The cross-sectional shape of an underground gas storage in a compressed air energy storage (CAES) power plant significantly influences its stress state

thereby affecting gas tightness and stability. It is conventionally considered that a circular cross-section yields the most favorable stress distribution. However

under anisotropic in-situ stress conditions

the hoop stress around a circular cavern is uneven and can induce localized lining cracking and gas leakage. To address this issue

this study investigates elliptical cross-section storage caverns using theoretical analysis based on elasticity theory. First

we propose a gas-tightness criterion based on the elastic stress state and derive an analytical solution for the elliptical cross-section’s optimal axial ratio. Second

we establish a stability criterion for lined rock caverns under anisotropic in-situ stress and develop a method to determine the operating pressure range for elliptical cross-sections

comparing it with the circular cross-section. Furthermore

we perform a parameter sensitivity analysis using FLAC3D to evaluate how factors affect the elliptical cross-section’s optimal axial ratio and operating pressure range. Finally

we establish an integrated calculation process to determine the optimal axial ratio and pressure range. Results show that

under anisotropic in-situ stress conditions

an elliptical cross-section designed with an optimal axial ratio can produce uniform hoop stress around the cavern. When an elliptical cross- section gas storage facility is designed with the optimal axis ratio

its pressure operating range is maximized. The lateral pressure coefficient

in-situ stress and internal pressure of gas storage are the main factors affecting the operating pressure range of elliptical section gas storage. These findings provide theoretical guidance for the shape optimization and pressure design of underground gas storage caverns.