Nanoparticle-Stabilized Carbon Dioxide Foam Used In Enhanced Oil Recovery: Effect of Different Ions and Temperatures
Summary This paper reports the study of the effect of different ions (monovalent, bivalent, and multiple ions) on nanosilica-stabilized carbon dioxide (CO2) foam generation. CO2 foam was generated by coinjecting CO2/5,000 ppm nanosilica dispersion (dispersed in different concentrations of brine) into a sandstone core under 1,500 psi and at different temperatures. A sapphire observation cell was used to determine the foam texture and foam stability. Pressure drop across the core was measured to estimate the foam mobility. The results indicated that more CO2 foam was generated as the sodium chloride (NaCl) concentration increased from 1.0 to 10%. In addition, the foam bubble became smaller and foam stability improved with the increase in NaCl concentration. The CO2-foam mobility decreased from 13.1 to 2.6 md/cp when the NaCl concentration increased from 1 to 10%. For the bivalent ions, the generated CO2-foam mobility decreased from 19.7 to 4.8 md/cp when CaCl2 concentration increased from 0.1 to 1.0%. Synthetic produced water with total dissolved solids (TDS) of 18,583 ppm was prepared to investigate the effect of multiple ions on foam generation. The results showed that stable CO2 foam was generated as the synthetic produced water and nanosilica dispersion/CO2 flowed through a porous medium. The lifetime of the foam was observed to be more than 2 days as the foam stood at room temperature. Mobility of the foam was calculated as 5.2 md/cp.