Abstract
At present, fault slip is considered as the main reason for casing shear deformation in horizontal shale gas wells. Therefore, most of the studies are focused on the diffusion law of fluid pressure during fracturing and ignored the path of fracturing fluid into the fault. Based on the fault slip mechanism, combined with the phenomenon of micro-seismic signals in non-fracturing areas, this paper summarizes three paths of fracturing fluid into the fault: micro-annulus between casing and cement sheath, micro-fractures near wellbore, large-scale natural fractures. Correspondingly, laboratory tests, numerical simulation and field analysis are carried out to demonstrate the possibility of casing deformation. Finally, the preventive measures are put forward. The research results show that during the fracturing, hydraulic fractures are easily captured by natural fractures and fluid pressure is transfered to the far end of the fracturing area, causing stress interference and even casing deformation in the non-fracturing zone. The use of temporary plugging and steering fracturing technology can improve the leakage of fracturing fluid into faults, and increase the complexity of hydraulic fractures at the same time, thereby improving the development benefit.
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