Enhancing Oil Recovery With Specialized Nanoparticles by Controlling Formation-Fines Migration at Their Sources in Waterflooding Reservoirs

Abstract

Summary Waterflooding is a conventional improved-oil-recovery method. When water flows into pores of the media in formations occupied by hydrocarbons, clays and other formation fines are released and flow with the injection water. The released formation particles can accumulate and plug the pore throats in the flow channels, causing lower water sweep efficiency and reduced oil recovery. The solution to this problem is adding additives into the injection water to stabilize formation clays and fine particles at their sources during waterflooding operations. Recent studies and field applications have confirmed that some inorganic nanoparticles can efficiently control formation-fines migration in proppant fractures by coating the nanoparticles onto the proppants in hydraulic-fracturing and frac-pack applications. The nanoparticles have significantly high surface forces, including van der Waals forces and electrostatic forces, to attach themselves to the surface of commonly used proppants. The nanoparticles that adhere to the proppants adsorb migrating formation fines onto the proppant surface as the fines flow into the fracture. This paper provides detailed laboratory evaluations of the use of the same nanoparticles to enhance oil recovery by stabilizing formation clays and fines in waterflooding operations. As water drives hydrocarbons toward producers, the nanoparticles fix the formation fines at their sources in the water flow channels. When the water breakthrough happens at producers, fewer fines accumulate at the near-wellbore region of producers to choke the production of hydrocarbons, and the water sweep efficiency is increased. Laboratory tests show that the effluent of a sandpack containing nanoparticles is cleaner than a pack containing no nanoparticles, and the pressure drop across the sandpack containing nanoparticles is less than that for a pack containing no nanoparticles under the same flow rate of 5%KCl and the same sand composition.