龙马溪页岩溶蚀液的室内探索

Laboratory Test and Exploration of Dissolution Solution of Longmaxi Shale Play

国内龙马溪页岩气水平井钻井过程中,存在井壁失稳、阻卡等复杂。页岩掉块卡钻,处理难度大,处理手段少,常用的解卡剂和常规盐酸、土酸都无法解除页岩掉块卡钻,针对该技术难题,根据龙马溪地层岩性组份特点室内合成了能溶蚀页岩掉块的关键处理剂CQ-YRS、CQ-YST和CQ-YHS,形成了能溶蚀龙马溪页岩掉块的溶蚀液。评价表明:溶蚀液在48 h的溶蚀率可达61.60%;与高密度水基钻井液和高密度油基钻井液的配伍性良好对钻井液无污染;对标准N80钢片、45^(#)钢片以及定向仪器各个配件的腐蚀率都低于国标规定的6 g/(m^(2)·h);该溶蚀液为解决龙马溪页岩钻进掉块卡钻提供了一个新的思路,并为其推广应用提供了可能。

In the process of drilling horizontal shale gas wells in Longmaxi shale play,there are some accidents such as borehole wall instability, falling block, blockage and pipe stuck. Sticking resulted from shale block loss accidents,as one of the sticking of shale impellers,is with difficult processing,less processing means,and can not be treated with commonly used pipe-freeing agent and conventional hydrochloric acid and mud acid. Aiming at this technical problems,according to the lithologic composition characteristics of Longmaxi formation,the key treating agents such as CQ YRS,CQ YST and CQ – YHS which can dissolve the shale falling block were synthesized in laboratory,forming a kind of dissolution fluid which can dissolve the falling block of Longmaxi shale. The evaluation showed that the dissolution rate of the solution in 48 h could reach 61. 60%.It is with good compatibility with high density water base drilling fluid and high density oil base drilling fluid,no pollution to drilling fluid. The corrosion rate of standard N80 steel sheet,45#steel sheet and all accessories of directional instrument is lower than 6 g/( m2. h) stipulated by national standard. The solution provides a new idea to solve the problem of loose block sticking in Longmaxi shale drilling and provides a possibility for its popularization and application.