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Digital recovery, modification, and analysis of Tetra Tech seismic horizon mapping, National Petroleum Reserve Alaska (NPRA), northern Alaska

By R.W. Saltus, C.S. Kulander, and C.J. Potter

U.S. Geological Survey Open-File Report 02-111

Version 1.0


We have digitized, modified, and analyzed seismic interpretation maps of 12 subsurface stratigraphic horizons spanning portions of the National Petroleum Reserve in Alaska (NPRA). These original maps were prepared by Tetra Tech, Inc., based on about 15,000 miles of seismic data collected from 1974 to 1981. We have also digitized interpreted faults and seismic velocities from Tetra Tech maps. The seismic surfaces were digitized as two-way travel time horizons and converted to depth using Tetra Tech seismic velocities. The depth surfaces were then modified by long-wavelength corrections based on recent USGS seismic re-interpretation along regional seismic lines. We have developed and executed an algorithm to identify and calculate statistics on the area, volume, height, and depth of closed structures based on these seismic horizons. These closure statistics are tabulated and have been used as input to oil and gas assessment calculations for the region. Directories accompanying this report contain basic digitized data, processed data, maps, tabulations of closure statistics, and software relating to this project.


OFR-02-111.pdf
OFR-02-111 PDF file (5.48 MB)
(This version of the report is accessible as defined in Section 508.)
Data
This directory contains ASCII data files for the basic digitized data and for the final seismic horizon grids.
Maps
This directory contains PDF formatted maps of the seismic horizons, time differences, and closure analyses.
Software
This directory contains the FORTRAN 77 source code for the three custom software codes developed for identification and measurement of closed structures on the seismic horizons.
Spreadsheets
This directory contains Microsoft Excel spreadsheets containing tables of closure statistics and summary statistics from the closure analyses.
Stats
This directory contains ASCII formatted printouts that detail the statistics of closure area verses height for the different horizons that were studied.

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