Scale-Dependent Models for Modified Salinity Waterflooding

Numerous attempts have been made to model the effect of modified salinity water flooding that leads to additional oil production in both sandstone and carbonate reservoirs. Since there is no consensus on the physicochemical mechanisms of modified salinity water flooding, it is challenging to develop a physics-based model and simulate the complete system. Therefore, a simple model based on linear interpolation between two sets of high salinity and low salinity relative permeability curves is widely used in the industry. This work investigates the impact of grid size and hysteresis effects on the numerical modelling of modified salinity water flooding. In order to include the hysteresis effect, we modify two different interpolation approaches, which are commonly used in commercial software, to switch from high salinity to low salinity relative permeability and capillary pressure curves. The results show that the grid-block sizes heavily influence the response time of the reservoir to the injection of low-salinity water and the final oil production, but to different extents for the two different interpolating approaches. It was also found that only a small discrepancy can be observed between two approaches by refining the grid.