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

Abstract

Provided is an oil well pipe with a threaded joint, for which excellent sintering resistance can be obtained without using a complex grease, rust generation at a pin contact surface can be suppressed, and a make-up torque can be suppressed. The oil well pipe with a threaded joint of the present disclosure includes a pipe body (10) including a first end portion (10A) and a second end portion (10B). The pipe body (10) includes a pin (40) formed at the first end portion (10A) and a box (50) formed at the second end portion (10B). A light oil (80) is applied to a pin contact surface (400) of the pin (40). A solid lubricating coating film (60) is formed on a box contact surface (500) of the box (50).

Description

Technical Field

[0001] This disclosure relates to a threaded well pipe, a method for manufacturing a well pipe connector using a threaded well pipe, and a method for manufacturing a threaded well pipe. Background Technology

[0002] For the exploitation of oil and gas fields (hereinafter collectively referred to as "oil wells"), threaded well tubing is used. Specifically, in the well excavation site, multiple threaded well tubing units are connected according to the depth of the well to form a well tubing connection. The well tubing connection is formed by threading the threaded well tubing units together. For the well tubing connection, it is pulled up and the threads loosened for inspection, and after inspection, the threads are tightened again for reuse.

[0003] Threaded well tubing includes a male thread and a female thread. The male thread has a male thread contact surface containing an external thread on the outer circumferential surface of the end of the threaded well tubing. The female thread has a female thread contact surface containing an internal thread on the inner circumferential surface of the end of the threaded well tubing.

[0004] The male and female thread contact surfaces of threaded well tubing are repeatedly subjected to strong friction during thread tightening and loosening. If these areas do not possess sufficient durability against friction, adhesion (irreparable sintering) will occur during repeated thread tightening and loosening. Therefore, threaded well tubing requires sufficient durability against friction, i.e., excellent resistance to sintering.

[0005] Previously, composite greases containing heavy metal powders, known as coatings, were used to improve sintering resistance. Applying composite grease to the male and / or female thread contact surfaces can improve the sintering resistance of threaded well tubing. However, there is a possibility that the heavy metal powders such as Pb, Zn, and Cu contained in the composite grease may have environmental impacts.

[0006] Furthermore, a significant portion of the composite grease applied to the male and / or female contact surfaces during thread tightening (threaded connection) is discharged from the tips of the male and female threads upon completion of the tightening (threaded connection). A portion of the composite grease is discharged from the tip of the male thread towards the inner surface of the well tubing. When the composite grease discharged to the inner surface of the well tubing accumulates there, it can lead to blockage of the tightened well tubing (well tubing connector). Based on the above reasons, it is desirable to develop a well tubing with threaded joints that exhibits excellent resistance to sintering even without the use of composite grease.

[0007] In the pipe threaded joint disclosed in International Patent Publication No. 2009 / 072486 (Patent Document 1), a solid lubricating film is formed on the female thread contact surface, and a solid anti-rust film (solid anti-corrosion film) formed of ultraviolet-cured resin is formed on the male thread contact surface. In this document, the solid lubricating film suppresses sintering even with repeated tightening and loosening of the threads. Furthermore, since the solid anti-rust film is rigid, it does not affect sintering resistance even when the male thread with the solid anti-rust film is tightened to the female thread with the solid lubricating film.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2009 / 072486 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] Furthermore, during thread tightening (threaded connection), if interference between the threads begins, the tightening torque increases sharply. The torque applied when the threads interfere with each other is called "shoulder torque" (Japanese: ショルダリングトルク). If the shoulder torque during thread tightening is low, the force applied to the rotation during thread tightening can be suppressed, allowing for smooth thread tightening.

[0013] Furthermore, threaded well tubing, after being manufactured at the factory, is not directly transported to the well excavation site. Instead, it is transported to a site service area as a transit point and temporarily stored there. The threaded well tubing stored at the site is then transported back to the well excavation site based on the demand for threaded well tubing at the site. Until this transport, the threaded well tubing is stored at the site for a relatively long period of approximately six months to two years. Additionally, the threaded well tubing transported to the well excavation site is not used immediately after transport but is stored there for a shorter period of approximately one week to one month until it is used. At the well excavation site, in most cases, the threaded well tubing is stored outdoors. During storage, if rust develops on the male thread contact surface, it may affect the tightness of the fit during tightening. Therefore, it is preferable to suppress the formation of rust on the male thread contact surface of the well tubing with threaded joints, at least during the storage period at the well excavation site.

[0014] In Patent Document 1, a solid anti-rust coating made of UV-curable resin is formed on the male thread contact surface of a threaded well pipe. This solid anti-rust coating can suppress the formation of rust on the male thread contact surface. Furthermore, as described above, the threaded well pipe is transported from the manufacturer to the well excavation site via a field site. During transport from the manufacturer to the field site, during transport within the field site, and during transport from the field site to the well excavation site, the male thread of the threaded well pipe comes into contact with other well pipes, causing partial damage to the solid anti-rust coating. When the solid anti-rust coating is damaged at the field site or the well excavation site, it is difficult to repair the damaged coating. Repairing the solid anti-rust coating requires preparing a composition to form a UV-curable resin, and also requires a UV irradiation device for curing the composition. Therefore, to repair the damaged solid anti-rust coating, a UV irradiation device needs to be placed at the field site and / or the well excavation site. Furthermore, to repair the solid rust-preventive coating, it is necessary to completely remove the damaged solid rust-preventive coating and then re-form it. In this case, the repair work is quite laborious. Therefore, it is preferable that the solid rust-preventive coating can be easily repaired when it is partially damaged or peeled off for some reason. Hereinafter, in this specification, the situation in which easy repair can be performed will be referred to as "excellent repairability".

[0015] The purpose of this disclosure is to provide an oil well pipe with a threaded connector that can achieve excellent sintering resistance without the use of composite grease, can suppress rust formation at the male thread contact surface, can suppress the shoulder torque during thread tightening, and has excellent repairability.

[0016] Another objective of this disclosure is to provide a method for manufacturing an oil well pipe connector that can suppress rust formation on the male thread contact surface even when stored outdoors in the field or oil well excavation site, suppress the environmental impact caused by the use of oil well pipes with threaded joints, and achieve excellent sintering resistance, reduce the shoulder torque during thread tightening, and provide excellent repairability.

[0017] Solution for solving the problem

[0018] The threaded well tubing disclosed herein is a threaded well tubing capable of being fastened to other threaded well tubings, wherein...

[0019] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0020] The tube body comprises:

[0021] A male thread, formed at the first end, is inserted into the female thread of the other threaded well tubing during tightening to secure it; and

[0022] A female thread, formed at the second end, is inserted into and fastened with the male thread of the other threaded well tubing during tightening.

[0023] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. During tightening, the male thread contact surface contacts the female thread of the other threaded well pipe.

[0024] A light oil is applied to the male contact surface.

[0025] The female buckle includes:

[0026] The female thread contact surface, which at least includes an internal thread formed on the inner circumferential surface of the second end of the pipe body, contacts the male thread contact surface of the male thread of the other threaded well pipe during tightening; and

[0027] A solid lubricating coating is formed on the female contact surface.

[0028] The threaded well tubing disclosed herein is a threaded well tubing, wherein,

[0029] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0030] The pipe body includes:

[0031] Male buckle, which is formed at the first end; and

[0032] The female buckle, which is formed at the second end,

[0033] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0034] The male contact surface is coated with anti-rust lubricating grease.

[0035] The female buckle includes:

[0036] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0037] A solid lubricating coating is formed on the female contact surface.

[0038] The method disclosed herein discloses a method for manufacturing an oil well pipe connector that is formed by fastening together multiple oil well pipes with threaded joints, wherein...

[0039] The manufacturing method of this oil well pipe connector includes an oil well pipe preparation step, in which an oil well pipe with a threaded joint is prepared.

[0040] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0041] The tube body comprises:

[0042] Male buckle, which is formed at the first end; and

[0043] The female buckle, which is formed at the second end,

[0044] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0045] The male contact surface is coated with anti-rust lubricating grease.

[0046] The female buckle includes:

[0047] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0048] A solid lubricating film is formed on the female contact surface.

[0049] The manufacturing method of the oil well pipe connector also includes the following steps:

[0050] The threaded well pipe is transported to the site, which serves as a temporary storage location for the threaded well pipe.

[0051] The threaded well pipe delivered to the site will be temporarily stored at the site.

[0052] Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connector, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed.

[0053] A threaded well pipe with the light oil coated on the male contact surface is supplied to the well excavation site; and

[0054] In the oil well excavation site, a threaded well pipe with the light oil coated on the male contact surface is fastened to other threaded well pipes to form an oil well pipe connector.

[0055] The method for manufacturing a threaded well pipe disclosed herein is a method for manufacturing a threaded well pipe, wherein,

[0056] The manufacturing method of the threaded well pipe includes the process of temporarily storing the delivered threaded well pipe at the site.

[0057] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0058] The tube body comprises:

[0059] Male buckle, which is formed at the first end; and

[0060] The female buckle, which is formed at the second end,

[0061] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0062] The male contact surface is coated with anti-rust lubricating grease.

[0063] The female buckle includes:

[0064] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0065] A solid lubricating film is formed on the female contact surface.

[0066] The manufacturing method of the oil well pipe with threaded joint also includes the following steps:

[0067] Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connection, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed.

[0068] The effects of the invention

[0069] For the threaded well tubing of this disclosure, excellent sintering resistance can be obtained without the use of composite grease, rust formation at the male thread contact surface can be suppressed, the shoulder torque during thread tightening can be suppressed to a low level, and the repairability is excellent.

[0070] Regarding the manufacturing method of the oil well pipe connector disclosed herein, even when stored outdoors in the field site and oil well excavation site, it is possible to suppress the formation of rust on the male thread contact surface, suppress the environmental impact caused by the use of oil well pipe with threaded joints, obtain excellent sintering resistance, suppress the shoulder torque during thread tightening, and have excellent repairability. Attached Figure Description

[0071] Figure 1 This is a graph (torque graph) showing the relationship between the number of revolutions and the torque when tightening a threaded well pipe.

[0072] Figure 2 The results of torque measurement tests are for a threaded well pipe (test numbers 1 and 2) with a solid lubricating coating formed on the female contact surface and a light oil coating on the male contact surface, and a conventional threaded well pipe (test number 3) with a solid lubricating coating formed on the female contact surface and a solid anti-rust coating formed on the male contact surface.

[0073] Figure 3 This is a structural diagram showing an example of the threaded well pipe 1 of this embodiment.

[0074] Figure 4 It means Figure 3 The diagram shows a partial sectional view of the pipe joint of an oil well pipe with a threaded fitting, taken along its length (longitudinal section).

[0075] Figure 5 yes Figure 4 The diagram shows a cross-sectional view of the portion of the threaded well tubing near the male thread, parallel to the length of the threaded well tubing.

[0076] Figure 6 yes Figure 4 The diagram shows a cross-sectional view of the portion of the well tubing near the female thread, parallel to the length of the well tubing.

[0077] Figure 7 This is a diagram illustrating an example of a threaded well pipe with a male thread including the external thread portion but excluding the male thread sealing surface and the male thread shoulder surface, and a female thread including the internal thread portion but excluding the female thread sealing surface and the female thread shoulder surface.

[0078] Figure 8 This is a partial cross-sectional view of the integral oil well pipe with threaded joint in this embodiment.

[0079] Figure 9 yes Figure 4The diagram shows a cross-sectional view of the portion of the well tubing near the female thread, parallel to the length of the well tubing.

[0080] Figure 10 This is a diagram illustrating an example of the structure of the female thread of the oil well pipe with threaded connector according to this embodiment.

[0081] Figure 11 yes Figure 4 The diagram shows a cross-sectional view of the portion of the threaded well tubing near the male thread, parallel to the length of the threaded well tubing.

[0082] Figure 12 This is a diagram illustrating an example of the male thread structure of the threaded well pipe of this embodiment.

[0083] Figure 13 This diagram schematically illustrates the locations where each step of the manufacturing method of the oil well pipe connector according to this embodiment is carried out.

[0084] Figure 14 This is a structural diagram showing an example of an oil well pipe with a threaded joint.

[0085] Figure 15 It means and Figure 14 A structural diagram of an example of a different type of oil well tubing with threaded fittings.

[0086] Figure 16 yes Figure 14 and Figure 15 A longitudinal sectional view of the portion near the male contact surface.

[0087] Figure 17 Is with Figure 16 Different Figure 14 and Figure 15 A longitudinal sectional view of the portion near the male contact surface.

[0088] Figure 18 This is a structural diagram showing the male buckle with the protective component installed.

[0089] Figure 19 It is a longitudinal sectional view of the external thread portion and the portion near the internal thread portion of the male thread protector when it is installed in the male thread state.

[0090] Figure 20 The torque graph is generated using the torque measurement test results from the embodiment. Detailed Implementation

[0091] Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. The same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0092] The inventors have conducted various studies on oil well tubing with threaded joints that achieve excellent resistance to sintering without the use of composite grease, suppress rust formation at the male thread contact surface, and suppress shoulder torque. As a result, the following insights have been obtained.

[0093] [Regarding shoulder torque]

[0094] When fastening threaded well tubing to each other, the optimal torque for ending the tightening should be determined in advance. Figure 1 This is a graph (torque graph) showing the relationship between the number of revolutions and the torque when tightening a threaded well casing. (Refer to...) Figure 1 When tightening the threads of a threaded well pipe, the initial torque increases slowly in proportion to the number of revolutions. If the threads are tightened further, the shoulder surfaces come into contact with each other. This torque is called the shoulder torque Ts. If the threads are tightened further after reaching the shoulder torque Ts, the torque increases sharply in proportion to the number of revolutions. The recommended torque (tightening torque To) for tightening threaded joints is set within a predetermined range higher than the shoulder torque Ts. Tightening is complete when the torque reaches the tightening torque To. At the tightening torque To, the male and female thread sealing surfaces interfere with each other with appropriate surface pressure. In this case, the airtightness of the well pipe connection formed by tightening multiple threaded well pipes is relatively high.

[0095] Furthermore, some threaded well tubing may lack a shoulder surface due to the structure of the male and female threads. In such cases, when the threads of the threaded well tubing are tightened, the torque increases sharply when the threads engage with each other during tightening. For example, there are threaded well tubing with wedge-shaped threads that do not include a shoulder surface. When such a wedge-shaped threaded well tubing is tightened, the torque increases sharply when the thread flanks come into contact with each other. That is, the torque diagram for threaded well tubing without a shoulder surface and with wedge-shaped threads is as follows... Figure 1 That is. The torque during the rapid rise when tightening the threads of a threaded well pipe with a wedge-shaped threaded section is not the shoulder torque, but is called the locking tooth flank torque (Japanese: ロックトフランクトルク). However, in this specification, the locking tooth flank torque during the tightening of the threads of a threaded well pipe with a wedge-shaped threaded section is also referred to as the "shoulder torque".

[0096] Furthermore, when it is particularly desirable to avoid loosening of the threaded joint after tightening, the tightening torque To is set relatively high. However, if the tightening torque To is too high, the following situation may occur: partial yielding of the male and / or female threads, leading to plastic deformation. This torque is called the yield torque Ty. Moreover, when the yield torque Ty is high, the tightening torque To can be set relatively high.

[0097] The inventors first studied threaded well tubing with a low shoulder torque. The results yielded the following insights.

[0098] Instead of forming a solid anti-rust film on the male contact surface as is common practice, a light oil is applied to the male contact surface. The light oil applied to the male contact surface is liquid. For example, the light oil is marketed under the trade name "WD-40". The light oil may contain, for example, 50-70% by weight of mineral spirit and less than 25% by weight of petroleum-based oil.

[0099] A solid lubricating film is formed on the female thread contact surface, and a light oil is applied to the male thread contact surface instead of a solid anti-rust film. In this case, the shoulder torque Ts during thread tightening of the oil well pipe with threaded joints can be suppressed to a lower level.

[0100] Figure 2 The results are from torque measurement tests using threaded well tubing (test numbers 1 and 2) with a solid lubricating coating formed on the female contact surface and light oil coated on the male contact surface, as described in the embodiments below, and conventional threaded well tubing (test number 3) with a solid lubricating coating formed on the female contact surface and a solid anti-rust coating formed on the male contact surface. Figure 2 In the example, the shoulder torque for test number 3 is set to 100, and the shoulder torque Ts and yield torque Ty for each test number are shown. Figure 2 In the bar charts for each test number, the upper end of the shaded area represents the shoulder torque Ts, and the upper end of the blank area represents the yield torque Ty.

[0101] Reference Figure 2 For threaded well tubing with a solid lubricating film on the female contact surface and a light oil coating on the male contact surface (Test No. 1, 2), the shoulder torque Ts was suppressed lower compared to conventional threaded well tubing with a solid lubricating film on the female contact surface and a solid anti-rust film on the male contact surface (Test No. 3). Furthermore, the yield torque Ty of Test No. 1 and Test No. 2 did not change as significantly as that of Test No. 3.

[0102] Furthermore, for the aforementioned threaded well tubing with a male thread contact surface coated with light oil, rust formation on the male thread contact surface can be suppressed even after being stored outdoors for about one month. Therefore, when threaded well tubing with a male thread contact surface coated with light oil is used, it exhibits excellent corrosion resistance during the period of temporary storage at the well excavation site (about one week to one month) after being transported from the field to the well excavation site until it is used.

[0103] However, the storage period at the site, which serves as a transit point, is typically quite long, ranging from six months to two years. Therefore, when threaded well tubing is stored at the site for extended periods, further rust prevention measures are required.

[0104] Therefore, in the manufacturing method of the oil well pipe connector of this embodiment, the threaded joint oil well pipe with rust-preventive grease coated on the male thread contact surface is stored in the field. The rust-preventive grease is in the form of grease. That is, the rust-preventive grease is semi-solid or paste-like, unlike liquid light oil. Rust-preventive grease is, for example, a high-viscosity rust-preventive composition in the form of grease, such as "RUST VETO AS EU" or "KENDEX", and is also called a storage coating (Japanese: ストレージドープ).

[0105] Even when stored outdoors for two years, the rust-preventive grease can suppress rust formation on the male thread contact surface. Furthermore, when transporting threaded tubing from the field to the well excavation site, the rust-preventive grease applied to the male thread contact surface of the threaded tubing is removed at the field site, and a light oil is applied to the grease-free male thread contact surface. Then, the threaded tubing with the light oil applied to the male thread contact surface is transported to the well excavation site. In this case, as described above, the light oil-coated male thread contact surface exhibits excellent corrosion resistance for approximately one month. Moreover, during use (thread tightening), the shoulder torque is reduced compared to threaded tubing with a solid rust-preventive coating. The viscosity of the liquid light oil is lower than that of the rust-preventive grease. Therefore, even when light oil is discharged from the male thread contact surface to the inner surface of the well pipe due to thread tightening, it is not easy to accumulate on the inner surface and not easy to cause blockage in the well pipe (well pipe connector) after thread tightening.

[0106] Furthermore, unlike solid rust-preventive coatings, light oil is a liquid that can be easily applied to the male thread contact surface. Therefore, even if some of the light oil applied to the male thread contact surface peels off during delivery in the oil well drilling area due to contact with other threaded well pipes, etc., it can be easily repaired by reapplying light oil. In other words, the repairability of the male thread contact surface coated with light oil is superior compared to that of the male thread contact surface with a solid rust-preventive coating.

[0107] Based on the above insights, the threaded well pipe, the method for manufacturing the threaded well pipe, and the method for manufacturing the well pipe connector include the following structures.

[0108] [1] A threaded well pipe, which is a threaded well pipe capable of being fastened to other threaded well pipes, wherein,

[0109] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0110] The tube body comprises:

[0111] A male thread, formed at the first end, is inserted into the female thread of the other threaded well tubing during tightening to secure it; and

[0112] A female thread, formed at the second end, is inserted into and fastened with the male thread of the other threaded well tubing during tightening.

[0113] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. During tightening, the male thread contact surface contacts the female thread of the other threaded well pipe.

[0114] A light oil is applied to the male contact surface.

[0115] The female buckle includes:

[0116] The female thread contact surface, which at least includes an internal thread formed on the inner circumferential surface of the second end of the pipe body, contacts the male thread contact surface of the male thread of the other threaded well pipe during tightening; and

[0117] A solid lubricating coating is formed on the female contact surface.

[0118] [2] According to the threaded well pipe described in [1], among which,

[0119] The male contact surface further includes:

[0120] A male thread sealing surface, formed in the outer peripheral surface of the first end at a position closer to the tip of the external thread; and

[0121] The male buckle shoulder surface is located at the top of the first end.

[0122] The female contact surface further includes:

[0123] A female thread sealing surface, formed in the inner circumferential surface of the first end at a position closer to the tip than the internal thread portion; and

[0124] The female buckle shoulder is located at the top of the second end.

[0125] [3] According to [1] or [2], the threaded well pipe, wherein,

[0126] The male buckle also includes a chemically converted coating formed on the male buckle contact surface.

[0127] The light oil is applied to the chemically converted coating.

[0128] [4] According to the threaded well pipe described in [3], among which,

[0129] In the chemical composition of the oil well pipe with threaded joint, the Cr content is less than 2.0% by mass.

[0130] [5] The threaded well pipe described in any of [1] to [4], wherein,

[0131] The female buckle also includes a plating film formed on the contact surface of the female buckle.

[0132] The solid lubricating coating is formed on the coated film.

[0133] [6] An oil well pipe with a threaded joint, wherein,

[0134] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0135] The pipe body includes:

[0136] Male buckle, which is formed at the first end; and

[0137] The female buckle, which is formed at the second end,

[0138] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0139] The male contact surface is coated with anti-rust lubricating grease.

[0140] The female buckle includes:

[0141] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0142] A solid lubricating coating is formed on the female contact surface.

[0143] [7] According to the threaded well pipe described in [6], among which,

[0144] The male contact surface further includes:

[0145] A male thread sealing surface, formed in the outer peripheral surface of the first end at a position closer to the tip of the external thread; and

[0146] The male buckle shoulder surface is located at the top of the first end.

[0147] The female contact surface further includes:

[0148] A female thread sealing surface, formed in the inner circumferential surface of the first end at a position closer to the tip than the internal thread portion; and

[0149] The female buckle shoulder is located at the top of the second end.

[0150] [8] According to [6] or [7], the threaded well tubing, wherein,

[0151] The male buckle also includes a chemically converted coating formed on the male buckle contact surface.

[0152] The rust-preventive grease is applied to the chemically converted coating.

[0153] [9] According to the threaded well tubing described in [8], among which,

[0154] In the chemical composition of the oil well pipe with threaded joint, the Cr content is less than 2.0% by mass.

[0155]

[10] According to any one of [6] to [9], the threaded well pipe, wherein,

[0156] The female buckle also includes a plating film formed on the contact surface of the female buckle.

[0157] The solid lubricating coating is formed on the coated film.

[0158]

[11] According to any one of [6] to

[10] , the threaded well pipe, wherein,

[0159] The threaded well tubing also includes a protective element that covers and secures the male thread.

[0160] The protective component includes:

[0161] The cylindrical portion has an internal thread formed on its inner circumferential surface; and

[0162] A cover portion, which is disposed at one end of the cylindrical portion,

[0163] The distance D1 between the thread root of the external thread of the male thread and the thread root of the internal thread of the cylindrical part of the protective member is longer than the distance D2 between the thread root of the external thread of the male thread and the thread root of the internal thread of the cylindrical part of the protective member.

[0164] The thickness T1 of the anti-rust grease between the thread of the external thread of the male thread and the thread root of the internal thread of the cylindrical part of the protective member is thicker than the thickness T2 of the anti-rust grease between the thread root of the external thread of the male thread and the thread of the internal thread of the cylindrical part of the protective member.

[0165]

[12] A method for manufacturing an oil well pipe connector, wherein the oil well pipe connector is formed by fastening multiple oil well pipes with threaded joints, wherein,

[0166] The manufacturing method of this oil well pipe connector includes an oil well pipe preparation step, in which an oil well pipe with a threaded joint is prepared.

[0167] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0168] The tube body comprises:

[0169] Male buckle, which is formed at the first end; and

[0170] The female buckle, which is formed at the second end,

[0171] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0172] The male contact surface is coated with anti-rust lubricating grease.

[0173] The female buckle includes:

[0174] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0175] A solid lubricating film is formed on the female contact surface.

[0176] The manufacturing method of the oil well pipe connector also includes the following steps:

[0177] The threaded well pipe is transported to the site, which serves as a temporary storage location for the threaded well pipe.

[0178] The threaded well pipe delivered to the site will be temporarily stored at the site.

[0179] Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connector, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed.

[0180] A threaded well pipe with the light oil coated on the male contact surface is supplied to the well excavation site; and

[0181] In the oil well excavation site, a threaded well pipe with the light oil coated on the male contact surface is fastened to other threaded well pipes to form an oil well pipe connector.

[0182]

[13] A method for manufacturing an oil well pipe with a threaded joint, wherein,

[0183] The manufacturing method of the threaded well pipe includes the process of temporarily storing the delivered threaded well pipe at the site.

[0184] The threaded well tubing includes a tubing body, which comprises a first end and a second end.

[0185] The tube body comprises:

[0186] Male buckle, which is formed at the first end; and

[0187] The female buckle, which is formed at the second end,

[0188] The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body.

[0189] The male contact surface is coated with anti-rust lubricating grease.

[0190] The female buckle includes:

[0191] The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and

[0192] A solid lubricating film is formed on the female contact surface.

[0193] The manufacturing method of the oil well pipe with threaded joint also includes the following steps:

[0194] Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connection, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed.

[0195] The following describes in detail the method for manufacturing a threaded well pipe, a well pipe connector using a threaded well pipe, and a well pipe with a threaded joint according to this embodiment.

[0196] [Structure of oil well tubing 1 with threaded connector]

[0197] [The case where the oil well tubing with threaded fitting 1 is of type T&C]

[0198] Figure 3 This is a structural diagram showing an example of the threaded well pipe 1 of this embodiment. Figure 3 This is a structural diagram of a T&C type (Threaded and Coupled) oil well tubing with threaded fittings. (Refer to...) Figure 3 The oil well pipe 1 with threaded joints includes the pipe body 10.

[0199] The tube body 10 extends along its length, and its cross-section perpendicular to the length direction is circular. The tube 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. Figure 3 In the T&C type threaded well tubing 1 shown, the tubing body 10 includes a male threaded tubing body 11 and a fitting 12. The fitting 12 is installed at one end of the male threaded tubing body 11. More specifically, the fitting 12 is fastened to one end of the male threaded tubing body 11 by threads.

[0200] Figure 4 It means Figure 3 A partial sectional view (longitudinal section) of the pipe fitting 12 of the threaded well pipe 1 shown along its length. (Refer to...) Figure 3 and Figure 4The pipe body 10 includes a male thread 40 and a female thread 50. The male thread 40 is formed at the first end 10A of the pipe body 10. When tightening, the male thread 40 is inserted into the female thread 50 of another threaded well pipe (not shown) and is tightened to the female thread 50 of the other threaded well pipe by threads.

[0201] The female thread 50 is formed at the second end 10B of the pipe body 10. During tightening, the male thread 40 of another threaded well pipe 100 is inserted into the female thread 50, and the male thread 40 of the other threaded well pipe 100 is tightened by threads.

[0202] [Regarding the structure of the 40-yuan deduction]

[0203] Figure 5 yes Figure 4 The cross-sectional view of the portion near the male thread 40 in the threaded well tubing 1 shown is parallel to the length direction of the threaded well tubing 1. Figure 5 The dashed line indicates the structure of the female thread 50 of other threaded well pipes 1, which are fastened to other threaded well pipes 1. (Refer to...) Figure 5 The male thread 40 includes a male thread contact surface 400 on the outer peripheral surface of the first end 10A of the pipe body 10. The male thread contact surface 400 contacts the female thread 50 of other threaded well pipes when fastened to other threaded well pipes.

[0204] The male contact surface 400 includes at least an external thread portion 41 formed on the outer peripheral surface of the first end 10A. Alternatively, the male contact surface 400 may also include a male sealing surface 42 and a male shoulder surface 43. Figure 5 In this configuration, the male thread sealing surface 42 is positioned on the outer peripheral surface of the first end portion 10A, closer to the top end of the first end portion 10A than the external thread portion 41. Specifically, the male thread sealing surface 42 is positioned between the external thread portion 41 and the male thread shoulder surface 43. The male thread sealing surface 42 is tapered. More specifically, at the male thread sealing surface 42, in the length direction of the first end portion 10A, the outer diameter gradually decreases from the external thread portion 41 towards the male thread shoulder surface 43.

[0205] When tightening with other threaded well tubing, the male thread sealing surface 42 contacts the female thread sealing surface 52 (described later) of the female thread 50 of the other threaded well tubing. More specifically, during tightening, the male thread 40 is inserted into the female thread 50 of the other threaded well tubing, thereby bringing the male thread sealing surface 42 into contact with the female thread sealing surface 52. Then, the male thread 40 is further screwed into the female thread 50 of the other threaded well tubing, thereby bringing the male thread sealing surface 42 and the female thread sealing surface 52 into close contact. Thus, during tightening, the male thread sealing surface 42 and the female thread sealing surface 52 are in close contact to form a seal based on metal-metal contact. Therefore, in the mutually tightened threaded well tubing 1, air tightness can be improved.

[0206] exist Figure 5 In the middle, the male buckle shoulder surface 43 is disposed on the top surface of the first end 10A. That is, in Figure 5 In the male thread 40 shown, an external thread portion 41, a male thread sealing surface 42, and a male thread shoulder surface 43 are sequentially arranged from the center of the pipe body 10 toward the first end 10A. When tightening with other threaded well pipes, the male thread shoulder surface 43 faces and contacts the female thread shoulder surface 53 (described later) of the female thread 50 of the other threaded well pipe. More specifically, during tightening, the male thread 40 is inserted into the female thread 50 of the other threaded well pipe, thereby bringing the male thread shoulder surface 43 into contact with the female thread shoulder surface 53. This allows for tightening with a higher tightening torque. In addition, the positional relationship between the male thread 40 and the female thread 50 in the tightened state can be stabilized.

[0207] Furthermore, the male contact surface 400 of the male thread 40 at least includes an external thread portion 41. That is, the male contact surface 400 may include the external thread portion 41 but not the male sealing surface 42 and the male shoulder surface 43. Alternatively, the male contact surface 400 may include the external thread portion 41 and the male shoulder surface 43 but not the male sealing surface 42. Alternatively, the male contact surface 400 may include the external thread portion 41 and the male sealing surface 42 but not the male shoulder surface 43.

[0208] [Regarding the structure of the female buckle 50]

[0209] Figure 6 yes Figure 4 The cross-sectional view of the portion near the female thread 50 in the threaded well tubing 1 shown is parallel to the length direction of the threaded well tubing 1. Figure 6 The dashed line indicates the male thread 40 structure of other threaded well tubing with threaded connections, used in conjunction with other threaded well tubing. (Refer to...) Figure 6The female thread 50 includes a female thread contact surface 500 on the inner circumferential surface of the second end 10B of the pipe body 10. The female thread contact surface 500 contacts the male thread contact surface 40 of the other threaded well pipe when it is tightened with other threaded well pipes.

[0210] The female contact surface 500 includes at least an internal thread portion 51 formed on the inner circumferential surface of the second end 10B. During tightening, the internal thread portion 51 engages with the external thread portion 41 of the male thread 40 of other threaded well pipes.

[0211] Alternatively, the female contact surface 500 may also include a female sealing surface 52 and a female shoulder surface 53. Figure 6 In this configuration, the female thread sealing surface 52 is positioned on the inner circumferential surface of the second end 10B, closer to the center of the pipe body 10 than the internal thread portion 51. Specifically, the female thread sealing surface 52 is positioned between the internal thread portion 51 and the female thread shoulder surface 53. The female thread sealing surface 52 is tapered. More specifically, at the female thread sealing surface 52, in the length direction of the second end 10B, the inner diameter gradually decreases from the internal thread portion 51 towards the female thread shoulder surface 53.

[0212] When tightening with other threaded well tubing, the female thread sealing surface 52 contacts the male thread sealing surface 42 of the male thread 40 of the other threaded well tubing. More specifically, during tightening, by screwing the male thread 40 of the other threaded well tubing into the female thread 50, the female thread sealing surface 52 contacts the male thread sealing surface 42, and by further screwing, the female thread sealing surface 52 and the male thread sealing surface 42 are tightly fitted together. Thus, during tightening, the female thread sealing surface 52 and the male thread sealing surface 42 are tightly fitted together to form a seal based on metal-metal contact. Therefore, in the mutually tightened threaded well tubing 1, air tightness can be improved.

[0213] The female thread shoulder surface 53 is positioned closer to the center of the pipe body 10 than the female thread sealing surface 52. That is, in the female thread 50, the female thread shoulder surface 53, the female thread sealing surface 52, and the internal thread portion 51 are sequentially arranged from the center of the pipe body 10 toward the second end 10B. The normal to the female thread shoulder surface 53 points towards the length direction of the pipe body 10. When tightening with other threaded well pipes, the female thread shoulder surface 53 is opposite and in contact with the male thread shoulder surface 43 of the male thread 40 of the other threaded well pipe. More specifically, during tightening, the male thread 40 of the other threaded well pipe is inserted into the female thread 50, thereby bringing the female thread shoulder surface 53 into contact with the male thread shoulder surface 43. This allows for tightening with a higher tightening torque. Furthermore, it stabilizes the positional relationship between the male thread 40 and the female thread 50 in the tightened state.

[0214] The female contact surface 500 includes at least an internal thread portion 51. During tightening, the internal thread portion 51 of the female contact surface 500 corresponds to and contacts the external thread portion 41 of the male contact surface 400. The female sealing surface 52 corresponds to and contacts the male sealing surface 42. The female shoulder surface 53 corresponds to and contacts the male shoulder surface 43.

[0215] When the male contact surface 400 includes an external thread portion 41 but does not include a male sealing surface 42 and a male shoulder surface 43, the female contact surface 500 includes an internal thread portion 51 but does not include a female sealing surface 52 and a female shoulder surface 53. When the male contact surface 400 includes an external thread portion 41 and a male shoulder surface 43 but does not include a male sealing surface 42, the female contact surface 500 includes an internal thread portion 51 and a female shoulder surface 53 but does not include a female sealing surface 52. When the male contact surface 400 includes an external thread portion 41 and a male sealing surface 42 but does not include a male shoulder surface 43, the female contact surface 500 includes an internal thread portion 51 and a female sealing surface 52 but does not include a female shoulder surface 53.

[0216] The male thread contact surface 400 may also include multiple external thread portions 41, multiple male thread sealing surfaces 42, and multiple male thread shoulder surfaces 43. For example, at the male thread contact surface 400 of the male thread 40, the male thread shoulder surface 43, male thread sealing surface 42, external thread portion 41, male thread sealing surface 42, male thread shoulder surface 43, male thread sealing surface 42, and external thread portion 41 may be arranged sequentially from the top of the first end 10A toward the center of the tube body 10. In this case, at the female thread contact surface 500 of the female thread 50, the internal thread portion 51, female thread sealing surface 52, female thread shoulder surface 53, female thread sealing surface 52, internal thread portion 51, female thread sealing surface 52, and female thread shoulder surface 53 may be arranged sequentially from the top of the second end 10B toward the center of the tube body 10.

[0217] exist Figure 5 and Figure 6 The diagram illustrates a so-called advanced connector where the male thread 40 includes an external thread portion 41, a male thread sealing surface 42, and a male thread shoulder surface 43, and the female thread 50 includes an internal thread portion 51, a female thread sealing surface 52, and a female thread shoulder surface 53. However, it is also possible for the male thread 40 to include an external thread portion 41, but not the male thread sealing surface 42 and the male thread shoulder surface 43, as described above. In this case, the female thread 50 includes an internal thread portion 51, but not the female thread sealing surface 52 and the female thread shoulder surface 53. Figure 7 This is a diagram illustrating an example of a threaded well pipe 1 with a male thread 40 including an external thread portion 41 but excluding a male thread sealing surface 42 and a male thread shoulder surface 43, and a female thread 50 including an internal thread portion 51 but excluding a female thread sealing surface 52 and a female thread shoulder surface 53.

[0218] [The oil well tubing 1 with threaded fittings is an integral type.]

[0219] Figure 3 and Figure 4 The threaded well tubing 1 shown is a so-called T&C type threaded well tubing 1, in which the tubing body 10 includes a male threaded tubing body 11 and a fitting 12. However, it is also possible that the threaded well tubing 1 of this embodiment is not T&C type, but integral type.

[0220] Figure 8 This is a partial cross-sectional view of the integral threaded well tubing 1 of this embodiment. (Refer to...) Figure 8 The integral threaded well tubing 1 includes a tubing body 10. The tubing body 10 includes a first end 10A and a second end 10B. The first end 10A is located on the side opposite to the second end 10B. As described above, in the T&C type threaded well tubing 1, the tubing body 10 includes a male threaded tubing body 11 and a fitting 12. That is, in the T&C type threaded well tubing 1, the tubing body 10 is constructed by fastening two separate components (male threaded tubing body 11 and fitting 12). In contrast, in the integral threaded well tubing 1, the tubing body 10 is formed integrally.

[0221] A male thread 40 is formed at the first end 10A of the pipe body 10. During tightening, the male thread 40 is inserted into and screwed into the female thread 50 of another integral threaded well pipe 1, thus securing it to the other integral threaded well pipe 1. A female thread 50 is formed at the second end 10B of the pipe body 10. During tightening, the female thread 50 is inserted into and screwed into the male thread 40 of another integral threaded well pipe 1, thus securing it to the other integral threaded well pipe 1.

[0222] The structure of the integral oil well tubing 1 with threaded connector 40 male thread is similar to Figure 5 The male thread 40 of the T&C type threaded well tubing 1 shown is the same as that of the female thread 50 of the integral type threaded well tubing 1. Figure 6 The female thread 50 of the T&C type threaded well tubing 1 shown is the same. Furthermore, in Figure 8 In the male thread 40, a male thread shoulder surface, a male thread sealing surface, an external thread portion, a male thread sealing surface, a male thread shoulder surface, a male thread sealing surface, and an external thread portion are sequentially arranged from the top of the first end 10A toward the center of the pipe body 10. Therefore, in the female thread 50, an internal thread portion, a female thread sealing surface, a female thread shoulder surface, a female thread sealing surface, an internal thread portion, a female thread sealing surface, and a female thread shoulder surface are sequentially arranged from the top of the second end 10B toward the center of the pipe body 10. However, with... Figure 5 Similarly, the male thread contact surface 400 of the integral threaded well tubing with threaded connectors should at least include the external thread portion 41. Additionally, with... Figure 6 Similarly, the female thread contact surface 500 of the integral threaded well pipe with threaded joint 50 shall at least include the internal thread portion 51.

[0223] The threaded well pipe 1 in this embodiment can be either T&C type or integral type.

[0224] [The external threaded portion 41 and the internal threaded portion 51 are threaded joints of wedge-shaped threads in the oil well tubing]

[0225] It could also be, such as Figure 7 As shown, the threaded well pipe of this embodiment does not include shoulder surfaces (male thread shoulder surface 43, female thread shoulder surface 53). In this case, the external thread portion 41 and the internal thread portion 51 can also be wedge-shaped threads (a tapered thread with a dovetail shape). When the external thread portion 41 and the internal thread portion 51 are wedge-shaped threads, the thread width of the external thread portion 41 gradually narrows towards the tip of the right-hand thread along the helix of the thread. Furthermore, the thread groove width of the internal thread portion 51, opposite to the external thread portion 41, also gradually narrows towards the tip of the right-hand thread along the helix of the thread. When the external thread portion 41 and the internal thread portion 51 are wedge-shaped threads, both the load-bearing tooth flank and the insertion tooth flank are at negative angles, and the load-bearing tooth flank and the insertion tooth flank are in contact with each other. Therefore, the threaded portion is firmly engaged, maintaining a high tightening torque. Furthermore, in the tightened state, the thread crest surfaces and thread groove bottom surfaces of threaded portions 41 and 51 are in contact with each other, thus ensuring sealing performance. As mentioned above, if the external threaded portion 41 and the internal threaded portion 51 are wedge-shaped threads, the well pipe with threaded joint may not include shoulder surfaces (male thread shoulder surface 43, female thread shoulder surface 53).

[0226] [Regarding the structure on the female contact surface 500 of the female buckle 50]

[0227] Reference Figure 9 The female contact 50 includes a solid lubricating film 60 on the female contact surface 500.

[0228] [Solid Lubricant Coating 60]

[0229] The solid lubricating coating 60 improves the lubricity of the female thread 50 relative to the male thread 40 of the threaded well tubing 1 during tightening. The solid lubricating coating 60 is a solid coating at room temperature (20℃±15℃). The solid lubricating coating 60 contains a binder and lubricating additives. Alternatively, the solid lubricating coating 60 may contain solvents and other components as needed, in addition to the binder and lubricating additives. The components (binder and lubricating additives) of the solid lubricating coating 60 are described in detail below.

[0230] [Binding agent]

[0231] The binder binds the lubricating additives within the solid lubricating coating 60. In this embodiment, the binder contains one or more types 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 types of thermosetting resins and thermoplastic resins. Thermosetting resins, for example, are one or more types selected from the group consisting of epoxy resins, polyimide resins, polycarbodiimide resins, polyethersulfone resins, polyetheretherketone resins, polyurethane resins, phenolic resins, furan resins, urea resins, and acrylic resins. Thermoplastic resins, for example, are one or more types selected from the group consisting of polyamide-imide resins, polyethylene resins, polypropylene resins, polystyrene resins, and ethylene vinyl acetate resins.

[0232] When using inorganic resins as binders, the inorganic resins are, for example, polyoxometalates. Polyoxometalates are polymeric compounds with repeating metal-oxygen bonds as the main chain backbone. Preferably, the inorganic resin is one or more selected from the group consisting of polytitanium oxane (Ti-O) and polysiloxane (Si-O). These inorganic resins can be obtained by hydrolyzing and condensing metal alkoxides. The alkoxy groups of the metal alkoxides are, for example, lower alkoxy groups such as methoxy, ethoxy, propoxy, isopropoxy, isobutoxy, butoxy, and tert-butoxy.

[0233] If the melt temperature of the binder is too high, it is difficult to apply the composition using a hot-melt method. On the other hand, if the melt temperature of the binder is too low, the solid lubricant coating 60 softens at high temperatures. In this case, the tightness of the solid lubricant coating 60 relative to the female contact surface 500 decreases. Therefore, it is preferable that the binder contains at least one selected from the group consisting of ethylene vinyl acetate resin and polyolefin resin with a melt temperature (or softening temperature) of 80 to 320°C. More preferably, the binder contains at least one selected from the group consisting of ethylene vinyl acetate resin and polyolefin resin with a melt temperature (or softening temperature) of 90 to 200°C.

[0234] For ethylene vinyl acetate resins, in order to suppress rapid softening caused by temperature rise, a mixture of two or more ethylene vinyl acetate resins with different melting temperatures is preferred. Similarly, a mixture of two or more polyolefin resins with different melting temperatures is also preferred for polyolefin resins.

[0235] Preferably, the binder content in the solid lubricant coating 60 is 50-80% by mass. If the binder content is 50% by mass or more, the tightness of the solid lubricant coating 60 is further improved. If the binder content is 80% by mass or less, the lubricity of the solid lubricant coating 60 is maintained better.

[0236] The lower limit of the binder content in the solid lubricant coating 60 is more preferably 55% by mass, further preferably 60% by mass, and even more preferably 65% ​​by mass. The upper limit of the binder content in the solid lubricant coating 60 is more preferably 78% by mass, and even more preferably 75% by mass.

[0237] [Lubricating Additives]

[0238] Lubricating additives are a general term for additives with lubricating properties. Lubricating additives reduce the coefficient of friction of the surface of a solid lubricating film 60. Lubricating additives are generally classified into the following four types. A lubricating additive contains at least one selected from the group consisting of (1) to (4) below.

[0239] (1) A lubricating additive that exhibits lubricity by having a specific crystal structure that allows it to slide easily, such as a hexagonal layered crystal structure (e.g., one or more selected from the group consisting of graphite, zinc oxide and boron nitride);

[0240] (2) A lubricating additive that exhibits lubricity by having reactive elements in addition to having a crystalline structure (e.g., one or more selected from the group consisting of molybdenum disulfide, tungsten disulfide, fluorinated graphite, tin sulfide and bismuth sulfide).

[0241] (3) Lubricating additives that exhibit lubricity through chemical reactivity (e.g., thiosulfate compounds);

[0242] (4) Lubricating additives that exhibit lubricity through plastic or viscoplastic behavior under frictional stress (e.g., polyamides, polytetrafluoroethylene (PTFE)).

[0243] Any of the lubricating additives mentioned in (1) to (4) above can be used. Multiple combinations of those mentioned in (1) to (4) above can also be used. That is, the solid lubricating coating may contain one or more selected from the group consisting of graphite, zinc oxide, boron nitride, molybdenum disulfide, tungsten disulfide, fluorinated graphite, tin sulfide, bismuth sulfide, thiosulfate compounds, and polyamide.

[0244] Preferably, the content of lubricating additive in the solid lubricating film 60 is 10 to 25% by mass. If the content of lubricating additive is 10% by mass or more, the bearing torque can be suppressed even further. On the other hand, if the content of lubricating additive is 25% by mass or less, the strength of the solid lubricating film 60 is further improved. Therefore, the wear of the solid lubricating film 60 can be suppressed.

[0245] The lower limit of the content of lubricating additive in the solid lubricating coating 60 is more preferably 12% by mass, and even more preferably 15% by mass. The upper limit of the content of lubricating additive in the solid lubricating coating 60 is more preferably 23% by mass, and even more preferably 20% by mass.

[0246] Solvents are used where it is necessary to dissolve or disperse the lubricating additives and binders. There are no particular limitations on the solvent, as long as it can disperse or dissolve the components contained in the solid lubricating coating 60. Examples of solvents include water, alcohols, and organic solvents. The solvent may also contain trace amounts of surfactants. There are no particular limitations on the proportion of the solvent. The proportion of the solvent is adjusted according to the coating method to achieve a suitable viscosity in the composition. For example, the proportion of the solvent is 40-60% by mass when the total of all components other than the solvent is set at 100% by mass. Organic solvents are, for example, one or more of toluene and isopropanol. Most of the solvent evaporates during the formation of the solid lubricating coating 60. However, for example, less than 1% by mass of solvent may remain in the solid lubricating coating 60.

[0247] [Other components in solid lubricant coating 60]

[0248] Alternatively, the solid lubricant coating 60 may contain, in addition to the above-mentioned components, one or more components selected from the group consisting of rust inhibitors, plasticizers, surfactants, colorants, antioxidants, and inorganic powders for adjusting slip properties. The inorganic powder may be, for example, one or more components selected from titanium dioxide and bismuth oxide. The total content of other components may be, for example, 5% by mass or less. Alternatively, the solid lubricant coating 60 may also contain a very small amount of extreme pressure agents, liquid oils, etc., at 2% by mass or less. The total content of other components in the solid lubricant coating 60 may be, for example, 10% by mass or less.

[0249] The thickness of the solid lubricant coating 60 is preferably 10 to 40 μm. If the thickness of the solid lubricant coating 60 is 10 μm or more, higher lubricity can be obtained more stably. On the other hand, if the thickness of the solid lubricant coating 60 is 40 μm or less, the tightness of the solid lubricant coating 60 is more stable. If the thickness of the solid lubricant coating 60 is 40 μm or less, the thread tolerance (clearance) of the sliding surface further widens, thus reducing the surface pressure during sliding. Therefore, it is possible to suppress the condition where the tightening torque becomes excessive. Therefore, the preferred thickness of the solid lubricant coating 60 is 10 to 40 μm. A further preferred lower limit for the thickness of the solid lubricant coating 60 is 15 μm, and more preferably 20 μm. A further preferred upper limit for the thickness of the solid lubricant coating 60 is 35 μm, and more preferably 30 μm.

[0250] The thickness of the solid lubricant coating 60 is determined by the following method: Prepare a female thread 50 including the solid lubricant coating 60. Cut the female thread 50 perpendicularly to the axial direction (length direction) of the well tubing. Observe the area containing the solid lubricant coating 60 in the cross-section under a microscope. Set the magnification of the microscope observation to 500x. Calculate the thickness of the solid lubricant coating 60 in any 10 fields of view. In each field of view, measure the thickness of the solid lubricant coating 60 at any 3 locations, and define the average value as the thickness of the solid lubricant coating 60 in that field of view. Define the average value of the thickness of the solid lubricant coating 60 in the 10 fields of view as the thickness of the solid lubricant coating 60 at the female thread 50 of the threaded well tubing.

[0251] [Regarding the coating film 70 formed on the female contact surface 500]

[0252] For the female thread 50 of the threaded well pipe 1 in this embodiment, a coating film 70 may be included on the female thread contact surface 500. In this case, a solid lubricating coating film 60 is formed on the coating film 70.

[0253] Figure 10 This is a diagram illustrating an example of the structure of the female thread 50 of the threaded well pipe 1 with a threaded connector according to this embodiment. (Refer to...) Figure 10 The female thread 50 of the threaded well pipe 1 includes a plating film 70 and a solid lubricating film 60 on the female thread contact surface 500. The plating film 70 is formed on the female thread contact surface 500. The solid lubricating film 60 is formed on the plating film 70.

[0254] The type of coating 70 is not particularly limited. For example, the coating 70 can be a Zn coating, a Ni coating, a Cu coating, a Zn-Ni alloy coating, a Zn-Co alloy coating, a Ni-W alloy coating, or a Cu-Sn-Zn alloy coating. The coating 70 can also be formed by stacking multiple coatings. For example, it can be formed by forming a Ni coating on the female contact surface 500, and then stacking a Zn-Ni coating.

[0255] When the coating 70 is a Zn-Ni alloy coating, the chemical composition of the Zn-Ni alloy coating includes, for example, 10-20% by mass of Ni and the remainder of Zn and impurities. When the coating 70 is a Cu-Sn-Zn alloy coating, the chemical composition of the Cu-Sn-Zn alloy coating includes, for example, 40-70% by mass of Cu, 20-50% by mass of Sn, 2-20% by mass of Zn, and the remainder of impurities. When the coating 70 is a Cu coating, the chemical composition of the Cu coating includes, for example, Cu and impurities.

[0256] In the case of forming the coating film 70, a chemical conversion treatment coating may also be formed on the surface of the coating film 70. In this case, a solid lubricant coating 60 is formed on the chemical conversion treatment coating. Details regarding the chemical conversion treatment coating will be described later.

[0257] [Regarding the structure on the male contact surface 400 of the male thread 40]

[0258] Reference Figure 11 The male thread 40 contains light oil 80 on the male thread contact surface 400.

[0259] [Light oil 80]

[0260] Light oil 80 is applied to the male contact surface 400. Light oil 80 is a liquid composition. The chemical composition of light oil 80, for example, contains 50 to 70% solvent oil by mass and less than 25% petroleum oil by mass.

[0261] [Soluble oil]

[0262] The solvent oil is equivalent to industrial gasoline No. 4 as specified in JIS K 2201 (1991). The preferred lower limit for the solvent oil content is 52%, more preferably 54%, more preferably 56%, and more preferably 58%. The preferred upper limit for the solvent oil content is 68%, more preferably 66%, more preferably 64%, and more preferably 62%.

[0263] [Petroleum-based oils]

[0264] Petroleum-based oils are oils obtained by refining crude oil. Petroleum-based oils may contain, for example, one or more oils selected from the group consisting of alkane oils, cycloalkane oils, and aromatic oils. The preferred lower limit for the petroleum-based oil content is 2%, more preferably 4%, more preferably 6%, and more preferably 8%. The preferred upper limit for the petroleum-based oil content is 22%, more preferably 20%, more preferably 18%, and more preferably 16%.

[0265] [Rust Inhibitor Additive]

[0266] Alternatively, light oil 80 may contain rust inhibitors in addition to solvent oils and petroleum-based oils. Rust inhibitors are a general term for additives with corrosion resistance. For example, rust inhibitors may contain one or more selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite, and calcium ion-exchanged silica. Preferably, the rust inhibitor includes one or more selected from the group consisting of calcium ion-exchanged silica and aluminum phosphite. Other commercially available reactive waterproofing agents may also be used as rust inhibitors.

[0267] Preferably, the content of rust-inhibiting additives in light oil 80 is 10% or less by mass%. The preferred upper limit for rust-inhibiting additives in light oil 80 is 9%, more preferably 8%. The preferred lower limit for rust-inhibiting additives in light oil 80 is 1%, more preferably 2%, and even more preferably 3%. Alternatively, light oil 80 may not contain the aforementioned rust-inhibiting additives. That is, the chemical composition of light oil 80 may contain solvent oil and petroleum-based oils, with the remainder being impurities.

[0268] Furthermore, light oil 80 does not substantially contain heavy metal powder. That is, in light oil 80, heavy metal powder is an impurity. Heavy metal powder is, for example, powder (particles) of Pb, Cu, Zn, etc. Therefore, even in marine oil wells where the use of composite greases containing heavy metal powder is prohibited, the threaded well tubing of this embodiment can be used.

[0269] [Preferred viscosity for light oil 80]

[0270] The preferred viscosity of light oil 80 at 22°C using viscosity cup #1 is 27.5 ± 1 second. However, the viscosity of light oil 80 is not limited to this.

[0271] [A public example of 80% light oil]

[0272] Light oil 80 is, for example, the brand name "WD-40".

[0273] Light oil 80 is a liquid with a lower viscosity than rust-preventive greases such as coatings. Therefore, no special equipment is required when applying light oil 80 to the male thread contact surface 400. Consequently, light oil offers superior repair properties compared to solid rust-preventive coatings. Furthermore, light oil 80 is applied thinly to the male thread contact surface 400. Therefore, as described above, blockage of the inner surface of the threaded well tubing (well tubing connector) caused by rust-preventive grease is virtually nonexistent.

[0274] [Regarding the chemical conversion coating 90 formed on the male contact surface 400]

[0275] Alternatively, for the male thread 40 of the threaded well pipe 1 in this embodiment, a chemical conversion treatment coating 90 may also be included on the male thread contact surface 400. In this case, light oil 80 is applied to the chemical conversion treatment coating 90.

[0276] Figure 12 This diagram illustrates an example of the structure of the male thread 40 of the threaded well pipe 1 with the threaded connector according to this embodiment. (Refer to...) Figure 12 The male thread 40 of the threaded well tubing 1 has a chemically converted coating 90 formed on the male thread contact surface 400. Furthermore, light oil 80 is coated onto the chemically converted coating 90.

[0277] The chemical conversion coating 90 includes, for example, one or more selected from the group consisting of phosphate chemical conversion coating, oxalate chemical conversion coating, and borate chemical conversion coating. Preferably, the chemical conversion coating 90 is a phosphate chemical conversion coating.

[0278] The chemically converted coating 90 is porous. Therefore, if a light oil 80 is formed on the chemically converted coating 90, the adhesion (holding force) of the light oil 80 on the male contact surface 400 is improved. The thickness of the chemically converted coating 90 is not particularly limited. A preferred thickness of the chemically converted coating 90 is 5–40 μm. If the thickness of the chemically converted coating 90 is 5 μm or more, the corrosion resistance is further improved. If the thickness of the chemically converted coating is 40 μm or less, the retention of the light oil 80 is further and stably improved.

[0279] Alternatively, the male thread 40 may be directly coated with light oil 80 on the male thread contact surface 400, without including the chemical conversion treatment coating 90. In particular, when the threaded well tubing 1 is made of carbon steel with a low alloy content, and more specifically, when the Cr content in the base material of the threaded well tubing 1 is 2.0% or less by mass, it is preferable that the male thread 40 has a chemical conversion treatment coating 90 formed on the male thread contact surface 400, and light oil 80 is coated on the chemical conversion treatment coating 90. For example, when the Cr content in the base material of the threaded well tubing 1 is 2.0% or less, the corrosion resistance of the base material itself is not very high. In the chemical composition of the base material of the threaded well tubing 1, if the Cr content is below 2.0%, and a chemical conversion coating 90 is formed on the male thread contact surface 400 of the male thread 40, and then a light oil 80 is applied to the chemical conversion coating 90, the corrosion resistance of the male thread contact surface 400 can be improved. In this case, during the period of temporary storage in the oil well excavation site (1 week to 1 month), the formation of rust on the male thread contact surface 400 of the male thread 40 can be more stably suppressed.

[0280] In the chemical composition of the base material of the threaded well pipe 1, if the Cr content is 2.0% or less, it is preferable that the male thread contact surface 400 of the threaded well pipe 1 is further subjected to blasting treatment, and a chemical conversion treatment coating 90 is formed on the blasted male thread contact surface 400, and light oil 80 is formed on the chemical conversion treatment coating 90. Here, the blasting treatment is a process in which the blasting material (abrasive) collides with the female thread contact surface 500 using a blasting device. The blasting treatment is, for example, sandblasting. In this case, the tight adhesion of the chemical conversion treatment coating 90 to the male thread contact surface 400 is further improved. Therefore, the tight adhesion of the light oil 80 to the male thread contact surface 400 is further improved.

[0281] [Regarding the application of light oil 80 to the male contact surface 400 after spraying treatment]

[0282] Alternatively, if the base material of the threaded well tubing 1 is stainless steel, such as 13Cr steel, the male thread contact surface 400 of the threaded well tubing 1 is blasted, and light oil 80 is formed on the blasted male thread contact surface 400. In this case, due to the microscopic irregularities formed on the blasted male thread contact surface 400, the tightness of the light oil 80 relative to the male thread contact surface 400 is improved.

[0283] [Base material for oil well tubing 1 with threaded fitting]

[0284] Furthermore, the base material of the oil well pipe 1 with threaded joints is not limited to the aforementioned carbon steel, and there are no particular restrictions. The base material can be, for example, carbon steel, stainless steel represented by so-called 13Cr steel, or alloy steel other than stainless steel. Ni alloys and duplex stainless steels containing alloying elements such as Cr, Ni, and Mo exhibit high corrosion resistance. Therefore, if Ni alloys and duplex stainless steels are used as the base material, excellent corrosion resistance can be obtained in corrosive environments containing hydrogen sulfide, carbon dioxide, etc.

[0285] [Regarding the function of the threaded well pipe 1 in this embodiment]

[0286] In the threaded well tubing 1 of this embodiment, the light oil 80 does not contain heavy metal powder. Furthermore, the light oil 80 does not require specialized equipment such as a heat-melting device needed to form a solid anti-rust coating. The light oil 80 can be easily applied to the male thread contact surface 400 by spraying, brushing, or similar methods. Therefore, before transporting the threaded well tubing 1 to the well excavation site, the anti-rust grease applied to the male thread contact surface 400 can be removed at the site, and then the light oil 80 can be easily applied to the male thread contact surface 400. Moreover, during the period of temporary storage at the well excavation site (1 week to 1 month) after transport from the site, the corrosion resistance of the male thread contact surface 400 of the male thread 40 can be improved, and rust formation on the male thread contact surface 400 can be suppressed until the threaded well tubing 1 is actually used at the well excavation site. Furthermore, assuming that during delivery in the oil well excavation site, if a portion of the light oil 80 coated on the male thread contact surface 400 peels off due to contact with other threaded well pipes, etc., it can be easily repaired if light oil 80 is applied. That is, the repairability of the male thread contact surface 400 coated with light oil 80 is superior compared to the male thread contact surface 400 with a solid anti-rust coating.

[0287] Furthermore, for the threaded well tubing 1 of this embodiment coated with light oil 80, the shoulder torque Ts can be suppressed to a low level when tightening with other threaded well tubing 1s. Figure 2 As shown, for threaded well tubing coated with light oil 80 (test numbers 1 and 2), the shoulder torque Ts is lower compared to threaded well tubing with a solid anti-rust coating (test number 3). Furthermore, as... Figure 2As shown, the yield torque Ty of the threaded well tubing coated with light oil 80 (test numbers 1 and 2) is the same as that of the conventional threaded well tubing with a solid anti-rust coating (test number 3). Therefore, even in the threaded well tubing 1 of this embodiment, it is possible to tighten it with a higher tightening torque To.

[0288] [Method for manufacturing an oil well pipe connector 1 with threaded joint according to this embodiment]

[0289] In this specification, the structure formed by fastening multiple threaded well pipes 1 together is referred to as a "well pipe connector". The well pipe connector may also be casing, tubing, or drill pipe. The well pipe connector is manufactured (fastened) in the well excavation site. The manufacturing method of the well pipe connector is described below.

[0290] In this specification, "well excavation site" refers to the location where well excavation is carried out. The well excavation site can be on land or at sea, and an excavation rig is installed there. The excavation rig is equipped with a derrick, at which a threaded well pipe is connected to form a well pipe connection. In the case of an offshore well excavation site, a floating production storage and offloading (FPSO) facility can be used instead of the excavation rig.

[0291] Figure 13 This diagram schematically illustrates the locations where each step of the manufacturing method for the oil well pipe connector according to this embodiment is carried out. (Refer to...) Figure 13 The manufacturing method of the oil well pipe connector in this embodiment includes the following steps: preparing an oil well pipe with a threaded connector (oil well pipe with threaded connector preparation step: S1); transporting the oil well pipe 1 with the threaded connector to the site A2 (site transport step: S2); temporarily storing the oil well pipe 1 with the threaded connector in the site A2 (site temporary storage step: S3); before transporting the oil well pipe 1 with the threaded connector from the site A2 to the oil well excavation site A3, removing the anti-rust grease and applying light oil 80 (light oil coating). Fabrication process: S4); The threaded well pipe 1 coated with light oil 80 is transported from site A2 to well excavation site A3 (well excavation site transport process: S5); The threaded well pipe is temporarily stored in well excavation site A3 (well excavation site temporary storage process: S6); The threaded well pipe temporarily stored in well excavation site A3 is used to fasten the threaded well pipe with other threaded well pipes 1 to form a well pipe connector (well pipe connector manufacturing process: S7).

[0292] The manufacturing processes S1 through S7 are performed at different locations. Specifically, the threaded well pipe preparation process S1 is performed at factory A1 (hereinafter referred to as manufacturing plant A1), where threaded well pipes are manufactured. The on-site temporary storage process S3 and the light oil coating process S4 are performed at on-site site A2. The oil well excavation site temporary storage process S6 and the oil well pipe connector manufacturing process S7 are performed at oil well excavation site A3.

[0293] The manufacturing plant A1, the field site A2, and the well excavation site A3 are located in different locations. Typically, the manufacturing plant A1 is located relatively far from the well excavation site A3 where the well excavation operation will take place. Therefore, the threaded tubing manufactured in the manufacturing plant A1 is transported to the well excavation site A3 by land or sea. However, there are often situations where the well excavation site A3 lacks a location to store all the threaded tubing used for the well excavation operation. For example, if the well excavation site A3 is an offshore excavation rig or FPSO, the number of threaded tubing that can be temporarily stored at the rig or FPSO is limited.

[0294] Therefore, in typical oil well drilling operations, a site A2 is prepared near the drilling site A3 to temporarily store multiple threaded well pipes. Thus, during oil well drilling operations, firstly, the threaded well pipes manufactured in the manufacturing plant A1 are transported to site A2 by land or sea (site transport step S2). Then, the threaded well pipes are temporarily stored in site A2. Then, in the stage before the threaded well pipes are to be used, the threaded well pipes are transported from site A2 to the drilling site A3 (drilling site transport step S5). In short, site A2 is utilized as a temporary storage location for the threaded well pipes.

[0295] As described above, in well drilling operations, a site A2 is typically set up as a transfer point between the manufacturing plant A1 and the well drilling site A3. Site A2 is naturally located closer to the well drilling site A3 than the manufacturing plant A1. Typically, threaded tubing from the manufacturing plant A1 is temporarily stored at site A2 for an extended period. Specifically, threaded tubing from the manufacturing plant A1 is temporarily stored at site A2 for a relatively long period of about six months to two years. Then, before being used at the well drilling site A3, the threaded tubing is transported from site A2 to the well drilling site A3. At the well drilling site A3, the threaded tubing is further temporarily stored for a shorter period of about one week to one month until it is used in a tubing connector, that is, until it is tightened with other threaded tubing to form a tubing connector.

[0296] As mentioned above, recently, in order to control pollution at oil well drilling sites, it is desirable to avoid the use of heavy metal powder in the manufacture of oil well pipe connectors. Therefore, in the past, solid lubricating films and solid anti-rust films have been used instead of composite greases containing heavy metal powder.

[0297] However, in cases where threaded well tubing with a solid anti-rust coating on the male thread contact surface and a solid lubricating coating on the female thread contact surface is transported from the manufacturing plant A1 to the field site A2, and from the field site A2 to the well excavation site A3, the following situations may occur: during transportation, the male threads of the threaded well tubing may collide with each other, or the male threads of the threaded well tubing may collide with facilities, etc. In the male thread, a male thread contact surface is formed on the outer circumferential surface of the tubing body end. Therefore, the following situations may occur: due to collisions during transportation, the solid anti-rust coating formed on the male thread contact surface may be damaged, or the solid anti-rust coating may be partially broken. Additionally, the following situations may occur: due to collisions, the external thread portion, the male thread sealing surface, and the male thread shoulder surface on the male thread contact surface may be damaged or broken.

[0298] Typically, in site A2, a male thread contact surface fabrication device is installed to address the possibility of damage to the male thread contact surface during transport. For example, if the male thread contact surface is damaged due to an impact, the male thread of the threaded well tubing is cut off. Then, using the male thread contact surface fabrication device, the cut end of the well tubing is threaded to re-form the male thread contact surface.

[0299] As described above, in the event of damage to the male contact surface, the male contact surface fabrication apparatus located at site A2 can be used to regenerate the male contact surface. However, it is difficult to regenerate the solid anti-rust coating at site A2. This is because, typically, a device for forming a solid anti-rust coating (hereinafter referred to as a solid anti-rust coating fabrication apparatus) is not located at site A2. If a solid anti-rust coating fabrication apparatus is located at site A2, the solid anti-rust coating can be regenerated (re-formed). However, if the solid anti-rust coating fabrication apparatus is located at site A2, there will naturally be costs associated with its installation.

[0300] Therefore, in the manufacturing method of the oil well pipe connector in this embodiment, a solid lubricating coating is formed on the female thread contact surface, but the use of a solid anti-rust coating on the male thread contact surface is avoided. As mentioned above, the storage period (six months to two years) for threaded oil well pipes in field site A2 is much longer than the storage period (one week to one month) for threaded oil well pipes in oil well excavation site A3. For the light oil 80 mentioned above, even during outdoor storage for about one month, rust formation on the male thread contact surface 400 can be suppressed. However, for periods exceeding one month, sufficient corrosion resistance cannot be obtained with light oil 80. Therefore, if a threaded oil well pipe 1 with light oil 80 coated on the male thread contact surface 400 is manufactured in factory A1 and transported to field site A2, rust formation on the male thread contact surface 400 of the threaded oil well pipe 1 occurs during storage in field site A2.

[0301] On the other hand, a method of forming a rust-preventive grease on the male contact surface 400 instead of a light oil 80 is also considered. The rust-preventive grease is a semi-solid or paste-like rust-preventive composition. Examples of rust-preventive greases include trade names such as "RUST VETOAS EU" and "KENDEX." Rust-preventive greases are also known as storage coatings. Compared to light oil 80, the rust-preventive grease exhibits corrosion resistance for a longer period. Specifically, even when stored outdoors for two years, the rust-preventive grease can suppress rust formation on the male contact surface 400. Furthermore, even if the male contact surface is re-formed due to impact or other reasons, the rust-preventive grease can be easily applied to the male contact surface.

[0302] However, it is not preferable to directly use threaded tubing with rust-preventive grease applied to the male contact surface in well excavation site A3 as a tubing connector. This is because, similar to one of the problems with composite greases mentioned above, rust-preventive grease can cause blockage inside the threaded tubing (tubing connector). Specifically, a significant portion of the rust-preventive grease applied to the male and / or female contact surfaces during thread tightening (threaded connection) is discharged outwards from the tips of the male and female threads upon completion of tightening. A portion of the rust-preventive grease is discharged into the tubing from the tip of the male thread. The rust-preventive grease has a high viscosity. Therefore, the rust-preventive grease discharged into the interior (inner surface) of the tubing accumulates on the inner surface. This accumulation of rust-preventive grease can lead to blockage of the tubing.

[0303] Therefore, in the manufacturing method of the well pipe connector of this embodiment, an operation is performed at the site A2 to replace the anti-rust grease on the male thread contact surface 400 with light oil 80. Specifically, for the threaded well pipe manufactured in the manufacturing plant A1, anti-rust grease is applied to the male thread contact surface (S1). Then, the threaded well pipe with anti-rust grease applied to the male thread contact surface is transported to the site A2 (S2). The threaded well pipe is temporarily stored at the site A2 (S3). In this case, the outdoor storage period at the site A2 is six months to two years. However, since anti-rust grease is applied to the male thread contact surface of the threaded well pipe, rust formation on the male thread contact surface of the threaded well pipe can be suppressed during outdoor storage at the site A2. Furthermore, if rust-preventive grease is applied, even if a portion of the rust-preventive grease peels off for some reason, it can be easily repaired by reapplying rust-preventive grease to that portion (excellent repairability).

[0304] Then, before conveying the threaded well tubing from site A2 to well excavation site A3, in site A2, the rust-preventive grease applied to the male thread contact surface 400 is replaced with light oil 80, thus manufacturing the threaded well tubing 1 (S4). Specifically, in site A2, the rust-preventive grease on the male thread contact surface of the threaded well tubing is removed. The rust-preventive grease is semi-solid or paste-like, and therefore easily removed. Then, light oil 80 is applied to the male thread contact surface 400 where the rust-preventive grease has been removed. Light oil 80 is a liquid with a lower viscosity compared to the rust-preventive grease. Therefore, light oil 80 can be easily applied to the male thread contact surface 400. That is, light oil 80 also has excellent repair properties.

[0305] The threaded well tubing 1, manufactured in site A2 through the above processes, is transported to well excavation site A3 (S5). Then, the threaded well tubing 1 is temporarily stored in well excavation site A3 (S6). The storage period of the threaded well tubing 1 in well excavation site A3 is shorter than that of the threaded well tubing in site A2 (the threaded well tubing with anti-rust grease applied to the male thread contact surface 400), approximately one week to one month. Therefore, it exhibits sufficient corrosion resistance even in the case of light oil 80. As a result, during the storage period in well excavation site A3, rust formation on the male thread contact surface 400 of the threaded well tubing 1 can be suppressed.

[0306] Using a threaded well pipe 1 temporarily stored at the well excavation site A3, a well pipe connector (S7) is manufactured. Specifically, the female thread 50 of another threaded well pipe 1 is inserted into and the male thread 40 of the threaded well pipe 1 is screwed in. At this time, the shoulder torque Ts is reduced for the light oil 80 on the male thread contact surface 400 compared to the solid anti-rust coating, as described above. Moreover, by removing the anti-rust grease and applying the light oil 80, when the threaded well pipe 1 is threadedly tightened at the well excavation site A3, almost no blockage caused by the light oil 80 occurs inside the threaded well pipe.

[0307] As described above, in the manufacturing method of the oil well pipe connector of this embodiment, the shoulder torque Ts can be reduced during the manufacturing of the oil well pipe connector. Furthermore, tightening with a higher tightening torque To can also be achieved. Moreover, the repairability of the anti-rust grease and light oil 80 is excellent. Furthermore, in the oil well excavation site A3, a threaded joint oil well pipe 1 coated with light oil 80 is used instead of a threaded joint oil well pipe 1 coated with anti-rust grease; therefore, almost no blockage caused by light oil 80 occurs inside the oil well pipe (oil well pipe connector) after thread tightening. In the manufacturing method of the oil well pipe connector of this embodiment, a threaded joint oil well pipe 1 with a solid lubricating coating 60 in the female thread 50 is also used, thus exhibiting excellent resistance to sintering. Hereinafter, each manufacturing step S1 to S7 in the manufacturing method of the oil well pipe connector of this embodiment will be described in detail.

[0308] [Preparation procedure for oil well tubing with threaded fittings: S1]

[0309] In the threaded well tubing preparation process S1, a threaded well tubing 200 coated with anti-rust grease is prepared. The threaded well tubing 200 is manufactured, for example, in manufacturing plant A1.

[0310] [Structure of 200mm oil well tubing with threaded fitting]

[0311] Figure 14 This is a structural diagram showing an example of an oil well pipe 200 with a threaded connector. Figure 15 It means and Figure 14 A structural diagram of an example of a 200 oil well pipe with different threaded fittings. Figure 14 It is a T&C type oil well pipe with threaded fittings. Figure 15 It is an integral oil well tubing with threaded fittings. (Refer to...) Figure 14 and Figure 15 Compared to the threaded well tubing 1, the threaded well tubing 200 includes a male thread 40A coated with anti-rust grease instead of a male thread 40 coated with light oil 80. The other structural features of the threaded well tubing 200 are the same as those of the threaded well tubing 1.

[0312] Figure 16 yes Figure 14 and Figure 15 A longitudinal sectional view of the portion near the male thread contact surface 400 of the male thread 40A. Here, the longitudinal sectional view shows a section parallel to the length direction of the well tubing 200 with the threaded connector. (Refer to...) Figure 16 The male thread 40A of the oil well tubing 200 with threaded connector is coated with anti-rust lubricating grease 80A on the male thread contact surface 400 instead of light oil 80.

[0313] [Rust-preventive grease 80A]

[0314] Rust-preventive grease 80A is a semi-solid or paste-like rust-preventive composition, unlike light oil 80, which is a relatively low-viscosity liquid. Rust-preventive grease 80A is marketed under trade names such as "RUST VETO AS EU" and "KENDEX." Rust-preventive grease 80A is also known as a storage coating. Compared to light oil 80, rust-preventive grease 80A provides longer-lasting corrosion resistance. Specifically, even when stored outdoors for two years, rust-preventive grease 80A can inhibit rust formation on the male-female contact surface 400.

[0315] Rust-preventive grease 80A, for example, contains 50-80% refined mineral oil, 2.5-10.0% metal soap, 1.0-2.5% petroleum sulfonate and / or its salts, by weight. 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.

[0316] Figure 17 Is with Figure 16 Different Figure 14 and Figure 15 A longitudinal sectional view of the portion near the male contact surface 400 of male thread 40A. (Refer to...) Figure 17 Alternatively, the male thread 40A of the threaded well tubing 200 may also include a chemical conversion coating 90 on the male thread contact surface 400. In this case, the chemical conversion coating 90 is formed on the male thread contact surface 400 of the threaded well tubing 1. Rust-preventive grease 80A is applied to the chemical conversion coating 90.

[0317] The threaded well pipe 200 having the above structure is manufactured in manufacturer A1, for example, by the following method. Hereinafter, an example of a manufacturing method for the threaded well pipe 200 will be described. However, the manufacturing method for the threaded well pipe 200 is not limited to this method. If a threaded well pipe 200 having the above structure can be prepared, the manufacturing method for the threaded well pipe 200 is not particularly limited.

[0318] The manufacturing method of the oil well pipe 200 with threaded joint includes a pipe blank preparation process, a solid lubricant coating formation process, and a rust-preventive grease coating process.

[0319] [Blank tube preparation process]

[0320] First, a threaded fitting tube blank is prepared without a solid lubricating film 60 or an anti-rust grease 80A. The threaded fitting tube blank includes a tube body 10. The tube body 10 includes a first end 10A and a second end 10B. A male thread 40A is formed at the first end 10A. A female thread 50 is formed at the second end 10B. The male thread of the threaded fitting tube blank includes a male thread contact surface 400. The female thread of the threaded fitting tube blank includes a female thread contact surface 500.

[0321] The tube blank with threaded fittings is manufactured, for example, by the following method: Raw materials are prepared using molten steel. Specifically, molten steel is used to manufacture castings (slabs, blooms, or billets) via continuous casting. Alternatively, molten steel is used to manufacture ingots via ingot casting. Alternatively, steel plates, ingots, or billets are rolled into blanks as needed to produce steel sheets (billets). The raw materials (slabs, ingots, or billets) are manufactured through the above processes. The prepared raw materials are then hot-worked to manufacture the tube blank. The hot-working method can be piercing rolling based on the Mannesmann process or hot extrusion. The hot-worked tube blank is subjected to known quenching and tempering to adjust its strength. The tube blank is manufactured through the above processes. Furthermore, in the case where the threaded well pipe 200 is of type T&C, a tube blank for the fitting 12 is also prepared. The manufacturing method for the tube blank for the fitting 12 is the same as the tube blank manufacturing method described above.

[0322] When the threaded well tubing 200 is of type T&C, the outer surfaces of both ends of the tube blank for the male threaded tube body 11 are threaded to form a male thread contact surface 400. Furthermore, the inner surfaces of both ends of the tube blank for the tube fitting 12 are threaded to form a female thread contact surface 500. The male thread at one end of the tube blank for the male threaded tube body 11 is inserted into the female thread at one end of the tube blank for the tube fitting 12 and screwed in. Through these processes, a tube blank containing the male threaded tube body 11 and the tube fitting 12 is manufactured.

[0323] When the well tubing 200 with threaded joints is integral, the outer surface of the first end 10A of the tubing blank, which corresponds to the tubing body 10, is threaded to form a male thread contact surface 400. Furthermore, the outer surface of the second end 10B of the tubing blank, which corresponds to the tubing body 10, is threaded to form a female thread contact surface 500.

[0324] The above steps are used to prepare a pipe blank containing male and female threads for threaded fittings.

[0325] [Solid Lubricant Coating Formation Process]

[0326] In the solid lubricant coating formation process, a solid lubricant coating 60 is formed on the female thread contact surface 500 of the female thread of the threaded fitting prepared in the tube blank preparation process. The solid lubricant coating formation process includes a coating process and a curing process. The curing process is performed after the coating process.

[0327] [Coating Process]

[0328] In the coating process, a composition for forming a solid lubricant coating 60 is coated onto the female contact surface 500. The composition contains a resin and solid lubricant powder. Except for the solvent, the composition is the same as the resin composition of the solid lubricant coating 60 described above.

[0329] The composition can be either solvent-free or solvent-based. Solvent-free compositions can be manufactured, for example, by heating a resin to a molten state and then adding solid lubricating powder and kneading it. Alternatively, a powder mixture formed by powdering all the components can be used as a composition.

[0330] Solvent-based compositions can be manufactured, for example, by dissolving or dispersing and mixing resins and solid lubricating powders in a solvent. Solvents include, for example, water, alcohols, and organic solvents. The solvent may also contain trace amounts of surfactants. The proportion of the solvent is not particularly limited. The proportion of the solvent is adjusted according to the coating method to achieve a suitable viscosity for the composition. For example, the proportion of the solvent is 40-60% by mass when the total of all components other than the solvent is set at 100% by mass.

[0331] The above-described composition is applied to the female contact surface 500 using a known method. When the composition is solvent-free, for example, a hot-melt method can be used to apply the composition. In the hot-melt method, the composition is heated to melt the resin, achieving a low-viscosity, flowing state. This is done by spraying the flowing composition from a spray gun with a temperature-maintaining function. Alternatively, brush application and dipping can be used instead of spray application. Preferably, the heating temperature of the composition is set to a temperature 10–50°C higher than the melting point of the resin.

[0332] When the composition is solvent-based, it is applied as a solution by spraying. In this case, the viscosity of the composition is adjusted to allow for spraying at room temperature and pressure. Alternatively, brush application or dipping can be used instead of spraying.

[0333] [Curing Process]

[0334] In the curing process, the coated composition is cured to form a solid lubricating film 60. If the composition is solvent-free, the solid lubricating film 60 is formed by cooling the composition coated on the female contact surface 500, thereby curing the molten composition. The cooling method can be implemented using known methods, such as atmospheric cooling and air cooling. If the composition is solvent-based, the solid lubricating film 60 is formed by drying the composition coated on the female contact surface 500. The drying method can be implemented using known methods, such as natural drying, low-temperature air drying, and vacuum drying. The composition can also be cured by heat curing.

[0335] In the solid lubricant coating formation process, the above-described coating and curing processes are performed to form a solid lubricant coating 60 on the female contact surface 500.

[0336] [Coating Formation Process]

[0337] When the threaded well tubing 200 includes a coating 70 between the threaded contact surface 500 and the solid lubricant coating 60, the coating formation process can be performed after the preparation process and before the solid lubricant coating formation process. That is, the coating formation process is arbitrary. If the threaded well tubing 200 does not include the coating 70, the coating formation process is not performed.

[0338] In the case of performing the coating film formation process, a coating film 70 is formed on the female contact surface 500 during the coating film formation process.

[0339] The formation of the coating film 70 can be carried out using known methods. The coating film 70 can be formed using electrolytic plating or non-electrolytic plating. For example, when forming the coating film 70 of a Zn-Ni alloy by electrolytic plating, the plating bath contains zinc ions and nickel ions. Preferably, the composition of the plating bath contains zinc ions: 1–100 g / L and nickel ions: 1–50 g / L. Conditions for electrolytic plating include, for example, plating bath pH: 1–10, plating bath temperature: 60°C, and current density: 1–100 A / dm³. 2 The processing time is 0.1 to 30 minutes. For example, when forming a Cu-Sn-Zn alloy coating 70 by electroplating, 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 electroplating conditions can also be the same as those described above for forming a Zn-Ni alloy coating 70. When the coating 70 is a Cu coating, it can be manufactured using known methods.

[0340] [Substrate Treatment Process]

[0341] Furthermore, in the manufacturing process of the threaded well pipe 200, a substrate treatment process can be included after the preparation process and before the coating formation process. That is, when the coating formation process is performed, the substrate treatment process can also be performed before the coating formation process. The substrate treatment process is, for example, pickling or blasting. The surface roughness of the female contact surface 500 of the threaded pipe blank can be adjusted by the substrate treatment process. In this case, the tightness of the coating 70 relative to the female contact surface 500 is improved. Pickling and blasting processes will be described below.

[0342] [Pickling treatment]

[0343] Pickling is performed by immersing the female contact surface 500 in a strong acid solution such as sulfuric acid, hydrochloric acid, nitric acid, or hydrofluoric acid to roughen it. This increases the surface roughness of the female contact surface 500.

[0344] [Spraying treatment]

[0345] A blasting process is, for example, a process in which abrasive material (abrasive) is brought into contact with the female contact surface 500 using a blasting device. A blasting process is, for example, sandblasting. A blasting process involves mixing abrasive material (abrasive) with compressed air and blasting it onto the female contact surface 500. Abrasive materials can be, for example, spherical shot or angular abrasive particles. Sandblasting can increase the surface roughness of the female contact surface 500. Sandblasting can be performed using known methods. For example, compressed air can be mixed with abrasive material using a compressor. The material of the abrasive material can be, for example, stainless steel, aluminum, ceramic, or alumina. The blasting speed and other conditions of the sandblasting process can be appropriately set.

[0346] [Rust-preventive grease coating process]

[0347] In the rust-preventive grease coating process, rust-preventive grease 80A is applied to the male thread contact surface 400 of the threaded joint tube blank prepared in the tube blank preparation process.

[0348] For the rust-preventive grease application process, there are no particular limitations as long as the rust-preventive grease 80A can be applied to the male contact surface 400. For example, the rust-preventive grease 80A can be applied by spraying, by brushing, or by other known methods.

[0349] [Chemical conversion treatment coating formation process]

[0350] When the male thread 40A of the threaded well tubing 200 contains a chemical conversion coating 90 between the male thread contact surface 400 and the anti-rust grease 80A, the chemical conversion coating formation process can be performed after the preparation process and before the anti-rust grease application process. That is, the chemical conversion coating formation process is arbitrary. If the threaded well tubing 200 does not contain a chemical conversion coating 90, the chemical conversion coating formation process is not performed.

[0351] In the case of performing a chemical conversion coating formation process, a known chemical conversion treatment is performed in the chemical conversion coating formation process to form a chemical conversion coating 90 on the male contact surface 400. The chemical conversion treatment can be performed using known methods. Commercially available chemical conversion treatment solutions can be used as the treatment solution. To promote the formation of the chemical conversion coating, surface conditioning can also be performed before the chemical conversion treatment. Surface conditioning is a treatment involving immersion in an aqueous surface conditioning solution containing colloidal titanium or the like. Preferably, after the chemical conversion treatment, the surface is dried after rinsing with water or hot water.

[0352] The threaded well tubing 200 can be manufactured through the above manufacturing process. In addition, the threaded well tubing 200 can also be prepared by other methods besides those described above.

[0353] [Protective component installation procedure]

[0354] Preferably, the protective element installation process is performed on the male thread 40A and / or female thread 50 of the threaded well tubing 200. The protective element may or may not be installed. When installed, the protective element installed on the male thread 40A (hereinafter referred to as the male thread protective element) is a cover covering the male thread contact surface 400 of the male thread 40A. The protective element installed on the female thread 50 (hereinafter referred to as the female thread protective element) is a cover covering the female thread contact surface 500 of the female thread 50.

[0355] The protective element for the female snap fastener is cylindrical, with an external thread formed on its outer circumferential surface that allows it to be screwed into the internal thread 51 of the female snap fastener 50. The protective element for the female snap fastener is, for example, made of a known resin.

[0356] Figure 18 This is a structural diagram showing the male buckle protective component installed on male buckle 40A. (Refer to...) Figure 18 A male thread protector 600 covers and secures the male thread 40A. The male thread protector 600 includes a cylindrical portion 601 and a cover portion 602. The cylindrical portion 601 has an internal thread on its inner circumferential surface. The internal thread is opposite to the male thread contact surface 400. The internal thread of the cylindrical portion 601 corresponds to the external thread 41 of the male thread contact surface 400. When the male thread 40A is inserted into the male thread protector 600, the internal thread of the cylindrical portion 601 engages with the external thread of the male thread contact surface 400. Thus, the male thread protector 600 is secured to the male thread 40A. At this time, the cylindrical portion 601 covers the male thread contact surface 400.

[0357] Figure 19 This is a longitudinal sectional view of the portion near the external thread 41 and the internal thread 610 of the male thread protector 600, with the male thread protector 600 installed on the male thread 40A. (Refer to...) Figure 19 With the male thread protector 600 installed, the distance between the thread root 41B of the external thread portion 41 of the male thread 40A and the thread tooth 610T of the internal thread portion 610 of the cylindrical portion 601 of the male thread protector 600 is defined as D1. Furthermore, the distance between the thread root 610B of the internal thread portion 610 of the cylindrical portion 601 of the male thread protector 600 and the thread tooth 41T of the external thread portion 41 of the male thread 40A is defined as D2. In this case, distance D1 is longer than distance D2.

[0358] The rust-preventive grease 80A applied to the male contact surface 400 fills the gap between the internal thread portion 610 of the male thread protector 600 and the external thread portion 41 of the male thread 40A with the male thread protector 600 installed on the male thread 40A. Therefore, the thickness T1 of the rust-preventive grease 80A between the thread root 41B of the external thread portion 41 of the male thread 40A and the thread tooth 610T of the internal thread portion 610 of the cylindrical portion 601 of the male thread protector 600 is thicker than the thickness T2 of the rust-preventive grease 80A between the thread tooth 41T of the external thread portion 41 of the male thread 40A and the thread root 610B of the internal thread portion of the cylindrical portion 601 of the male thread protector 600.

[0359] When the male thread 40 of a threaded well pipe 1 is screwed into and tightened onto the female thread 50 of another threaded well pipe 1 in the well excavation site A3, the thread root 41B of the external thread portion 41 of the male thread 40 of the threaded well pipe 1 contacts the thread teeth of the internal thread portion 51 of the other threaded well pipe 1. On the other hand, during tightening, some gaps are formed between the thread teeth 41T of the external thread portion 41 of the male thread 40 of the threaded well pipe 1 and the thread root of the internal thread portion 51 of the other threaded well pipe 1. As a result, in the threaded well pipe 200 with the male thread protective member installed, the anti-rust grease 80A in the thread root 41B area forms a thicker layer. In this case, it is possible to further suppress the formation of rust in the thread root 41B area of ​​the external thread portion 41 of the male thread 40A that contacts the internal thread of the female thread when tightening.

[0360] [On-site transport process: S2]

[0361] The threaded well pipe 200 prepared in the threaded well pipe preparation step S1 is transported to the site A2 by land or sea. Any known method can be used for transport. By land, multiple threaded well pipes 200 are transported using large vehicles such as trucks. By sea, multiple threaded well pipes 200 are transported on ships.

[0362] [On-site temporary storage procedure: S3]

[0363] In the temporary storage process S3 at the site, multiple threaded well pipes 200 transported to site A2 are temporarily stored at site A2. The storage period for the threaded well pipes 200 at site A2 is longer than the storage period for the threaded well pipes 1 at the well excavation site A3. For example, the storage period for the threaded well pipes 200 at site A2 is approximately six months to two years.

[0364] In the field transport process S2, multiple threaded well pipes 200 are transported. Therefore, situations may arise where the male threads 40A of the threaded well pipes 200 collide with each other during transport, or where the male threads 40A of the threaded well pipes 200 collide with structures other than the threaded well pipes 200. Due to these collisions during transport, a portion of the anti-rust grease 80A formed on the male thread contact surface 400 may be removed. However, as described above, the anti-rust grease 80A can be easily repaired by applying it to the male thread contact surface 400. Therefore, assuming that even if a portion of the anti-rust grease 80A is removed during transport, it can be easily repaired by applying the anti-rust grease 80A to the male thread contact surface 400 in the field area A2, achieving excellent repairability. Therefore, it is not necessary to install dedicated equipment in the field area A2 as is required for forming a solid anti-rust coating.

[0365] Additionally, there is a possibility that during transport, the external thread 41, male thread sealing surface 42, and male thread shoulder surface 43 on the male thread contact surface 400 may be damaged or broken due to collision. In this case, the damaged male thread 40A of the threaded well pipe 200 is cut off at site A2. Then, using a male thread contact surface fabrication device located at site A2, the end of the cut-off threaded well pipe 200 with male thread 40A is thread-cut to re-form the male thread contact surface 400. Furthermore, rust-preventive grease 80A is applied to the re-formed male thread contact surface 400. As a result, the rust-preventive grease 80A can be easily regenerated, achieving excellent repairability.

[0366] In site A2, the threaded well tubing 200 is stored outdoors for a relatively long period of six months to two years. However, as mentioned above, the anti-rust grease 80A exhibits excellent corrosion resistance. Therefore, during storage in site A2, rust formation on the male thread contact surface 400 can be suppressed. Furthermore, a solid lubricating film 60 is formed on the female thread contact surface 500 of the threaded well tubing 200. The solid lubricating film 60 also serves as an anti-rust agent. Therefore, during storage in site A2, rust formation on the female thread contact surface 500 can also be suppressed.

[0367] [Light oil coating process: S4]

[0368] In well excavation site A3, when the number of threaded well pipes 1 in storage decreases, new threaded well pipes 1 are supplied from site A2 to well excavation site A3. Before supplying the threaded well pipes 1 from site A2 to well excavation site A3, in site A2, the anti-rust grease 80A of the threaded well pipe 200 is removed and light oil 80 is applied, thus establishing the threaded well pipe 1.

[0369] Specifically, firstly, in site A2, remove the anti-rust grease 80A from the male thread contact surface 400 of the threaded well pipe 200. The anti-rust grease 80A is semi-solid or paste-like, and therefore easily removed. For example, it can be removed by high-pressure water. Then, apply light oil 80 to the male thread contact surface 400 after removing the anti-rust grease 80A. The light oil 80 is liquid, and therefore easily applied to the male thread contact surface 400. It can be applied by spraying, by brushing, or by other known methods.

[0370] Through the above procedures, in site A2, the anti-rust grease 80A can be easily replaced with light oil 80. This prevents blockage caused by the rust inhibitor from occurring inside the threaded well tubing (well tubing connector). Furthermore, as described later, the threaded well tubing 1 coated with light oil 80 reduces the shoulder torque Ts.

[0371] [Oil well excavation and transportation process: S5]

[0372] In the oil well excavation site transport process S5, the threaded well tubing 1 manufactured at site A2 is transported from site A2 to the oil well excavation site A3. The transport method can be any known method. In the case of land transport, multiple threaded well tubing 1s are transported using large vehicles such as trucks. In the case of sea transport, multiple threaded well tubing 1s are transported by ship.

[0373] [Temporary storage procedure at oil well excavation site: S6]

[0374] In the temporary storage procedure S6 at the oil well excavation site, the threaded well tubing 1 transported from site A2 is temporarily stored. The storage period of the threaded well tubing 1 at the oil well excavation site A3 is significantly shorter than the storage period of the threaded well tubing 200 at site A2. The storage period of the threaded well tubing 1 at the oil well excavation site A3 is, for example, 1 week to 1 month.

[0375] As mentioned above, the storage period for the threaded well tubing 1 in well excavation site A3 is relatively short. Therefore, sufficient corrosion resistance can be obtained by applying light oil 80 to the male thread contact surface 400.

[0376] Furthermore, in the well excavation site transport process S5, during transport from site A2 to well excavation site A3, the following situation may occur: the external thread 41, male thread sealing surface 42, and male thread shoulder surface 43 on the male thread contact surface 400 may be damaged or broken due to collision. In this case, the damaged threaded well tubing 1 is returned from well excavation site A3 to site A2. Then, at site A2, the damaged male thread 40A of the threaded well tubing 1 is cut off, thread cutting is performed, and the male thread contact surface 400 is reformed. Moreover, light oil 80 is applied to the reformed male thread contact surface 400. As a result, the threaded well tubing 1 coated with light oil 80 can be easily regenerated.

[0377] [Oil well tubing connector manufacturing process: S7]

[0378] An oil well pipe connector (S7) is manufactured using a threaded well pipe 1 temporarily stored at the oil well excavation site A3. Specifically, the female thread 50 of another threaded well pipe 1 is inserted into and screwed into the male thread 40 of the threaded well pipe 1. At this time, the light oil 80 on the male thread contact surface 400 reduces the shoulder torque Ts.

[0379] Through the above manufacturing process, an oil well pipe connector formed by fastening multiple threaded joint oil well pipes 1 can be manufactured in oil well excavation site A3. In this manufacturing method, a solid anti-rust coating is not formed on the male thread contact surface 400. Instead, anti-rust grease 80A is applied to the male thread contact surface 400 just before use. Therefore, even if the male thread 40A is damaged, it can be remanufactured, and the anti-rust grease 80A can be easily applied (repaired), resulting in excellent repairability. Moreover, the anti-rust grease 80A provides anti-rust function for a longer period. Therefore, during storage in site A2, rust formation on the male thread contact surface of the threaded joint oil well pipe 200 can be suppressed. Then, before transporting from site A2 to oil well excavation site A3, the anti-rust grease 80A is removed, and light oil 80 is applied to the male thread contact surface 400. Therefore, blockage caused by rust inhibitors can be suppressed inside the threaded well tubing (well tubing connector) after threading. Furthermore, by manufacturing the well tubing connector using a threaded well tubing 1 with a light oil 80 coated on the male thread contact surface 400, the shoulder torque Ts can be kept low when the threaded well tubing 1 is screwed into and tightened into other threaded well tubing 1s. In addition, the tightening torque To can be maintained at a high level. Moreover, excellent resistance to sintering is exhibited due to the solid lubricating film formed on the female thread 50.

[0380] Example

[0381] The following describes an embodiment. However, the threaded well tubing of this embodiment is not limited to this embodiment. Unless otherwise specified, % in the embodiments represents mass%.

[0382] [Fabrication of threaded well tubing for tests 1-3]

[0383] Prepare threaded well tubing for tests 1-3. The threaded well tubing used is the T&C type threaded fitting 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. The tubing is made of carbon steel, equivalent to API 5CT standard P110, with a carbon content of 0.2% and a chromium content of 1.0%.

[0384] [Regarding the male thread contact surfaces of tests 1 and 2]

[0385] A zinc phosphate chemical conversion coating was formed on the male contact surfaces of test items 1 and 2. Specifically, the male contact surfaces were first mechanically ground for finishing. Then, a commercially available zinc phosphate treatment solution was used to perform a chemical conversion treatment using known methods to form a zinc phosphate chemical conversion coating.

[0386] The manufacturing method for the simulated oil well tubing connector involves first applying a rust-preventive grease to the zinc phosphate chemical conversion treatment coating of Test Nos. 1 and 2. Specifically, the product name "RUST VETO AS EU" is applied to the zinc phosphate chemical conversion treatment coating of Test Nos. 1 and 2. Two hours after application, the rust-preventive grease is removed using high-pressure water. At this point, the zinc phosphate chemical conversion treatment coating remains on the male thread contact surfaces of Test Nos. 1 and 2.

[0387] After removing the rust-preventive grease, a light oil is applied to the zinc phosphate chemical conversion coating. Specifically, the trade name "WD-40" is applied to the zinc phosphate chemical conversion coating of test numbers 1 and 2. WD-40 is sprayed from a position 500 mm away from the male thread contact surface. During spraying, the male thread is rotated around its central axis, and WD-40 is applied to the entire male thread contact surface. The threaded well tubing of test numbers 1 and 2 is manufactured using the above structure.

[0388] [Regarding the male thread contact surface of test number 3]

[0389] The male contact surface of test number 3 was coated with the same zinc phosphate chemical conversion treatment as test numbers 1 and 2. The manufacturing conditions for the zinc phosphate chemical conversion treatment coating were the same as those for test numbers 1 and 2.

[0390] A solid anti-rust coating is formed on a zinc phosphate chemical conversion treatment coating. The composition for forming the solid anti-rust coating is mainly composed of an acrylic resin-based UV-curable resin. The coated solid anti-rust coating composition is irradiated with ultraviolet light under known conditions to form a solid anti-rust coating with a thickness of approximately 20 μm. The obtained solid anti-rust coating is transparent.

[0391] [Regarding the female contact surfaces of test numbers 1-3]

[0392] On the female contact surfaces of test numbers 1 to 3, a Cu-Sn-Zn alloy coating with a thickness of approximately 8 μm was formed by a known electroplating process. The chemical composition of the Cu-Sn-Zn alloy coating is approximately 63% Cu, approximately 30% Sn, and approximately 7% Zn.

[0393] On a Cu-Sn-Zn alloy coating, a composition containing approximately 70% by mass of binder (mainly a mixture of resin and paraffin (mass ratio of approximately 4:3)), approximately 20% by mass of lubricant (earthy graphite, PTFE, etc.), approximately 7% by mass of rust inhibitor, and approximately 1% by mass of plasticizer is heated to 130°C, spray-coated, and cooled to form a solid lubricating film with a thickness of 50 μm.

[0394] A plurality of oil country tubular goods with threaded joints of test Nos. 1 to 3 are manufactured through the above manufacturing steps.

[0395] [Torque measurement test]

[0396] Using the oil country tubular goods with threaded joints of each test No., the torque during screw tightening (the screw tightening process) is measured, and Figure 20 the torque diagram shown is produced. Specifically, the tightening torque is gradually increased at a tightening speed of 10 rpm, and the test is ended when the material yields. Figure 20 Ts in represents the shoulder torque. Figure 20 MTV in represents the torque value at which line L intersects the torque diagram. Line L is a straight line that has the same slope as the linear region in the torque diagram after shouldering, and has a rotation number 0.2% higher than that of the linear region. In this embodiment, the yield torque Ty (the boundary between the linear region and the non-linear region in the torque diagram after shouldering) is unclear, so line L is used to define MTV, and MTV is used as an index instead of the yield torque Ty. The diagram related to the torque values of test Nos. 1 to 3 is shown in Figure 2 . In Figure 2 , with the shoulder torque of test No. 3 set as 100, the shoulder torque and shoulder torque resistance ΔT of each test No. are shown. In Figure 2 the bar chart of each test No. in, the upper end of the shaded part represents the shoulder torque Ts value, and the upper end of the blank part represents the MTV value.

[0397] [Galling resistance evaluation test]

[0398] Galling resistance evaluation is carried out by repeated tightening tests. Using the pin and box of test No. 1 and test No. 3, repeated screw tightening and unscrewing are carried out at room temperature (20°C) to evaluate galling resistance. The tightening torque is set to 24350 ft.lbs. After each time of screw tightening and unscrewing, the contact surface of the pin and the contact surface of the box are visually observed. The occurrence of galling in the threaded part and the metal seal part is confirmed by visual observation. The test is ended when galling occurs in the metal seal part. When the galling in the threaded part is slight and can be repaired by maintenance with a file or the like, the galling defect is repaired and the test is continued. The maximum number of repeated tightenings is set to 5 times. When no unrecoverable galling occurs in the threaded part and no galling occurs in the metal seal part after the maximum number of repeated tightenings, the sample is determined as qualified (marked as E (excellent) in Table 1).

[0399] Outdoor exposure test]

[0400] A protector of the same shape is installed on the pin of the oil country tubular goods with threaded joint of test No. 1 to 3, and left outdoors for 6 weeks. After being left for 6 weeks, the presence or absence of rust on the pin contact surface of each test No. is confirmed visually. When no rust is confirmed, it is rated as pass (marked as E (excellent) in Table 1).

[0401] [Evaluation Results]

[0402] The test results are shown in Figure 2 and Table 1.

[0403] [Table 1]

[0404] Table 1

[0405]

[0406] See Figure 2 , in the oil country tubular goods with threaded joint of test No. 1 and test No. 2, compared with the conventional oil country tubular goods with threaded joint of test No. 3, the shoulder torque Ts is reduced. Moreover, the MTV of test No. 1 and 2 is at the same level as the MTV of test No. 3.

[0407] In addition, referring to Table 1, all the oil country tubular goods with threaded joint of test No. 1 to 3 have excellent galling resistance. Moreover, no rust was confirmed in the outdoor exposure test for any of the oil country tubular goods with threaded joint of test No. 1 to 3, and all have excellent corrosion resistance.

[0408] The embodiments of the present invention have been described above. 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 appropriate modifications can be made to the above-described embodiments for implementation without departing from the scope of the gist of the present invention.

[0409] Explanation of reference numerals in the attached figures

[0410] 1, Oil country tubular goods with threaded joint; 10, Pipe body; 10A, First end; 10B, Second end; 11, Pin tube body; 12, Coupling; 40, 40A, Pin; 41, External threaded portion; 42, Pin sealing surface; 43, Pin shoulder surface; 50, Box; 51, Internal threaded portion; 52, Box sealing surface; 53, Box shoulder surface; 60, Solid lubricating coating; 80, Light oil; 200, Oil country tubular goods with threaded joint; 400, Pin contact surface; 500, Box contact surface.

Claims

1. A threaded well pipe, which is a threaded well pipe capable of being fastened to other threaded well pipes, wherein, The threaded well tubing includes a tubing body, which comprises a first end and a second end. The tube body comprises: A male thread, formed at the first end, is inserted into the female thread of the other threaded well tubing during tightening to secure it; and A female thread, formed at the second end, is inserted into and fastened with the male thread of the other threaded well tubing during tightening. The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. During tightening, the male thread contact surface contacts the female thread of the other threaded well pipe. A light oil is applied to the male contact surface. The female buckle includes: The female thread contact surface includes at least an internal thread portion formed on the inner circumferential surface of the second end of the pipe body, and during the tightening, the female thread contact surface contacts the male thread contact surface of the male thread of the other threaded well pipe. as well as A solid lubricating coating is formed on the female contact surface.

2. The oil well pipe with threaded joint according to claim 1, wherein, The male fastening contact surface further includes: A male thread sealing surface, formed in the outer peripheral surface of the first end at a position closer to the tip of the external thread; and The male buckle shoulder surface is located at the top of the first end. The female contact surface further includes: A female thread sealing surface, formed in the inner circumferential surface of the second end at a position closer to the center than the internal thread portion; and The female buckle shoulder surface is located at the second end, at a position closer to the center than the female buckle sealing surface.

3. The oil well pipe with threaded joint according to claim 1 or 2, wherein, The male buckle also includes a chemically converted coating formed on the male buckle contact surface. The light oil is applied to the chemically converted coating.

4. The oil well pipe with threaded joint according to claim 3, wherein, In the chemical composition of the oil well pipe with threaded joint, the Cr content is less than 2.0% by mass.

5. The oil well pipe with threaded joint according to any one of claims 1 to 4, wherein, The female buckle also includes a plating film formed on the contact surface of the female buckle. The solid lubricating coating is formed on the coated film.

6. An oil well pipe with a threaded joint, wherein, The threaded well tubing includes a tubing body, which comprises a first end and a second end. The pipe body includes: Male buckle, which is formed at the first end; and The female buckle, which is formed at the second end, The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. The male contact surface is coated with anti-rust lubricating grease. The female buckle includes: The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and A solid lubricating coating is formed on the female contact surface.

7. The oil well pipe with threaded joint according to claim 6, wherein, The male fastening contact surface further includes: A male thread sealing surface, formed in the outer peripheral surface of the first end at a position closer to the tip of the external thread; and The male buckle shoulder surface is located at the top of the first end. The female contact surface further includes: A female thread sealing surface, formed in the inner circumferential surface of the second end at a position closer to the center than the internal thread portion; and The female buckle shoulder surface is located at the second end, at a position closer to the center than the female buckle sealing surface.

8. The oil well pipe with threaded joint according to claim 6 or 7, wherein, The male buckle also includes a chemically converted coating formed on the male buckle contact surface. The rust-preventive grease is applied to the chemically converted coating.

9. The oil well pipe with threaded joint according to claim 8, wherein, In the chemical composition of the oil well pipe with threaded joint, the Cr content is less than 2.0% by mass.

10. The oil well pipe with threaded joint according to any one of claims 6 to 9, wherein, The female buckle also includes a plating film formed on the contact surface of the female buckle. The solid lubricating coating is formed on the coated film.

11. The oil well pipe with threaded joint according to any one of claims 6 to 10, wherein, The threaded well tubing also includes a protective element that covers and secures the male thread. The protective component includes: The cylindrical portion has an internal thread formed on its inner circumferential surface; and A cover portion, which is disposed at one end of the cylindrical portion, The distance D1 between the thread root of the external thread of the male thread and the thread tooth of the internal thread of the cylindrical part of the protective member is longer than the distance D2 between the thread tooth of the external thread of the male thread and the thread root of the internal thread of the cylindrical part of the protective member. The thickness T1 of the anti-rust grease between the thread root of the external thread of the male thread and the thread tooth of the internal thread of the cylindrical part of the protective member is thicker than the thickness T2 of the anti-rust grease between the thread tooth of the external thread of the male thread and the thread root of the internal thread of the cylindrical part of the protective member.

12. A method for manufacturing an oil well pipe connector, wherein the oil well pipe connector is formed by fastening multiple oil well pipes with threaded joints, wherein... The manufacturing method of this oil well pipe connector includes an oil well pipe preparation step, in which an oil well pipe with a threaded joint is prepared. The threaded well tubing includes a tubing body, which comprises a first end and a second end. The tube body comprises: Male buckle, which is formed at the first end; and The female buckle, which is formed at the second end, The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. The male contact surface is coated with anti-rust lubricating grease. The female buckle includes: The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and A solid lubricating film is formed on the female contact surface. The manufacturing method of the oil well pipe connector also includes the following steps: The threaded well pipe is transported to the site, which serves as a temporary storage location for the threaded well pipe. The threaded well pipe delivered to the site will be temporarily stored at the site. Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connector, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed. The threaded well pipe with the light oil coated on the male contact surface is delivered to the well excavation site. as well as In the oil well excavation site, a threaded well pipe with the light oil coated on the male contact surface is fastened to other threaded well pipes to form an oil well pipe connector.

13. A method for manufacturing an oil well pipe with a threaded joint, wherein, The manufacturing method of the threaded well pipe includes the process of temporarily storing the delivered threaded well pipe at the site. The threaded well tubing includes a tubing body, which comprises a first end and a second end. The tube body comprises: Male buckle, which is formed at the first end; and The female buckle, which is formed at the second end, The male thread includes a male thread contact surface, which at least includes an external thread portion formed on the outer peripheral surface of the first end of the pipe body. The male contact surface is coated with anti-rust lubricating grease. The female buckle includes: The female contact surface includes at least an internal thread formed on the inner circumferential surface of the second end of the tube body; and A solid lubricating film is formed on the female contact surface. The manufacturing method of the oil well pipe with threaded joint also includes the following steps: Before transporting the threaded well pipe, which is temporarily stored at the site, to the well excavation site forming the well pipe connection, the rust-preventive grease applied to the male thread contact surface of the threaded well pipe is removed, and light oil is applied to the male thread contact surface after the rust-preventive grease has been removed.

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