油包水钻井液钻穿煤层的可行性

摘要

Through analyzing the collapsing mechanism of coal layers, the difficulties of drilling fluid for coal layer are generalized and the measures to stabilize coal layer are proposed. The experiments, such as HTHP swelling, size distribution, recovery ratio and strength, the possibility of W/O drilling fluid for coal layer is evaluated, and experimental results show that in W/O drilling fluid, the strength of coal rock decreases by 23% than in fresh water, and by applying non-invasion agent the wellbore stability of coal layer is improved while using W/O drilling fluid system.%通过分析煤岩地层垮塌机理,总结了煤层钻井液技术难点,并提出了稳定煤系地层的钻井液技术对策.室内通过高温高压膨胀实验、粒度分布、回收率及强度实验,评价了油包水钻井液钻穿煤层的可行性.实验表明,煤岩在油包水乳化钻井液中的强度较清水中降低了23％.通过在油包水乳化钻井液中引入无渗透钻井液处理剂,可提高油包水乳化钻井液的封堵能力,降低了油包水钻井液钻遇煤层时井壁失稳的风险.