Double-layer combined casing with girth weld and assembling method thereof

Abstract

The invention discloses a double-layer combined casing with a girth weld and an assembling method thereof. The double-layer combined casing comprises an internal thread coupling joint, an external thread coupling joint, an outer casing layer and an inner casing layer; the outer casing layer is divided into an internal thread coupling joint section and an external thread coupling joint section, a connecting ring is arranged at the connecting position of the internal thread coupling joint section and the external thread coupling joint section, and the internal thread coupling joint section and the external thread coupling joint section are connected with the connecting ring in an overlap welding manner; and the outer casing layer is connected with the internal thread coupling joint and the external thread coupling joint, and the inner casing layer is connected with the internal thread coupling joint and the external thread coupling joint. The connecting and sealing performance of the double-layer combined casing is effectively improved, meanwhile, the anti-outward extrusion performance of the double-layer combined casing is effectively improved, a sealed cavity is formed in an annular space of the inner casing layer and the outer casing layer, effective buoyancy of the casing in drilling fluid is increased, centering of the double-layer casing in a horizontal section is facilitated, and the fixing mass is improved.

Description

technical field [0001] The invention belongs to the technical field of casings used in the exploration and development of oil and gas fields, and in particular relates to a double-layer composite casing with a girth weld and an assembly method thereof. 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 a large area, 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, making the oil recovery project impossi...

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. In a large area, 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, making it impossible to carry out the oil production project, and the construction is complicated and difficult to operate

At the same time, there is no specific assembly method for the double-layer composite casing in the existing documents and patents.

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