Aqueous Solution of Ketone For Enhanced Water Imbibition in Shale Reservoirs

Abstract

This paper presents an experimental study of improved oil recovery from fractured shale cores by huff-n-puff of the aqueous solutions of 3-pentanone. The huff-n-puff experiments with different 3-pentanone concentrations were analyzed by the material balance for components: oil, brine, and 3-pentanone. Naturally sulfate-rich brine of low salinity was used as the injection brine. Results show that the 3-pentanone solution recovered more oil from the shale matrix than the injection brine alone. The oil recovery increased when the 3-pentanone concentration increased from 0.56-wt% to 2.85-wt%. Huff-n-puff with the 2.85-wt% 3-pentanone solution showed the highest improved oil recovery by 3-pentanone. However, the huff-n-puff experiment with the 1.07-wt% 3-pentanone solution showed the highest efficiency measured by the mass ratio of the produced oil to the injected 3-pentanone. That is, an optimal concentration of 3-pentanone appeared to exist. The material balance analysis showed that 3-pentanone was efficiently imbibed into the shale matrix, and that oil was recovered from shale mainly by the displacement by brine after the wettability alteration by 3-pentanone.