硬脆性泥页岩井壁稳定评价新方法

New method for evaluating borehole stability in brittle shale

王建华 鄢捷年 苏山林

WANG Jian-hua YAN Jie-nian SU Shan-lin

中国石油大学, 北京 102249 胜利石油管理局黄河钻井公司, 山东 东营 257000

以伊利石、伊蒙混层为主的硬脆性泥页岩微裂缝发育,容易引起井壁失稳,一直未能找到很好的评价方法。因此,建立对硬脆性泥页岩井壁稳定的评价手段十分迫切。介绍了一种新型的硬脆性泥页岩井壁稳定评价方法——微裂缝的模拟及其封堵。室内利用加工的3种岩心模拟出了1~50μm的微裂缝,分别研究了流速、围压和裂缝宽度之间的关系,并用不同介质对不同宽度的裂缝进行了封堵试验,构建的硅酸盐钻井液体系对3种岩心的封堵效率均达到90%以上。试验结果表明:该方法具有一定的可行性,对提高钻井液体系的封堵能力有一定的指导作用。

In the present,the typical experience can’t solve all the problems of borehole instability.Especially in brittle shale formation,there are not optical methods to solve in the lab.So setting up methods for brittle shale is very urgent.To solve the borehole instability in brittle shale because of micro-fractures,this paper set up a new evaluation method of hard brittle shale——the simulation and sealing about micro-fracture.The method could simulate little fracture from 1 μm to 50 μm,and the experiments of seal have been done.The relationship among velocity,peripheral pressure and fracture width was studied.Sealing efficiency of the silicate drilling fluid was reached to 90%.The result of experiments indicates that the method is possible,and has some guidance for improving the sealing capacity of drilling fluids.

10.3969/j.issn.1000-7393.2006.02.009