Downhole constant pressure valve for oil tube

Abstract

The invention discloses a downhole constant pressure valve for an oil tube. The downhole constant pressure valve for the oil tube comprises a valve body and a spool. The spool is disposed in the valve body. A gap between the spool and the middle of the valve body is sealed by a spring. The spring is located on a spring holder connected to the lower portion of the valve body. The upper portion of the valve body is connected with a bonnet through a shear pin. The lower portion of the valve body is provided with a water hole for drilling fluid circulation. The upper portion of the bonnet is connected with the oil tube, an anti-fall cap holding the valve body from falling is connected to the lower portion of the bonnet, and a gas production mesh sealed by the valve body which does not fall yet is arranged in the middle of the bonnet. The downhole constant pressure valve in the mechanical structure is capable of effectively and temporarily plug a running oil string when inside the running oil string, so that leakage of borehole pressure from the oil string is guaranteed, cycle operation can be achieved effectively when the oil string runs down and after the oil string is in position, gas production can be achieved effectively after a Christmas tree is installed, and dependence on environmental factors such as temperature is not needed. The downhole constant pressure valve for the oil tube has the advantages of reasonable design, simple structure, low cost, high reliability, high stability, convenience in operation, high safety, high practicality and the like, and construction progress is quickened effectively.

Description

technical field [0001] The invention relates to a downhole control valve, in particular to an oil pipe downhole constant pressure valve, which is especially suitable for oil and gas exploitation in underbalanced drilling. Background technique [0002] In recent years, underbalanced drilling technology at home and abroad has achieved remarkable results in reducing costs and increasing oil and gas reservoir productivity, and has become an inevitable trend in the development of drilling technology. However, the conventional underbalanced drilling technology cannot effectively solve the problem of continuous maintenance of the underbalanced pressure difference at the bottom of the well during tripping and completion, and cannot reliably implement the underbalanced operation throughout the process, making the application of this technology restricted to a certain extent. limits. [0003] In order to ensure the continuous maintenance of the underbalanced pressure difference at th...

AI Technical Summary

Problems solved by technology

These downhole control valves can all be suitable for use as underbalanced drilling in the whole process, but there is no downhole control valve with the same or similar structure as the present invention so far.

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