Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

CO2 flooding is recognized as an efficient method for enhancing shale oil recovery, while CO2-oil MMP (minimum miscibility pressure) in the micro-nanoscale a crucial parameter. This paper presents calculating MMPs of pure hydrocarbons (C4H10, C6H14, C8H18, and C10H22) systems nanopores (3 nm to 10 nm) with temperature ranging from 290.15 K 373.15 K. Firstly, we modify Peng-Robinson equation state (PR-EOS) by considering influence confinement effect capillary pressure nanopores. Secondly, flash calculation algorithm employed determine whether gas phases have reached equilibrium according equality fugacity two phases. Thirdly, calculate interfacial tension (IFT) between using Macleod-Sugden equation. When extrapolated IFT zero, treat corresponding system Simulation results indicate that calculated this has relative error about 0.62% compared multiple mixing cell (MMC) method, indicating high reliability prediction. Moreover, measured at nanoscale generally smaller than bulk phase due effect. The positively correlated reservoir temperature, carbon atom number alkanes, nanopore radius.