The origin and characteristics of dolomite from unconventional Bakken reservoirs in southeast Saskatchewan

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My research focuses on studying the nature of dolomite and processes of dolomitization and their implications for spatial distribution of dolomite reservoirs. Dolomitization is commonly assumed to occur in open diagenetic systems with high water/rock ratios where effective fluid flow imports Mg into the system and allows for the formation of the massive amount of dolomite as evidenced in the geologic record. Previous research on dolomitization has almost exclusively focused on dolomitization in open diagenetic systems. ***Our preliminary investigations have identified variable amounts of dolomite in Bakken reservoirs. Occurrences of dolomite in these tight, unconventional reservoirs contradict our general assumption that dolomitization occurs in an open diagenetic system. Despite the large amounts of oil/gas produced from unconventional Bakken reservoirs, there has been no systematic study concerning the petrography and geochemistry of these dolomites and their nature and origin remain speculative. As a result, dolomite from the unconventional Bakken reservoirs provides a unique opportunity to unravel the nature of dolomite in a relatively closed diagenetic system. ***The proposed research plans to systematically study the petrography, spatial distribution, diagenetic paragenesis, and geochemical signature of the dolomites identified from the unconventional Bakken reservoirs in SE Saskatchewan. Results of this study will provide a better understanding of the nature of dolomite and factors that control dolomitization in relatively closed diagenetic systems, which will advance our general knowledge about the origin of dolomite and the timing of dolomitization in different diagenetic settings. The proposed research is a natural progression of my previous work over the last 15 years on dolomite from conventional reservoirs in SE Saskatchewan, where I have successfully applied an integrated petrographical and geochemical approach to study dolomite from different strata. ***The Bakken Formation is currently the hottest exploration target for unconventional oil resources in SE Saskatchewan thanks to the successful application of multi-stage hydraulic fracturing technology to horizontal wells. Better documentation of dolomite and its host rock litholology in Bakken reservoirs could contribute to a better understanding of the geomechanical properties of these unconventional reservoirs, which can be used for optimization of hydraulic fracture pressure to maximize oil production. Lithological information derived from the proposed research will also provide important data for risk assessment of the long-term storage of CO2 within Bakken reservoirs.**