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

我的研究重点是研究白云岩的性质和白云石化作用过程，以及它们对白云岩储层空间分布的意义。白云石化通常被认为发生在具有高水岩比的开放成岩系统中，在这种系统中，有效的流体流动将镁输入到系统中，并允许形成大量的白云岩，如地质记录所证明的那样。以往对白云石化的研究主要集中在开放成岩系统中的白云石化作用。*我们的初步调查在巴肯水库中发现了数量不等的白云岩。在这些致密的非常规储集层中发现的白云石与我们认为白云石化发生在开放的成岩系统中的一般假设相矛盾。尽管巴肯非常规储集层产出了大量的油气，但目前还没有关于这些白云岩的岩石学和地球化学的系统研究，它们的性质和成因仍然是推测的。因此，来自巴肯非常规储层的白云岩为在相对封闭的成岩系统中揭示白云岩的性质提供了独特的机会。*拟议的研究计划系统地研究萨斯喀彻温省东南部巴肯非常规储层中发现的白云岩的岩石学、空间分布、成岩共生作用和地球化学特征。这一研究结果将有助于我们更好地了解相对封闭的成岩系统中白云岩的性质和控制白云化作用的因素，从而促进我们对不同成岩环境中白云岩的成因和白云化作用时间的总体认识。这项拟议的研究是我过去15年来在萨斯喀彻温省东南部常规储层中研究白云岩工作的自然发展，在那里我成功地应用了岩石学和地球化学的综合方法来研究不同地层中的白云岩。*由于多阶段水力压裂技术在水平井中的成功应用，巴肯组目前是萨斯喀彻温省东南部非常规石油资源最热门的勘探目标。巴肯油藏中白云岩及其围岩岩性的更好记录有助于更好地了解这些非常规油藏的地质力学性质，可用于优化水力压裂压力，以最大限度地提高石油产量。从拟议研究中获得的岩性信息还将为巴肯水库内二氧化碳长期储存的风险评估提供重要数据。**

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.**