet light under known conditions to form a solid anti-rust coating with a thickness of about 20 μm. The obtained solid anti-rust coating was transparent.

[0194] [Regarding the box contact surfaces of test numbers 1 to 3] A Cu-Sn-Zn alloy plating layer having a thickness of about 8 μm was formed by a known electroplating process on the contact surfaces of the boxes of test numbers 1 to 3. The chemical composition of the Cu-Sn-Zn alloy plating layer was about 63% Cu, about 30% Sn, and about 7% Zn.

[0195] A composition containing, by mass%, approximately 70% binder (mainly a mixture of resin and paraffin wax (mass ratio of approximately 4:3)), approximately 20% lubricant (amorphous graphite, PTFE, etc.), approximately 7% rust prevention additive, and approximately 1% plasticizer was heated to 130°C, sprayed onto the Cu-Sn-Zn alloy plating layer, and then cooled to form a solid lubricating coating with a thickness of 50 μm.

[0196] By the above manufacturing process, a number of oil country tubular goods with threaded joints, test numbers 1 to 3, were manufactured.

[0197] [Torque measurement test] The torque during screw tightening (screw tightening process) was measured using oil country tubular goods with threaded joints of each test number, and the torque chart shown in FIG. 20 was created. Specifically, the tightening torque value was gradually increased at a tightening speed of 10 rpm, and the test was terminated when the material yielded. Ts in FIG. 20 indicates the shouldering torque. MTV in FIG. 20 indicates the torque value where the line segment L intersects with the torque chart. The line segment L is a straight line with the same gradient as the gradient of the linear region in the torque chart after shouldering, and the rotation speed is 0.2% higher than that of the linear region. In this example, since the yield torque Ty (the boundary between the linear region and the nonlinear region in the torque chart after shouldering) was unclear, the MTV was defined using the line segment L, and the MTV was used as an index instead of the yield torque Ty. A graph of the torque values ​​of test numbers 1 to 3 is shown in FIG. 2. In Fig. 2, the shouldering torque and torque-on-shoulder resistance ΔT for each test number are shown, with the shouldering torque for test number 3 set as 100. In the bar graph for each test number in Fig. 2, the top of the hatched portion indicates the shouldering torque Ts value, and the top of the white portion indicates the MTV value.

[0198] [Seizure resistance evaluation test] The seizure resistance was evaluated by a repeated fastening test. Using the pins and boxes of test numbers 1 and 3, the screws were repeatedly tightened and loosened at room temperature (20°C) to evaluate the seizure resistance. The fastening torque was 24350 ft.lbs. The contact surfaces of the pin and the box were visually observed after each screw tightening and loosening. The occurrence of seizure in the threaded part and the metal seal part was confirmed by visual observation. The test was terminated when seizure occurred in the metal seal part. In the case where the seizure in the threaded part was minor and could be restored by care such as filing, the seizure damage was repaired and the test continued. The maximum number of repeated fastenings was 5 times. If there was no irreparable seizure in the threaded part or seizure in the metal seal part after the maximum number of repeated fastenings, it was judged to have passed (denoted as E (excellent) in Table 1).

[0199] [Outdoor exposure test] The pins of the oil well pipes with threaded joints of test numbers 1 to 3 were fitted with protectors of the same shape and left outdoors for six weeks. After leaving them for six weeks, the presence or absence of rust on the contact surface of the pins of each test number was visually confirmed. If no rust was found, the test was deemed to have passed (denoted as E (excellent) in Table 1).

[0200] [Evaluation Results] The test results are shown in FIG.

[0201] [Table 1]

[0202] 2, the threaded joint oil country tubular goods of Test Nos. 1 and 2 had a lower shoulder torque Ts than the conventional threaded joint oil country tubular goods of Test No. 3. Furthermore, the MTVs of Test Nos. 1 and 2 were comparable to that of Test No. 3.

[0203] Also, referring to Table 1, the oil country tubular goods with threaded joints of test numbers 1 to 3 all had excellent galling resistance. Furthermore, the oil country tubular goods with threaded joints of test numbers 1 to 3 all showed no rust in outdoor exposure tests, and all had excellent corrosion resistance.

[0204] The above describes the embodiments of the present invention. However, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and carried out without departing from the spirit of the present invention. [Explanation of symbols]

[0205] 1. Oil well pipe with threaded joint 10 Tube body 10A 1st end 10B 2nd end 11 pin body 12 Coupling 40, 40A pin 41 Male thread 42 Pin seal surface 43 Pin shoulder surface 50 Box 51 Female thread 52 Box seal surface 53 Box Shoulder Surface 60 Solid lubricant coating 80 Light Oil 200 Oil well pipe with threaded joint 400 pin contact surface 500 Box Contact Surface

Claims

1. An oil well pipe with a threaded joint that can be fastened to another oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: a pin that is formed at the first end portion and that is inserted into a box of the other oil well tubular good with a threaded joint at the time of fastening to be fastened to the box of the other oil well tubular good with a threaded joint; a box formed at the second end portion, into which a pin of the other oil well tubular good with a threaded joint is inserted and fastened to the pin of the other oil well tubular good with a threaded joint during the fastening; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer peripheral surface of the first end portion of the pipe body, the pin contact surface contacting the box of the other oil well tubular good with a threaded joint during the fastening; The pin contact surface is coated with light oil; The box includes: a box contact surface including at least a female thread portion formed on an inner peripheral surface of the second end portion of the pipe body, the box contact surface coming into contact with the pin contact surface of the pin of the other oil well tubular good with a threaded joint during the fastening; a solid lubricant coating formed on the contact surface of the box; Including, Oil well pipe with threaded joint.

2. 2. The oil country tubular good with a threaded joint according to claim 1, The pin contact surface further comprises: a pin seal surface formed on the outer circumferential surface of the first end portion on a tip side of the male thread portion; a pin shoulder surface provided at a tip of the first end; Including, The box contact surface further comprises: A box seal surface is formed on the inner circumferential surface of the second end portion toward the center side of the female thread portion; a box shoulder surface provided on the second end portion closer to the center than the box seal surface; Including, Oil well pipe with threaded joint.

3. The oil well tubular good with a threaded joint according to claim 1 or 2, The pin further comprises: a conversion coating formed on the pin contact surface; The light oil is applied onto the chemical conversion coating. Oil well pipe with threaded joint.

4. The oil country tubular good with a threaded joint according to claim 3, In the chemical composition of the oil well pipe with the threaded joint, the Cr content is 2.0% or less by mass%, Oil well pipe with threaded joint.

5. 2. The oil country tubular good with a threaded joint according to claim 1, The box further comprises: a plating coating formed on the box contact surface; the solid lubricating coating is formed on the plating coating, Oil well pipe with threaded joint.

6. An oil well pipe with a threaded joint, a tube body including a first end and a second end; The tube body includes: a pin formed on the first end; a box formed at the second end; Equipped with The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the pipe body; a solid lubricant coating formed on the contact surface of the box; Including, Oil well pipe with threaded joint.

7. 7. An oil country tubular good with a threaded joint according to claim 6, The pin contact surface further comprises: a pin seal surface formed on the outer circumferential surface of the first end portion on a tip side of the male thread portion; a pin shoulder surface provided at a tip of the first end; Including, The box contact surface further comprises: A box seal surface is formed on the inner circumferential surface of the second end portion toward the center side of the female thread portion; a box shoulder surface provided on the second end portion closer to the center than the box seal surface; Including, Oil well pipe with threaded joint.

8. The oil well tubular good with a threaded joint according to claim 6 or 7, The pin further comprises: a conversion coating formed on the pin contact surface; The anti-rust grease is applied onto the chemical conversion coating. Oil well pipe with threaded joint.

9. The oil country tubular good with a threaded joint according to claim 8, In the chemical composition of the oil well pipe with the threaded joint, the Cr content is 2.0% or less by mass%, Oil well pipe with threaded joint.

10. 7. An oil country tubular good with a threaded joint according to claim 6, The box further comprises: a plating coating formed on the box contact surface; the solid lubricating coating is formed on the plating coating, Oil well pipe with threaded joint.

11. The threaded joint oil well tubular good according to claim 6, further comprising: a protector that is fastened to the pin, The protector comprises: A cylindrical portion having an internal thread formed on an inner circumferential surface thereof; A cover portion disposed at one end of the cylindrical portion; Including, a distance D1 between the thread bottom of the male thread of the pin and the thread of the female thread of the cylindrical portion of the protector is longer than a distance D2 between the thread bottom of the male thread of the pin and the thread bottom of the female thread of the cylindrical portion of the protector; a thickness T1 of the anti-rust grease between the thread bottom of the male screw of the pin and the thread of the female screw of the cylindrical portion of the protector is thicker than a thickness T2 of the anti-rust grease between the thread bottom of the male screw of the pin and the thread bottom of the female screw of the cylindrical portion of the protector; Oil well pipe with threaded joint.

12. A method for manufacturing an oil well tubular good joint in which a plurality of oil well tubular good joints with threaded joints are fastened together, comprising the steps of: The method includes a process for preparing oil well pipes with threaded joints, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: a pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; Anti-rust grease is applied to the pin contact surface, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the pipe body; a solid lubricant coating formed on the contact surface of the box; Including, The method for producing the oil well tubular good joint further comprises the steps of: transporting the oil well tubular goods with the threaded joint to a local yard which is a place for temporarily storing the oil well tubular goods with the threaded joint; a step of temporarily storing the oil well tubular good with the threaded joint transported to the on-site yard at the on-site yard; before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where the oil well tubular goods connected body is to be formed, removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; transporting the oil well tubular good with a threaded joint having the light oil applied to the pin contact surface to the oil well drilling site; a step of fastening, at the oil well drilling site, an oil well tubular good with a threaded joint having said light oil applied to said pin contact surface, to another oil well tubular good with a threaded joint to form an oil well tubular good connected body; Equipped with A method for manufacturing an oil well tubular good joint.

13. A method for manufacturing an oil well tubular good with a threaded joint, comprising the steps of: The method includes a process of temporarily storing the transported oil well pipes with threaded joints at a local yard, The oil well tubular good with a threaded joint is a tube body including a first end and a second end; The tube body includes: a pin formed on the first end; a box formed at the second end; Including, The pin is a pin contact surface including at least a male thread portion formed on an outer circumferential surface of the first end of the tube body; The pin contact surface is coated with anti-rust grease, The box includes: a box contact surface including at least a female thread portion formed on an inner circumferential surface of the second end of the pipe body; a solid lubricant coating formed on the contact surface of the box; Including, The method for manufacturing the oil well tubular good with a threaded joint further comprises: removing the anti-rust grease applied to the pin contact surfaces of the oil well tubular goods with the threaded joint temporarily stored at the on-site yard before transporting the oil well tubular goods with the threaded joint temporarily stored at the on-site yard to an oil well drilling site where an oil well tubular goods connection is to be formed, and applying light oil to the pin contact surfaces from which the anti-rust grease has been removed; Equipped with A manufacturing method for oil country tubular goods with threaded joints.

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