Geochemical simulation of Single-Phase Ion-Engineered water interactions with carbonate Rocks: Implications for enhanced oil recovery

Abstract

Ion-engineered water flooding (EWI) has attained considerable attention as an efficient and low-cost enhanced oil recovery (EOR) technique with multiple privileges in recent years. Different mechanisms have been proposed for water displacement improvement when seawater with modified composition is injected into carbonate formations. Due to the complexity of rock/fluid interaction, prediction of the EWI process poses a big challenge, and it is vital to identify the main mechanisms governing the EWI process. Thus, the focus of this study is to develop a novel single-phase geochemical model using CMG-GEM simulator and to explore important rock/fluid interactions. The compositional model was developed efficiently; accordingly, a combination of ion-exchange and adsorption reactions have been used to represent surface complexation reactions and reduce the time of simulations without compromising the accuracy of the results. Also, mineral dissolution/precipitation was considered in the model to match simulation results and experimental data. For having a better interpretation of rock/fluid interactions, the effluent ions concentration, ion-exchange equivalent fractions, and the amount of dissolved and precipitated minerals were evaluated. According to the results, the amount of dissolved calcite and precipitated dolomite was found to be insignificant in the carbonate core samples; however, the calcite dissolution and dolomite precipitation, and sulfate adsorption are the main factors affecting the single-phase water displacement process.