Aqueous Solution of Ketone Solvent for Enhanced Water Imbibition in Fractured Carbonate Reservoirs

Abstract

Summary This paper presents four dynamic imbibition experiments using fractured limestone cores with aqueous solutions of 3-pentanone and a nonionic surfactant. Results of the dynamic imbibition experiments were analyzed by the material balance for components: oil, brine, and chemical (3-pentanone or surfactant). The analysis resulted in a quantitative evaluation of the imbibed fraction of the injected components (brine and chemical additives) and the relative contribution of these components to the oil displacement in the matrix. Results show that 3-pentanone and surfactant both can enhance the imbibition of brine through wettability alteration; however, 3-pentanone is more efficient in transferring from a fracture to the surrounding matrix. The imbibed fraction was more than 57.0% for 3-pentanone, and only 6.0% for surfactant at the end of the chemical-slug stage. During injection of the 3-pentanone solution, brine and 3-pentanone both displaced oil from the matrix pore volume (PV). Results of the material-balance analysis suggest that an optimal process with an aqueous wettability modifier will have a large imbibed fraction to rapidly enhance the oil displacement by brine in the matrix. Such a process will benefit from chase brine and soaking (or shut-in) so that the oil recovery can be maximized for a small amount of chemical injection.