Publications

In assessing continuous oil and gas resources, such as shale gas, it is important to describe not only the ultimately producible volumes, but also the expected well performance. This description is critical to any cost analysis or production scheduling. A probabilistic approach facilitates (1) the inclusion of variability in well performance within a continuous accumulation, and (2) the...

Reserve growth (growth-to-known) is the addition of oil and gas quantities to reported proved or proved-plus-probable reserves in discovered fields. The amount of reserve growth fluctuates through time with prevailing economic and technological conditions. Most reserve additions are the result of investment in field operations and in development technology. These investments can be...

Shale-gas well productivity estimates in USGS assessments from 1995 to present are based on studies that require decline curve fits and analysis to a large sample or to all wells within a particular assessment unit. Probabilistic type curves can be created on nearly any size well group and were designed for use within a resource context. The probabilistic type curve was designed to...

Accurate S-wave velocities for shallow sediments are important in performing a reliable elastic inversion for gas hydrate-bearing sediments and in evaluating velocity models for predicting S-wave velocities, but few S-wave velocities are measured at low effective pressure. Predicting S-wave velocities by using conventional methods based on the Biot-Gassmann theory appears to be...

Using a geologic-based assessment methodology, the U.S. Geological Survey estimated an in-place oil shale resource of 1.07 trillion barrels under Federal mineral rights, or 70 percent of the total oil shale in place, in the Piceance Basin, Colorado. More than 67 percent of the total oil shale in-place resource, or 1.027 trillion barrels, is under Federal surface management.

Gas, oil, and water production data for tight gas reservoirs were compiled from selected wells in western Colorado. These reservoir rocks—the relatively shallow Paleogene Wasatch G sandstone interval in the Parachute and Rulison fields and fluvial sandstones in the deeper Upper Cretaceous Mesaverde Group in the Grand Valley, Parachute, Rulison, and Mamm Creek fields—are characterized by...

In the Bighorn Basin of north-central Wyoming and south-central Montana, the Frontier Formation of early Late Cretaceous age consists of siliciclastic, bentonitic, and carbonaceous beds that were deposited in marine, brackish-water, and continental environments. Most lithologic units are laterally discontinuous. The Frontier Formation conformably overlies the Mowry Shale and is...

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a total of 1.32 trillion barrels of oil in place in 18 oil shale zones in the Eocene Green River Formation in the Uinta Basin, Utah and Colorado.

The U.S. Geological Survey estimated means of 1.8 billion barrels of recoverable oil, 223 trillion cubic feet of recoverable gas, and 6 billion barrels of natural gas liquids in the Nile Delta Basin Province using a geology-based assessment methodology.

Described in this report is an updated subsurface stratigraphic framework of the Paleocene Fort Union Formation and Eocene Wasatch Formation in the Powder River Basin (PRB) in Wyoming and Montana. This framework is graphically presented in 17 intersecting west-east and north-south cross sections across the basin. Also included are: (1) the dataset and all associated digital files and (2)...

Large amplitude waveform features have been identified in pulse-transmission shear-wave measurements through cylinders that are long relative to the acoustic wavelength. The arrival times and amplitudes of these features do not follow the predicted behavior of well-known bar waves, but instead they appear to propagate with group velocities that increase as the waveform feature's dominant...

Using a geology-based assessment methodology, the U.S. Geological Survey (USGS) estimated means of 21.6 billion barrels of oil and 299 trillion cubic feet of undiscovered natural gas in 22 provinces of southeast Asia.