Steady seepage simulation of underground oil storage caverns based on Signorini type variational inequality formulation

To analyze the seepage characteristics of water-sealed underground oil storage caverns, a calculation software was programmed based on the Signorini type variational inequality formulation. The storage region and boundary condition of oil-groundwater contact surface were generalized, and a two-dimensional numerical simulation model of finite-element method was built. The seepage characteristics and the water inflow of oil storage caverns were analyzed, while the conditions of different oil levels in caverns with water curtain system were taken into account. The effect of a water curtain system was assessed, and the design parameters of water curtain system such as width, water pressure, borehole space, and elevation were evaluated. The seepage simulation model was applied to estimate the seepage field and water inflow of the Huangdao underground oil storage caverns during the future operation period.