The IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project
This project, launched in 2000 and continuing through to 2012, has studied carbon dioxide (CO2) injection and storage into two depleted oilfields in south-eastern Saskatchewan.
The first phase, completed in 2004, sought to predict and verify that the Weyburn oil reservoir could securely and economically contain CO2. The second phase sought to expand upon the work of the first, and help to recommend a framework to encourage implementation of CO2 geological storage on a worldwide basis. The end result was the publication of a manual (Best Practices for Validating CO2 Geological Storage: Observations and Guidance from the IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project) in 2012. Copies of this publication are available in hard copy from the publisher, Geoscience Publishing.
The project was operated in conjunction with two billion-dollar commercial CO2 floods in Saskatchewan, Canada.
Approximately 8500 tonnes per day of the CO2 are captured from an coal gasification facility – owned by the Dakota Gasification Company located in Buelah, North Dakota. The gas is compressed to a liquid phase and transported via a 320 km pipeline to the Weyburn and Midale oil fields for injection. This is the first time that a man-made source of CO2 has been used for enhanced oil recovery.
CO2-EOR (Enhanced Oil Recovery) in the Weyburn and Midale Oil Fields
CO2 has been used as a solvent to help improve recovery from oil reservoirs for decades. Oil field operators in West Texas, for example, have been injecting CO2 into depleted fields for decades.
At Weyburn and Midale, CO2 is injected along with water deep underground (approx. 1,500 metres) into the two depleted fields.
In an operating strategy that alternates gas and water injection, the CO2 injection increases reservoir pressure and oil fluidity, enabling oil to escape from rock pores and flow more readily toward production wells. As a general rule, it takes about 8,000 cubic feet of CO2 to get an extra barrel of oil. Each tonne of CO2 increases oil production in Weyburn by two to three barrels
Some of the injected CO2 at both Weyburn and Midale is pumped back to the surface together with oil and water, then separated and re-injected. At the end of the enhanced oil recovery period, virtually all injected and recycled CO2 is permanently stored. The Weyburn-Midale CO2 Monitoring and Storage Project is ensuring that the CO2 used for EOR will remain safely stored underground.