Nanopore confinement effects on phase behavior and capillary pressure in a Wolfcamp shale reservoir

摘要: Abstract As unconventional oil production is the main focus in petroleum industry, phase behavior of fluids nanopore media draws high attention nowadays. The extremely small pore sizes shale reservoirs affect fluid equilibrium. In this study, equilibrium Wolfcamp nanopores studied by coupling cubic Peng–Robinson equation state (PR-EOS) with Young–Laplace capillary pressure equation, fugacity vapor–liquid calculation, and shifted critical properties. A mercury injection experiment showed that 93.7% diameters cores were less than 10 nm. curve a real reservoir multicomponent was generated for first time. results show bubble point suppressed 17.3% when radius (r) 10 nm, 63.8% r 1.5 nm. interfacial tension (IFT) decreases slowly bigger 50 nm. However, as becomes smaller, IFT rapidly, especially confinement narrows two-phase region, resulting lower elongating gas–oil ratio period.