Objective In response to helium resource scarcity and stringent sealing performance requirements for storage in salt caverns, a study was conducted to assess sealing performance and optimize operating pressure for layered salt rock helium storage, aiming to enhance the safety and effectiveness of underground helium storage.

Methods The steady-state method test was performed using a physical simulation device for salt cavern hydrogen/helium storage to measure the permeability of helium in salt rock and interlayer samples under a confining pressure of 30 MPa, providing a parameter basis for numerical simulation. A seepage model for salt cavern helium storage was established to simulate the seepage behavior and leakage characteristics of helium under various operating pressure conditions, allowing for the analysis and determination of the optimal operating pressure range that considered both sealing safety and gas storage efficiency.

Results The test results indicated that the permeability of helium in salt rock was about 7.58×10⁻²¹ m², which was significantly lower than that in interlayer (1.31×10⁻¹⁷ m²), indicating that salt rock had far better gas-sealing performance than the interlayer. Numerical simulations revealed that the helium leakage rate increased with the minimum operating pressure over a 30-year operation cycle: the total leakage rate was about 5.3％ at a lower limit of pressure of 8 MPa and increased to approximately 5.7％ at 10 MPa. Additionally, raising the lower limit pressure enhanced effective helium storage capacity. Considering both helium leakage control and the gas storage capacity of the salt cavern, an optimal operating pressure range of 9 MPa to 21 MPa was determined.

Conclusion Layered salt rock exhibits excellent natural sealing performance for helium. Within a reasonable operating pressure range, helium leakage can be controlled within 5.5％, allowing for optimal utilization of storage capacity. These research findings provide valuable insights for the design and safe, efficient operation of salt cavern helium storage.