Numerical investigation of casing deformation patterns in shale gas wells under different fault slip conditions

Casing shear deformation caused by multistage fracturing has severely constrained the development of deep shale gas resources in the Luzhou Block of southern Sichuan. To accurately distinguish the differences in casing deformation patterns caused by fault slip, this paper establishes a 3D numerical model for simulating casing shear deformation due to fault slip. This model contains formation-cement sheath-casing, and the parameter settings are based on the actual site, with different casing deformation patterns are obtained by setting the slip displacement and slip direction pieces of different fault parts. The results indicate: (1) Fault slip cause extrusion of the casing at the fault interface and the center of the section is offset from the original wellbore axis, and the relative slip displacement determines the magnitude of casing deformation; (2) The deformation caused by normal faults is more symmetrical than that caused by strike-slip faults, resulting in greater deformation amount of the casing; (3) When asynchronous sliding occurs on one side of the fault , the deformation of the casing will be greater when the fault slides up and down on one side compared to sliding left and right on one side. The conclusion can provide a reference for casing deformation cause identification and early prevention in shale gas wells.