Characterization of Reservoir Quality Using Ichnological, Sedimentological, and Geochemical Methods

  • Author / Creator
    Baniak, Gregory M
  • A detailed analysis of subsurface reservoirs from offshore Norway and Alberta, Canada is undertaken in this thesis to better categorize the influence trace fossils have on reservoir quality. Specifically, the data collected focuses on understanding burrow fabrics in two- and three-dimensions (2D and 3D), assessing the influence trace fossils have on fluid flow, and understanding burrow-associated diagenesis.
    Using imaging techniques such as microtomography (micro-CT) and computed tomography (helical-CT), a better understanding of burrow fabrics and their associated properties is completed. Particularly, each sample is found to have
    a distinctive X-ray attenuation due to factors such as grain size and sorting. This is
    particularly true for samples that contain moderate to extreme contrasts in lithology
    and permeability between the burrows and matrix. As such, the 3D generated volumes of the burrows help show that the distribution of X-ray attenuations within
    a sample can be linked to measured permeabilities.
    The influence of bioturbation on reservoir quality within carbonates (Upper Devonian Wabamun Group, central Alberta) and siliciclastics (Upper Jurassic Ula Formation, offshore Norway) is investigated using spot-permeametry measurements, thin sections, analytical models, and numerical models. In both case studies, analytical and numerical models show that the arithmetic mean best characterizes intervals dominated by moderate to high bioturbation intensities or horizontal to sub-vertical burrows. The harmonic mean best represents intervals with vertical burrows or low bioturbation intensities. The geometric mean best characterizes intervals where horizontal and vertical permeabilities within the sample are roughly equal. A new term, Ichnofossil Hosted Tight Gas (IHG), is also
    introduced in this thesis to demarcate tight gas reservoirs, such as the Wabamun
    Group, wherein natural gas is produced primarily from the burrows relative to the
    low-permeability matrix.
    Using core data, thin sections, and isotopes (carbon and oxygen), the influence
    burrows have on mediating dolomitization is examined in the Mississippian Debolt
    Formation (Dunvegan gas field, northwestern Alberta). Compositional differences observed in the isotopic distributions reflect the different biogeochemical processes occurring within and adjacent to the burrows. Organic matter, an essential component for bacterial sulfate reduction and subsequent near-surface dolomitization, is likely derived in part from the organisms and their by-products.

  • Subjects / Keywords
  • Graduation date
    Fall 2013
  • 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.