Duvernay Reserves and Resources Report

Alberta Energy Regulator
2.4 Geological Prospectivity
When choosing drilling locations and optimizing completion strategies, operators may consider a number
of geological factors that control prospectivity in the Duvernay. The amount of hydrocarbons and how
the rock will respond to hydraulic fracturing is influenced by carbonate thickness, the porosity, the TOC,
and the brittleness. To identify regions of greater prospectivity within the Fox Creek play, these four
factors were combined and normalized by their range with equal weighting in terms of contribution
to prospectivity. Figure 4 shows that Duvernay shales are regionally heterogeneous, and based on this
analysis, the geologically most optimal area for prospectivity is around the Town of Fox Creek.
2.5 Expected Fluid Regions
In addition to mapping the Duvernay and its geological parameters, petroleum geologists can predict
the fluids occupying the pore space of the rock. In an organic-rich shale deposited in a marine basin like
the Duvernay, the organic material is expected to be mostly derived from phytoplankton and algae. This
type of organic material, called Type II kerogen, will produce both oil and natural gas when buried and
exposed to elevated pressure and temperature. The relative amount of oil versus natural gas produced will
depend mostly on the temperature the rocks are exposed to.
The temperature at which the maximum rate of hydrocarbon generation is achieved is commonly called
T max . Rock analysis can be performed to determine T max , which can be used to estimate the expected fluid
type encountered at that location in the reservoir. For 35 wells in the Fox Creek play area, T max data was
analyzed and the expected fluid types were mapped, resulting in expected fluid regions (Figure 5). This
map is considered accurate on a regional scale, but local variations in geological history and organic
material-type make actual production quite variable, especially near fluid boundaries. As well, the
type of organic matter in the Duvernay can produce oil and natural gas simultaneously over a range of
temperatures.
Fluid regions may continue to be revised based on new information obtained from operators and
additional core analysis data. Additional information on T max can be found in Appendix 3.
When the prospectivity map of Figure 4 is combined with expected fluid regions of Figure 5 and
knowledge of present and forecasted commodity prices, drilling costs, etc., one can understand historical
patterns of development and begin to make reasonably constrained projections of development over a
moderate time horizon.
3 Development History
The Duvernay Formation was first defined by geological staff at the western division of Imperial Oil
Limited (1950) for dark grey to brown, bituminous shales in wells drilled near the town site of Duvernay,
east-central Alberta. The reference well in Alberta is the Anglo Canadian Beaverhill Lake No. 2 11-11-
050-17W4M well.
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