Introduction

The oil-sands reservoir related to the Long Lake South (LLS) project is contained within the McMurray formation, which is the basal unit of the Lower Cretaceous Mannville Group. The McMurray formation directly overlies the sub-Cretaceous unconformity, which is developed on Paleozoic carbonates of the Beaver Hill Lake Group and is overlain by the Wabiskaw, Clearwater, and Grand Rapids Formations of the Mannville Group.

The study area (Figure 1) is located along the axis of the McMurray Valley system, which was localized by the dissolution of underlying Devonian evaporates, creating the preferred depositional fairway for the Lower Cretaceous McMurray sediments. The most significant bitumen reservoirs within the McMurray formation are found within the multiple channels that represent lowstand system tracts, incised into the regional, prograding parase-quence sets that represent highstand system tracts. During sea level rise, these incised channel systems were filled with a transgressive estuarine complex, consisting of sandy to muddy estuarine point bars. In the Long Lake area, the McMurray formation is dominantly composed of these multiple, sand-rich, fluvial, and estuarine channels, which are incised into each other and stacked along a preferred path of deposition. This preferred path is aligned north-northwest to south-southeast in the Long Lake area (Dumitrescu et al., 2009).