Geochemical modeling of engineered water injection effect on oil recovery from carbonate cores

In the field of enhanced oil recovery, the engineered/low salinity water injection (EWI/LSWI) is one of the promising development in recent years. Several mechanisms describing the EWI/LSWI recovery process have been suggested without a common consensus. Wettability alteration have been considered as the prime reason behind the incremental oil recovery; however, several other possible mechanisms are also suggested. This paper investigates the effect of engineered water injection (EWI) on oil recovery from carbonates cores along with recovery, pH and effluent-ion predictions, which is based on numerical simulations using laboratory coreflood data. An EWI model is proposed based on multi-ion exchange for capturing the incremental oil recovery by EWI in carbonates. The model includes geochemical reactions, homogeneous (aqueous) and heterogeneous (precipitation/dissolution and ionic exchange reactions), as well as the resulting wettability alteration in carbonates. Oil recovery, pressure drop, pH, and effluent-ion were successfully history match and the results showed there is an improvement in oil displacement as EW is injected. Also, the findings of this study were supported by fractional flow analysis. This work provides more insight into the benefits of EWI and hence, supports new field applications.