断层滑移剪切套管变形内径变化规律研究

Variation of Inner Diameter After Casing Shear Deformation Induced by Fault Slippage

页岩气多级压裂过程中出现的套管变形问题亟待解决。现场测量数据表明,剪切变形是主要破坏形式。建立了基于断层滑移的页岩气井套管剪切变形数值模型,计算了剪切变形后套管内径沿轴向变化规律。研究结果表明:断层滑移后套管最小内径出现在套管滑移面附近;随着滑移距离的不断增加,套管内径缩径量不断增加;断层面与套管垂直时,套管剪切变形最为显著。为避免引起断层滑移,应在设计中尽量使井眼轨迹避开天然裂缝带,或者顺裂缝带走向钻进,以利于套管完整性的保护。研究结果可为页岩气井压裂过程中套管完整性的控制提供参考。

Casing defomation is a problem to be urgently solved occurred during the multi-stage fracturing of shale gas.According to the multi-arm caliper measurement data,shear deformation is the main type of casing deformation.Based on the fault slipping in practice,a numerical model of casing shear deformation was established,and the axial variation of casing inner diameter after shear deformation was calculated.The results show that with the increase of slip distance,the reduction of casing inner diameter increases.When the fault surface is perpendicular to the casing,the casing shear deformation is the most significant.It is suggested that the trajectory of the well section be designed to avoid from the natural fracture zone,or it be drilled along the fracture zone so as to protect the casing integrity.The research results can provide reference for the control of casing integrity during the fracturing of shale gas wells.