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Frequently occurring casing deformation in horizontal wells has severely affected the efficient development of shale gas in the Sichuan Basin, China. To mitigate casing deformation, a good understanding of casing deformation mechanisms is necessary. In this work, a seismic-based analysis on casing deformation mechanism of shale gas wells in the Luzhou block of the Sichuan basin is presented. Based on seismic data, faults and fractures are interpreted, pore pressure and in-situ stresses are estimated, and the casing deformation mechanism is analyzed. The results show that 70% of the casing deformation points are located on faults or fractures with a high stress difference (>15 MPa). The faults/fractures in critical stress state before drilling may be activated by the redistribution of stress after drilling, thereby leading to pre-fracking casing deformation. The faults/fractures in steady stress state before drilling can be activated by the stress perturbation from hydraulic fracturing, thus resulting in casing deformation during hydraulic fracturing. Overall, the main cause of casing deformation in the Luzhou block is fault slip. As seismic data has the potential to provide pre-drill information, seismic-based analyses hold great significance in optimizing drilling and fracturing plans for shale gas wells.