The Athabasca oil sands deposit is not only one of the largest petroleum reservoirs in the world (870 billion bbl of oil in place), it is virtually the only supergiant oil accumulation that can be examined at outcrop. Sedimentologic and petrographic knowledge, gleaned both from the outcrop and from many subsurface cores, has direct and immediate implication for surface mining and in-situ reservoir engineering.

Most of the Athabasca reserves are contained in the Lower Cretaceous McMurray Formation, a 40 to 100-m-thick sequence of uncemented quartz sandstones and associated shales, saturated with heavy oil in virtually all zones where there is significant primary porosity and permeability. Through most of the deposit region, sedimentation was dominated by fluvial and related depositional systems, culminating in the localized development of very large channels in which were deposited distinctive solitary sets of epsilon cross-strata up to 25 m thick.

Insight into the characteristic facies patterns of the McMurray Formation sediments has important applications in surface mining; for projecting high-grade trends and locating prospective mine sites; for predicting variations in reservoir grade and designing mine layout accordingly; for identifying natural discontinuities (e.g., the sloping epsilon beds) that adversely affect pit high-wall stability; and for numerous other engineering uses. In the subsurface, detailed knowledge of the reservoir facies is of critical importance: in outlining the geometry of steam- or fire-flood patterns; in selecting zones which optimally may be treated with solvents, emulsifiers, or heat in order to establish inter-well communications; in identifying permeability barriers that can be exploited to cont in a given stimulation flood; and, given the current context of fledgling experimental technologies, in explaining what went wrong in specific pilot programs.

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