Study on the ability and heterogeneity of oil water two-phase flow in sandstone

Abstract

Abstract It is difficult to analyze the heterogeneity of sandstone reservoir and the seepage law of multi-phase fluid in Porous medium. Traditional experimental methods are difficult to accurately characterize the multi-phase flow and seepage characteristics of heterogeneous sandstone. This study focuses on the marine continental transitional sandstone reservoir in the the Pearl River Mouth Basin, South China Sea, and analyzes the influence of oil-water permeability of sandstone and pore throat radius on permeability. The finite element seepage model of oil-water two-phase in heterogeneous sandstone is constructed based on the Weibull distribution function, and the seepage simulation is carried out in combination with the actual geological profile. The analysis results indicate that the transitional sandstone between sea and land has higher bound water saturation and narrower pore throat radius compared to conventional sandstone. The numerical simulation results show that the porosity, permeability, and pressure gradient of sandstone have a significant impact on the two-phase flow ability of sandstone, while the influence of bound water saturation is relatively small, while the residual oil saturation has no effect. Weibull distribution function can better characterize the heterogeneity of sandstone reservoir. The shape parameters of Weibull distribution have more significant influence on rock heterogeneity. The larger the shape parameter of Weibull distribution function is, the more concentrated the sandstone seepage velocity field and oil saturation distribution are, and the farther the seepage distance is; The larger the scale parameter of Weibull distribution is, the more dispersed the sandstone seepage velocity field and oil saturation distribution are, and the farther the seepage distance is. Based on physical simulation experiments and numerical simulation results of crude oil migration, due to the heterogeneity between sandstone and mudstone, the fluid selectively fills sandstone reservoirs with better physical properties. The simulated oil water seepage characteristics are also in good agreement with the distribution of actual oil reservoirs.