Integrated Investigation of Enhanced Oil Recovery in South Slattery Minnelusa Reservoir, Part 2: CO2 Miscible Injection

Abstract

The authors used experiment and full-field reservoir modeling to investigate and optimize the design of a CO2 miscible flooding project for the Minnelusa reservoir of the South Slattery field. Minimum miscibility pressure and core flooding tests were conducted to estimate the CO2 injection feasibility at Slattery conditions. A full-field CO2 model with finely gridded patterns was built using oil saturations and pressures at the end of history in the waterflood model. The CO2 model identified the best patterns for CO2 flooding and was instrumental in selecting a strategy for sizing the initial flood area and in determining the size, location, and timing of future expansions of the CO2 flood. Continuous CO2 miscible injection (CMI) and alternating (WAG) were simulated. WAG injections were simulated mainly to observe the improvement of low sweep efficiency caused by override and unfavorable mobility ratio. The integrated recovery efficiency comparison of CMI and WAG was used to demonstrate the mobility control of the WAG process.