The role of injection fluid elasticity in microscopic displacement efficiency of residual non-wetting phase: An in-situ experimental investigation

摘要: Polymer flooding has been employed extensively over the years as a mature enhance oil recovery (EOR) technique to improve volumetric displacement (sweep) efficiency in oil reservoirs. In the last few years, groundbreaking laboratory and pilot tests have demonstrated that the use of polymers with viscoelastic properties may potentially enhance the efficacy of polymer flooding and result in improvements in both volumetric (macroscopic) and microscopic (pore-scale) displacement efficiencies. The transport and pore-level displacement mechanisms responsible for such microscopic improvements, however, have been poorly understood. This study was thus designed to improve the current understanding of the displacement of waterflood residual oil with viscoelastic polymers in natural porous media. We performed a series of micro-scale two-phase core-flooding experiments on miniature water-wet Berea …