中文摘要：

在页岩气开发的水力压裂过程中，岩层滑移引发的剪切套损时有发生。某级压裂引发套损后，导致在后续压裂施工中下放工具受阻，最终被迫放弃对部分区段的压裂改造，使页岩气采收率降低。目前研究者对于是否在滑移面附近固井，以及降低固井水泥刚度能否有效缓解剪切套损2个问题的认识存在分歧，数值模拟可为解决这一问题提供理论支撑。引入了表征剪切套损中套管变形程度的参数：单位横向位移和椭圆度。根据压裂中剪切套损的特点，建立了相应的三维有限元模型，模拟了岩层滑移过程中套管-水泥环-地层系统的变形，分析了不固井长度和固井水泥力学性能对套管剪切变形的影响。研究结果表明：在滑移面附近不固井能有效缓解剪切套损，但单纯改变固井水泥力学性能的效果微乎其微。研究成果对明确缓解剪切套损的固井方法有一定的理论指导意义。

英文摘要：

Casing shear damage arising from rock sliding is common in the hydraulic fracturing of shale gas development. Casing damage in fracturing at a certain stage may cause tool trip-in failure in the follow-up fracturing operation,and thereby result in abandonment of fracturing for some intervals and reduce shale gas recovery. Researchers have different opinions on cementing near sliding surface and cementing stiffness reduction for effective casing shear damage relief. Numerical modeling can provide theoretical supports for solving the above divergence. Casing deformation parameters of casing shear damage are introduced,including unit lateral displacement and ovality. Based on the characteristics of casing shear damage in the fracturing,a corresponding 3D finite element model is built to simulate the deformation of casing-cement ring-formation system in the rock sliding and analyze the effects of non-cementing length and mechanical properties for cementing on casing shear deformation. Results show that non-cementing near the sliding surface can effectively reduce the casing shear damage but simple change of mechanical properties for cementing has little effect. The results have certain theoretical significance on defining the cementing method for reduction of casing shear damage.