The injection of Sulphonated-smart water (SW) could be an attractive application as it results in the formation of a mechanically rigid oil-water interface, and hence possible higher oil recovery in combination with the polymer. Therefore, detailed experimental investigation and fluid flow analysis through porous media are required to understand the possible recovery mechanisms. This paper evaluates the potential influence of Sulphonated/Polymer water injection in oil recovery by coupling microfluidics and core flooding experiments.
The possible mechanisms are evaluated utilizing a combination of experiments and fluids. Initially, synthetic seawater (SSW) and Sulphonated-Smart water (SW) were optimized to be used in combination with a viscoelastic HPAM polymer. Fluid characterization was achieved by detailed rheological characterization focusing on steady shear and in-situ viscosity. Moreover, single and two-phase core floods and micromodels experiments helped to define the behavior of different fluids. The data obtained was cross-analyzed to draw conclusions on the process effect and performance. First, Sulphonated/polymer water solutions showed a slight decrease in the polymer shear viscosity as compared to the SSW-polymer. Similar behavior was also confirmed in the single-phase core flood-through the differential pressure, looking at the in-situ viscosity. Second, on the one hand, smart water produced only ~3% additional oil recovery as compare to the SSW through micromodel due to improved interfacial viscoelasticity, where no local wettability alteration was observed in the porous media. On the other hand, core flood experiments using SW led to ~12% additional oil as compare to SSW. This excessive extra recovery in core flood compare to micromodel could be due to the combined effect of interfacial viscoelasticity and wettability alteration. Micromodel is coat with a hydrophobic chemical; hence, wettability becomes hard to be altered through SW while in the core flood it is dominated with ionic exchange (local wettability alteration). Finally, a combination of SW with polymer flood can lead to ~6% extra oil as compare to the combination of polymer flood with SSW. Overall, coupling microfluidics with core flooding experiments confirmed that IFV and wettability alteration both are the key recovery mechanisms for SW.
The evaluation confirmed that the main recovery mechanisms of smart-water injection are interfacial viscoelasticity and wettability alteration. Furthermore, it confirmed that the combination of SW with polymer flood could sweep the reservoir efficiently resulting in higher oil recovery. This topic has been addressed in the literature with mixed results encountered.
