Pressure control device for whole-process underbalanced drilling and use method

Abstract

The invention relates to the technical field of unbalanced drilling in oil and gas fields and provides a pressure control device for whole-process underbalanced drilling and a use method. The pressure control device comprises a wellhead blowout preventer stack, a rotary control head, a downhole deployment valve, a casing string, a drilling fluid circulating processing device, a special choke manifold, a drilling pump unit and a drilling fluid continuous pouring device which is capable of detecting injecting pressure and flow, wherein the downhole deployment valve is fixedly mounted on the casing string on the upper layer, a ground control device for opening and closing the downhole deployment valve is connected onto the downhole deployment valve, and the rotary control head and the wellhead blowout preventer stack are fixedly mounted sequentially from top to bottom at the top of the casing string above the downhole deployment valve. Reasonable back pressure is applied to a wellhead by regulating the opening degree of a throttle valve of the special choke manifold, so that downhole pressure is controlled dynamically, the downhole is enabled to be in a controllable unbalanced state all along, accordingly, the quantity of a formation fluid invading a shaft in a snubbing process is controlled effectively, reservoirs of the oil and gas fields can be protected, and the drilling operation safety is guaranteed effectively.

Description

technical field [0001] The invention relates to the technical field of underbalanced drilling in oil and gas fields, and relates to a pressure control device for underbalanced drilling in the whole process and a use method thereof. Background technique [0002] After entering the 21st century, underbalanced drilling technology has developed rapidly, but as far as the current underbalanced drilling technology is concerned, the most common one is still simple underbalanced drilling, which cannot achieve the purpose of protecting oil and gas layers during the entire drilling process. It is mainly reflected in the imperfect tripping operation; in order to avoid complications or accidents such as overflow and blowout, it is necessary to inject heavy slurry into the wellbore to balance the formation pressure before tripping out. Balance state, thus losing the achievement of protecting oil and gas layers during underbalanced drilling. [0003] During the implementation of underbal...

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Problems solved by technology

[0005] The present invention provides a whole-process underbalanced drilling pressure control device, which overcomes the deficiencies of the prior art and can effectively solve the lack of continuous compensation for wellbore hydrostatic column pressure and The problem of control, more effectively solves the problem that the existing downhole drilling needs to use the kelly pump to assist in opening the downhole casing valve, and its operating procedures are cumbersome and complicated

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