Tertiary Recovery Potential of CO2 Flooding in Joffre Viking Pool, Alberta

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Abstract Reservoir simulation models were used to investigate the feasibility and predict performance of a tertiary CO2 flood in Joffre Viking sand unit of central Alberta. Using a black oil simulator, history matching of primary and water flood production performance on a selected portion of the Joffre Viking Pool involving 85 wells was first undertaken. This step provided for proper initialization of fluid and pressure distribution and a reservoir description for the miscible CO2 flood model. Reservoir fluid samples taken from a producing well were recombined for laboratory swelling and slim tube displacement tests. The results of these tests were then used for characterization of the CO2-oil system for the miscible model. Further sensitivity analysis and process optimization using a " typical pattern" approach was conducted to optimize the tertiary CO2 flood performance. Simulation results indicated that in the presence of a trapped oil saturation due to water blocking oil from contact by the injected CO2 a larger CO2 slug and/or a smaller water slug were required in a water-alternating-with-gas (WAG) process for more efficient displacements. In addition, the CO2 flood performance prediction of a potential development scheme for the study area based on a fully developed 32-hectare drilling density, five-spot pattern with a three-cycle WAG process and a total CO2 volume equal to 25 per cent hydrocarbon pore volume is presented. Introduction Significant potential for tertiary oil recovery by CO2 flooding as determined in an earlier preliminary model study(1) prompted further detailed evaluation of the CO2 tertiary recovery process for the Joffre Viking Pool in Alberta. This investigation is particularly timely in view of the enhanced oil recovery (EOR) incentives provided by both the federal and provincial governments. It is also considered timely in view of the longlead time required for the design, planning and implementation of an EOR scheme. As indicated by the expanded efforts put forth by the oil companies in the United States, EOR can be a significant contributor to increasing domestic oil production and therefore improving the chances of achieving energy elf-sufficiency in Canada. To provide a more detailed evaluation and prediction of the tertiary CO2 flood, laboratory testing and reservoir modelling were used in this study. The application of reservoir simulation models for the design and evaluation of CO2 floods has been reported previously in the literature(2–6). The main objective of this study was to investigate the feasibility of CO2 flooding in he Joffre Viking reservoir. A substantial portion of the pool was chosen for detailed study of past production performance and potential oil recovery by CO2 injection. Laboratory results based on recombined reservoir fluids taken from the field were used for characterization of the CO2-oil system for the miscible flood reservoir models. A reservoir parametric sensitivity study was also conducted to investigate the impact of some least known reservoir parameters on the CO2 flood performance. Finally, a potential development scheme for the study area is presented.