Injection of ionically modified water (smart water) is an effective and one of the most economic and environmentally safe enhanced oil recovery (EOR) techniques. It is a promising EOR method for tight and oil wet carbonate reservoirs with harsh formation conditions. In this work, altering rock surface wettability by the effect of the potential determining ions (PDI) was evaluated for the core plugs of an Iranian carbonate oil reservoir. Persian Gulf sea water (SW) was selected as the base smart water. Spontaneous imbibition tests and contact angle measurments were conducted in presence of formation brine (FW) and SW and two other synthesized brines. The results of the imbibition tests showed incremental oil recovery (up to 20%) by application of different types of the tested smart water, after FW. The change in contact angle confirmed the altering wettability of the rock samples toward water-wet conditions, due to activation of PDIs close to the rock surface.

Keywords