Experimental Study of the Simultaneous Effect of Ion-tuned Water and Clay Particles on the Behavior of Water-in-Oil Emulsion; New Insight into Asphaltene Molecular Structure

Abstract

Enhancing oil recovery in sandstone reservoirs, particularly through smart water flooding, is an appealing area of research that has been thoroughly documented. However, few studies have examined the formation of water-in-heavy oil emulsion because of the incompatibility between the injected water-folded ions, clay particles, and heavy fraction in the oil phase. In this study, we investigated the synergistic roles of asphaltene and clay in the smart water flooding process using a novel experimental approach. Our results provide new insights into how the behavior and properties of water in heavy oil emulsions are affected by changes in ion-tuned water in clay-rich sandstone reservoirs. To investigate this, heavy oil was combined with aqueous phases (in the absence and presence of clay) for 20 days at 80°C. Then, the emulsion phases were centrifuged to separate the oil and brine phases (aged oil and brine). The separated oil phases were analyzed using Interfacial Tension (IFT), oil viscosity measurements, and asphaltene onset point precipitation (AOP) experiments. We observed significant decreases in viscosity and AOP when crude oil was exposed to the aqueous phases containing brine and clay, which was also reflected in the IP-143 results. Additionally, ATR (Attenuated Total Reflection) results and elemental analysis obtained from asphaltenes extracted from the aged oil phase, along with zeta potential measurements of the aged oils, indicated a reduction in the concentration of aliphatic groups as well as in the polar and negative components of the asphaltene molecular structure from the oil phases. Furthermore, the analysis of the simultaneous effects of ion-tuned water and clay on emulsion properties revealed differing impacts on the stability of the emulsion phase. These variations were attributed to the contribution of polar asphaltene components at the interface. These findings could potentially reduce undesirable emulsion damage during heavy oil recovery with ion-tuned water flooding in clay-rich reservoirs.