Abstract:

Significant differences exist in the geological and production characteristics between normal-pressure shale gas reservoirs and high-pressure shale gas reservoirs. The current shale gas reserve calculation standards are primarily based on the initial investment in shale gas exploration and the production patterns of high-pressure shale gas. With breakthroughs in normal-pressure shale gas exploration in blocks such as Wulong and Daozhen in southeastern Chongqing, it is imperative to conduct targeted research on reserve calculation standards by considering the geological characteristics, technical and economic indicators, and production patterns of normal-pressure shale gas. Based on the break-even principle, this study analyzed the sensitivity of economic parameters to reserve calculation standards and developed a calculation model tailored to the characteristics of normal-pressure shale gas according to the production performance of atmospheric shale gas. Taking Wulong block as an example, the reserve calculation standards were estimated at different burial depths by incorporating technical parameters and economic factors such as investment, costs, and gas prices. The variation patterns in the calculation results were analyzed. It was suggested that the reserve calculation standards for single well in normal-pressure shale gas reservoirs ranged from 2.0×10⁴ m³/d to 5.5×10⁴ m³/d when the burial depth was 2 000 m to 7 000 m. The study of reserve calculation standards for normal-pressure shale gas provides valuable insights for revising relevant standards, facilitating the addition of proven reserves and large-scale production of normal-pressure shale gas outside the Sichuan Basin.

Key words: normal-pressure shale gas, Southeastern Chongqing, Wulong block, reserve calculation standards, Wufeng and Longmaxi Formation, break-even principle