Deep shale sedimentary environment, diagenesis, and pore evolution are closely related to the occurrence state and content of shale gas, exerting significant control on reservoir quality. In this study, scanning electron microscopy (SEM), mineral composition, spectral gamma-ray logging, elemental logging, and comprehensive well log data were used to analyze the sedimentary environment. Combined with pore structure and storage space experiments, the geological conditions for deep shale gas accumulation were discussed. The Longmaxi Formation high-quality shale reservoirs in southern Sichuan (Luzhou area) are laterally extensive, vertically thick, and contain well-developed natural fractures; thus, reasonable well pattern deployment is crucial to avoid casing deformation, mitigate fracture interference, and improve productivity. Results show that shale gas enrichment and accumulation are controlled by four main factors: (1) Deep-water anoxic deposition enriching organic matter ("source control"), (2) Source–reservoir coupling controlling accumulation, (3) Temperature–pressure coupling controlling gas content, and (4) Faults controlling preservation. Based on static reservoir characteristics and production dynamics, a three-dimensional inter-well development model was established. Horizontal well spacing is 300--400 m, vertically targeting two layers (Long 1-11 and upper Long 1-13 sublayers) with staggered hydraulic fracturing and phased production. Field statistics show that this multi-layer phased scheme reduces engineering problems, lowers casing deformation incidence, and increases average EUR per 1000 m by about 10% compared with conventional single-layer deployment.