High-resolution sequence stratigraphic framework for the late Albian Viking Formation in central Alberta

Abstract

High-resolution sequence stratigraphic frameworks detail the changes in the orientation and distribution of systems tracts in a basin, making it possible to identify areas encompassing reservoir units that have been previously overlooked. The Viking Formation is a stratigraphically complex unit that accumulated in a shallow foreland basin (Western Canada Sedimentary Basin) during the Lower Cretaceous (late Albian). To date, the Viking Fm has only been described using a low-resolution allostratigraphic framework. Herein, we present a high-resolution sequence stratigraphic framework, and discuss the utility of this framework to further petroleum exploration.Two hundred and ten cores that intersect the Viking Fm were logged and these data were used to develop a facies model for the various sequences of the Viking Fm through central Alberta. The formation is mapped and described using Depositional Sequence IV nomenclature, which includes the recognition and correlation of deposits attributed to one of four systems tracts: falling-stage, lowstand, transgressive and highstand. Four depositional sequences are identified and the architecture of deposits in each sequence are discussed. By carefully mapping these deposits in a high-resolution context, we: i) delineate and refine the mapping of regional trends; ii) correlate valley incision to lowstand shorelines; and iii) provide additional criteria for identifying future reservoir units in a mature basin.Based on the high-resolution sequence stratigraphic framework, four additional stratigraphic plays are identified including: forced regressive shorelines, incised valleys, lowstand shorelines and trangressively incised shorefaces, and new lateral facies relations that potentially could produce reservoir compartmentalization. These additional play types are not the typical reservoirs explored for in the Viking Fm and may have been overlooked as non-prospective.