A Seepage–Temperature–Stress Coupling Model to Simulate Water-Sealing Performance of Underground Oil Storage Caverns During Operation

Abstract Underground oil storage caverns serve as an effective oil storage technology, with the crude oil sealed by a water curtain system. The water curtain system injects water into the rock layer through water curtain holes, creating a stable water-seal environment to prevent oil vapor leakage. A multi-physics coupling model for seepage, temperature, and stress was established to analyze the water-sealing performance of the caverns based on large-scale underground water-sealed oil storage caverns in a coastal area. The variation patterns for the water-sealing integrity and surrounding rock stability of the caverns were elucidated by analyzing various physical fields under the selected working conditions. The effects of the pressure and spacing of water curtain holes on the water-sealing performance were further investigated on this basis. The results indicate that the water-sealing integrity of the caverns gradually weakens as the operation time increases at a low hole pressure. The subsidence at the top of the caverns exceeds that at the bottom at the final stage of operation. As the hole pressure increases from 150 kPa to 250 kPa, the water inflow rate at the final stage of operation increases by 48%, while the amount of crude oil leakage decreases by 98%. With the spacing between water curtain holes increasing from 5 m to 25 m, the water inflow rate decreases by 13%, while the amount of crude oil leakage increases by 534%. Ultimately, the established model was validated based on an engineering case.