Lithofacies Characteristics, Reservoir Properties, and Ichnology of the Upper Montney Member (Spathian)

  • Author / Creator
  • The Lower Triassic Montney Formation in west-central Alberta and northeastern British Columbia has become one of the most productive reservoirs in Western Canada over the past 15 years. It is projected that it will play a leading role in satisfying Canada’s energy requirements over the next 20 years. This study focuses on the Upper Montney Member (UMM), which is interpreted to represent the deposition within a wave- to storm-influenced, low-gradient, predominantly siliciclastic ramp setting. The lithology is dominated by the interbedding or interlamination of dolomitic, medium- to coarse-grained siltstone and bituminous, fine- to medium-grained siltstone, with subordinate dolomitic, very fine-grained sandstone locally occurring towards the UMM top. Seven lithofacies are identified in the UMM, comprising a conformable, shoaling-upward (coarsening-upward) sequence. Along with the measured porosity-permeability data, analyses of high-resolution scanning electron microscopy (SEM) and thin-section based petrography are conducted to evaluate reservoir qualities of different lithofacies. Notably, the shoreface successions of the Upper Montney are classified by the lithofacies-dependent reservoir properties using Winland porosity-permeability plots. In addition, integrating the mineralogical analyses by X-ray-diffraction (XRD) and the measured values of total organic carbon (TOC), the origin of the bitumen is investigated and the Upper Montney is inferred to be a self-sourcing reservoir system.
    This work also considers some ichnological attributes of the UMM to refine an understanding of environmental conditions during reservoir deposition. To do this, the ichnology of the eastern UMM, in Alberta, is compared to more distal positions in the western MMR, In British Columbia. In Alberta, trace fossils identified mainly include Phycosiphon, Teichichnus, Planolites, Cylindrichnus and Skolithos and are consistent with somewhat impoverished trace fossil assemblages associated with proximal offshore and lower shoreface settings. In British Columbia, lack of idiomorphic ichnogenera is observed in bioturbated siltstones and sandstones: this is owing in part to a lack of grainsize variabilities of the host strata. To deal with these ichnotaxonomic problematica, five ichnofossil types (Type a, b, c, d and e) are designated and interpreted ethologically. In order to investigate the ichnological variability of the shoreface successions within the Upper Montney Member in different areas, process ichnology data (bioturbation intensity, burrow diameter, bioturbation diversity, and size-diversity index) are collected and analyzed. The distinct hydrodynamic conditions and the oxygen deficiency are interpreted to be the most significant physico-chemical stresses leading to the ichnological distributions and variability.

  • Subjects / Keywords
  • Graduation date
    Spring 2022
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • 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.