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a
6 mi
T53
LLOYDMINSTER AREA
30 foot contours on
Sparky net sand ………
T52
T51
b
T50
T49
T48
T47
T46
57.1 km
57.1 km
R. 6
R. 5
R. 4
R. 3
R. 2
R. 1
Fig. 1.12 (a). Contour map of Sparky sandstone thickness after Burnett and Adams (1977). (b).
Pattern used as input for Quantimet 720 (After Agterberg
1980
, Fig. 3)
can be determined by subtracting from
A
the covariance for a single picture point in direction
In practice, the intercept in direction
α
.
A practical example is as follows: Fig.
1.12a
was taken from a study by Burnett
and Adams (
1977
) concerned with the Lloydminster Sparky Pool, Alberta. The
Sparky sand accumulations in this area are northwest-southeast trending bodies
with maximum thickness of 9-16 m. Most commonly the Sparky unit consists of an
upper and lower sand separated by a shale bed 1-3 m thick. The 30 feet (9.14 m)
contour shown in Fig.
1.12a
does not include the thickness of this intermediate
shale bed. Comparison of the pattern to present-day features in the North Sea
and elsewhere suggests that the contours delineate tidal-current ridges formed
parallel to the tidal current. Oil production in the Lloydminster area of east-central
Alberta and adjacent Saskatchewan is from sands in the Mannville Group of Early
Cretaceous (Albian) age. The middle Mannville Sparky sandstone is the main oil
producing horizon. Originally, high viscosity coupled with fine-grained unconsol-
idated nature of the sand kept primary production relatively low.
The black and white pattern of Fig.
1.12b
was extracted from Fig.
1.12a
and used
as input for the Quantimet 720 textural analyzer in order to determine the intercept,
a smoothed version of which is shown in Fig.
1.13a
. In Agterberg
(1979b)
an
algorithm is presented to estimate the frequency values of rose diagrams for
α
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