Effect of Salinity on Wettability Alteration to Intermediate Gas-Wetting

摘要

The effect of salinity on the alteration of wettability from water-wetting to intermediate gas-wetting is studied in this work. We find that NaCl salinity increases water-wetting when a core is saturated with brine. NaCl also reduces gas absolute permeability, as reported in the literature. CaCl_2 salinity effect is dramatically different from that of NaCl brine and has a minor effect on permeability. The NaCl, KC1, and CaCl_2 brines have an adverse effect on wettability alteration. To alleviate the effect of salt on chemical treatment, we suggest pretreatment by displacement of brine with water and subsequent drainage by nitrogen.