Interpreted Regional Seismic
Reflection Lines,
National Petroleum Reserve, Alaska
By
C.S. Kulander, C.J. Potter, J.A. Grow, and R.W. Saltus (U.S. Geological Survey)
The United States Geological Survey (USGS) has
reprocessed and interpreted a regional grid of public-domain 2-D seismic
data
in
the National Petroleum Reserve—Alaska (NPRA). These lines include 24 of the
original Regional Compressed Sections totaling over 4000 line-miles. Using these
lines, formation tops of units that generate regionally significant reflectors
were interpreted. These included the tops of the Mississippian Endicott and
Lisburne groups and the Triassic, Shublik in the Ellesmerian sequence; and the
Jurassic Kingak Shale and Cretaceous pebble shale units in the Beaufortian
sequence. In addition, the unconformities on top of the pre-Mississippian
basement and the Lower Cretaceous unconformity were interpreted.
Digital well logs provided the synthetic seismograms
necessary to correlate formation tops to their respective seismic
horizons.
Faults throughout the section, from the extensional Mississippian basins to the
Brookian-aged thrust complexes in the Colville and Nanushuk formations, have
been interpreted.
In order to compare this reprocessed dataset and
interpretation
with an earlier
interpretation
by Tetra Tech Inc, which covered a
more extensive grid of unreprocessed
data
, time-difference maps have been
constructed. These maps highlight areas with considerable differences between
the two interpretations, and allow for the merging of the older, more extensive,
interpretation
and interpretations based on the newer, better-imaged dataset.
Once formation tops were interpreted and compared across the NPRA, isopach maps
were constructed using velocities taken from well log
data
.
AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.