Abstract

In this paper, we present an integrated approach to study the effect of low salinity water flooding on the oil recovery. This is achieved in four steps: first, we have extended our multiphase fluid flow simulation in porous matrix discrete fractures by integrating the electrochemical model. The electrochemical model estimates disjoining pressure from the knowledge of which in turn is a function of different chemical species and their concentration, pH and temperature. Next, the film thickness, which is controlled by different chemical species is determined by using atomic force microscopy and compared with the values estimated by the chemical model. In the third step, we carried out low salinity water flooding on fractured carbonate core samples using a combination of different ions and their concentrations and recovered oil was measured. In these laboratory experiments water floods in core samples with single fractures are simulated to study the effect of heterogeneity (discontinuity) on oil recovery. In the final step we have used our multiphase flow simulator to study low salinity water flooding in laboratory core scale. The results of this study are evaluated by comparing with the results obtained in the laboratory.

The results of this study show that the water film thickness is directly related to brine concentration. There exist, however, an optimum concentration at which maximum thickness can be reached. Above this optimum concentration water film thickness gradually decreases. Core flood tests have shown similar results, that is maximum oil recovery can be obtained at an optimum brine concentration.

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