Effects of mechanical dispersion on CO2 storage in Weyburn CO2-EOR field—Numerical history match and prediction

Modeling the long-term fate of CO2 in the Weyburn CO2-EOR field is a key component of the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project located in Saskatchewan, Canada. This study presents a mechanistic modeling approach to model the fate of CO2 in the CO2-EOR field. It evaluates the kinetics and dispersion mechanisms in CO2 partitioning and distributions in an area 2.15 km2 of the Weyburn CO2-EOR field. Numerical history matches were conducted for the three production phases: primary, secondary water flood and tertiary CO2 flood. The history matching results validate the reliability and accuracy of our proposed mechanistic approach for modeling CO2 partitioning and distributions in the Weyburn CO2-EOR field. Long-term predictions for the period from 2010 to 2070 were conducted for several operating scenarios. The predictive simulations showed an additional recovery of 19% of the original oil-in-place over the course of a 60-year miscible flood. Total CO2 stored in the simulated area at the end of 70 years is 2.48 million tonnes with 12%, 18% and 70% stored in the oleic, aqueous and gaseous phases, respectively. The numerical simulations systematically demonstrated that the mechanical dispersion plays a critical role in the performances of CO2-EOR and subsequent CO2 geological storage. Several recommendations were given, primarily targeting mechanical dispersion in the CO2-EOR for improving longer term oil recovery and CO2 geological storage.

► A mechanistic approach is proposed to model the mechanical dispersion on CO2 storage in CO2-EOR process.
► An excellent numerical history match for the Weyburn CO2-EOR field data was obtained.
► 60-Year CO2 miscible prediction showed an addition oil recovery of 19% of the original oil-in-place.
► 51% of the total injected CO2 was produced by the end of 2010 which increased to 74% over the length of 60-year prediction.
► CO2 storage in the Weyburn CO2-EOR field was simulated over a 60-year CO2 miscible flood.