Self-balanced underground full-bore check valve

Abstract

The invention provides a self-balanced underground full-bore check valve which comprises a first connector (10), a second connector (20), a switch valve (30) and a sliding sleeve (40), wherein the switch valve (30) comprises a valve seat (31) and a valve sheet (32); a first seal cavity (211) communicated with a space in a pipe and a second seal cavity (212) communicated with a space outside the pipe are respectively defined by the sliding sleeve (40) together with the first connector (10), the second connector (20) and the switch valve (30); and the valve sheet (32) is provided with a first working state of closing a valve port when the external pressure of an operating pipe column is greater than the internal pressure of the operating pipe column and a second working state of opening the valve port when the internal pressure of the operating pipe column is greater than or equal to the external pressure of the operating pipe column. The self-balanced underground full-bore check valve provided by the invention can be automatically opened or closed in time according to the real-time change of the internal and external pressure difference of the pipe column, thereby preventing blowout accidents from happening, improving the production safety, shortening the operation time and lowering the operation cost.

Description

technical field [0001] The invention relates to the fields of well completion testing and downhole operation in oil and gas fields, and in particular relates to a self-balancing downhole full-bore check valve. Background technique [0002] At present, in well completion testing and downhole operations at home and abroad, it is often encountered that the liquid in the pipe string overflows due to the formation pressure being greater than the internal pressure of the pipe string, which may lead to blowout in severe cases; Sometimes, due to the suction effect, the internal and external pressure of the pipe string may be unbalanced and accidents may occur, etc. These situations seriously endanger the safety of underground construction operations. At present, well killing and shutting in are commonly used to avoid such accidents. [0003] However, there are many disadvantages in eliminating well control risks by shutting in and killing wells: first, the pressure change in the we...

AI Technical Summary

Problems solved by technology

[0003] However, there are many disadvantages in eliminating well control risks by shutting in and killing wells: first, the pressure change in the well cannot be known in time, resulting in a delay in closing the well; second, well killing will cause oil layer pollution; third, shutting in and killing wells prolongs construction operations time, reducing operating efficiency and increasing operating costs

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