Hermetic seal connecting structure for special buckle of oil casing

Abstract

The invention discloses a hermetic seal connecting structure for a special buckle of an oil casing. The two ends of a pipe body of the oil casing are provided with conical buttress external threads; the two ends of a coupling of the oil casing are provided with conical buttress internal threads; the pipe body external thread and the coupling internal thread have the same taper; both the pipe body and the coupling are provided with torque shoulders; the tail end of the pipe body external thread is provided with a pipe body conical sealing surface; the tail end of the coupling internal thread is provided with a coupling conical sealing surface; a taper difference of between 0 and 1.5 exists between the pipe body conical sealing surface and the coupling conical sealing surface; simultaneously, the transition circular arc or the transition convex arc between the pipe body sealing surface and the pipe body torque shoulder is larger than the transition circular arc between the coupling sealing surface and the coupling torque shoulder. The pipe body is connected with the coupling through the conical buttress thread, gradual interference fit is realize due to the presence of the small taper difference between the pipe body conical sealing surface and the coupling conical sealing surface in a buckling process, the torque shoulder bears major torque and contact stress and has an auxiliary sealing effect, a geometry space formed by the large transition circular arc or convex arc of the pipe body and a small circular arc of the coupling can effectively provide a deformation space for stress deformation under a complex condition, so that the conical sealing surface and the torque shoulder can be protected effectively and the pipe body and the coupling can be used repeatedly.

Description

Technical field: [0001] The invention belongs to the technical field of drilling equipment for oil exploitation, and relates to the casing screw connection technology of the drilling equipment, in particular to an airtight connection structure of a special connection of the oil casing. Background technique: [0002] With the sharp increase in the world's demand for fossil energy and the decrease in the amount of oil that can be recovered year by year, the current oil exploration field is gradually developing in the direction of deep wells, ultra-deep wells, high-pressure oil and gas wells, heavy oil thermal recovery wells, and directional wells. As a result, more and more stringent technical requirements are put forward for the sealing between oil pipes and pipes. API (American Petroleum Institute) standard round thread and buttress thread joints widely used in the past cannot meet the needs of oil and gas wells with harsh environmental conditions in terms of air tightness, ...

AI Technical Summary

Problems solved by technology

The above-mentioned patent mainly proposes a variety of sealing structures between the pipe body and the coupling for the connection method of the oil casing. Tests in harsh environments such as high temperature and high pressure, through the analysis of pipe joint accidents in the oil well production site and the finite element analysis of various sealing fit pipe joints show that excessive stress on the sealing surface is one of the reasons for plastic deformation and scratches, followed by Due to the lack of deformation release space or no deformation release space at all due to the elastoplastic deformation of the sealing surface during interference fit under complex working conditions in the mine, it will also lead to plastic deformation of individual parts of the sealing surface, causing scratches and scratches on the sealing surface leakage

Although the above-mentioned patents have announced different sealing forms, the patent itself focuses on the design of the thread itself or the design of the thread fit. The stress on the sealing surface is bad, and the patent does not take into account the deformation release space of the sealing surface.

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