Compatibility Test and Nanoparticles Stability: Comparison between Smart Soft Water and Smart Hard Water

Abstract

Summary Smart water is one of the most common methods for increasing oil recovery factor (RF) widely used in both sandstone and carbonate reservoirs. Smart water changes oil reservoir rock wettability from oil-wet to water-wet and increases oil RF. When smart water is combined with formation water, it can form sediments that will be called incompatibility, the results of which will be precipitation of inorganic scale deposition in surface facilities, flow lines, well tubing, gravel packs, and in the reservoirs. In contrast, by stabilizing the various nanoparticles in water, beneficial changes such as wettability alteration, sand production prevention, and decreased fines migration can be realized in oil reservoirs. Therefore, water compounds should be designed to have a minimum amount of incompatibility and the greatest amount of nanostability. For this study, the formation water and seawater were created in the laboratory. Seawater was diluted in different concentrations and combined with formation water, and the best-diluted seawater was selected. Sensitivity analysis was performed using the Taguchi algorithm on diluted water, and it was used to make smart soft water (SSW) and smart hard water (SHW). In this project, we aimed to compare the amount of incompatibility and nanostability in SSW and SHW. To analyze the amount of incompatibility, different compositions of SSW and SHW were made and combined with formation water. In all cases, soft water was more compatible with formation water. To compare stability, different nanofluids were made in optimized soft water and hard water. By testing the zeta potential, it was observed that soft water shows more stability. In general, this study proved two advantages of SSW over SHW.