Abstract
This work describes the flow behavior of the oil recovery obtained by the injection of sulfate-modified/low-salinity water in micromodels with different wettabilities. It provides a detailed microscopic visualization of the displacement taking place during modified water flooding at a pore-scale level, while evaluating the effect of wettability on oil recovery. A comprehensive workflow for the evaluation is proposed that includes fluid–fluid and rock–fluid interactions. The methods studied comprise flooding experiments with micromodels. Artificial and real structure water-wet micromodels are used to understand flow behavior and oil recovery. Subsequently, water-wet, complex-wet, and oil-wet micromodels help understand wettability and rock–fluid interaction. The effect of the sulfate content present in the brine is a key variable in this work. The results of micromodel experiments conducted in this work indicate that sulfate-modified water flooding performs better in mixed-wet/oil-wet (artificial structure) than in water-wet systems. This slightly differs from observations of core flood experiments, where oil-wet conditions provided better process efficiency. As an overall result, sulfate-modified water flooding recovered more oil than SSW injection in oil-wet and complex-wet systems compared to water-wet systems.
Highlights
The concept of smart/modified water flooding was first proposed by Morrow et al [1]; leading to further investigations with regards to the impact of injected water composition on oil recovery [2,3,4,5,6,7,8,9].In simple words, smart/modified water flooding deals with either the addition of active ions/salts or removal of in-active ions/salts from the injection brine
InvestigateTable its impact on oil recovery sandstone and carbonates. We have addressed this topic in a previous work, where the results of interfacial viscoelasticity (IFV) are presented for the same oil sample and different brine compositions used in this work [32]
Based on the experimental investigation and collected data outlined in this study, it can be concluded that the mechanisms of both wettability alteration and fluid interfacial interaction are of great importance for reducing the ROS
Summary
The concept of smart/modified water flooding was first proposed by Morrow et al [1]; leading to further investigations with regards to the impact of injected water composition on oil recovery [2,3,4,5,6,7,8,9]. Smart/modified water flooding deals with either the addition of active ions/salts or removal of in-active ions/salts from the injection brine This addition or removal of some specific salts changes the salinity and the hardness of the brine [10,11]. The manipulation of injected brine composition is believed to be able to disturb the established rock-oil-brine (ROB) equilibrium, and detach the oleic polar compounds from the rock surface. Karoussi and Hamouda and Tahir et al [14,15,16] showed that sulfate, as the most effective PDI, helps to detach the long chain carboxylic group from the oil-wet surface, and control the further adsorption of these compounds on the rock surface
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