Double-layer combination casing pipewith strength mismatch

Abstract

The invention discloses a double-layer combination casing pipewith strength mismatch. The double-layer combination casing pipe includes an outer screwed joint, an inner screwed joint, an outer layer casing pipe, and an inner layer casing pipe, wherein the outer layer casing pipe and the inner layer casing pipe are made of materials with different strength grades; after the layer outer casing pipehas plastic deformation and is in contact with the inner layer casing pipe, due to the fact that stiffness of the inner layer casing pipe is much higher than that of the outer layer casing pipe, a coating with small friction coefficient exists on the outer wall of the inner layer casing pipe, then the anti-friction effect of a lubricant is matched with, under the action of outer extruding force, metal plastic flow deformation of the outer layer casing pipe occurs along the outer wall of the inner layer casing pipe, part of an outer extruding load is adsorbed, the outer extruding load on the inner layer casing pipe is reduced, anti-outer-extruding performance of the double-layer combination casing pipe is improved effectively, the risk of plastic deformation failure of the inner layer casing pipe is reduced and lowered, and the double-layer combination casing pipe is suitable for conventional casing pipe deformation regions caused by a non-uniform load.

Description

technical field [0001] The invention belongs to the technical field of casing for oil and gas development, and in particular relates to a double-layer composite casing with strength mismatch. Background technique [0002] With the deepening of the production and development of various oilfields at home and abroad, casing damages of varying degrees have occurred in most oilfields, which has caused a great impact on oil production and development. Double-layer composite casing is an important means of early casing protection. At present, most double-layer composite casings use the method of injecting cement between the inner and outer casings, which can improve the collapse resistance of the casing. In large areas, the extrusion force of the formation is directly transmitted to the inner casing through the outer casing and the cement sheath, causing damage to the inner casing, resulting in the failure of the oil production project, and the construction is complicated and diffi...

AI Technical Summary

Problems solved by technology

Double-layer composite casing is an important means of early casing protection. At present, most double-layer composite casings use the method of injecting cement between the inner and outer casings, which can improve the collapse resistance of the casing. In large areas, the extrusion force of the formation is directly transmitted to the inner casing through the outer casing and the cement sheath, causing damage to the inner casing, resulting in the failure of the oil production project, and the construction is complicated and difficult to operate; at the same time, the existing The double-layer composite casing has no research results on the material strength matching of the inner and outer casings, and the performance of the casings is uneven

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