Improving Co2 Efficiency for Recovering Oil in Heterogeneous Reservoirs

Abstract

Efficiency for Recovering Oil in Heterogeneous Reservoirs." This research improved our knowledge and understanding of CO 2 flooding and included work in the areas of injectivity and mobility control. Chapter 1 summarizes a survey performed for all the CO 2 injection projects in the Permian Basin. Chapter 2 covers CO 2 -brine-reservoir rock interactions that were studied to better understand injectivity implications. Chapter 3 summarizes work performed to determine possible injectivity and productivity reduction due to high flow rate in near-wellbore regions, and Chapter 4 summarizes work in the areas of foam stability, interfacial tension, surfactant adsorption and desorption, and mobility control. Chapter 5 lists the papers, reports, workshops, and presentations produced as a result of the research work under this contract.The work performed under this contract and the results achieved through this research in the related fields of mobility control and injectivity will improve industry understanding of CO 2 flooding mechanisms, with the ultimate goal of economically recovering more of the U.S. oil reserves. Results include:• Identification of the extent that various properties affect foaming agent adsorption, i.e.: rock type, surfactant type, surfactant concentration, co-surfactants, sacrificial agents, brine salinity, pH, and temperature.• Understanding of the extent of synergistic effects on adsorption and desorption in dual chemical systems for five powdered minerals and three rock types.• Identification of parameters that change injectivity and improve sweep efficiency.• Identification of causes of injectivity changes: fines migration, permeability changes, dissolution, precipitation, stress/pressure gradient, phase behavior, flow rate, etc.• Development of models to predict advancing rates of individual components in mixed chemical systems with adsorption and desorption kinetic and equilibrium rates, foam behavior in heterogeneous systems, and injectivity.iv