Modeling Low Salinity Waterflooding in Mineralogically Different Carbonates

Low salinity waterflooding can significantly enhance oil recovery (IOR) in carbonate reservoirs by altering rock wettability from oil-wet to more water-wet. A novel mechanistic model, incorporating surface complexation and aqueous reactions, demonstrates that reducing sodium and chloride concentrations while maintaining sulfate in seawater can improve IOR by up to 6% OOIP in Stevns Klint (SK) chalk. The presence of anhydrite further boosts recovery due to its role as a natural sulfate source. This study extends previous work on spontaneous imbibition, using core flooding experiments and simulations with PennSim to dynamically adjust relative permeability and residual oil saturation based on mineralogy and chemical interactions. Results align closely with experimental data, highlighting the critical importance of aqueous chemistry and mineralogy in optimizing IOR strategies for carbonate reservoirs.

Qiao, C., Johns, R., Li, L., & Xu, J. (2015). Modeling Low Salinity Waterflooding in Mineralogically Different Carbonates. SPE Annual Technical Conference and Exhibition. https://doi.org/10.2118/175018-ms