Q.P. Nguyen, G. Ren
The University of Texas at Austin, United States
pp. 152 - 155
Keywords: supercritical CO2 foam, CO2 soluble surfactants, oil recovery, mobility control
Sweep efficiency in CO2 enhanced oil recovery processes are major problem owing to the unfavorable mobility of CO2. One method of controlling CO2 mobility is through the use of foam. CO2 foam in the past has predominately utilized commercial surfactant formulations, but with mixed results. This work pertains to the development of a new class of surfactants that can be injected with CO2 rather than in water to improve foam performance, surfactant efficiency, and reduce water use. The paper describes the methodology used for designing the surfactants and screening the foaming properties. Surfactant solubility and partitioning among supercritical CO2 (scCO2) and an aqueous phase (water or brine) were measured as a function of electrolyte concentration and pressure. Foam core flood was conducted to determine foam and surfactant transport. In general, the surfactant solubility in scCO2 increased with pressure and decreased with temperature. The partitioning of surfactants into scCO2 from brine was almost proportional to pressure, and decreased as temperature increased, where the latter held more sensitivity. Surfactant partition strongly influenced CO2 displacement of brine in carbonate cores. In-situ foam generation during the injection of CO2 with dissolved surfactant was remarkable.