Use of Entrainers for Improving Gas Mobility Control and Displacement Efficiency.

摘要

The use of entrainers to improve CO2 mobility control for enhanced oil recovery was investigated. Entrainers serve as miscible additives that modify the phase behavior of supercritical solvents and enhance the solubility of crude oil components in the CO2 -rich phase. The presence of entrainers increases the viscosities and densities of gas phases. The improvement in supercritical extraction power and the enhancement of bulk fluid properties result in improved mobility ratios. Solution viscosities, densities, and solubilities of entrainers in gaseous carbon dioxide at 104/degree/ and 122/degree/F (40/degree/ and 50/degree/C) and pressures from 800 to 3200 psia (55.16 to 220.63 bars) were determined. Viscosity and density data were determined with a high-pressure capillary viscometer and a Mettler-Paar density meter. Results indicate that CO2 -rich phase viscosities and densities are increased when entrainers are solubilized into the gas phase. The effects of selected entrainers on the preferential solubilization of high-molecular-weight hydrocarbons into the gas phase were also determined. The addition of entrainers causes a preferential extraction of the heavier components of synthetic oils, in comparison with extraction by use of pure supercritical CO2. Coreflooding and slim tube displacement experiments were performed to determine the effects of the presence of selected entrainers on oil displacement efficiency. Results indicate a delay in gas breakthrough and an increased oil recovery at breakthrough. 23 refs., 16 figs., 4 tabs. (ERA citation 14:012579)