Experimental investigation of carboxylate-alumoxane nanoparticles for the enhanced oil recovery performance

In this study, two nanoparticle types of functionalized alumina (functionalized boehmite and functionalized pseudo-boehmite which are named B.MA-Alumoxane and S.B.MA-Alumoxane, respectively) were produced by the sol-gel method and were dispersed in deionized water without surfactants. Field emission scanning electron microscopy (FE-SEM) images were taken to observe morphology of the nanoparticles, type of the functional group was characterized by Fourier-transform infrared spectroscopy (FT-IR), zeta potential analysis was conducted for investigating the stability of the nanofluids, the nanoparticles size distribution was measured by dynamic light scattering (DLS), and also Brunauer-Emmett-Teller (BET) analysis was performed to characterize the surface properties of the prepared nanoparticles. For studying the application of these nanofluids in enhanced oil recovery (EOR), nanofluids with different concentrations (200, 300, 400, and 500 ppm) of each nanoparticle were prepared. The interfacial tensions (IFT) of nanofluids with crude oil were measured by pendant drop method and wettability alteration of oil-wet sandstone rock samples was investigated via contact angle measurement method when they were exposed to nanofluids. In order to investigate the adsorption of the nanoparticles on the sandstone rocks, the adsorption tests were performed. In following, micromodel tests were done to observe the effect of nanoparticles in displacing oil from the porous media of the glass micromodel. Coreflood tests were performed in order to observe the application of carboxylate-alumoxane nanofluids in sandstone core plugs. The morphology of S.B.MA-Alumoxane nanoparticle is as agglomerated particles and B.MA-Alumoxane has nanosheet morphology. The size distribution for S.B.MA-Alumoxane and B.MA-Alumoxane is 12 nm to 35 nm and 32 nm to 155 nm, respectively. By increasing the concentration of nanoparticles, IFT value was reduced from 19.34 mN/m for deionized water to 8.52 mN/m for 500 ppm S.B.MA-Alumoxane and to 11.84 mN/m for 500 ppm B.MA-Alumoxane. The rock samples also became more water-wet in higher concentrations of both nanoparticle types. S.B.MA-Alumoxane showed better performance in comparison to B.MA-Alumoxane. The micromodel test showed the maximum increase of 52% in oil recovery for S.B.MA-Alumoxane and 33% for B.MA-Alumoxane with respect to deionized water. Moreover, coreflood test shows that S.B.MA-Alumoxane has better performance in comparison with B.MA-Alumoxane at the concentration of 500 ppm. In this research, for the first time Carboxylate-Alumoxane nanoparticles were used in EOR by two different morphologies and sizes. The smaller size and higher specific surface area of S.B.MA-Alumoxane in comparison with B.MA-Alumoxane provide its better performance in enhanced oil recovery.