ABSTRACT

A detailed study area, located within the Syncrude oil sands mine, contained over 200 drill holes in an area approximately 1 sq. km in size. Drill hole spacing averages 80 m to 100 m, with spacings as close as 40 m in the vicinity of active mining benches. All drill holes were supported by dipmeter logs and alternate holes were cored. Mapping was carried out on a 1:500 scale, with the aim of characterizing major reservoir facies, heterogeneities, and permeability barriers. Syncrude's high-wall mapping program and exploration test pits provided additional verification. With this quantity and quality of data, detailed models of a McMurray-type reservoir were developed.

The McMurray Formation consists of 50 m to 70 m of uncemented quartzose sands and associated shale, deposited in an estuarine valley-fill complex. The richest oil sands (reservoir) are contained in the Middle McMurray tidal channel successions. Repetitive scour and fill cycles result in stacked channel deposits.

Little, if any, cementation or clay authigenesis has occurred, so the porosity and permeability patterns are a direct function of the primary facies distribution. With the absence of diagenetic factors, reservoir characterization is simplified considerably. An understanding of the facies controls and facies architecture (vertical and lateral extent of each facies) leads to a better understanding of reservoir behaviour. Studies are underway to quantitatively assess each reservoir facies on the basis of permeability, porosity, grain size, oil saturation, and analysis of pore systems.

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