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.