In 2005, a polymer flood was implemented at pilot scale in the six billion barrels OOIP, 800 to 80,000cp oil viscosity, Pelican Lake heavy oil field (Northern Alberta - Canada), to evaluate the potential of polymer to significantly increase the primary recovery limited to 5–7% OOIP. The pilot comprising 5 parallel horizontal wells (2 injectors and 3 producers) is still continuing in 2013 with excellent results (oil rate increase beyond expectations and surprisingly very slow water-cut increase in the 50–60% range) that have led the operator to extend polymer injection to field scale.
Understanding the wells responses to polymer flood, not totally expected in such a high viscosity oil, and optimizing the process have been undertaken through the following steps: 1) generation of a simplified reservoir model, consistent with geological trends and calibrated with core data, 2) automatic history matching of the pilot using dedicated tools, 3) investigation of sensitive parameters on oil recovery (well spacing, well length, polymer concentration, slug size, oil viscosity etc.), 4) range definition of optimum sensitive parameters both technically and economically.
Successful history matching of the pilot gives some insights on the main influence of reservoir heterogeneities on oil recovery. The history matched reservoir model has allowed to investigate the influence of various parameters for the implementation of polymer flood in heavy oil fields, and evaluate additional recovery compared to continued primary recovery or waterflood. It also provides some guidelines on the applicability of the process to other reservoirs.
History matching the pilot performance opens the door to a better understanding of polymer flooding in heavy oil reservoirs such as Pelican Lake and to increasing the number of potential application of polymer flood to similar fields.