Current Status of Polymer Flooding in Heavy Oil Fields: When Performances Beat Theory

Abstract In the past few years many new (including large-scale) polymer flood projects in heavy oil fields have been implemented and have shown very good success; the Milne Point project in Alaska is just a case in point. The goal of this paper is to provide a review of the current situation for polymer flood in heavy oil fields and explore the potential reasons for their success. This paper is based on a review of the ongoing polymer floods projects in heavy oil fields to obtain a good understanding of the performances that can be expected and indeed have been achieved in the field, and to explore the reasons for the differences in responses. Not only do polymer floods in heavy oil achieve recovery factors that are much higher than expected - up to 50% OOIP @ 1 PV injected in some Canadian cases, but they also provide significant reductions in water consumption and a better carbon footprint than steam-based projects. Moreover, thanks to generations of new polymers, those projects can use any kind of water quality without need for water softening, as opposed to steam-based projects. Polymer injection in heavy oil fields should thus have a bright future. The reasons for the high recoveries are not completely clear and are even more puzzling when considering that these results are achieved with relatively low polymer viscosity - in most cases only 25-50 cP which still corresponds to unfavorable Mobility Ratios. One potential explanation put forward by some authors involves some elements of viscous crossflow and field experience in some cases will be compared to theory to better appreciate the validity of this potential mechanism. A complete review of polymer flood field cases in heavy oil will be presented together with an analysis of the high recoveries achieved with relatively low injected polymer viscosities and some hypotheses for these good performances will be discussed.