The Lower Cambrian Qiongzhusi Formation shale has been recognized as a strategic replacement area for natural gas reserve expansion and production enhancement in Sichuan Basin following Longmaxi Formation. In recent years, multiple high-yield industrial gas flows have been obtained from shale gas wells in both the western slope outside the extensional trough and the intra-trough regions of the Qiongzhusi Formation. However, the primary controlling factors and geological models governing the enrichment of organic-bearing shales in extra-trough areas and organic-rich shales in intra-trough areas remain unclear, which has constrained the exploration and development progress of the Qiongzhusi Formation. To address these issues, focusing on the Qiongzhusi Formation shales both inside and outside the extensional trough, through comprehensive technical approaches including organic geochemical analysis, reservoir pore structure characterization, caprock breakthrough pressure testing, and vein fluid inclusion analysis, three key findings were obtained. Superior source-reservoir configurations were identified in the intra-trough region, particularly in the sublayers from ⑥ to ⑧ where complete hydrocarbon accumulation elements were assembled with high total hydrocarbon gas logging values. In contrast, limited hydrocarbon generation capacity was observed in the western slope region outside the trough, where the source-reservoir configuration in sublayers from ⑥ to ⑧ was found to gradually improve for shale gas enrichment from west to east and south to north. Effective top-seal and floor-seal systems were confirmed in both the intra-trough region and northern structural zone of the western slope outside the trough. These areas were characterized by stable structures with minimal faulting impacts, predominantly high formation pressures, and multiple pressure compartment systems, indicating favorable preservation conditions. Conversely, the southern structural zone of the western slope outside the trough was distinguished by well-developed faults, formation dip angles generally exceeding 12°, and predominantly normal pressures, suggesting moderate preservation conditions. Three geological enrichment models were established for the study area: enrichment through strong hydrocarbon generation and limited dissipation in organic-rich black shales, enrichment via strong lateral migration supply and effective self-sealing in organic-bearing shales, and suboptimal enrichment resulting from limited hydrocarbon generation and caprock leakage in organic-bearing shales. The research is of great significance for shale gas exploration and development in Sichuan Basin.