Print this pageMARK, SANDRA, and ROGER M. SLATT, Petroleum Technology Transfer Council, Colorado School of Mines, Golden, CO; and DAVID C. RAMPTON, Shell Oil Company, The Hague, Netherlands
Abstract: Characterizing a Morrow Sandstone Reservoir Through Stratigraphic Interpretation of 3-D Seismic Data, Sorrento Field, Colorado
Sorrento Field, southeastern Colorado,
contains an estimated 21 million barrels of original oil in place in the
Pennsylvanian Morrow sandstone. The reservoir consists of a complex of
stacked channel sequences within an incised valley. Interpretation of 3D
compressional seismic data has outlined the configuration of the incised
valley and provided essential information about the characteristics of
the rocks that fill it. This seismic interpretation provides stratigraphic
details on the compartmentalization of the four flow units which explain
the multiple fluid contacts and 
variable
performance of wells in the field.
The petroleum industry has been challenged to
characterize Morrow reservoirs because the sandstone reservoir is encased
in marine mudstone; normal compressional seismic data are not capable of
imaging reservoir rock because the acoustic impedance is not sufficient
to distinguish the two lithologies. Rather, seismic modeling shows that
the compressional seismic character of the Morrow interval is primarily
due to high velocity
/high density non-reservoir rocks. The distribution
of these non-reservoir rocks is critical in delineating the reservoir because
the channel sandstone is bordered by reflective rocks such as floodplain
deposits or high density facies which lie outside of the valley wall. Non-reservoir
rocks which are barriers to flow within the reservoir, such as carbonate-cemented
zones, define the compartmentalization.
AAPG Search and Discovery Article #90921©1999 AAPG Mid-Continent Section Meeting, Wichita, Kansas