Three-Dimensional Geological Characterization and Modeling of Fine-Grained Petroleum Reservoirs: An Evaluation of the Montney Formation in Westcentral Alberta and Bakken Formation in Southeastern Saskatchewan, Canada

In Canada, tight and shale plays such as the Montney, Bakken, and Duvernay (to mention but a few) have over the past decade become the focus of exploration and development activities. However, despite the successes recorded in drilling and completing multi-fractured horizontal wells (MFHws) in Canada and the United States of America (USA), the geological characteristics of shale and tight reservoirs remain poorly understood; evidenced by frequent production and development challenges faced by operators. These challenges include (but are not limited to) rapid well decline rates, parent-child well production interference, and difficulty in reconciling multi-scale geological heterogeneities. The challenge of unconventional reservoir (this terminology is used in this thesis to solely refer to shale and tight reservoirs) development is further compounded when there is a lack of data such as three dimensional (3D) seismic, microseismic, borehole imagery, or well logs suites in MFHw laterals (to mention but a few) to support integrated reservoir studies and dynamic simulation. Given the above, the aim of this dissertation was two-pronged: (1) to develop novel approaches for geologically characterizing tight reservoirs such that the importance of understanding nano to macro-scale heterogeneity is demonstrated through reconciliation with production data or validation using independent complementary datasets (2) to develop geological characterization and modeling techniques that can be used in the absence of traditional geological and geophysical datasets (as earlier mentioned). The Montney Formation in west-central Alberta and the Bakken Formation in southeastern Saskatchewan Canada were used as case studies to demonstrate how commonly acquired datasets such as well logs can be leveraged to improve the geological characterization of tight reservoirs. Seismic data available in the Bakken Formation was used to validate the applicability of a new well log to seismic inversion workflow that was developed and applied in the Montney Formation. New insights on the role of the dominant pore throat size control on fluid distribution and influence on production variation in tight reservoirs are presented. Furthermore, in the Bakken Formation, a natural fracture zone identification technique was developed, along with a new subdivision of the Middle Bakken producing interval into five geomechanical zones based on dynamic elastic properties. The Bakken natural fracture zone identification technique was facilitated by neural network modeling and a newly developed multi-log attribute relation. The natural fracture zones identified were shown to be consistent with independent results from seismic attribute analysis. Finally, this work expands the paradigm of unconventional resource exploitation (which is primarily driven by the intent to increase production) to include the consideration of exploration and development drilling pathways that can potentially reduce the pre-production greenhouse gas emission of MFHws. Where available, core and field data were used for quality-controlling and validating results.

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