--> Abstract: The Upper Devonian Duperow Formation of Southwestern Saskatchewan: An Example of a Natural CO2 Flood, by J. H. Lake, S. G. Whittaker, and D. M. Kent; #90039 (2005)
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The Upper Devonian Duperow Formation of Southwestern Saskatchewan: An Example of a Natural CO2 Previous HitFloodNext Hit

J. H. Lake1, S. G. Whittaker2, and D. M. Kent3
1 Lake Geological Services Inc, Swift Current, SK
2 Saskatchewan Industry and Resources, Regina, SK
3 D.M. Kent Consulting Geologist Ltd, Regina, SK

Natural occurrences of CO2 in the subsurface have attracted increasing scientific interest recently as they represent proxies for anthropogenic geosequestration of greenhouse gases. In southwestern Saskatchewan, CO2, H2, He and minor amounts of natural gas occur naturally within Upper Devonian carbonates of the Duperow Formation. DST's of inert gases in the Duperow Formation have indicated rates as high as 425 x 103 m3/day, and early estimates suggest nearly two million tonnes of CO2 in place, or about one billion m3 of recoverable gas are present in these rocks. Remnant natural gas suggests that hydrocarbons may have occupied pore-spaces in these carbonates, but have been displaced by what was essentially a natural CO2 Previous HitfloodTop. Of interest in this study is the direction of potential displacement of hydrocarbons, the source of the CO2, and the long term affect of CO2 on the carbonate matrix.

The Duperow Formation is a series of stacked cycles of shallowing upward carbonates grading to evaporites. Sedimentation occurred on a stable platform subjected to limited sea level fluctuations although variable argillaceous influx, eroded and karsted surfaces and open marine cements record changing environments as will be discussed in this presentation. The CO2 originated during Tertiary intrusion of alkali syenites in north-central Montana, and migrated north at least 100 km through the Devonian section. The direction and potential displacement of hydrocarbons is currently unproven, but likely areas suggested by this work include the Sweetgrass Arch and the Devonian subcrop edge in central Saskatchewan.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005