FEASIBILITY INVESTIGATION OF CO2 MISCIBLE FLOODING IN SOUTH SLATTERY MINNELUSA RESERVOIR, WYOMING

Chemical floods are challenged by the low permeability and high salinity in many special reservoirs due to the sensitivities of chemical injections. The large range of permeability and non‑sensitive to salinity of CO2 miscible injection makes it become more and more popular in the past decades. The Slattery Minnelusa A is a low permeability and high salinity sandstone reservoir. Currently, the water cut and oil rate are getting close to the economic limits after near two decades of water injection. It is necessary to figure out a way to stabilize the oil output. In this research, the technical feasibility of CO2 miscible injection was investigated in the Slattery. Both experimental and numerical simulations were employed in the methodology research. The minimum miscibility pressure (MMP) of CO2/Slattery oil was determined with the slim‑tube method as a precondition. The reservoir simulations were performed to estimate the field scale flooding efficiency of both the pure gas (PGI) and water alternating gas (WAG) injections. The research validated the feasibility of the CO2 miscible flooding in the Slattery. Two disadvantages of current production system, the unfavorable well pattern and reservoir pressure, were presented and analyzed. Solutions were also suggested to improve the CO2 injection. The results of the field scale simulations showed the PGI injection was more suitable in Slattery. Simulation predictions were also fully employed to optimize injection parameters. This investigation is an excellent opportunity to: (1) demonstrate the method to assess the potential of a CO2 miscible flood in the South Slattery field, (2) show that this should be of reference value to many other similar reservoirs.