A casing coupling with continuous multi-segment sealing structure

Abstract

This invention discloses an oil casing joint with a continuous multi-segment sealing structure, including a male end and a mating female end. The male end has an external thread on its outer diameter and a torque shoulder I at its end. A multi-segment sealing structure I is provided on the outer diameter of the male end between the external thread and the torque shoulder I. The female end has an internal thread on its inner diameter and a torque shoulder II at its end. A multi-segment sealing structure II is provided on the inner diameter of the female end between the internal thread and the torque shoulder II. The external thread and the internal thread are meshed, and the multi-segment sealing structure I and the multi-segment sealing structure II are interference fits. This invention is intended to meet the needs of oil and gas extraction.

Description

Technical Field

[0001] This invention relates to the field of oil pipe technology, and more specifically, to an oil casing joint having a continuous multi-segment sealing structure. Background Technology

[0002] The casing and tubing, connected by joints, form a conduit connecting oil and gas resources thousands of meters underground to the surface. The casing and tubing joint is the weakest link in the entire tubing string. With advancements in petroleum exploration and drilling technology, deep wells, ultra-deep wells, high-temperature wells, and highly corrosive wells are increasingly being developed, necessitating increasingly stringent requirements for casing and tubing connections. The integrity of the joint's seal under complex load conditions, including high tension, high internal pressure, high temperature, high compression, high bending, and high fatigue, is crucial, and traditional sealing casing and tubing joints cannot meet these requirements. ISO 13679-2002, "Test Procedures for Threaded Connections of Casing and Tubing in the Oil and Gas Industry," proposes an evaluation scheme for casing and tubing joints. The standard emphasizes the seal integrity of the joint under tensile and compressive conditions. To meet even higher performance requirements for casing and tubing joints, API published API RP 5C5-2017 in 2017, and ISO 13679 was subsequently updated to the 2019 version. Both standards share the characteristic of imposing more stringent design requirements on joints under high temperature and multiple cycles, which most traditional sealing casing and tubing joints cannot satisfy.

[0003] Threaded joints for oil casing are generally divided into ordinary API joints and gas-tight special threaded joints. The former is mainly used in crude oil extraction and does not have stable gas-tight sealing capabilities, unlike the technology of this invention. The latter, the gas-tight special threaded joint 1, generally refers to a joint composed of threads 2, a metal sealing surface 3, a torque shoulder 4, etc., to meet the joint's sealing and other performance requirements. Figure 1 As shown.

[0004] In existing patent applications, such as 99240437.1, 99240438.X, 01253367.X, 02209453.9, 02257690.8, 200420059633.1, 200720096474.6, 200720027706.2, 200720027707.7, 200720199432.5, 200920154275.5, 201 Designs such as 020013334.X, 200920277215.2, 201020254008.8, 00249827.8, 201020506375.2, 201120037927.4, 97115288.8, 386953, CN102011557A, and CN102071881A are all based on single-structure seals and cannot meet the requirements of existing standards or application conditions. Summary of the Invention

[0005] To address the aforementioned deficiencies in the existing technology, the purpose of this invention is to provide an oil casing joint with a continuous multi-segment sealing structure to meet the needs of oil and gas extraction.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An oil casing fitting with a continuous multi-segment sealing structure includes a male end and a female end adapted thereto;

[0008] The male end has an external thread on its outer diameter, and the end of the male end is a torque shoulder I. The outer diameter of the male end between the external thread and the torque shoulder I is provided with a multi-segment sealing structure I.

[0009] The inner diameter of the female end is provided with an internal thread, the end of the female end is a torque shoulder II, and the inner diameter of the female end between the internal thread and the torque shoulder II is provided with a multi-segment sealing structure II.

[0010] The external thread and the internal thread are meshed, and the multi-segment sealing structure I and the multi-segment sealing structure II are interference fit.

[0011] Preferably, both the external thread and the internal thread are threads with a negative load angle.

[0012] Preferably, the outer diameter D of the male end is 40 to 400 mm.

[0013] Preferably, the pitch and thread height h1 of the external thread are set as follows:

[0014] When the outer diameter D of the male end is less than 74mm, the pitch is 3.175mm and the thread height h1 is 0.8 to 1.2mm;

[0015] When the outer diameter D of the male end is less than 74-114 mm, the pitch is 4.233 mm and the thread height h1 is 1.0-1.3 mm.

[0016] When the outer diameter D of the male end is less than 115-220mm, the pitch is 6.35mm and the thread height h1 is 1.5-1.8mm;

[0017] When the outer diameter D of the male end is less than 221-400mm, the pitch is 6.35mm and the thread height h1 is 2.0-2.5mm.

[0018] Preferably, the pitch of the internal thread is the same as the pitch of the external thread;

[0019] The difference between the thread height h2 of the internal thread and the thread height h1 of the external thread is 0.1 to 0.4 mm.

[0020] Preferably, the multi-segment sealing structure I includes an arc segment I, a straight segment I, and an arc segment II arranged sequentially from the torque shoulder I to the external thread direction.

[0021] Preferably, the radius of the arc segment I is R1≤2.0mm, the radius of the arc segment II is R2 is 3~10mm, and the angle α1 between the straight segment I and the horizontal axis of the male end is 10~40°.

[0022] Preferably, the multi-segment sealing structure II includes an arc segment III, a straight segment II, and an arc segment IV arranged sequentially from the torque shoulder II to the internal thread direction.

[0023] Preferably, the radius of the arc segment III is R3≤3.0mm, the radius of the arc segment IV is R4 is 3~15mm, and the angle α2 between the straight segment II and the horizontal axis of the mother end is 10~40°.

[0024] Preferably, the wall thickness t of the male end satisfies t / D≤12% and t≤20mm;

[0025] D is the diameter of the male end; and / or

[0026] The difference between the inner diameter of the torque shoulder I and the torque shoulder II and D-2t is between -2.0 and 1.0.

[0027] The oil casing joint with a continuous multi-segment sealing structure provided by the present invention has the following beneficial effects:

[0028] 1) The sleeve should not stick during multiple uncoupling processes (nine times for D < 120mm, three times for D ≥ 120mm);

[0029] 2) The tensile, internal pressure, and external extrusion properties of the joint shall not be lower than those of the pipe body itself;

[0030] 3) The joint sealing capacity is the same as the internal pressure of the pipe, and the joint bending can reach 20° / 30m;

[0031] 4) The connector meets the evaluation requirements of API RP 5C5-2017. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of an existing gas-tight special threaded joint;

[0033] Figure 2 This is a schematic diagram of the male end of the oil casing joint of the present invention;

[0034] Figure 3 yes Figure 2 Schematic diagram of the multi-segment sealing structure I;

[0035] Figure 4 This is a schematic diagram of the female end of the oil casing joint of the present invention;

[0036] Figure 5 yes Figure 4 Schematic diagram of the multi-segment sealing structure II;

[0037] Figure 6 This is a schematic diagram of the cooperation between the multi-segment sealing structure I and the multi-segment sealing structure II in the oil casing joint of the present invention;

[0038] Figure 7 This is a schematic diagram of the thickness of torque shoulder I and torque shoulder II in the oil casing joint of the present invention. Detailed Implementation

[0039] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] Combination Figures 2 to 5 As shown, the oil casing joint with a continuous multi-segment sealing structure provided by the present invention includes a male end 100 and a female end 200 adapted thereto.

[0041] The male end 100 has an external thread 5 on its outer diameter, and the end of the male end 100 is a torque shoulder I6. The male end 100 between the external thread 5 and the torque shoulder I6 has a multi-segment sealing structure I7 on its outer diameter.

[0042] The inner diameter of the female end 200 is provided with an internal thread 8, and the end of the female end is a torque shoulder II9. The inner diameter of the female end 200 between the internal thread 8 and the torque shoulder II9 is ​​provided with a multi-segment sealing structure II10.

[0043] The outer diameter D of the male end 100 ranges from 40 to 400 mm, and the wall thickness t satisfies t / D≤12% and t≤20 mm.

[0044] External thread 5 is a thread with a negative load angle. Its pitch and thread height h1 are adjusted according to different outer diameters D, as follows:

[0045] When the outer diameter D of the male end 100 is less than 74mm, the pitch is 3.175mm and the thread height h1 is 0.8~1.2mm;

[0046] When the outer diameter D of the male end 100 is less than 74-114mm, the pitch is 4.233mm and the thread height h1 is 1.0-1.3mm;

[0047] When the outer diameter D of the male end 100 is less than 115-220mm, the pitch is 6.35mm and the thread height h1 is 1.5-1.8mm;

[0048] When the outer diameter D of the male end 100 is less than 221-400mm, the pitch is 6.35mm and the thread height h1 is 2.0-2.5mm.

[0049] The multi-segment sealing structure I7 includes an arc segment I11, a straight segment I12, and an arc segment II13 arranged sequentially from the torque shoulder I6 to the external thread 5.

[0050] The radius of the arc segment I11 is R1≤2.0mm, the radius of the arc segment II13 is R2 is 3~10mm, and the angle α1 between the straight segment I12 and the horizontal axis of the male end 100 is 10~40°.

[0051] The internal thread 8 is also a thread with a negative load angle. Its pitch is the same as that of the external thread. The difference between the thread height h2 of the internal thread and the thread height h1 of the external thread is 0.1 to 0.4 mm.

[0052] The segment sealing structure II10 includes an arc segment III14, a straight segment II15, and an arc segment IV16 arranged sequentially from the torque shoulder II9 to the internal thread 8.

[0053] The radius of the arc of arc segment Ⅲ14 is R3≤3.0mm, the radius of the arc of arc segment Ⅳ16 is R4 is 3~15mm, and the angle α2 between straight segment Ⅱ15 and the horizontal axis of the mother end 200 is 10~40°.

[0054] In this invention, the external thread 5 and the internal thread 8 of the oil casing joint are meshed, and the multi-segment sealing structure I7 and the multi-segment sealing structure II10 are interference fit, thereby achieving complete sealing performance.

[0055] Oil casing and tubing are connected by a joint to bring high-pressure natural gas, oil-water mixtures, and other products from thousands of meters underground to the surface, requiring reliable sealing integrity. Oil casing and tubing are collectively referred to as tubing and casing. Generally, steel pipes with a diameter (D) of less than 120mm used for gas production are used as tubing, while steel pipes with a diameter (≥120mm) used for drilling and cementing are used as casing. The biggest difference between the two in application is the number of times they can be reused. Tubing requires a higher number of reuses, generally nine or more times for threading and unthreading, while casing requires three or more. The pitch design of the external thread 5 of this invention's oil casing and tubing joint effectively improves the thread's anti-adhesion performance; the unequal tooth height design between the internal thread 8 and the external thread 5 allows for filling the unequal tooth height areas with thread grease after screwing, effectively preventing thread adhesion; the main structures of the multi-segment sealing structure I7 and multi-segment sealing structure II10 are conical interference and intermediate arc interference, which effectively improve anti-adhesion capabilities.

[0056] The thread pitch of the oil casing joint of this invention is highly innovative. For casings with an outer diameter >115mm, a 6.35mm thread pitch (4TPI) is used, which significantly increases the tightening speed during casing use and reduces the risk of adhesion. Correspondingly, to ensure the integrity of the connection and the resulting seal, different tooth heights are used for different outer diameter segments.

[0057] Combination Figure 6 As shown, after the male end 100 and the female end 200 are screwed together, the multi-segment sealing structure I7 of the male end 100 and the multi-segment sealing structure II10 of the female end 200 are engaged in corresponding positions. At this time, the arc of the arc segment III14 is larger than the arc of the arc segment I11, forming a gap for storing thread grease after screwing. The straight segment I12 and the straight segment II15 are a conical surface sealing interference. The diameter of the straight segment I12 is smaller than the diameter of the straight segment II15, thus forming an interference to ensure sealing capability. Similarly, the arc segment IV16 and the arc segment II13 are also connected, with an arc interference near the straight segment II15. At the same time, a gap is formed on the right side of the arc segment IV16 and the arc segment II13 for storing thread grease.

[0058] Combination Figure 7 As shown, in order to ensure sufficient strength of the sealing end, the torque shoulder I6 and torque shoulder II9 need to have sufficient thickness. Therefore, in the design, the diameter of torque shoulder I6 and torque shoulder II9 should be as small as possible. The difference between the inner diameter of torque shoulder I6 and torque shoulder II9 of the oil casing joint of the present invention and D-2t is between -2.0 and 1.0, where D is the outer diameter of male end 100 and t is the wall thickness of male end 100.

[0059] Example

[0060]

[0061] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A casing coupling having a continuous multi-segment seal, characterized by: The male end and the female end are adapted to each other; An outer thread is arranged on the outer diameter of the male end, and an end of the male end is a torque shoulder I, a plurality of sealing structures I are arranged on the outer diameter of the male end between the outer thread and the torque shoulder I; An inner thread is arranged on the inner diameter of the female end, and an end of the female end is a torque shoulder II, a plurality of sealing structures II are arranged on the inner diameter of the female end between the inner thread and the torque shoulder II; The outer thread and the inner thread are in meshing engagement, and the plurality of sealing structures I and the plurality of sealing structures II are in interference fit, The outer thread and the inner thread are both threads with negative load angles, The outer diameter D of the male end is 40-400 mm, The pitch and the thread height h1 of the outer thread are set as follows: When the outer diameter D of the male end is less than 74 mm, the pitch is 3.175 mm, and the thread height h1 is 0.8-1.2 mm; When the outer diameter D of the male end is less than 74-114 mm, the pitch is 4.233 mm, and the thread height h1 is 1.0-1.3 mm; When the outer diameter D of the male end is less than 115-220 mm, the pitch is 6.35 mm, and the thread height h1 is 1.5-1.8 mm; When the outer diameter D of the male end is less than 221-400 mm, the pitch is 6.35 mm, and the thread height h1 is 2.0-2.5 mm, The pitch of the inner thread is the same as the pitch of the outer thread; The difference between the thread height h2 of the inner thread and the thread height h1 of the outer thread is 0.1-0.4 mm, The plurality of sealing structures I include a circular arc segment I, a straight line segment I and a circular arc segment II arranged in sequence from the torque shoulder I to the outer thread, The circular arc radius R1 of the circular arc segment I is ≤2.0 mm, the circular arc radius R2 of the circular arc segment II is 3-10 mm, and the included angle α1 between the straight line segment I and the horizontal axis of the male end is 10-40°, The plurality of sealing structures II include a circular arc segment III, a straight line segment II and a circular arc segment IV arranged in sequence from the torque shoulder II to the inner thread, The circular arc radius R3 of the circular arc segment III is ≤3.0 mm, the circular arc radius R4 of the circular arc segment IV is 3-15 mm, and the included angle α2 between the straight line segment II and the horizontal axis of the female end is 10-40°.

2. The oil casing joint with continuous multi-segment seal structure according to claim 1, characterized in that: The wall thickness t of the male end satisfies t / D≤12%, and t≤20 mm; D is the diameter of the male end; and / or The difference between the inner diameter of the torque shoulder I and the torque shoulder II and D-2t is between -2.0 and 1.0.

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