精细控压压力平衡法固井技术的应用实践

Application precise MPD & pressure balance cementing technology

精细控压钻井技术多用于解决同一裸眼油气井段存在多压力系统、窄安全密度窗口地层的安全钻进难题,其尾管固井作业若采用常规方法,在满足小间隙尾管固井顶替效率的前提下,施工过程中必然造成井漏;若采用"正注反打"工艺,固井质量又难以满足后期超深井试油工程的需要。为此,以四川盆地剑阁构造上所钻龙岗70井?114.3 mm尾管固井作业为例,探索精细控压压力平衡法固井技术在多储层、高低压互存、长裸眼段(859 m)中的固井应用。具体做法如下:①采取了确保水泥浆环空充填效率、固井施工全过程压力平衡等针对性的技术措施;②依靠精细控压钻井装置和中心管泵注加重钻井液的方式,精确控制环空压力平衡来降低钻井液密度,实现窄安全密度窗口地层的固井施工全过程井筒压力平稳。现场试验结果表明,该井?114.3 mm尾管固井质量良好,分阶段降密度期间喇叭口无窜流,试压合格。结论认为,该方法能够提高复杂超深气井尾管的固井质量,改善了后期高压气井试油安全作业的井筒条件。

The precise managed pressure drilling （MPD） technology is mainly used to deal with the difficulties encountered when oil and gas open hole sections with multiple pressure systems and the strata with narrow safety density window are drilled through. If its liner ce- menting is carried out according to the conventional method, lost circulation is inevitable in the process of cementing while the displace- ment efficiency of small-clearance liner cementing is satisfied. If the positive and inverse injection technology is adopted, the cementing quality cannot meet the requirements of later well test engineering of ultradeep wells. In this paper, the cementing operation of O114.3 mm liner in Well Longgang 70 which was drilled in the Jiange structure of the Sichuan Basin was taken as an example to explore the applica- tion of the cementing technology based on the precise MPD and pressure balancing method to the cementing of long open-hole sections （as long as 859 m） with both high and low pressures running through multiple reservoirs. On the one hand, the technical measures were taken specifically to ensure the annulus filling efficiency of slurry and the pressure balance in the whole process of cementing. And on the other hand, the annulus pressure balance was precisely controlled by virtue of precise MPD devices and by injecting heavy weight drilling fluids through central pipes, and thus the wellbore pressure was kept steady in the whole process of cementing in the strata with narrow safety density window. It is indicated that O114.3 mm liner cementing in this well is good with qualified pressure tests and no channeling emerges at a funnel during the staged density reduction. It is concluded that this method can enhance the liner cementing quality of com- plex ultradeep gas wells and improve the wellbore conditions for the later safe well tests of high-pressure gas wells.