Browsing by Author "McKean, Scott Harold"

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    Geomechanical Properties of the Montney and Sulphur Mountain Formations
    (2017) McKean, Scott Harold; Priest, Jeffrey A.; Wong, Ron Chik-Kwong; Clarkson, Christopher R.
    Accurate modelling of hydraulic fracturing is critical for improving the cost efficiency and societal acceptance of unconventional hydrocarbon exploitation. This thesis investigates the geomechanical inputs required to improve hydraulic fracturing using X-Ray fluorescence, helium pyncnometry, microhardness, point load strength testing, unconfined compressive strength testing, Brazilian testing, multi-stage triaxial testing, and ultrasonic pulse transmission. The Montney Formation and its outcrop equivalent, the Sulphur Mountain Formation, are studied. Static and dynamic experimental results are interpreted and compared using a transversely isotropic framework. The Sulphur Mountain samples were more brittle and heterogeneous than Montney samples, which were harder and failed in a more stable fashion. Heterogeneity was a stronger control on failure, strength, and elastic constants than anisotropy caused by layering. Complex failure mechanisms were observed in Brazilian and triaxial tests and yielded insights into fracture propagation processes, inhomogeneity, and stress concentrations.
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    The Stochastic Characterization of Natural and Hydraulic Fractures in Unconventional Reservoirs
    (2023-01-13) McKean, Scott Harold; Dettmer, Jan; Priest, Jeffrey Alan; Eaton, David WS; Wan, Richard G; Davidsen, Joern; Dusseault, Maurice Bernard
    An informed understanding of the subsurface is critical for mining, tunnelling, wastewater injection, carbon sequestration, and hydraulic fracturing (HF). Unfortunately, subsurface characterization is full of uncertainty. This is especially true when trying to understand or mitigate induced seismicity (IS), or the triggering of earthquakes by anthropogenic processes. This research focuses on hydraulic fracturing caused IS in unconventional reservoirs. The interaction between HF and IS is complicated by geomechanical variability and the presence of natural fractures. Our research accomplishes three objectives. We study natural fractures through outcrop analogues, discrete fracture network modelling, and induced seismicity. We characterise geomechanical rock properties along with their uncertainty. Finally, we develop a repeatable and scalable workflow to separate HF microseismicity from IS in order to characterise hydraulic and natural fractures. The research focuses on the Duvernay Formation in the Western Canadian Sedimentary Basin. An alpine outcrop equivalent of the Duvernay is characterized to quantify small- and large-scale fractures. This study reveals irreducible small-scale heterogeneity, as well as discernable patterns in large-scale fractures. Statistics and geostatistics are used to investigate elastic moduli and brittleness. The work shows how measurement and modelling uncertainity can propogate from laboratory to basin-scale. It reveals fundamental differences between elastic moduli and brittleness and shows why holistic modelling and uncertainty quantification approaches are essential to understanding and modelling the subsurface. We then introduce methods for the separation of HF microseismicity from IS. Physics-based clustering and Bayesian inference of diffusivity are used for the separation. This permits HF characterization which highlights the large variability of diffusivity and HF dimensions. We show why physics-based constraints are essential for microseismic analysis. The separated IS allows us to infer information about the natural fractures linked with induced seismicity. Application of the methods to the Duvernay shows HFs propogating directly into natural fractures and rotating away from the maximum principal stress direction towards natural fractures. Discrete fracture network modelling and parameter estimation is able to constrain the architecture of multiple fracture sets. We demonstrate that aseismic fracture sets are essential for establishing pressure connectivity and displaying IS.