Chemical Compositions in Salinity Waterflooding of Carbonate Reservoirs: Theory

Abstract Higher oil recovery after waterflood in carbonate reservoirs is attributed to increasing water wettability of the rock that turn relies on complicated surface chemistry. In addition, calcite mineral reacts with aqueous solutions and can alter substantially composition injected by dissolution. Carefully designed chemical and/or brine flood compositions laboratory may not remain intact while pass through reactive reservoir rock. This especially true for a low-salinity process, where some finely tuned improve performances, whereas others cannot. We present 1D transport numerical model captures changes during flow porous include highly coupled bulk carbonate-reaction chemistry, detailed reaction mass transfer kinetics, 2:1 calcium ion exchange, axial dispersion. At typical rates, local equilibrium established immediately upon injection. SI, we validate against analytic dissolution, longitudinal dispersion, each considered separately. Accordingly, using an open-source algorithm (Charlton Parkhurst Comput Geosci 37(10):1653–1663, 2011. 10.1016/j.cageo.2011.02.005 ), outline design tool specify chemical/brine flooding formulations correct alteration Subsequent works compare proposed theory experiments core plugs Indiana limestone give examples how salinity deviate from those water-wettability improvement.