A downhole check valve

Abstract

The invention discloses a downhole check valve. The downhole check valve comprises a valve body, an upper supporting base, an upper sliding valve element, a lower sliding valve element, a lower supporting base, a spring and a sealing ring. A top-bottom through flow channel is machined in the valve body in the axial direction. The upper supporting base is arranged on the upper part of the flowing channel, the lower supporting base is arranged on the lower part of the flowing channel, and a sliding sleeve is machined in the lower supporting base in the axial direction. The spring, the lower sliding valve element and the upper sliding valve element are sequentially arranged in the sliding sleeve from bottom to top. The lower sliding valve element is a step cylinder. The upper sliding valve element is cylindrical, an outer cylinder face of the upper sliding valve element is in sliding connection with the sliding sleeve, and an inner cylinder face of the upper sliding valve element is in sliding connection with an upper end cylinder face of the lower sliding valve element. The sealing ring is arranged between a lower end face of the upper sliding valve element and a step face of the lower sliding valve element, and extrusion sealing is formed. The downhole check valve has the beneficial effects that a soft sealing manner of metal to non-metal is adopted, and sealing is easy; and a pressure-assisted sealing structure can achieve high-pressure sealing, and compensation to abrasion of the sealing ring can be achieved.

Description

technical field [0001] The invention relates to downhole tools for petroleum exploration and development, in particular to a downhole check valve used in the process of petroleum drilling and completion. Background technique [0002] The downhole check valve is an internal blowout prevention tool commonly used in oil and gas drilling, well completion and workover operations. Under the action of circulating pressure and spring force, the check valve closes quickly, cuts off the inner channel of the pipe, and plays the purpose of preventing blowout in the pipe. In the exploration and development of high-pressure oil and gas reservoirs, when the formation pressure is greater than the drilling fluid column pressure, overflow or even blowout in the drilling tool may occur. Commonly used check valves mainly include arrow check valves and floating check valves. During drilling operations, when the arrow-shaped check valve is in the standby condition, the arrow-shaped valve core is...

AI Technical Summary

Problems solved by technology

[0003] However, the sealing ability, working reliability and service life of the arrow check valve and the floating check valve are insufficient. space, causing erosion damage to the valve core and valve seat, resulting in poor sealing; the single-arm bending torsion spring of the floating check valve must support the valve plate in a suspended state, because the spring itself has a weak supporting force, so that the spring is in a Eccentric state, uneven force, resulting in poor sealing performance, poor repositioning, and not easy to be reused; the valve core and the valve seat are metal seals, which are difficult to process and surface treatment, and often leak under low pressure

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