High salinity and high oil content present major challenges to the effectiveness of foam in enhanced oil recovery(EOR).This study introduces RCS,a novel oil-resistant foam system designed for reservoirs with salinity ...High salinity and high oil content present major challenges to the effectiveness of foam in enhanced oil recovery(EOR).This study introduces RCS,a novel oil-resistant foam system designed for reservoirs with salinity levels reaching 2.1×10^(5)mg/L.RCS forms stable foams at oil-water ratios up to 60%and is effective across a wide crude oil viscosity range(10.8-7890 mPa·s).We investigated the film properties of oil-containing foam and the co-permeation behavior of the crude oil-N_(2)-foam system to elucidate the mechanisms underlying foam stability and steady-state flow.RCS emulsified high-viscosity crude oil into stable,large droplets that accumulated within the plateau borders,reducing drainage.Even at concentrations as low as 0.01 wt%,RCS formed stable pseudoemulsion films that prevented intrusion into the gas-water interface,allowing the foam half-life to be mainly controlled by the dilatational viscoelasticity of the interface.With increasing oil-water ratios,both drainage resistance and dilatational modulus increased,extending the drainage and foam half-lives.Coreflood experiments showed that co-injection of RCS with N_(2) and crude oil produced stable foams and in-situ emulsions.At 5%oil fractional flow,the critical foam quality(f_(g)^(*))remained unchanged compared to oil-free conditions,although the maximum apparent viscosity decreased by 29.8%.At 10%oil fractional flow,f_(g)^(*)shifted to a lower value,while the apparent viscosity in the low-quality regime increased markedly—exceeding that of the oil-free condition.These findings highlight that while crude oil more strongly impairs foam stability in porous media than in bulk,the formation of in-situ emulsions can partially offset or even enhance mobility control through a synergistic Jamin effect.Therefore,in-situ emulsification should be emphasized in foam applications within oil-containing environments.展开更多
基金financial support of National Natural Science Foundation of China(52474049)Oil&Gas Major Project(2025ZD1407202)+1 种基金Natural Science Foundation of Sichuan Province(2024NSFSC0198)the Tianfu Yongxing Laboratory Organized Research Project Funding(2023KJGG17)。
文摘High salinity and high oil content present major challenges to the effectiveness of foam in enhanced oil recovery(EOR).This study introduces RCS,a novel oil-resistant foam system designed for reservoirs with salinity levels reaching 2.1×10^(5)mg/L.RCS forms stable foams at oil-water ratios up to 60%and is effective across a wide crude oil viscosity range(10.8-7890 mPa·s).We investigated the film properties of oil-containing foam and the co-permeation behavior of the crude oil-N_(2)-foam system to elucidate the mechanisms underlying foam stability and steady-state flow.RCS emulsified high-viscosity crude oil into stable,large droplets that accumulated within the plateau borders,reducing drainage.Even at concentrations as low as 0.01 wt%,RCS formed stable pseudoemulsion films that prevented intrusion into the gas-water interface,allowing the foam half-life to be mainly controlled by the dilatational viscoelasticity of the interface.With increasing oil-water ratios,both drainage resistance and dilatational modulus increased,extending the drainage and foam half-lives.Coreflood experiments showed that co-injection of RCS with N_(2) and crude oil produced stable foams and in-situ emulsions.At 5%oil fractional flow,the critical foam quality(f_(g)^(*))remained unchanged compared to oil-free conditions,although the maximum apparent viscosity decreased by 29.8%.At 10%oil fractional flow,f_(g)^(*)shifted to a lower value,while the apparent viscosity in the low-quality regime increased markedly—exceeding that of the oil-free condition.These findings highlight that while crude oil more strongly impairs foam stability in porous media than in bulk,the formation of in-situ emulsions can partially offset or even enhance mobility control through a synergistic Jamin effect.Therefore,in-situ emulsification should be emphasized in foam applications within oil-containing environments.
