Abstract
Within recent decades, smart water (SW) injection has become an attractive approach to improve oil recovery from conventional oil reservoirs. However, less attention has been devoted to the application of this method to asphaltenic oil reservoirs. This study aims to evaluate the performance of the injection of SW + silica nanoparticles (SNPs) in improving oil recovery from such reservoirs. To this end, an extended series of measurements were conducted, including of oil-water interfacial tension (IFT), wettability, emulsion formation/stability, and core flooding tests. After the introduction of SNPs to formation brine (FB) and SW solutions, oil-water IFT was reduced by 17.5% and 52.5% respectively compared to their corresponding initial values. In addition, the SW + SNP solution could improve the wettability of the rock surface compared to FB + SNPs. Interestingly, we found that, due to its high asphaltene content, the crude oil used forms sludge in contact with FB, which will impose serious operational problems and production costs associated with the system. However, we observe that the presence of SNPs restrains sludge formation by breaking down asphaltene molecules as well as destabilizing oil-water emulsions. This is demonstrated by several centrifuge tests conducted to evaluate emulsion stability in the presence of FB + SNP and SW + SNP solutions. SARA analyses were also performed on the oil produced from core plugs after the injection of SW and SW + SNPs to better understand the role of SNPs in the deposition of complex structures like asphaltenes and resins groups in crude oil.
NSTL