中文摘要：

为深入研究页岩的水化特征及水化对井壁稳定的影响,以鄂尔多斯盆地石盒子组页岩为研究对象,开展了钻井液浸泡前后岩样的超声波透射实验、层理面直剪实验、三轴压缩实验,探讨了页岩水化的声学性质变化与岩石力学特征,分析了页岩水化对坍塌压力的影响。结果表明：弹性模量、泊松比等参数的变化难以准确评价页岩的水化特征,声波时差、衰减系数、时域曲线、频域曲线等超声波信号可作为研究页岩水化特征的有效手段;页岩水化直接导致其岩石力学性质发生变化,水化是坍塌压力上升的主要原因之一,对井壁稳定造成潜在的威胁;井壁稳定设计时应充分认识页岩的水化特征,避免井壁坍塌,确保钻井施工安全进行。

英文摘要：

In order to investigate the hydration characteristics of shale and the influence of hydration on the wellbore stability,taking the shale of Shihezi formation in Ordos Basin as the research object,the ultrasonic transmission experiments,the bedding plane direct shear experiments and the triaxial compression experiments of rock samples before and after soaking in drilling fluid were conducted. The acoustic properties variation and rock mechanics characteristics of shale hydration were discussed,and the influence of shale hydration on the collapse pressure was analyzed. The results showed that the change of elastic modulus,Poisson＇s ratio and other parameters are difficult to evaluate the hydration characteristics of shale accurately,while the ultrasonic signals,such as acoustic travel time,attenuation coefficient,time domain curve and frequency domain curve can be used as the efficient methods to study the hydration characteristics of shale. The shale hydration directly lead to the change of its rock mechanics properties,and the hydration is one of the major reasons for the increase of collapse pressure,which causes a potential threat to the borehole stability. Therefore,it is imperative to fully recognize the hydration characteristics of shale when carrying out the borehole stability design,so as to avoid the borehole collapse and ensure the safety of drilling operation.