Effect of Interfacial Characteristics on Oil Removal Efficiency of Different Surfactants
Surfactants are widely used to reduce oil-water interfacial tension,alter wettability of rock surface,and thus reduce the adhesion between residual oil and rock surfaces,which can improve mobility of heavy oil and enhance recovery rate.However,the effect of the change of interfacial forces on oil removal/recovery rate can hardly be quantified accurately.Here,based on laser scanning confocal microscopy,an image analysis method was proposed for the measurement and calculation of oil removal rate for different surfactant-oil-rock systems.In the oil-removal experiments,micro-structured glass surfaces were first saturated with oil.Then sonicator was used to assist the oil removal from the saturated surfaces by different surfactants.The results showed that the increase of oil removal rate was mainly caused by reduction of work-of-adhesion and wettability alteration rather than change of interfacial tension.In fact,work-of-adhesion is a combination of interfacial tension and wettability,which makes it a preferable parameter for evaluation of surfactants.Meanwhile,the oil removal efficiency of surfactants with different concentration changes with time,which is also caused by wettability alteration.By integrating oil removal experiments with laser scanning confocal microscopy and image analysis,accurate calculation for oil removal efficiency was carried out to reveal the effects of interfacial characteristics on oil removal efficiency.This paper provides insights into heavy oil EOR by chemical flooding.
SurfactantsInterfacial tensionWettabilityWork of adhesionOil removal efficiency
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