Modeling the effect of engineered water injection on oil recovery from carbonate cores

In the field of enhanced oil recovery the engineered/low salinity water injection (EWI/LSWI) is the latest and promising development. Several mechanisms describing the EWI/LSWI process have been suggested in the literature; however, there is no consensus on a single main mechanism for its effect on oil recovery. Wettability alteration is believed to be the main 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 carbonate cores. The recovery predictions are based on numerical simulations using laboratory coreflood data. The results show that heterogeneity effect on oil recovery history matching is more pronounced compared to capillary pressure effect. Moreover, an EWI model is proposed based on multi-ion exchange reactions for capturing incremental oil recovery by EWI in carbonates. The model includes other geochemical reactions, homogeneous (aqueous) and heterogeneous (precipitation/dissolution reactions), as well as the resulting wettability alteration in carbonates. Coreflood experiments are simulated and history matched using the proposed EWI model. This model can be used for oil recovery predictions and optimization in carbonate fields. This work provides more insight into the benefits of EWI and hence, supports new field applications.