Assessing the effects of nanoparticle type and concentration on the stability of CO2 foams and the performance in enhanced oil recovery

Utilizing nanoparticles (NPs) for stabilizing CO2-foams has recently become an interesting subject among petroleum engineers. It has been proven that silica (SiO2) NP is a good agent for stabilizing CO2-foams. Investigating the role of other types of NPs is ongoing and this research attempted to determine and compare the effects of three hydrophilic metal oxide NPs, namely aluminium oxide (Al2O3), titanium dioxide (TiO2), copper oxide (CuO) as well as the effect of SiO2 on the stability of CO2-foams. For this aim, the listed NPs in concentrations from 0.002 to 0.1 wt% were dispersed in de-ionized water to make suspensions. These suspensions were utilized in a chromatography column to produce foam. The stability of the generated NPs-CO2-foams was determined by measuring the half-life time. The results revealed that the highest stability of NPs-CO2-foams was reached at an optimum concentration of 0.008 wt% for all NP types. Moreover, SiO2, Al2O3, TiO2, and CuO NPs-CO2 foams half-life times were obtained 28.1, 24.6, 20.1, and 17.9min, respectively. In addition, the applicability of generated NPs-CO2 foams on oil displacement through quartz sand porous media was determined. The amounts of oil recoveries via SiO2, Al2O3, TiO2, and CuO NPs-CO2 foams achieved were 71.7%, 65.7%, 58.2%, and 57.3% respectively. Overall, it was found that stability of a NP-CO2-foam is strongly dependent on NP type and concentration, and NP stability against deposition in aqueous phase. Based on the findings, more oil recoveries can be achieved by more stable NP-CO2 foams. (C) 2016 Elsevier B.V. All rights reserved.