ABSTRACT

A geographic information system (GIS) was used to evaluate gas, oil, coal, and gravel resources on the Fort Peck Reservation. Analysis was performed using ARC/INFO on a SUN workstation.

Resource data layers were constructed in the Geographix Exploration System on a 486-based, PC computer for Cretaceous gas zones and Paleozoic oil horizons. Selected contour lines, structural trends, and well and geophysical data were transferred to the GIS where cultural features, ownership, and lease data reside. USGS Coal resource maps were digitized into the GIS for ownership evaluation. Gravel data was imported from a Paradox database for tribal tracts that overlie geologic formations known to contain gravel. Field investigations confirmed the existence or absence of gravel. GIS overlay techniques checked the manual overlay method, identified additional prospect areas, and provided a statistical and spatial ranking of the resource.

Two GIS analysis techniques are employed: GRID Sum and polygon overlay; grid analysis simply stacked, added, weighted and averaged the resource cells which were created in the GIS. Results were statistically grouped, ranked, and reported in maps, tables, and graphs. This computer technique performed years of work in a few hours.