In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Th...In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Therefore,seawaters spiked with divalent ions were used with sulfonated polyacrylamide(SPAM)polymer to investigate the effects of potential determining ions on SPAM performance in wettability alteration,polymer adsorption,carbonate surface charge,viscosity enhancement,emulsion type,and oil recovery.Among divalent anions and cations,only excess amounts of Mg^(2+)in a smart water-polymer solution could alter the wettability from oil-wet to neutral-wet and make the rock/brine zeta potential positive.Additionally,higher SPAM adsorption onto carbonate surfaces was observed as Mg^(2+)concentration was doubled,driven by interactions between sulfonate groups(-SO_(3)^(-))and the positively charged rock surface.Conversely,excess SO_(4)^(2-)impeded interactions between -SO_(3)^(-) and positively charged carbonate rock species,reducing SPAM adsorption.At 5000 ppm SPAM concentration,excess divalent ions increased solution viscosity due to the shielding effect,with the highest viscosity achieved by doubling Mg^(2+)concentration.However,at 10,000 ppm SPAM concentration,only SO_(4)^(2-) improved viscosity,while Ca^(2+)and Mg^(2+)reduced the viscosity of smart water-polymer solutions.As for emulsions produced by smart water-polymer solutions,the presence of SPAM in smart water led to the production of water-in-oil(W/O)emulsions and increased the mean droplet size of water droplets due to the salt-out effect.According to the results obtained from calcite-coated micromodel flooding experi ments,the ultimate oil recovery for SW+SPAM(5000 ppm)was 34.2%.Also,a two-fold increase in the Mg^(2+)concentration rose the oil recovery by 6.5%.展开更多
文摘In low salinity polymer flooding(LSPF),an advanced hybrid method for enhanced oil recovery(EOR),less attention has been given to the impacts of potential determining ions on polymer behavior in carbonate reservoirs.Therefore,seawaters spiked with divalent ions were used with sulfonated polyacrylamide(SPAM)polymer to investigate the effects of potential determining ions on SPAM performance in wettability alteration,polymer adsorption,carbonate surface charge,viscosity enhancement,emulsion type,and oil recovery.Among divalent anions and cations,only excess amounts of Mg^(2+)in a smart water-polymer solution could alter the wettability from oil-wet to neutral-wet and make the rock/brine zeta potential positive.Additionally,higher SPAM adsorption onto carbonate surfaces was observed as Mg^(2+)concentration was doubled,driven by interactions between sulfonate groups(-SO_(3)^(-))and the positively charged rock surface.Conversely,excess SO_(4)^(2-)impeded interactions between -SO_(3)^(-) and positively charged carbonate rock species,reducing SPAM adsorption.At 5000 ppm SPAM concentration,excess divalent ions increased solution viscosity due to the shielding effect,with the highest viscosity achieved by doubling Mg^(2+)concentration.However,at 10,000 ppm SPAM concentration,only SO_(4)^(2-) improved viscosity,while Ca^(2+)and Mg^(2+)reduced the viscosity of smart water-polymer solutions.As for emulsions produced by smart water-polymer solutions,the presence of SPAM in smart water led to the production of water-in-oil(W/O)emulsions and increased the mean droplet size of water droplets due to the salt-out effect.According to the results obtained from calcite-coated micromodel flooding experi ments,the ultimate oil recovery for SW+SPAM(5000 ppm)was 34.2%.Also,a two-fold increase in the Mg^(2+)concentration rose the oil recovery by 6.5%.
