NEOR mechanisms and performance analysis in carbonate/sandstone rock coated microfluidic systems

Abstract Performance and mechanisms of nanofluids should be recognized and developed well because of increasing demands on nanotechnology assistance in enhancing oil recovery (NEOR) methods. Nanofluid effects on rock/fluid and fluid/fluid interfaces require more attention to be steadied. Also, it could be the main basis for future academia and industrial researches. The objective of this study is to specify and characterize the interfacial phenomena of nanofluid injection in the porous medium. The aims are achieved utilizing visualization and analytical method analysis through micromodel systems. Mentioned systems were selected to be used in two innovative rock-coated micro-scale porous media systems. The invention was to mimic the reservoir lithology condition in mechanistic analysis when nanotechnology is involved. This study tries to present the differences of optimal concentrations regarding mechanisms, actions, and performance for both carbonate and sandstone lithologies. Rock/nanofluid interfacial interactions were analyzed by adsorption studies through spectrophotometric UV/Visible and Fourier-transform infrared analytical methods. Direct insights into the pore scales are offered to analyze the interactions of nanofluids with rock and crude oil. Comprised interactions within sandstone and carbonate rock/nanofluid/crude oil and nanofluid/crude oil interfaces are visualized and their mechanisms were expanded throughout mentioned rock coated micro-scale porous medium models. Results showed that the adsorption of nanoparticles on two applied lithologies are occurred with two different mechanisms and proved that one concentration gained different adsorptions. Micromodel systems visualized the rock/nanofluid interfacial phenomena including the wettability alteration and nanofluid/oil interfacial phenomena including the emulsion creation. The wettability alteration mechanism of wedge-like structural disjoining pressure reported by most of the related literature is compared with a newly introduced mechanism of electrical double layer (EDL) in wettability alteration. EDL mechanism activated at a low concentration of nanofluid and gained the best performance in carbonate system while at this concentration the reverse performance observed in sandstone systems. Whereas in sandstone systems the best performance was gained at a high concentration of nanofluid because of wedge-like structural disjoining pressure mechanism. Therefore, the mechanisms and performances were different depending on the optimal concentrations in each lithological system of carbonate and sandstone.