Effects of TiO2, MgO and γ-Al2O3 nano-particles on wettability alteration and oil production under carbonated nano-fluid imbibition in carbonate oil reservoirs

Abstract

Wettability is an important factor in the reduction of oil saturation, especially when the imbibition process is the main mechanism of production from the reservoir. This process is activated towards oil production, which tends the wettability of the rock to hydrophilicity, and the rock’s hydrophilic intensity on this parameter is very effective. Both carbonated water and nanofluids injection methods are effective methods for altering the carbonate rock wettability to hydrophilicity, but stronger hydrophilicity can be achieved by combining these two methods with respect to obtain the greater dissolution of carbon dioxide in nanofluids in comparison to saline water and increase the oil production under imbibition considerably. In this study, wettability alteration based on contact angle experiments using TiO2, MgO and γ-Al2O3 nanoparticles in carbonated water were investigated and the oil production was estimated using imbibition experiments and the optimum carbonated nanofluids for the minimum contact angle was evaluated. In fact, the main goal in this study was to correct the carbon dioxide injection and increase its solubility in saline water by dispersed nanoparticles in order to alter the carbonate rock's wettability towards a highly hydrophilic and subsequently increasing the oil production under the imbibition. Finally, the lowest contact angle values for carbonated TiO2, γ-Al2O3 and MgO nanofluids at 13.79 MPa and 80 °C and salinity levels of 10 times water dilution were obtained as the base fluid, which decreased, respectively, by 55, 26 and 17% compared to carbonated water in the absence of nanoparticles, the amounts obtained, especially for nanofluids containing TiO2 nanoparticles, are placed in a highly hydrophilic zone. In addition, carbonated nanofluids containing TiO2, γ-Al2O3 and MgO nanoparticles recovered by 75.93, 71.25 and 64.98 percent of primary oil under the imbibition mechanism at 13.79 MPa and 80 °C and salinity of 10 times of dilution of base fluid, which shows an increase of about 30, 25 and 18%, respectively, relative to the oil production under imbibition with nanoparticle free carbonated water, respectively.