Thomas F. Moslow1
(1) Ulster Petroleums Ltd, Calgary, AB
Abstract: Reservoir modeling of shoreface conglomerates in the Deep Basin of Western Canada: Insights from outcrop
Conglomerate shoreface reservoir trends in the Cretaceous Deep Basin have produced approximately 3.0 TCF of sweet, liquids-rich natural gas since their initial exploitation in the late 1970's, and form some of the most prolific hydrocarbon pools and fields (i.e. Elmworth, Wapiti, Noel) in Western Canada. However, their lack of seismic expression has made exploration for these high permeability (10's to 1,000's of md), low porosity (8-10%) reservoirs an almost strictly geological play with a heavy reliance on core-based sedimentologic and stratigraphic observations.
Along the Front Ranges of north-eastern British Columbia, detailed sedimentologic descriptions and synthetic gamma-ray logs of closely spaced measured sections from laterally continuous outcrop provide the observational base for documenting the architecture of analogous shoreface conglomerate reservoirs. A pattern of offlapping cyclicity of facies associations in outcrop occurs within all parasequences, but on varying orders of magnitude and frequency. This variability is predictable and predominantly a function of conglomerate-sandstone ratio at the time of deposition. Shoreface facies associatons, or cycles, are a product of shoreline progradation and lateral accretion during phases of episodic sedimentation. Each association is bounded by an abrupt to erosional, and laterally discontinous, ravinement surface or Facies Association Boundary (FAB) that may serve as a significant permeability barrier on a reservoir level.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana