J. W. Schmoker D. H. Root T. S. Dyman 1998 <p>The U.S. Geological Survey (USGS) estimated in 1995 that 1,412 tcf of technically recoverable natural gas remained to be discovered or developed in U.S. onshore areas. A significant part of that resource base, 114 tcf, is undiscovered gas in deep sedimentary basins assessed by the USGS in onshore areas and state waters. These deep gas accumulations, at or below 15,000 ft, occur in numerous, widely differing geologic settings (Fig. 1 [138,549 bytes]).</p> application/pdf en PennWell Corporation USGS assesses deep undiscovered gas resource article