A Blowout Prevention Check Valve in Spiral Drill String

Abstract

The invention relates to oil and natural gas drilling technology, in particular to a helical anti-blowout check valve in a drill string, which includes an upper shell and a lower shell connected to each other, and a valve seat is arranged in the upper shell, and the valve seat includes a partition plate. And the cylindrical inner wall, the separator one is provided with flow hole one, the cylindrical inner wall is provided with flow hole two, and the middle part of the valve seat is provided with a screw hole; the screw hole is equipped with a screw, the screw hole and the thread of the screw Match each other and do not meet the self-locking conditions; the lower end of the screw is fixedly connected to the valve core, the valve core has a cylindrical outer wall, and the cylindrical outer wall is provided with three flow holes, and the bottom of the valve core is provided with a limit step; the lower shell is provided with a partition Two, the second partition is provided with flow hole four, and the middle part of the second partition is provided with a limit seat. The invention greatly improves the service life of the equipment on the premise of ensuring the safety function of the check valve, and at the same time solves the problems of valve core impact load and structural vibration damage, improves the overall safety of the drill string and downhole tools, and improves the drilling efficiency. Improvement and maintenance cost reduction.

Description

technical field [0001] The invention relates to the technical field of oil and gas drilling equipment, in particular to a blowout prevention check valve in a helical drill string. Background technique [0002] In the process of drilling, workover or well killing, in order to prevent blowout or drilling fluid backflow, it is necessary to use both internal blowout prevention and external blowout prevention equipment; for internal blowout prevention equipment, cock type or piston type check valve equipment is usually used on site , connect it to the drill string and go downhole with the drill string. When overflow occurs at the bottom of the well, the check valve can close the inner cavity of the drill string through its mechanical structure, thereby preventing blowout or drilling fluid from flowing back and overflowing along the inner cavity of the drill string. It plays a very important role in the safety of oil and gas drilling. [0003] With the continuous improvement of d...

AI Technical Summary

Problems solved by technology

[0004] First, the spring is easily damaged

Most of the existing piston-type check valves use a return spring to match the structure of the valve core. The spring is usually set in the drilling fluid flow channel and is directly impacted by the drilling fluid; the spring’s return ability decays quickly after being washed by the drilling fluid for a long time, and it is prone to aging , damage or even failure, and eventually lead to the failure of the check valve, causing safety hazards;

[0005] Second, the spool cannot achieve self-positioning

Most of the existing piston check valves use the structure of the return spring to cooperate with the valve core. In this structure, the position of the valve core is kept stable by the spring, and the valve core itself has no position maintaining structure. Once the spring fails, the valve core cannot be kept stable. If the position is too small, severe vibration will be generated under the impact of drilling fluid, not only the plugging function cannot be realized, but also the structural damage of the entire drill string may be caused by structural damage or vibration;

[0006] Third, spool action produces undesirable shock loads

There is no buffer structure in the spool stroke of the existing piston check valve, that is, every movement of the spool will produce an axial impact on the drill string, and this impact may cause damage to the spool itself and the overall structure. Potential safety hazards; and when other downhole tools or precision instruments are installed on the drill string, this impact may cause damage to other equipment and cause unpredictable losses

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