Combined Fracturing Mode Based on Avoiding Fault Activation Mechanism
The problem of casing shear deformation in the multistage fracturing process of shale gas wells is becoming increasingly serious,and more seriously,a phenomenon of hydraulic fracturing induced fault activation which causes casing deformation in adjacent wells occurs,which leads to the inability of fracturing in adjacent hori-zontal wells to proceed smoothly,seriously affecting the productivity operation of blocks.However,the existing methods such as reducing pump pressure and displacement have not shown significant control effects on casing de-formation.Based on the Mohr-Coulomb criterion,an interwell fault activation evaluation model for shale gas wells was built,revealing the interwell fault activation mechanism under conventional fracturing modes,and proposing a combined fracturing mode based on avoiding hydraulic fracturing induced fault activation mechanism.The results show that under conventional fracturing mode,the fault areas between wells would all be activated,leading to the loss of section in adjacent horizontal wells.As the well spacing increases and the included angle of horizontal well decreases,the lost section length of horizontal well increases.By means of adopting the zipper-sequential-synchro-nous combined fracturing mode to optimize the multi-well multistage fracturing sequence in the vicinity of fault,the effect of avoiding early activation of faults and reducing the lost section length of horizontal well can be achieved.The research results provide theoretical guidance for fault activation and casing deformation control in shale gas hor-izontal wells.
shale gas horizontal wellmultistage fracturingfault activationfracturing modecasing de-formation