Natural CO₂ occurrences compared to anthropogenic CO₂ injection sites within the Williston Basin, Central North America

The CO₂ occurrences in Devonian carbonates of southwestern Saskatchewan are suggested to represent a natural analogue for the Weybum injection site due to their similar basinal environment and geological framework. On the western flank of the Williston Basin, southwestern Saskatchewan, Canada, CO₂ occurs in natural accumulations within Devonian carbonates and Cambrian silicielastics. Inert gases from some carbonate reservoirs contain greater than 80 per cent CO₂ and have sustained flow rates up to 425, 000 m³/day. Early estimates of this resource suggested nearly two million tons of CO₂ or about one billion m³ of recoverable gas are present in these rocks. These natural CO₂ occurrences are found about 400 km west of the site of the IEA Weyburn CO₂ Storage and Monitoring Project that is directed toward assessing the potential for safe geological storage of anthropogenic CO₂ in Mississippian carbonates. The Devonian strata containing natural CO₂ accumulations in southwestern Saskatchewan are geologically very similar to the Mississippian beds being injected with CO₂ at the Weyburn Field.