Alkaline water flooding with a precipitation inhibitor for enhanced oil recovery

摘要

An enhanced oil recovery method is provided utilizing an alkaline waterflood injection fluid including a water-soluble precipitation inhibitor such as a polyacrylate, an acrylate-containing copolymer, an organophosphonate, a carboxylate-containing organophosphonate or a polymaleic anhydride whereby divalent metal cations dissolved within the injection fluid or within the reservoir water in the immediate vicinity of the injection well are substantially prevented from precipitating. Additionally, the injection fluid preferably provides sufficient alkaline material whereby beyond the immediate vicinity of the injection well the permeability characteristics of the reservoir are modified by precipitation of, e.g., divalent metal hydroxides or divalent metal carbonates.