Geology topics
Publications and source records attributed to Stanley T. Paxton.
The U.S. Geological Survey (USGS) recently completed an assessment of undiscovered, technically recoverable oil and gas resources in the Susitna Basin of southern Alaska. Using a geology-based methodology, the USGS estimates that mean undiscovered volumes of about 2 million barrels of oil and nearly 1.7 trillion cubic feet of gas may be found in this area.
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 2.9 billion barrels of conventional oil and 108.6 trillion cubic feet of natural gas in the Upper Jurassic Bossier Formation in onshore lands and State waters of the U.S. Gulf Coast region.
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 1.1 billion barrels of conventional oil and 195.8 trillion cubic feet of gas in the Upper Jurassic Haynesville Formation in onshore lands and State waters of the U.S. Gulf Coast region.
The Eagle Ford shale is a major continuous oil and gas resource play in southcentral Texas and a source for other oil accumulations in the East Texas Basin. As part of the U.S. Geological Survey’s (USGS) petroleum system assessment and research efforts, a coring program to obtain several immature, shallow cores from near the outcrop belt in central Texas has been undertaken. The first of these cores, USGS Gulf Coast #1 West Woodway, was collected near Waco, Texas, in September 2015 and has undergone extensive geochemical and mineralogical characterization using routine methods to ascertain variations in the lithologies and chemofacies present in the Eagle Ford at this locale. Approximately 270 ft of core was examined for this study, focusing on the Eagle Ford Group interval between the overlying Austin Chalk and underlying Buda Limestone (~20 ft of each). Based on previous work to identify the stratigraphy of the Eagle Ford Group in the Waco area and elsewhere (Liro et al., 1994; Robison, 1997; Ratcliffe et al., 2012; Boling and Dworkin, 2015; Fairbanks et al., 2016, and references therein), several lithological units were expected to be present, including the Pepper Shale (or Woodbine), the Lake Waco Formation (or Lower Eagle Ford, including the Bluebonnet, Cloice, and Bouldin or Flaggy Cloice members), and the South Bosque Member (Upper Eagle Ford). The results presented here indicate that there are three major chemofacies present in the cored interval, which are generally consistent with previous descriptions of the Eagle Ford Group in this area. The relatively high-resolution sampling (every two ft above the Buda, 432.8 ft depth, and below the Austin Chalk, 163.5 ft depth) provides great detail in terms of geochemical and mineralogical properties supplementing previous work on immature Eagle Ford Shale near the outcrop belt.
Using a geology-based assessment methodology, the U.S. Geological Survey assessed mean undiscovered, technically recoverable resources of 121 million barrels of oil and 212 billion cubic feet of gas in the Lusitanian Basin Province, Portugal.
Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered mean volumes of 14 million barrels of conventional oil, 430 billion cubic feet of conventional gas, 34,028 billion cubic feet of continuous gas, and a mean total of 391 million barrels of natural gas liquids in sandstone reservoirs of the Upper Jurassic–Lower Cretaceous Cotton Valley Group in onshore lands and State waters of the U.S. Gulf Coast region.
Wireline logs were used to document the stratigraphic framework of Upper Devonian–Mississippian strata in the Arkoma Basin, and maps of high-gamma ray (HGR) log response were used to analyze the spatial distribution of potential source rocks in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems. The Woodford–Chattanooga shale is a transgressive deposit that accumulated on an arid continental margin influenced by marine upwelling and minimal sediment influx. A broad HGR depocenter along the southwestern margin of the basin includes two areas of higher accommodation containing the thickest HGR concentrations. Basin-wide patterns of HGR likely reflect broad tectonic influence on accommodation. The proportion of chert in the formation increases eastward and southward, likely reflecting latitudinal and bathymetric influence on the accumulation of siliceous ooze. The Lower Mississippian Burlington sequence, which lies between the two shale-gas systems, comprises carbonate ramp and distal shale deposits. Proximal ramp facies form an apron around the southern flank of the Ozark uplift and grade radially basinward into distal facies. An Upper Mississippian succession in the east includes lowstand deposits of the Batesville delta, which onlap the relict Burlington ramp. Basinwide, the succession includes the transgressive Fayetteville–Caney shale overlain by regressive deposits of the proximal Pitkin Limestone and distal upper Fayetteville (Arkansas) and “false” Caney (Oklahoma) shale. The HGR shale is concentrated in an area of intermediate accommodation on the western margin of the Mississippi Embayment and just basinward of the Pitkin Limestone pinchout in Arkansas, and in an area of relatively high accommodation in Oklahoma.
Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean volumes of 38 trillion cubic feet (TCF) of undiscovered natural gas, 159 million barrels of natural gas liquid (MMBNGL), and no oil in accumulations of 0.5 million barrels (MMBO) or larger in the Arkoma Basin Province and related areas. More than 97 percent of the undiscovered gas occurs in continuous accumulations-70 percent in shale gas formations, 18 percent in a basin-centered accumulation with tight sandstone reservoirs, and 9 percent in coal beds. Less than 3 percent of the natural gas occurs in conventional accumulations.
How gas is stored in shale-gas systems is a critical element in characterizing these potentially prolific, low-porosity/permeability reservoirs. An integrated mineralogic, geochemical, and porosity/permeability study is of the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, southern Oklahoma, at locations previously described through detailed stratigraphic and spectral gamma surveys, was undertaken to provide insights into possible mechanisms by which natural gas might be stored in Woodford reservoirs in the adjacent Anadarko Basin. The outcrops in the Arbuckle Mountains are an ideal location to study the Woodford because here the formation is immature or marginally mature for oil generation (Comer and Hinch, 1987; Lewan, 1987), so deep burial and thermal maturation are much less pronounced than is the case for the Woodford in the basin, and as such the samples we studied are not overprinted by possible alterations resulting from deep burial and heating.