Low-salinity water(LSW)and CO_(2) could be combined to perform better in a hydrocarbon reservoir due to their synergistic advantages for enhanced oil recovery(EOR);however,its microscopic recovery mechanisms have not ...Low-salinity water(LSW)and CO_(2) could be combined to perform better in a hydrocarbon reservoir due to their synergistic advantages for enhanced oil recovery(EOR);however,its microscopic recovery mechanisms have not been well understood due to the nature of these two fluids and their physical reactions in the presence of reservoir fluids and porous media.In this work,well-designed and inte-grated experiments have been performed for the first time to characterize the in-situ formation of micro-dispersions and identify their EOR roles during a LSW-alternating-CO_(2)(CO_(2)-LSWAG)process under various conditions.Firstly,by measuring water concentration and performing the Fourier transform infrared spectroscopy(FT-IR)analysis,the in-situ formation of micro-dispersions induced by polar and acidic materials was identified.Then,displacement experiments combining with nuclear magnetic resonance(NMR)analysis were performed with two crude oil samples,during which wettability,interfacial tension(IFT),CO_(2) dissolution,and CO_(2) diffusion were quantified.During a CO_(2)-LSWAG pro-cess,the in-situ formed micro-dispersions dictate the oil recovery,while the presence of clay minerals,electrical double-layer(EDL)expansion and multiple ion exchange(MIE)are found to contribute less.Such formed micro-dispersions are induced by CO_(2) via diffusion to mobilize the CO_(2)-diluted oil,alter the rock wettability towards more water-wet,and minimize the density contrast between crude oil and water.展开更多
The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been ...The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been proposed for chelating agent flooding;however,little attention has been paid to fluid-fluid interaction thus far.The assessment of these mechanisms has primarily relied on macroscopic techniques such as core flooding.This paper aims to investigate the injection of DTPA brine and its dominant mechanisms at the pore scale using a clay-coated micromodel.The micromodel tests were performed under oil-wet and water-wet states.For a more precise examination of fluid/fluid interactions,the dynamic interfacial tension(IFT)and Zeta potential were measured.It was observed that the injection of DTPA brine in water-wet state changed the saturation distribution and increased oil recovery.Based on visual inspections,this change in saturation distribution could potentially be linked to the formation of micro-dispersions and viscoelastic interfacial phenomena.Micro-dispersions facilitate flow to unswept areas,and viscoelastic interface formation reshapes the interface between oil and brine,causing disconnected oil droplets to coalesce and thus increase recovery.Under the oil-wet state,the micro-dispersion formation and wettability alteration can be the dominant mechanisms,and the amount of recovered oil was higher than that observed in the water-wet state.Furthermore,Zeta potential measurements at the interface between brine and oil showed a more negative value for DTPA brine,which is effective in wettability alteration and micro-dispersions stability.The results indicate that IFT reduction was not significant enough to be considered the dominant mechanism,although it assists in DTPA brine penetration into the crude oil and subsequent micro-dispersion formation.展开更多
基金support by The CO_(2) Flooding and Storage Safety Monitoring Technology(Grant 2023YFB4104200)The Dynamic Evolution of Marine CO_(2) Geological Sequestration Bodies and The Mechanism of Sequestration Efficiency Enhancement(Grant U23B2090)The Efficient Development Technology and Demonstration Project of Offshore CO_(2) Flooding(Grant KJGG-2022-12-CCUS-0203).
文摘Low-salinity water(LSW)and CO_(2) could be combined to perform better in a hydrocarbon reservoir due to their synergistic advantages for enhanced oil recovery(EOR);however,its microscopic recovery mechanisms have not been well understood due to the nature of these two fluids and their physical reactions in the presence of reservoir fluids and porous media.In this work,well-designed and inte-grated experiments have been performed for the first time to characterize the in-situ formation of micro-dispersions and identify their EOR roles during a LSW-alternating-CO_(2)(CO_(2)-LSWAG)process under various conditions.Firstly,by measuring water concentration and performing the Fourier transform infrared spectroscopy(FT-IR)analysis,the in-situ formation of micro-dispersions induced by polar and acidic materials was identified.Then,displacement experiments combining with nuclear magnetic resonance(NMR)analysis were performed with two crude oil samples,during which wettability,interfacial tension(IFT),CO_(2) dissolution,and CO_(2) diffusion were quantified.During a CO_(2)-LSWAG pro-cess,the in-situ formed micro-dispersions dictate the oil recovery,while the presence of clay minerals,electrical double-layer(EDL)expansion and multiple ion exchange(MIE)are found to contribute less.Such formed micro-dispersions are induced by CO_(2) via diffusion to mobilize the CO_(2)-diluted oil,alter the rock wettability towards more water-wet,and minimize the density contrast between crude oil and water.
文摘The use of diethylenetriaminepentaacetic acid(DTPA)chelating agent has shown promising results for enhanced oil recovery(EOR)in prior research.Several mechanisms,mainly resulting from rock-fluid interaction,have been proposed for chelating agent flooding;however,little attention has been paid to fluid-fluid interaction thus far.The assessment of these mechanisms has primarily relied on macroscopic techniques such as core flooding.This paper aims to investigate the injection of DTPA brine and its dominant mechanisms at the pore scale using a clay-coated micromodel.The micromodel tests were performed under oil-wet and water-wet states.For a more precise examination of fluid/fluid interactions,the dynamic interfacial tension(IFT)and Zeta potential were measured.It was observed that the injection of DTPA brine in water-wet state changed the saturation distribution and increased oil recovery.Based on visual inspections,this change in saturation distribution could potentially be linked to the formation of micro-dispersions and viscoelastic interfacial phenomena.Micro-dispersions facilitate flow to unswept areas,and viscoelastic interface formation reshapes the interface between oil and brine,causing disconnected oil droplets to coalesce and thus increase recovery.Under the oil-wet state,the micro-dispersion formation and wettability alteration can be the dominant mechanisms,and the amount of recovered oil was higher than that observed in the water-wet state.Furthermore,Zeta potential measurements at the interface between brine and oil showed a more negative value for DTPA brine,which is effective in wettability alteration and micro-dispersions stability.The results indicate that IFT reduction was not significant enough to be considered the dominant mechanism,although it assists in DTPA brine penetration into the crude oil and subsequent micro-dispersion formation.
