Anti-stick oil casing gas sealing threaded connection joint

Abstract

A gas-tight threaded connection joint for oil casing and casing that prevents galling, comprising a first connection piece and a second connection piece wrapped around the outside thereof, wherein the contact surface of the first connection piece comprises an external thread contact area and an external shoulder contact area, and the contact surface of the second connection piece comprises an internal thread contact area and an internal shoulder contact area, the threads of the external thread contact area and the internal thread contact area are fitted together by buckling, and the internal and external thread sealing areas of the internal thread contact area and the external thread sealing area of the external thread contact area are buckled together for interference contact. Compared with the prior art, the technical effect of the present invention is that the present invention optimizes the connection parameters of the threaded connection joint, effectively reduces the stress concentration factor by more than 80%, and effectively improves the anti-galling ability of the thread.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas development, and in particular to well completion technology and production tubing (including casing and tubing). Specifically, the present invention relates to a special gas-tight threaded joint that ensures safe and efficient development of high-temperature, high-pressure and unconventional gas wells. Background Art

[0002] The threaded connections for oil and gas development, production, completion, casing, and tubing are used in complex and demanding environments, including:

[0003] The make-up operation environment at the oil field site includes wind and sand, grouting during the downhole process, collisions during transportation and make-up, rotation during downhole cementing, and high temperature and high pressure loads during production and gas extraction, all of which are major factors causing threaded connection seal failure.

[0004] Therefore, it is necessary to develop high-performance anti-pollution and anti-seizing gas-sealed special threaded connections that meet the oil field production environment, which is an important prerequisite for ensuring safe and efficient production in oil fields.

[0005] To this end, patent document No. 103397853A discloses a special airtight threaded joint structure for a casing.

[0006] The problems existing in existing airtight special threaded connections are as follows:

[0007] 1. The development goal of special threaded connections for oil casing and tubing, both on the market and in patent applications, is to meet the envelope limit load cycle test specified in ISO 13679, a performance testing standard recognized by the international oil industry, and to provide excellent airtightness under tension / compression, bending, internal / external pressure, and high-temperature environments. However, these connections fail to consider the operating environment, specifically the field operating requirements.

[0008] 2. The structural characteristics of existing special thread structures for gas seals are as follows: the threads all adopt the improved stepped thread type specified in the API 5B standard, with an external thread tooth height of 1.575mm and an internal thread tooth height of 1.775mm. The disadvantage is that they are not suitable for thin-walled, high-performance special thread connections for gas seals. Due to the large tooth height, the effective wall thickness from the tooth bottom to the inner wall and the end sealing surface is reduced when using thin-walled special tapered threads for gas seals, causing the sealing surface to be easily deformed and reducing the compression and over-torque resistance.

[0009] 3. The special thread structure characteristics of existing air seals are: the sealing surface is located 1 to 4 mm from the nose of the external thread, and a cone-to-spherical surface or cone-to-cone surface sealing structure is used. During on-site operations in the oil field, if the internal thread surface of the downhole grouting coupling is contaminated with mud, the make-up process causes the accumulation of contaminants on the sealing surface, resulting in thread puncture and failure during high internal pressure production. Summary of the Invention

[0010] The technical problem to be solved by the present invention is how to design an anti-galling gas-tight threaded connection joint for oil casing with good anti-galling effect, achieve anti-pollution and anti-seal during oilfield operations (preventing sealing surface contamination caused by grouting) and anti-bruising (preventing bruising during bolting operations), and meet international standard indicators (high compression resistance to achieve 100% compression of the pipe body and torque resistance (twice the optimal torque for conventional bolting)) and the development requirements of high-temperature and high-pressure gas wells and horizontal wells in oil fields.

[0011] The technical solution of the present invention is specifically as follows:

[0012] A gas-tight threaded connection joint for oil casing and casing with an anti-sticking effect comprises a first connecting piece and a second connecting piece wrapped around the outside thereof, wherein the contact surface of the first connecting piece comprises an external thread contact area and an external shoulder contact area, and the contact surface of the second connecting piece comprises an internal thread contact area and an internal shoulder contact area, the threads of the external thread contact area and the internal thread contact area are matched by buckling, the internal and external thread sealing areas of the internal thread contact area and the external thread sealing area of the external thread contact area are buckled in interference contact, and the external shoulder contact area and the internal shoulder contact area are in interference contact; the arc radius of the bearing surface at the bottom of the external thread tooth on the rear side of the external thread tooth of the external thread contact area is 0.15 to 0.35 mm, and the arc radius of the bearing surface at the top of the external thread tooth of the external thread tooth is 0.25~0.45mm, the load-bearing surface flank angle of the rear side of the external thread tooth is 1.65°~4.65°, the load-bearing surface arc radius at the internal thread tooth bottom on the rear side of the internal thread tooth in the internal thread contact area is 0.35~0.55mm, the load-bearing surface arc radius at the internal thread tooth top on the rear side of the internal thread tooth is 0.3~0.7mm, the load-bearing surface flank angle on the rear side of the internal thread tooth is 0.65°~3.65°, the load-bearing surface arc radius at the internal thread tooth bottom is 1.5-2 times the load-bearing surface arc radius at the external thread tooth bottom, the load-bearing surface arc radius at the internal thread tooth top is 1.5-2 times the load-bearing surface arc radius at the external thread tooth top, and the angle of the external tooth flank angle is greater than that of the internal tooth flank angle.

[0013] The external thread width of the external thread teeth in the external thread contact area is 1.495~3.629mm, the external thread groove width of the external thread teeth is 1.51~3.644mm, the internal thread groove width of the internal thread teeth in the internal thread contact area is 1.525~3.659mm, the internal thread width of the internal thread teeth is 1.48~3.614mm, and the gap between the tooth width and the tooth groove after buckling is between 0.015~0.05mm.

[0014] The arc radius of the guide surface at the external thread bottom on the front side of the external thread tooth in the external thread contact area is 0.25~0.40mm, the arc radius of the guide surface at the external thread top on the front side of the external thread tooth is 0.3~0.5mm, and the guide surface side angle of the front side of the external thread tooth 101 is 8°~13°. The arc radius of the guide surface at the internal thread bottom on the front side of the internal thread tooth in the internal thread contact area is 0.25~0.45mm, the arc radius of the guide surface at the internal thread top on the rear side of the internal thread tooth is 0.5~0.65mm, and the guide surface side angle on the rear side of the internal thread tooth is 10°~15°.

[0015] The external thread height of the external thread teeth in the external thread contact area is 1.05~1.555mm, the height from the median diameter to the tooth bottom is 0.65~0.85mm, the height from the median diameter to the tooth top is 0.4~0.705mm, and the height from the median diameter to the tooth bottom is greater than the height from the median diameter to the tooth top; the external thread height of the internal thread teeth in the internal thread contact area is 1.15~1.805mm, the height from the median diameter to the tooth bottom is 0.65~0.85mm, the height from the median diameter to the tooth top is 0.5~0.955mm, and the height from the median diameter to the tooth bottom is greater than the height from the median diameter to the tooth top.

[0016] The outer shoulder contact area includes a primary sealing area and a secondary sealing area. The secondary sealing area is the first side surface of the outer shoulder contact area, and the sealing area includes the second side surface of the outer shoulder contact area and its first adjacent area and second adjacent area; the inner shoulder contact area includes a primary sealing area and a secondary sealing area. The secondary sealing area is the first side surface of the inner shoulder contact area, and the sealing area includes the second side surface of the inner shoulder contact area and its first adjacent area and second adjacent area; the shoulder angle of the first side surface of the outer shoulder contact area is the same as the shoulder angle of the first side surface of the inner shoulder contact area, both of which are between 0.5° and 16.5°.

[0017] The shoulder angle of the second side of the outer shoulder contact area is the same as that of the second side of the inner shoulder contact area, both of which are between 8° and 15°;

[0018] The ratio of the projected length of the second side surface of the outer shoulder contact area to the projected length of the main sealing area of the outer shoulder contact area is between 0.216 and 0.266, and the ratio of the projected length of the second side surface of the inner shoulder contact area to the projected length of the main sealing area of the inner shoulder contact area is between 0.216 and 0.266, and the two ratios are equal.

[0019] The included angle between the second adjacent area of the outer shoulder contact area and the oil pipe axis is between 8° and 15°, the included angle between the second adjacent area of the inner shoulder contact area and the oil pipe axis is between 8° and 15°, and the two included angles are equal.

[0020] The distance from the second adjacent area of the outer shoulder contact area to the shoulder and the thread end is 9 to 20 mm, and the distance from the second adjacent area of the inner shoulder contact area to the shoulder and the thread end is 9 to 20 mm.

[0021] The arc radius of the sealing surface of the second adjacent area of the inner shoulder contact area and the arc radius of the left connecting area of the second adjacent area of the inner shoulder contact area are 2.0-10 mm, which match the conical surface of the left connecting area of the second adjacent area of the outer shoulder contact area.

[0022] The angle between the first adjacent area of the inner shoulder contact area and the oil pipe axis is between 0° and 5°, and the angle between the first adjacent area of the outer shoulder contact area and the oil pipe axis is between 0° and 5°; the projected length of the sum of the main sealing area and the left connecting area of the inner shoulder contact area is 10 to 20 mm, and the projected length of the sum of the main sealing area and the left connecting area of the outer shoulder contact area is 10 to 20 mm, so as to ensure that the main seal design is away from the shoulder end face and the shoulder support surface length to achieve the anti-sticking purpose under over-torque and compression load.

[0023] Compared with the prior art, the technical effect of the present invention is that the present invention optimizes the joint parameters of the threaded connection joint, effectively reduces the stress concentration factor by more than 80%, and effectively improves the anti-galling ability of the thread. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional schematic diagram of the present invention.

[0025] Figure 2 It is an enlarged schematic diagram of the thread teeth of the first connecting member.

[0026] Figure 3 It is an enlarged schematic diagram of the shoulder of the first connecting member.

[0027] Figure 4 This is an enlarged schematic diagram of the thread teeth of the second connecting member.

[0028] Figure 5 This is an enlarged schematic diagram of the shoulder of the second connecting member.

[0029] Figure 6 It is a three-dimensional cross-sectional schematic diagram of the present invention.

[0030] Figure 7 This is a high-temperature envelope load diagram for the airtight thread engineering of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments thereof.

[0032] Note: In this manual, the threads, thread teeth, and shoulders located on the inner surface of the component are called internal threads, internal thread teeth, and inner shoulders, and the threads, thread teeth, and shoulders located on the outer surface of the component are called external threads, external thread teeth, and outer shoulders.

[0033] In this manual, the side close to the shoulder ( Figure 1 The right side of the platform is the front, away from the shoulder side ( Figure 1 The left side of the ) is the rear.

[0034] like Figure 1-6 A gas-tight threaded connection joint for oil casing and casing with anti-sticking includes a first connection piece 100 and a second connection piece 200 wrapped around the outside thereof. The contact surface of the first connection piece includes an external thread contact area 1 and an external shoulder contact area 2. The contact surface of the second connection piece includes an internal thread contact area 3 and an internal shoulder contact area 4. The threads of the external thread contact area 1 and the internal thread contact area 3 are matched by buckling to achieve the yield strength of the pipe body under tensile load, thereby preventing the threaded connection from being disengaged.

[0035] like Figure 1 The internal and external thread sealing areas of the internal thread contact area 3 are in interference contact with the external thread sealing area of the external thread contact area 1, and the external shoulder contact area 2 is in interference contact with the internal shoulder contact area 4, achieving sealing integrity under tension / compression + internal pressure / external pressure + over-torque + bending load.

[0036] See also Figure 2 、 4The radius of the load-bearing surface arc 1g at the external thread tooth bottom on the rear side of the external thread tooth 101 in the external thread contact area 1 is 0.15~0.35mm, the radius of the load-bearing surface arc 1h at the external thread tooth top of the external thread tooth 101 is 0.25~0.45mm, and the load-bearing surface flank angle (see reference numeral 1a) of the rear side of the external thread tooth 101 is 1.65°~4.65°. The radius of the load-bearing surface arc 3h at the internal thread tooth bottom on the rear side of the internal thread tooth 312 in the internal thread contact area 3 is 0.35~0.55mm, the radius of the load-bearing surface arc 3g at the internal thread tooth top on the rear side of the internal thread tooth 312 is 0.3~0.7mm, and the load-bearing surface flank angle (see reference numeral 3a) on the rear side of the internal thread tooth 312 is 0.65°~3 .65°, the radius of the load-bearing arc 3h at the bottom of the internal thread is 1.5-2 times the radius of the load-bearing arc 1g at the bottom of the external thread, the radius of the load-bearing arc 3g at the top of the internal thread is 1.5-2 times the radius of the load-bearing arc 1h at the top of the external thread, the angle of the external tooth side angle 1a is greater than the angle of the internal tooth side angle 3a. After finite element optimization analysis, this design effectively reduces the stress concentration factor by more than 80%, effectively improves the thread's anti-galling ability, and the application effect is shown in the specific implementation. The thread is made and unfastened 10 times with the maximum torque without galling; the external thread load-bearing surface angle is greater than the internal thread load-bearing surface angle, which is verified by experiments to facilitate the fastening and formation of micro-gap to eliminate contaminants in the thread while ensuring the effective tensile bearing area.

[0037] See also Figure 2 、 4 The external thread tooth width 1b of the external thread tooth 101 in the external thread contact area 1 is 1.495~3.629mm, the external thread groove 1c width of the external thread tooth 101 is 1.51~3.644mm, the internal thread groove 3b width of the internal thread tooth 312 in the internal thread contact area 3 is 1.525~3.659mm, the internal thread tooth width 3c width of the internal thread tooth 312 is 1.48~3.614mm, and the gap between the tooth width and the groove after buckling is between 0.015~0.05mm. This design effectively realizes the thread buckle resistance to over-torque. Under the condition of 0.005~0.01 circle interference of the shoulder at the end of the thread buckle, the thread guide surface contacts, effectively improving the thread's anti-sticking over-torque ability. The application effect is shown in the table below.

[0038] See also Figure 2 、 4The radius of the guide surface arc 1e at the external thread bottom of the front side of the external thread tooth 101 in the external thread contact area 1 is 0.25~0.40mm, the radius of the guide surface arc 1i at the external thread top of the front side of the external thread tooth 101 is 0.3~0.5mm, and the guide surface tooth side angle (see the reference numeral 1d) of the front side of the external thread tooth 101 is 8°~13°. The radius of the guide surface arc 3i at the internal thread bottom on the front side of the internal thread tooth 312 in the internal thread contact area 3 is 0.25~0.45mm, the radius of the guide surface arc 3e at the internal thread top on the rear side of the internal thread tooth 312 is 0.5~0.65mm, and the guide surface tooth side angle (see the reference numeral 3d) on the rear side of the internal thread tooth 312 is 10°~15°. After finite element optimization analysis, it was found that this design is consistent with the "API The 5B stepped thread profile has an inner and outer arc radius of 0.2mm, which ensures lower stress concentration on the guide surface contact under over-torque threading, achieving good anti-galling properties.

[0039] See also Figure 2 、 4 The external thread height (see reference numeral 1m) of the external thread tooth 101 in the external thread contact area 1 is 1.05-1.555 mm, the height from the mid-diameter line to the tooth bottom (see reference numeral 1j) is 0.65-0.85 mm, the height from the mid-diameter line to the tooth top (see reference numeral 1k) is 0.4-0.705 mm, and the height from the mid-diameter line to the tooth bottom (see reference numeral 1j) is greater than the height from the mid-diameter line to the tooth top (see reference numeral 1k); the external thread height (see reference numeral 3m) of the internal thread tooth 311 in the internal thread contact area 3 is 1.15-1.805 mm, the height from the mid-diameter line to the tooth bottom (see reference numeral 3j) is 0.65-0.85 mm, the height from the mid-diameter line to the tooth top (see reference numeral 3k) is 0.5-0.955 mm, and the height from the mid-diameter line to the tooth bottom (see reference numeral 3j) is greater than the height from the mid-diameter line to the tooth top (see reference numeral 3k). After the internal and external threads are threaded, the gap between the external thread tooth top and the internal thread tooth bottom is between 0.1 and 0.25 mm, which can better adapt to the excessive application of thread compound during thread ...

[0040] See also Figure 2 、 4 The external thread pitch 1f of the external thread contact area 1 and the internal thread pitch 3f of the internal thread contact area are both set according to the number of 3 teeth per inch to 9 teeth per inch, which has better applicability to different specifications and wall thicknesses, and can meet the requirements of large-diameter quick-makeup with large pitch and small-diameter oil pipe with thin wall, low thread height and small pitch.

[0041] See also Figure 3 The outer shoulder contact area 2 includes a primary sealing area and a secondary sealing area. The secondary sealing area is the first side surface of the outer shoulder contact area 2 (see reference numeral 242). The sealing area includes the second side surface of the outer shoulder contact area 2 (see reference numeral 241) and its first adjacent area (see reference numeral 230) and the second adjacent area (see reference numeral 220).

[0042] See also Figure 5 The inner shoulder contact area 4 includes a primary sealing area and a secondary sealing area. The secondary sealing area is the first side surface of the inner shoulder contact area 4 (see reference numeral 442). The sealing area includes the second side surface of the inner shoulder contact area 4 (see reference numeral 441) and its first adjacent area (see reference numeral 430) and second adjacent area (see reference numeral 420).

[0043] See also Figure 3 、 5 The shoulder angle (see reference numeral 2b) of the first side surface of the outer shoulder contact area 2 (see reference numeral 242) is the same as the shoulder angle (see reference numeral 4b) of the first side surface of the inner shoulder contact area 4 (see reference numeral 442), both of which are between 0.5° and 16.5°. According to finite element analysis, this design has the best anti-over-torque and anti-sticking performance. The low shoulder angle does not turn outward under over-torque buckling and high compression load, and will not cause the problem of difficulty in running the downhole tool into the pipe string and failure.

[0044] See also Figure 3 、 5 The shoulder angle (see reference numeral 2d) of the second side surface of the outer shoulder contact area 2 (see reference numeral 241) is the same as the shoulder angle (see reference numeral 4d) of the second side surface of the inner shoulder contact area 4 (see reference numeral 441), both ranging from 8° to 15°, ensuring sufficient shoulder width. The ratio of the projected length (see reference numeral 2e) of the second side surface of the outer shoulder contact area 2 (see reference numeral 241) to the projected length of the primary sealing area of the outer shoulder contact area 2 (see reference numeral 2g) is between 0.216 and 0.266, while the ratio of the projected length (see reference numeral 4e) of the second side surface of the inner shoulder contact area 4 (see reference numeral 441) to the projected length of the primary sealing area of the inner shoulder contact area 4 (see reference numeral 4g) is also between 0.216 and 0.266. These two ratios are equal, adapting to different outer diameter tubing and casing specifications. Finite element analysis shows that this design offers optimal over-torque and compression support, as well as reverse support, increasing primary seal contact pressure for improved sealing performance. Compared to traditional single-angle shoulders, the composite shoulder exhibits enhanced over-torque and compression resistance.

[0045] The above projection is the projection along the axis of the oil pipe.

[0046] See also Figure 3 、 5 The angle between the second adjacent area of the outer shoulder contact area 2 (see reference numeral 220) and the tubing axis (see reference numeral 2f) is between 8° and 15°. The angle between the second adjacent area of the inner shoulder contact area 4 (see reference numeral 420) and the tubing axis (see reference numeral 4f) is between 8° and 15°, and these two angles are equal. The appropriate sealing angle ensures sufficient contact pressure under tensile loads.

[0047] See also Figure 3 、 5 The distance from the second adjacent area of the outer shoulder contact area 2 (see reference numeral 220) to the shoulder and the thread end (see reference numeral 2g) is 9 to 20 mm, and the distance from the second adjacent area of the inner shoulder contact area 4 (see reference numeral 420) to the shoulder and the thread end (see reference numeral 4g) is 9 to 20 mm, which can prevent the threads from being fastened on site and the sealing surface from being damaged during transportation.

[0048] See also Figure 3 、 5 The sealing surface arc radius (see reference numeral 4i) of the second adjacent area (see reference numeral 420) of the inner shoulder contact area 4 and the arc radius (see reference numeral 4i) of the left connecting area (see reference numeral 410) of the second adjacent area (see reference numeral 420) of the inner shoulder contact area 4 are 2.0 to 10 mm. They mate with the conical surface of the left connecting area (see reference numeral 210) of the second adjacent area (see reference numeral 220) of the outer shoulder contact area 2. This achieves high local contact pressure and effectively removes contaminants such as grouting mud or windblown sand from the sealing surface during the make-up process, significantly improving thread applicability.

[0049] See also Figure 3 、 5 The angle between the first adjacent area of the inner shoulder contact area 4 (see reference numeral 430) and the axis of the oil pipe (see reference numeral 4c) is between 0° and 5°, and the angle between the first adjacent area of the outer shoulder contact area 2 (see reference numeral 230) and the axis of the oil pipe (see reference numeral 2c) is between 0° and 5°, ensuring that the sealing structure has sufficient stability under compression load. At the same time, the gap between the two can store contaminants discharged from the main sealing contact.

[0050] See also Figure 3 、 5The projected length (see reference numeral 2h) of the sum of the main sealing area and the left connecting area (see reference numeral 410) of the inner shoulder contact area 4 is 10 to 20 mm, and the projected length (see reference numeral 2h) of the sum of the main sealing area and the left connecting area (see reference numeral 210) of the outer shoulder contact area 2 is 10 to 20 mm, to ensure that the main sealing design is away from the shoulder end face and the shoulder support surface length to achieve the anti-sticking purpose under over-torque and compression load.

[0051] Its working principle is:

[0052] Different specifications of this high-performance, anti-fouling, anti-sticking, and anti-galling special threaded connection for oil casing and casing are available to meet specific working conditions. Processed using CNC machine tools, the coupling is made of the same steel grade as the pipe body or one grade higher, and the internal threads are phosphated to a thickness of 15-25 μm. When making up, evenly apply API thread compound to both ends, clamp the center of the coupling, and apply the optimal torque both at the factory and in the field.

[0053] 139.7×7.72mm casing steel grade P110 for unconventional tight gas development Figure 6 .

[0054] The thread structure function is shown in the table below

[0055]

[0056] Its performance indicators are shown in the table below

[0057]

[0058] The thread structure is analyzed under the envelope load conditions used in engineering design and application. Figure 7 .

[0059] Anti-galling test: The thread compound shall comply with the thread compound performance requirements specified in API RP 5A3 "Evaluation and Testing of Thread Compounds for Casing, Tubing, Line Pipe, and Drill String Components in the Petroleum and Natural Gas Industry".

[0060] The thread make-up torque value and thread compound dosage are shown in the table below.

[0061]

[0062] For other contents, please refer to the prior art.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. An anti-sticking oil casing gas-tight threaded connection joint, comprising a first connection piece (100) and a second connection piece (200) wrapped around the outside thereof, wherein the contact surface of the first connection piece comprises an external thread contact area (1) and an external shoulder contact area (2), and the contact surface of the second connection piece comprises an internal thread contact area (3) and an internal shoulder contact area (4), and the threads of the external thread contact area (1) and the internal thread contact area (3) are engaged by buckling, and the invention is characterized in that: The internal and external thread sealing areas of the internal thread contact area (3) are in interference contact with the external thread sealing area of the external thread contact area (1), and the external shoulder contact area (2) is in interference contact with the internal shoulder contact area (4); The radius of the load-bearing arc (1g) at the bottom of the external thread tooth (101) on the rear side of the external thread contact area (1) is 0.15 to 0.35 mm, the radius of the load-bearing arc (1h) at the top of the external thread tooth (101) is 0.25 to 0.45 mm, and the load-bearing surface angle of the rear side of the external thread tooth (101) is 1.65° to 4.65°. The radius of the load-bearing arc (3h) at the bottom of the internal thread tooth (312) on the rear side of the internal thread contact area (3) is 0.35 to 0.55 mm, and the internal thread The radius of the load-bearing surface arc (3g) at the internal thread tooth top on the rear side of the thread tooth (312) is 0.3 to 0.7 mm, the load-bearing surface tooth side angle at the rear side of the internal thread tooth (312) is 0.65° to 3.65°, the radius of the load-bearing surface arc (3h) at the internal thread tooth bottom is 1.5 to 2 times the radius of the load-bearing surface arc (1g) at the external thread tooth bottom, the radius of the load-bearing surface arc (3g) at the internal thread tooth top is 1.5 to 2 times the radius of the load-bearing surface arc (1h) at the external thread tooth top, and the angle of the external tooth side angle (1a) is greater than the angle of the internal tooth side angle (3a); The outer shoulder contact area (2) includes a primary sealing area and a secondary sealing area, the secondary sealing area is a first side surface of the outer shoulder contact area (2), and the sealing area includes a second side surface of the outer shoulder contact area (2) and a first adjacent area and a second adjacent area; The inner shoulder contact area (4) includes a primary sealing area and a secondary sealing area, the secondary sealing area is a first side surface of the inner shoulder contact area (4), and the sealing area includes a second side surface of the inner shoulder contact area (4) and a first adjacent area and a second adjacent area; The first side shoulder angle of the outer shoulder contact area (2) is the same as the first side shoulder angle of the inner shoulder contact area (4), both ranging from 0.5° to 16.5°; The second side shoulder angle of the outer shoulder contact area (2) is the same as the second side shoulder angle of the inner shoulder contact area (4), both being between 8° and 15°; The ratio of the projected length of the second side surface of the outer shoulder contact area (2) to the projected length of the main sealing area of the outer shoulder contact area (2) is between 0.216 and 0.266, and the ratio of the projected length of the second side surface of the inner shoulder contact area (4) to the projected length of the main sealing area of the inner shoulder contact area (4) is between 0.216 and 0.266, and the two ratios are equal; The angle between the second adjacent area of the outer shoulder contact area (2) and the axis of the oil pipe is between 8° and 15°, and the angle between the second adjacent area of the inner shoulder contact area (4) and the axis of the oil pipe is between 8° and 15°, and the two angles are equal; The distance from the second adjacent area of the outer shoulder contact area (2) to the shoulder and the thread end is 9 to 20 mm, and the distance from the second adjacent area of the inner shoulder contact area (4) to the shoulder and the thread end is 9 to 20 mm; The arc radius of the sealing surface of the second adjacent area of the inner shoulder contact area (4) and the arc radius of the left connecting area of the second adjacent area of the inner shoulder contact area (4) are 2.0 to 10 mm, and they match the conical surface of the left connecting area of the second adjacent area of the outer shoulder contact area (2); The angle between the first adjacent area of the inner shoulder contact area (4) and the axis of the oil pipe is between 0° and 5°, and the angle between the first adjacent area of the outer shoulder contact area (2) and the axis of the oil pipe is between 0° and 5°; The projected length of the sum of the main sealing area and the left connecting area of the inner shoulder contact area (4) is 10 to 20 mm, and the projected length of the sum of the main sealing area and the left connecting area of the outer shoulder contact area (2) is 10 to 20 mm; A gap is provided between the first adjacent area of the inner shoulder contact area (4) and the first adjacent area of the outer shoulder contact area (2).

2. The anti-galling oil casing airtight threaded connection joint according to claim 1, characterized in that: The external thread tooth width (1b) of the external thread tooth (101) in the external thread contact area (1) is 1.495 to 3.629 mm, the external thread tooth groove (1c) of the external thread tooth (101) is 1.51 to 3.644 mm, the internal thread tooth groove (3b) of the internal thread tooth (312) in the internal thread contact area (3) is 1.525 to 3.659 mm, the internal thread tooth width (3c) of the internal thread tooth (312) is 1.48 to 3.614 mm, and the gap between the tooth width and the tooth groove after buckling is between 0.015 and 0.05 mm.

3. The anti-galling oil casing airtight threaded connection joint according to claim 1, characterized in that: The radius of the guide surface arc (1e) at the external thread tooth bottom on the front side of the external thread tooth (101) in the external thread contact area (1) is 0.25 to 0.40 mm, the radius of the guide surface arc (1i) at the external thread tooth top on the front side of the external thread tooth (101) is 0.3 to 0.5 mm, and the guide surface tooth side angle on the front side of the external thread tooth (101) is 8° to 13°. The radius of the guide surface arc (3i) at the internal thread tooth bottom on the front side of the internal thread tooth (312) in the internal thread contact area (3) is 0.25 to 0.45 mm, the radius of the guide surface arc (3e) at the internal thread tooth top on the rear side of the internal thread tooth (312) is 0.5 to 0.65 mm, and the guide surface tooth side angle on the rear side of the internal thread tooth (312) is 10° to 15°.

4. The anti-galling oil casing airtight threaded connection joint according to claim 1, characterized in that: The external thread height of the external thread teeth (101) in the external thread contact area (1) is 1.05 to 1.555 mm, the height from the mid-diameter line to the tooth bottom is 0.65 to 0.85 mm, the height from the mid-diameter line to the tooth top is 0.4 to 0.705 mm, and the height from the mid-diameter line to the tooth bottom is greater than the height from the mid-diameter line to the tooth top; the internal thread height of the internal thread teeth (312) in the internal thread contact area (3) is 1.15 to 1.805 mm, the height from the mid-diameter line to the tooth bottom is 0.65 to 0.85 mm, the height from the mid-diameter line to the tooth top is 0.5 to 0.955 mm, and the height from the mid-diameter line to the tooth bottom is greater than the height from the mid-diameter line to the tooth top.

Images