Methodology for Identification of Oil Reservoirs Suitable for CO2-EOR in Alberta, Canada, and Estimation of Their Storage Capacity Using Reserves Databases

Carbon dioxide capture and storage in geological media is a short-to-medium term technology that can reduce significantly atmospheric emissions of anthropogenic CO₂. Geological storage of CO₂, particularly through CO₂ enhanced oil recovery (CO₂-EOR) and in deep saline aquifers, has been identified by Alberta’s government as an important component of its strategy for reducing greenhouse gas emissions. Use and storage of CO₂ in EOR operations provides the advantage that some of the costs associated with CO₂ capture and transportation are offset by the monetary value of the incremental oil produced as well as utilizing existing facilities. While oil companies may perform feasibility studies for CO₂-EOR on individual oil pools, these studies are confidential and limited in scope. Considering that there are close to 13,000 oil reservoirs in Alberta, a methodology for the quick assessment of the potential for CO₂-EOR in the province using reserves databases maintained by the provincial regulator of the oil and gas industry has been developed and applied.

A set of screening criteria for CO₂-EOR suitability was developed based on a review of literature to date and of the characteristics of more than 130 miscible CO₂-EOR operations worldwide, and on the availability of data in the reserves and production databases of the Alberta Energy Regulator. These screening criteria include oil gravity and viscosity, reservoir depth, temperature and porosity, minimum miscibility pressure, original and remaining oil in place, and some operational characteristics. Based on operational and reservoir characteristics, approximately 3,300 oil reservoirs in Alberta would be suitable for CO₂-EOR. However, when the original and remaining oil in place are taken into account, only 136 oil reservoirs in 85 oil fields are deemed as being suitable for CO₂-EOR, i.e., these oil reservoirs are of sufficient size to justify their development for tertiary oil recovery.  

Based on the statistical production characteristics of 31 CO₂-EOR operations in USA which have injected to date CO₂ between 100% and more than 300% HCPV, the incremental oil recovery from these 136 oil reservoirs has been estimated.  The CO₂ storage capacity in these 136 oil reservoirs has been evaluated as well based on net CO₂ utilization factors. The location and CO₂ storage capacity through CO₂-EOR of these oil reservoirs has been compared with the location of 38 large stationary CO₂ emitters in Alberta which emit individually more than 500 kt CO₂/yr and cumulatively slightly more than 100 Mt CO₂/yr. Finally, a methodology for source-sink matching is proposed, to identify the oil reservoirs best suited for any particular large CO₂ source. The results of this work will be presented at the conference.