层理性页岩各向异性井壁失稳机理研究

Study on Anisotropic Wellbore Instability Mechanism of Bedding Shale

松辽盆地北部陆相页岩层理发育、岩性复杂、质地硬脆,该区块页岩油水平井井壁失稳事故频繁发生,严重制约了页岩油的高效开发进程。为此,以松辽盆地北部陆相页岩为研究对象,通过XRD衍射实验分析其属于硬脆性页岩,单轴和三轴抗压强度实验测定了页岩各向异性弹性参数和强度参数,页岩基质内聚力和内摩擦角为10.0 MPa、33.0°,弱面内聚力和内摩擦角为3.0 MPa、27°;基于孔隙弹性力学,建立层理性页岩各向异性井壁稳定模型,以松辽盆地页岩油水平井G1井进行实例分析。结果表明:G1井实钻情况与预测结果基本一致,证实了模型的准确性,可用于指导层理性页岩油水平井钻井工程设计。

The continental shale in the north of Songliao basin has developed bedding, complex lithology and hard brittle texture. The wellbore instability accidents of shale oil horizontal wells in this block occur frequently, which seriously restricts the efficient development process of shale oil. Therefore, taking the continental shale in the north of Songliao Basin as the object, it was analyzed by XRD, it was pointed out that it belongs to hard brittle shale. The anisotropic elastic parameters and strength parameters of shale were measured by uniaxial and triaxial experiments.The cohesion and internal friction angle of shale matrix were 10.0 MPa and 33.0°, and the weak plane cohesion and internal friction angle were 3.0 MPa and 27°;Based on the pore elasticity, the anisotropic wellbore stability model of layered shale was established, and the example analysis was carried out for the shale oil horizontal well G1 in Songliao basin. The results showed that the actual drilling situation of well G1 was basically consistent with the prediction results, which confirmed the accuracy of the model. It can be used to guide the drilling engineering design of shale oil horizontal wells.