Crude Oil Quantity and Its Effect on Chalk Surface Wetting

Injection of a Smart Water, with a modified and optimized ionic composition, is an environmentally friendly and cheap enhanced oil recovery (EOR) method. To be able to optimize the ionic composition to cause wettability alteration in the reservoir, one must understand the initial wetting of the reservoir. Experimental studies have confirmed that acidic material in the crude oil, especially negatively charged carboxylates, R–COO–, are the most important wetting parameters toward positively charged carbonate surfaces that dictate the rock wettability. The carboxylate molecules bond strongly to the carbonate surface, and these crude oil anchor molecules can only be removed from the calcite surface by chemical reactions. Generating representative core wettability during core restoration in the laboratory is important for doing realistic oil recovery studies, capillary pressure and relative permeability measurements. Water-wet outcrop chalk cores showing good reproducibility were used to study adsorption of ca...