Evaluating EOR Potential in an Unconventional Heavy-Oil Reservoir with Strong Foamy Solution Gas Drive
Authors: Jamaloei B. Yadali , Singh A. R. 
Published: May 2015

Abstract
Murphy's Seal asset in the Peace River Oil Sands region in North West Alberta has a tremendous potential for a significant increase in production and reserves using enhanced oil recovery (EOR) methods. Seal asset, in general, is an unconventional pool due to presence of compositional gradient, faulting, water pockets, and significant variations in oil viscosity and pay-zone thickness, and varying rock dilation/fracturing in some parts. Gravity and viscosity are marked by declining quality with depth, biodegradation and compartmentalization. Murphy Oil have already been operating polymer flood and horizontal cyclic steam stimulation in the area.
Some individual wells in Seal came on stream at 150 BOPD with cumulative production to date of 125 to 225 MSTB per well. In this portion of Seal, reservoir thickness ranges 7 to 12 meters with the dead oil viscosity of 7,500 to 200,000 cp. Despite the high viscosities, strong historical production is as a result in part to good permeability, and to the foamy solution gas drive mechanism. The foamy solution gas drive has the effect of both lightening the combined oil/gas/water emulsion and providing the necessary drive mechanism to mobilize the fluids and emulsion toward the producers.
The reservoir characteristics in this portion, with strong foamy oil drive, are highly variable, and the most suitable EOR method is indeterminable without an integrated reservoir characterization and modeling. Some of the potential EOR candidates which are being evaluated for this portion include non-thermal methods (carbonated and conventional waterflood, polymer flood, polymer waterflood, water-alternating-gas (WAG) injection, solvent flood, or combinations thereof) and non-steam thermal techniques (hot waterflood, hot WAG, and hot polymer flood).
The development plan involves several steps to develop an EOR strategy for the area. Stratigraphic wells have been drilled and core samples were taken from these wells and analyzed. Carbonated waterflood and conventional cold/hot waterflood, hot/cold polymer flood, polymer waterflood, and WAG have been tested on the cores in the laboratory. The results of EOR core floods, core analysis, logging, detailed seismic and petrophysical studies as well as history-matched reservoir simulation and forecast (based on detailed lab-measured PVT) have been integrated into a full field study. Moreover, a great deal of sensitivity analysis and uncertainty assessment (using Latin hypercube design, Monte Carlo simulation, and response surface method) has also been conducted to assist in evaluating the reservoir performance using the above-mentioned EOR methods.
Addressing geological/reservoir/operational variances, this integrated field EOR study helps determine optimum EOR development in this area. It provides insight on how to screen the reservoir/operational parameters for successful EOR application in geologically-complex unconventional heavy-oil reservoirs with varying PVT behavior and strong foamy solution gas drive.