Water/oil emulsion and asphaltene instability in different formations during low-salinity waterflooding: an experimental study

Document Type : Article


Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran, postal code: 145888694


Low-salinity waterflooding is an important method in enhanced oil recovery. Previous studies have extensively investigated the effects of salinity on asphaltene behavior at the water-oil contact surface. However, the influence of rocks has often been overlooked in these studies. This study investigates the impact of rock type (calcite/quartz) on these phenomena in the presence of various brines. UV-Vis spectroscopy was used to assess the asphaltene separation from fresh or aged bulk oil with brine. also, we utilized the recently developed “indirect method” by our group. Microscopic analysis of water droplet size was performed to evaluate emulsion stability. The results demonstrate that the UV-Vis absorbance for fresh oil is approximately 13.6 and that decreases to 11, 10.5, and 10.5 for the 2DSW/oil, calcite/SW/oil, and quartz/2DSW/oil emulsions, respectively. Additionally, the results show that for rock/FW/oil emulsion, compared to quartz, calcite presence increases asphaltene precipitation/deposition by about 38 wt%. Furthermore, the findings reveal that, across all salinities, the average size of water droplets is larger when calcite is present than quartz, suggesting greater instability in the calcite. These outcomes align with the results of IFT measurement, FTIR spectral analysis of oil, and zeta-potential determination for suspended calcite/quartz particles in different brine samples.


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