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Abstract As many oil and gas reservoirs approach depletion stages in the future, alongside growing energy storage demands, constructing gas storage facilities becomes critical for ensuring a stable natural gas supply. Consequently, a comprehensive geological analysis is essential to evaluate the feasibility of converting depleted gas reservoirs into gas storage facilities. The W gas reservoir in the Sichuan Basin, China, is nearing depletion and presents potential for conversion into a gas storage facility. This study provides a comprehensive geological evaluation to determine its feasibility for such conversion. Exploration and production data indicate that the W gas reservoir is a pore-fracture type carbonate reservoir. Vertically, the sub-layer beneath C2hl2 demonstrates the best physical properties. Horizontally, the area enclosed by wells C30, C10, and C18 exhibits favorable reservoir characteristics. The reservoir’s caprock comprises a superimposed composite system, including the direct caprock of the Liangshan Formation and an overlying ultra-thick dense rock layer, which is extensive and exhibits high breakthrough pressure. Nine major faults control the structural trap’s shape and scale. These faults, in a compressive state, are well-sealed due to fault gouge, enhancing their closure. The reservoir space is primarily pore-fracture type, and rapid injection and withdrawal induce minimal pressure changes, indicating low stress sensitivity. The comprehensive evaluation concludes that the Carboniferous gas reservoir possesses favorable geological conditions, making it suitable for conversion into a gas storage facility. This study offers a preliminary geological evaluation of the feasibility of converting fault-controlled fracture-type carbonate reservoirs into gas storage facilities and outlines directions for future research.

The Cambrian strata of Sichuan Basin, China, present many dolomite-evaporite paragenesis systems (DEPS), which contain oil and gas resources for industrial exploitation. However, despite their wide distribution, the formation models and influencing factors of DEPS remain poorly understood. By analyzing an abundance of literature from China, this study comprehensively summarizes the sedimentary characteristics, combination patterns of rocks, and formation models of DEPS. The research significance, research questions, and future research directions of DEPS are also clarified. Firstly, the distribution of DEPS is clarified based on published studies: DEPS are widely distributed in the Longwangmiao Formation, the Gaotai Formation, and the Xixiangchi Formation of the eastern and southern Sichuan Basin. Evaporite and dolostone combination patterns in DEPS include the following modes: interbedding of dolostone and evaporite, evaporite overlying thick dolostone, thick dolostone mixed with thin evaporite, and thick evaporite mixed with thin dolostone. Secondly, five types of evaporites and five types of dolostones have been identified. Thirdly, spatiotemporal distribution, influencing factors, and developmental models are summarized. Studies on DEPS provide new insight into the origin of dolomite. Such research also provides theoretical guidance for the exploration of oil and gas resources in DEPS.