Study on Interaction Characteristics of Injected Natural Gas and Crude Oil in a High Saturation Pressure and Low-Permeability Reservoir

Natural gas injection is considered for enhanced oil recovery (EOR) in a high saturation pressure reservoir block B111 of the Dagang oilfield, China. To investigate interaction characteristics injected natural and crude oil, ability dissolution–diffusion miscibility–extraction was tested using piece high-temperature high-pressure PVT equipment. The physical properties minimum miscible (MMP) gas–crude system their during dynamic displacement were analyzed numerical simulation method. results show following: (1) Under static gas–oil contact conditions, has significant effect on B111, especially near interface. content condensate phase 10.14–18.53 wt%, while dissolved reaches 26.17–57.73 wt%; (2) reservoir’s saturated solubility relatively small. swelling viscosity reduction limited. As increases with more state can change from liquid to gas; accordingly, density will be greatly reduced, presenting (3) MMP estimated larger than 40 MPa. It mainly forms forward-contact evaporative drive B111. depends maintenance level formation pressure. extraction medium light components oil. C2–C15 at front, as well CH4 C16+ residual trailing edge, increase markedly. Accordingly, also increase. These have certain guiding significance understanding flooding mechanisms designing