钻井液对煤层气井壁稳定性影响实验研究

Experimental study on borehole stability in coal bed methane wells induced by drilling fluid

汪伟英 夏健 陶杉 田文涛 马丽 孙玉英

WANG Weiying XIA Jian TAO Shan TIAN Wentao MA Li SUN Yuying

长江大学油气资源与勘探技术教育部重点实验室，湖北荆州　434023 华北油田公司采油工艺研究院，河北任丘　062552

Key Laboratory of Exploration Technologies for Oil and Gas Resources in Yangtze University, Ministry of Education, Jingzhou 434023, China Production Technology Research Institute of Company of Huabei Oil Field, Renqiu 062552, China

在对煤层气储层岩石组成及理化性能分析的基础上，通过测定煤岩与钻井液接触后的力学性质，研究各种理化性能对煤层井壁稳定性的影响。研究结果表明，钻井液侵入煤层后容易引起黏土膨胀，煤层气储层存在由于水敏引起的煤层井壁失稳的危险；在岩石强度大、无水敏的煤储层可采用清水钻进，在水敏性强的储层应在钻井液中加入黏土抑制剂，并采用欠平衡等钻井方式，控制钻井液侵入。

Based on the analysis of rock components and physicochemical properties for coal bed methane reservoir, this paper studied the influence of different physical and chemical properties on borehole stability of coal bed by measuring the coal rock mechanical properties when it contacted with the drilling fluid. The results indicated that clay expansion easily happened when drilling fluid invading into the coal beds, so the coal bed methane reservoir potentially occurred borehole instability induced by water sensitivity; we adopted water drilling in strong rock strength and non-water sensitivity coal bed, while clay inhibitor was added into drilling fluid in strong water sensitive reservoir to control the drill fluid invasion., combining with the under-balanced drilling.