A review of the Lower Cretaceous stratigraphy of the Alberta Basin and petroleum systems of the Lower Mannville Group in the southern Alberta Plain, Canada

Abstract

The Manville Group in the Alberta Basin, Canada, contains large amounts of hydrocarbon resources and has long been a target of petroleum exploration and production. However, there exists no standard stratigraphic classification system that can be applied for the basin-wide underground reservoirs and petroleum systems, mainly due to the limitations that most stratigraphic nomenclatures were defined by information obtained from underground boreholes. In this review, after extensive literature survey we reinterpret the spatio-temporal relationships of the Mannville Group and its correlative strata on the basis of the depositional history and stratigraphic context in the Alberta Plain region. It seems appropriate to distinguish the Deville Formation lying immediately above the sub-Mannville unconformity as a stratigraphic unit separated from the overlying Mannville Group and the underlying Jurassic strata based on its unconformable relationship both above and below and its depositional origin. The Basal Quartz, commonly used unofficially, is a stratigraphic unit referring to the lower Mannville strata beneath the Ostracod Beds. The Bluesky and the Wabiskaw sandstones in the Mannville Group are very similar to the Glauconitic Sandstone in terms of lithology, but their depositional histories are different from the latter. The former sandstones had been deposited during the overall transgressive stages, whereas the latter is a deposit that was formed during the following regressive stage after the deposition of the former sandstones. The main reservoirs in the southern Alberta region are the Basal Quartz sandstones, which represent fluvial channel sandstones that filled the main channels having a N-S orientation and dendritic tributary channels connected to the main channels. The main source rocks are interpreted to be organic matter-rich marine shales of the Jurassic Fernie Group. The Ostracod Beds are very poor in permeability and thus form a regional seal, forming stratigraphic traps in numerous areas.