Abstract: The deep shale gas reservoir (3500-5000m) in the Silurian Longmaxi Formation in Luzhou block in Sichuan Basin is an important replacement field for shale gas development in China. However, the geomechanical properties of reservoir rock and variation in in-situ stress lead to difficulties in the development process, such as the long drilling cycle and large difference in gas rate of a single well. The geomechanical study enables to deepen the understanding of in-situ stress field in the block and provides basis for optimizing well location placement, drilling engineering and fracturing design of horizontal shale gas wells. The acoustic logging, diagnostic fracture injection testing (DFIT), imaging logging, and laboratory stress measurement data are combined to construct a high-precision geomechanical model in Petrel software, which supports to identify the reservoir geomechanical property in the study area, and the application of geomechanical study results in engineering is discussed. The results show that Young’s modulus gradually increases and Poisson’s ratio decreases with the increasing burial depth in Luzhou block. The shale reservoir in Longmaxi Formation is characterized by abnormally high pressure, with pore pressure gradient ranging in 16.7-21.7 kPa/m. The strike-slip type stress regime is dominant in Luzhou block, with an overlying rock pressure gradient of 25.5 kPa/m, a minimum horizontal principal stress gradient ranging in 18.8-24.5 kPa/m, and the average ratio of the maximum horizontal principal stress to the minimum horizontal principal stress of 1.165, and the reservoir horizontal principal stress increases with the increase of Young’s modulus and pore pressure. The geomechanical study results are used to guide the well location placement, optimization of drilling fluid density in drilling engineering, and optimization of fracturing stages and clusters and engineering parameters in fracturing design. For example, the drilling fluid density was optimized to 1.85 g/cm³ in Well Y65-X, achieving “one trip drilling” of the deviated-horizontal section and a 67% reduction in drilling cycle compared to adjacent wells; The fine fracturing stages and clusters and engineering parameters were optimized for Well Y2-X, and a gas flow rate of 50.69×10⁴ m³/d was tested. The study concludes that the high-precision geomechanical model and achievements enable to effectively improve the drilling operation efficiency and gas flow rate of a single well, and serve for the benefit development.