气体连续循环钻井在苏里格地区的应用

APPLICATION OF THE CONTINUOUS CIRCULATION GAS DRILLING TECHNOLOGY IN THE SULIGE REGION

气体钻井有提高机械钻速、避免井漏等诸多优点,但在地层出水时接单根/立柱导致井内积水严重,浸泡井壁和注气压力增加、井底压力波动,而引起井下事故复杂的发生。针对苏里格地区水层多、水量大特点,开展了气体连续循环钻井作业,得到了接立柱过程中立管压力变化曲线,即马-魏曲线,该曲线证实了气体连续循环钻井技术的有效性和实用性,实现了在不停注气情况下接立柱过程中维持恒定的钻井循环排量和当量循环密度,同时持续携带地层水、防止因地层水聚集引起过高的立管压力,确保气体钻井安全。

Gas drilling technology has many advantages such as improving ROP,handling lost circulation and so on,but the time of pressure relief aimed to connect the triple and gas injection aimed to re- develop circulation is too long,so that the formation water was congregated seriously in the bottomhole.Borehole wall soaked by the formation water and the bottomhole pressure fluctuation caused by starting or stopping gas injection can cause the occurrence of complex bottomhole accident easily.For the features of the many crossing water layers and larger water,the continuous circulation gas drilling technology has been applied successfully in the SULIGE region,and the Ma- Wei curves showing the variableness of the standpipe pressure during making a triple operation acquired from those field operations fully demonstrate the validity and practicability of the continuous circulation gas drilling technology. Utilizing this technology,we are able to maintain the constant drilling circulation rate and steady equivalent circulation density and we can avoid a series of bottomhole complex accidents caused by stopping or starting the circulation during making a connection or triple and tripping. In addition,the high standpipe pressure due to the appearance of the formation water in gas drilling can also be prevented,because of continuing to carry the formation water. So this technology could effectively shorten the non- drilling time and broaden the scope of application of gas drilling.