Anti-loosening and high airtight threaded casing connection structure

Abstract

An anti-loosening and high-airtight threaded casing connection structure, including factory-end casing, oilfield-end casing and couplings, the three are screwed into one body through screw threads, so that one end of the coupling is firmly connected with the casing, and the coupling's The other end is screwed into the internal thread of the coupling by means of constant torque, so that the butt end faces of the casings at both ends form a pressurized interference sealing butt joint structure; or through the sealing step of the coupling, or through the middle sleeve to form a pressure Interference seal butt joint structure; the connection strength between factory end casing and oil field end casing and coupling is guaranteed by threaded connection, and the sealing performance between the three is guaranteed by end surface interference seal butt joint structure. Ensure end face interference seal by using a torque wrench. It not only guarantees the connection strength between the casing at the oilfield end, the casing at the factory end and the coupling, but also ensures the formation of a high-seal end surface interference seal connection between the casing at the oilfield end and the casing at the factory end.

Description

Technical field: [0001] The invention relates to a casing screw connection structure used in oil and natural gas exploitation drilling, in particular to a connection structure of a high airtight thread casing. Background technique: [0002] High-strength, high-air-tight casing joints must be used in oil and natural gas drilling. Hou Yi of Tianjin disclosed a "High-air-tight partial trapezoidal threaded casing connection structure" in ZL96106583.4. The two ends of the pipe are made with tapered partial trapezoidal external threads, and the two ends of the coupling are made with tapered partial trapezoidal internal threads. The wall thickness end faces at both ends of the casing are arc-shaped surfaces. If the gap is "△", the pipe ends of the two casings are pressed against each other, and the pipe wall produces weak plastic deformation in the axial direction, forming a metal-to-metal sealing surface. The patent also discloses its three optimized structures, that is, the part...

AI Technical Summary

Problems solved by technology

[0003] First, although there is a standard line on the tight end of the oil field of the coupling, and a marking line on the casing at the oil field end, in actual use, it is often necessary to disassemble and assemble between the casing at the oil field end and the coupling, and the standard line On the other hand, the radius of curvature of the butt end faces of the factory casing and the oil field casing will inevitably undergo plastic deformation after repeated disassembly and assembly, so that the axial direction of the originally designed casing threaded connection The interference "△" gradually decreases. It is very inaccurate to judge whether the two are fastened in place based on the original standard line and the marking line. less than sealing requirements

[0004] Second, in order to overcome the above defects, people usually use the method of screwing the casing at the oilfield end to overcome the defect that may cause the end faces of the two casings to be unsealed. There is an interference contact between the contact end faces, and when the casing at the oil field end is rotated, it will cause the casing at the factory end to reverse, thereby causing looseness between the casing at the factory end and the coupling, thereby reducing the connection strength, which is very dangerous Defects, in severe cases, will cause the oil pipe to be separated from the coupling, and the consequences will be disastrous

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