Overall process under-balance drilling pressure compensation system and method

Abstract

The invention relates to an overall process under-balance drilling pressure compensation system and a method for oil and gas drilling, an underground casing valve (10) is connected on a superior casing string, a wellhead rotary blowout preventer (11) is arranged at an upper end of a wellhead blowout preventer group and is connected with an under-balance throttle manifold (8) through a high-pressure hose (9), a well control manifold (12) which is connected out of a normal wellhead control device by four-pass is connected with a drilling fluid continuous pouring system in parallel by two-pass; and drilling is pulled to the front of the underground casing valve (10), the drilling fluid continuous pouring system grouts, the under-balance throttle manifold (8) controls the pressure in a shaft, and the drilling fluid which is circulated out enters a normal drilling fluid circulating system. In the drilling pulling process, the drilling fluid can be continuously poured into the shaft by a ground pressure compensation system and the bottom-hole pressure can be dynamically controlled simultaneously, thus effectively preventing formation fluid from intruding into the shaft in the drilling pulling process and keeping the steady under-balance state of the shaft.

Description

technical field [0001] The invention relates to an oil and gas underbalanced drilling method, in particular to a method capable of implementing the whole process of underbalanced drilling, that is, a whole process underbalanced drilling pressure compensation system and method. Background technique [0002] In recent years, Underbalanced Drilling (Unbalanced Drilling) technology has developed rapidly worldwide, but as far as the current Underbalanced Drilling technology is concerned, there are still imperfections in the protection of oil and gas layers, mainly reflected in tripping During the process, due to the limitations of the current process and technology, in order to avoid accidents such as overflow and blowout during tripping, it is necessary to inject heavy drilling fluid into the well before tripping to balance the formation pressure. The heavy injection of drilling fluid before tripping will often lead to the loss of the underbalanced state in which the wellbore fl...

AI Technical Summary

Problems solved by technology

However, during the tripping process, the drilling fluid in the wellbore stops circulating, and the formation fluid continuously enters the wellbore with the increase of the drill string volume under the action of pressure difference, which increases the difficulty of wellbore pressure control

Especially when drilling in natural gas reservoirs, natural gas slips and rises in the annular space after entering the wellbore. Under the condition of restricting natural gas expansion, the rising natural gas will bring formation trap pressure to the surface, resulting in overpressure at the wellhead, thus increasing the underbalance of the whole process. Difficulty in pressure control during drilling and tripping

Images