Sedimentology, Ichnology and Biogenic Permeability of the upper Montney Formation, northeast British Columbia

• Author / Creator

  Gegolick, Aimee E

• The upper Montney Formation is a tight gas reservoir that consists of silt and very fine-grained sandstone in its entirety. Despite its limited variation in grain-size, this formation is highly heterogeneous and the distribution of facies is complex, both vertically and laterally. Subtle changes in characteristics affect reservoir properties, resulting in compartmentalization of resources. These changes include frequently interbedded facies and sporadically distributed bioturbation. A detailed analysis of the subsurface reservoir was conducted in order to provide insight into these subtle heterogeneities. Fourteen cores within the upper Montney of northeast British Columbia were studied in order to interpret depositional processes and assess bioturbated fabrics and their relationship with permeability and porosity. Five facies were identified, representing deposition within the distal offshore to offshore transition zone. Sediment was sourced from low-density turbidity currents. Varying velocity within the boundary layer of turbulent flow was likely the mechanism for the physical separation of coarser and finer silt components. This mechanical separation resulted in the development of pinstripe laminae that dominate the formation. Permeability was assessed with a Core Laboratories Pressure Decay Profile Permeameter (PDPK-400) to characterize the effects of bioturbation on permeability and assess its utility for fine-grained rocks. Spot permeametry provides the most discrete measurement that can be obtained and the bulk permeability provides a representative value for a given fabric. Results from the permeability testing demonstrate that pervasively bioturbated fabrics locally enhance permeability relative to nonbiotubated fabrics. Bioturbation needs to be pervasive in order to significantly adjust pore aperture sizes. Permeability anisotropy was tested, however, spot-permeametry is unable to characterize anisotropy resulting in more homogenous trends vertically.

• Subjects / Keywords

  • Biogenic permeability
  • Montney
  • Ichnology
  • Sedimentology

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3DZ03F9N

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.