Suitability of Kentucky Reservoirs for Carbon Dioxide-Enhanced Oil Recovery and Sequestration

Kathryn G. Takacs, Thomas M. (Marty) Parris, and Brandon C. Nuttall
Kentucky Geological Survey, University of Kentucky, Lexington, KY 40506 [email protected], [email protected], [email protected]

Seventy reservoirs in 51 oil fields in the Appalachian and Illinois Basins, and the Cincinnati Arch of Kentucky, were evaluated for carbon dioxide-enhanced oil recovery (CO₂- EOR) and sequestration. We first examined the relationship between initial reservoir pressure, fracture pressure, and minimum miscibility pressure, which was calculated using the Cronquist correlation. This analysis, done to determine the extent reservoirs could be repressurized during enhanced oil recovery, showed that initial pressure is less than minimum miscibility pressure for 92 percent of reservoirs, and therefore immiscible conditions would likely prevail. Immiscibility would result in less added production than miscible conditions.

The fields were further analyzed and ranked into quartiles using a combination of measured (e.g., porosity, permeability) and calculated (CO₂ storage density and volume) reservoir parameters. The parameters permeability times pay thickness (k X h), and CO₂ storage density, measured in tons per acre-feet, had considerable influence on which reservoirs placed in the upper quartile (i.e. more positive for CO₂-EOR). The 50^th percentile (Q₅₀) values for both parameters tend to have significantly higher values in the first quartile versus quartiles 2-4: (k X h), Q1₅₀ = 4,944, Q2-4₅₀ = 1,347; CO₂ storage density, Q1₅₀ = 562, Q2-4₅₀ = 112. Other parameters analyzed (initial oil saturation X porosity, API gravity) did not have as significant an impact on placing fields into the upper quartile. This analysis underscores the importance of injectivity, as described by the product k X h, and CO₂ storage density as important parameters influencing enhanced oil recovery-sequestration projects.

AAPG Search and Discovery Article #90095©2009 AAPG Eastern Section Meeting, Evansville, Indiana, September 20-22, 2009