Synthetic Seismograms Related to Detailed Geology in the Celtic Field, Saskatchewan
Abstract
In the L10ydminster area of Saskatchewan, heavy oil commonly occurs
in thin, less than five-metre thick, vertically-stacked lenses within
the sand beds of the Lower Cretaceous Mannville Group. Seismic mapping
of the Mannville section has proved difficult due to the thinness of the
beds, the lateral variation of these beds, and the lack of acoustic
markers. The comparison of synthetic seismograms to detailed
stratigraphic and core-analysis data allowed the interpretation of
subtle seismic responses on these computer-simulated seismograms.
Synthetic seismograms, which included the effects of absorption and
dispersion, were constructed for seven closely-spaced wells located in
and near an enhanced-recovery pilot-project in the Celtic field. Input
parameters of an impulse source buried at 29.9 m and a Q curve derived
from published Q-values provided the best synthetic-seismic response to
the zones of economic importance located within the Mannville Group.
In the Celtic field, the seismic-reflection method could be used
for heavy-oil exploration or development if sufficient frequency-content
in the 60 to 115 hz range is returned from the Mannville section.
However, the dominant frequency imposed by the natural filtering of the
earth is only 39 hz in all but one of the wells studied. Data
acquisition and processing techniques must, therefore, be chosen to
accentuate the 60 to 115 hz range.