Prediction of fluid phase behaviors in a CO2-EOR process in Weyburn field, Saskatchewan, Canada

Abstract

The objective of the multidisciplinary “Weyburn CO2 Miscible Flooding Project” is to develop a Pressure-Volume-Temperature (PVT) model for the CO2-Weyburn oil system that can be coupled with compositional reservoir models for the short- and long-term field-scale reservoir simulations. This project is operated by Encana Corporation in southeastern Saskatchewan, Canada, provides a unique opportunity for the “lEA GHG Weyburn CO2 Monitoring and Storage Project” to add to the knowledge and understanding of the process mechanisms of enhanced oil recovery (EOR) and CO2, a greenhouse gas (GHG), storage in oil depleted reservoir. The model is continuously modified as the field process proceeds to capture the dynamic change in fluid properties, including minimum miscibility pressure (MMP) and the effect of contaminates in the injecting CO2. Accurate prediction of the CO2 distribution in different phases (that is, aqueous, oleic, and gaseous) in the reservoir after the CO2-EOR process is essential for long-term risk assessment that is relied on the understanding of the fluid phase behaviors. For example, estimations of mineral trapping, ionic trapping, and solubility trapping of CO2 are based on the amount of CO2 stored in the aqueous phase. On the other hand, the amount of CO2 stored in the gaseous phase, which is the most mobile phase of CO2 in the reservoir, is essential in the estimation of CO2 leakage.