Thread joint structure for high-performance oil casing

Abstract

The invention provides a thread joint structure of high-performance oil casing. The structure comprises a casing of which one end is provided with external threads and a coupling with internal threads, wherein the casing and the coupling are screwed together; the external threads at the end part of the casing and the internal threads of the coupling are both negative-angle taper threads; the threads are designed to be tooth-side interference; and the internal threads of the coupling are provided with a torque-stop shoulder. Due to the simultaneous adoption of the negative-angle thread design and the tooth-side interference design, the thread structural design is optimized, the stability of sealing performance of a sealing surface under a stretching and compression load is improved, and the use of the oil casing under extreme conditions is facilitated. As the stretching and compression performance is improved, the bending resistance is enhanced; the torque-stop shoulder is arranged at a corresponding position of the coupling so as to ensure a screwing position; and the connection efficiency of the joint is maximized and the compression performance is optimized.

Description

Technical field [0001] The patent of the invention relates to a threaded connection structure, especially a high-performance oil casing threaded joint structure. Background technique [0002] The tubing string is formed by connecting a single oil well pipe with threads, and the threaded connection part of the tubing string is the key link of weakness. In the general API standard, the casing adopts round thread or eccentric thread connection form. These connection forms have certain problems in ensuring the structural integrity and sealing integrity of the pipe string. The threaded connection strength of the round threaded casing is only 60% to 80% of the strength of the pipe body. Although the connection strength of the eccentric thread is close to or reaches the strength of the pipe body, the air-tight performance is insufficient. In addition, the acidic components of hydrogen sulfide contained in the oil and gas will cause slow stress corrosion of ordinary API casings, result...

AI Technical Summary

Problems solved by technology

Such as: high import costs; special thread connection maintenance and accessories processing difficulties

These limit the use of special buckle casing

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