Présentations Colloques

Oral Presentation
8.06
Session 8.06: Verification of conceptual patterns and expected natural effects of regional groundwater flow by interpretation of relevant field observations
Daniel Skoreyko
Regional Hydrogeology of the Bakken Formation in the Williston Basin
The Bakken Formation is currently the most productive oil producing formation in the Williston Basin, and one of the most economically important tight oil plays in North America. The Williston basin is a large intracratonic sedimentary basin located on the western shelf of the North American craton, and host to many natural resources. Within the Bakken Formation it has been shown that oil has migrated from the thermally mature central portion of the basin, outwards toward the less mature portion of the basin, and north to Canada. Despite the economic significance of the Bakken Formation, its regional hydrogeology, and the influences of groundwater flow on oil migration and accumulations have been poorly studied. **To further our understanding of the regional hydrogeology of the Bakken Formation a newly created database spanning the entire Williston basin was generated. This database compiled information from historical records including drill stem tests, initial potential tests, scientific literature, government reports, and data previously collected by the University of Alberta hydrogeology research group. Once the database was assembled, an intensive iterative culling procedure was implemented to remove any data which may have been affected by nearby production and injection wells or hydraulic fracturing operations.**From the culled data a potentiometric surface map and water chemistry maps were generated. The potentiometric surface map shows a large central area with greater than hydrostatic formation pressures while conditions in distal areas are near hydrostatic. Hydrochemical analyses reveal highly variable water chemistry with total dissolved solids ranging from less than 10,000 mg L to over 300,000 mg L with salinity generally increasing toward the centre of the basin.**This study provides the most complete depiction of the governing hydraulic processes and water chemical characterization of the Bakken Formation across the entire Williston Basin. These results advance our understanding of the hydrogeological conditions of the poorly studied Bakken Formation and help to reveal the potential effect of regional groundwater flow on oil accumulations within this formation.
Canada