ABSTRACT

The Winterburn-Woodbend succession has been redefined using event stratigraphy as opposed to the traditional lithostratigraphic approach. Carbonate reservoirs in the Upper Devonian Woodbend-Winterburn succession collectively account for approximately 66 per cent of Western Canada's initial conventional oil reserves. Consequently, utilization of event stratigraphy could lead to new exploration opportunities within the Western Canada Sedimentary Basin.

An event-stratigraphic framework has been developed that closely approximates the division of the Woodbend-Winterburn sequence into time-bounded units. This framework was established by repicking and correlating 10,000+ wells on the basis of traceable "time-synchronous" log events which give a better illustration of the macro-depositional processes and overall basin evolution.

Six major bounding events with associated basin infill and/or reef development are recognized. The upper-bounding event for the Woodbend-Winterburn succession, used in this study, is congruent with the Frasnian-Famennian boundary as defined from outcrop in the Northwest Territories. In the subsurface, this event correlates with a marker just below the base of the Graminia Silt. The second major event corresponds to the base of the Calmar Formation, and the third is equivalent to the base of the Nisku Formation as defined in the Chevron Norcen 7-4-49-12 W5M reference well. Specifically, this event correlates with the industry defined 'Z' marker within the basin-fill sequences and can be confidently correlated over much of the basin. The fourth major event approximates the termination of the traditional Woodbend reef-building and basin-fill sequence. The top of the Cooking Lake Formation and its equivalents represent the fifth event. The final, lower-bounding event for the Woodbend-Winterburn succession corresponds approximately to the base of the Cooking Lake Formation and equivalents.

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