Greater Green River Basin Stratigraphy as IT Relates to Natural Gas Potential

Abstract

ABSTRACT Major reserves of natural gas remain to be discovered in the Greater Green River Basin of southwestern Wyoming and northwestern Colorado. This basin, occupying approximately 21,000 square miles, includes four sub-basins. These are the Green River Basin proper, west of the Rock Springs Uplift, and the Red Desert, Washakie, and Sand Wash Basins, on the east side of the uplift. Thick sections of Tertiary and Upper Cretaceous rocks exist throughout most parts of the Greater Green River Basin. Drilling depths to penetrate these sections range from relatively shallow depths on the flanks of the individual basins to depths greater than 20,000 ft in certain areas of the Green River Basin proper. The Mesaverde Group, Lewis, Lance and Lower Tertiary Fort Union and Wasatch Formations have significant thick intervals of tight and near tight sandstones containing natural gas. Most of the new discoveries will probably come from stratigraphic traps. Although many of these reservoirs are currently non-commercial, there is a tremendous future potential with improvements in drilling and completion practices. With increased gas prices, new interests in deep drilling have been created. Five generalized lithofacies maps of the environments of the Upper Cretaceous section of the Greater Green River Basin of Wyoming were constructed to provide information on the productive areas of the stratigraphic section. These maps also indicate the extent of these intervals in the basin, those areas in the basin with the thickest section and some key strand plain trends. This report and the lithofacies maps should provide a good overview of the geology of the Upper Cretaceous and Lower Tertiary stratigraphic section in the Greater Green River Basin of Wyoming and help determine where the most future potential exists for natural gas.