Stratigraphy and reservoir properties, Devonian Kee Scarp Formation, Norman Wells, Northwest Territories
Date
1969-07
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Masters
Abstract
The Kee Scarp Formation in the subsurface at Norman
Wells, Northwest Territories, forms an elongate, northeast
trending, flat-topped mound. Oil is produced on
the up-dip northeast edge. The formation consists of
two distinct members; a lower, argillaceous, bedded coralline
limestone referred to as the platform member and an overlying,
massive member of variable facies referred to as
the reef complex. Cores were examined from the Norman
Wells oil field, underlying the Mackenzie River, and
from outcrops a few miles to the northeast. Reconstructions
suggest that the oil field cores are from one atoll-like
structure and the outcrop carbonates from another.
These structures may have been moditied by pre-Canol
erosion.
Stromatoporoids are the most abundant fossils found
in the Kee Scarp reef complex, and were the principal
reef builders. The shape and size of the coenostea are
useful in making environmental interpretations, since
individuals commonly assume a variety of environmentallycontrolled
shapes.
The petrographic and palaeontologie characteristics
of the sediments are used to define six major facies within
the Kee Scarp. These are the Amphipora packstone facies, the massive stromatoporoid grainstone facies, the stromatoporoid
packstone facies, the fine pellet packstone facies,
the dendroid stromatoporoid packstone facies, and the coral
packstone facies. Division of the Kee Scarp reef complex
into fore-reef, organic reef and back-reef zones is based
on the environmental interpretation of the six main facies.
In general, the fore-reef zone is characterized by the
stromatoporoid packstone and fine pellet packstone facies,
the organic reef by the massive stromatoporoid grainstone
facies, and the back-reef zone by the fine pellet packstone
and Amphipora packstone facies.
Three pore types are recognized in the Kee Scarp;
interparticle pores (mainly interpelletal), pores
associated with stylolites, and pores associated with
spar cement. Interparticle matrix pores are quantitatively
the most important pore type.
Reservoir properties were determined using an air
displacement porometer and a mercury injection apparatus.
They are most favorable in the fine pellet packstone and
stromatoporoid packstone facies. In these facies, the
average porosity is 20 per cent, the average permeability
is 2 millidarcies, and the average pore size is 0.1
millimeters in diameter. Porosities and permeabilities
are better in the subsurface than in the outcrop, for comparable lithologies. At best, the reservoir properties
of the Kee Scarp are only fair when compared to the
reservoir properties of other western Canada Devonian
reservoirs.
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Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geological Sciences