FRACTIONAL FLOW ANALYSIS OF DISPLACEMENT IN A CO2 ENHANCED GAS RECOVERY PROCESS FOR CARBONATE RESERVOIRS

This paper presents fractional flow analysis of displacement of gas/condensate in a wet/condensate gas reservoir by CO2 that includes interactions between CO2 and condensate. Phase behavior affects the performance of carbon dioxide enhanced oil/ gas recovery processes in a significant manner. It also controls the effectiveness of carbon dioxide sequestration processes. In the past, there has been a focus on understanding interactions of CO2 with matrix and other fluids in oil reservoirs by various researchers. However, there is now an increasing interest in understanding carbon dioxide interactions in gas condensate reservoirs so that CO2 can be used to increase recovery. For a carbonate reservoir containing gas-condensates, this new focus requires a fundamental understanding of the interactions of carbon dioxide with condensate and gas phases. This paper describes the relative effect that these mechanisms have by conducting a fractional flow analysis for Enhanced Gas Recovery. These mechanisms include miscibility and partitioning of CO2 in various phases. Understanding these mechanisms is essential to modeling Enhanced Oil/Gas Recovery using CO2. The analysis honors the material balance and accounts for miscibility between carbon dioxide and condensate. The results of the fractional flow analysis are important for validation of computer simulation of the comparable processes. This work is expected to serve as a foundation work in understanding the mechanisms involved in CO2 assisted enhanced oil and gas recovery.