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Research about Powder River Basin

Source-linked reports with geographic coverage including Powder River Basin.

At least 37 records · Page 2Linked to original sources
USGS2009

Geochemistry of inorganic nitrogen in waters released from coal-bed natural gas production wells in the Powder River Basin, Wyoming

Water originating from coal-bed natural gas (CBNG) production wells typically contains ammonium and is often disposed via discharge to ephemeral channels. A study conducted in the Powder River Basin, Wyoming, documented downstream changes in CBNG water composition, emphasizing nitrogen-cycling processes and the fate of ammonium. Dissolved ammonium concentrations from 19 CBNG discharge points ranged from 95 to 527 μM. Within specific channels, ammonium concentrations decreased with transport distance, with subsequent increases in nitrite and nitrate concentrations. Removal efficiency, or uptake, of total dissolved inorganic nitrogen (DIN) varied between channel types. DIN uptake was greater in the gentle-sloped, vegetated channel as compared to the incised, steep, and sparsely vegetated channel and was highly correlated with diel patterns of incident light and dissolved oxygen concentration. In a larger main channel with multiple discharge inputs ( n = 13), DIN concentrations were >300 μM, with pH > 8.5, after 5 km of transport. Ammonium represented 25−30% of the large-channel DIN, and ammonium concentrations remained relatively constant with time, with only a weak diel pattern evident. In July 2003, the average daily large-channel DIN load was 23 kg N day −1 entering the Powder River, an amount which substantially increased the total Powder River DIN load after the channel confluence. These results suggest that CBNG discharge may be an important source of DIN to western watersheds, at least at certain times of the year, and that net oxidation and/or removal is dependent upon the extent of contact with sediment and biomass, type of drainage channel, and time of day.

Wyoming↗
USGS2005

Effects of coal-bed methane discharge waters on the vegetation and soil ecosystem in Powder River Basin, Wyoming

Coal-bed methane (CBM) co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from affected and reference sites (upland elevations and wetted gully) in Juniper Draw to investigate the effects of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation density and diversity. Results indicate an increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil are correlated with consistent exposure to CBM waters. Clay-loam soils in the study area have a much larger specific surface area than the sandy soils and facilitate a greater sodium adsorption. However, there was no significant relation between increasing water sodium adsorption ratio (SAR) values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species density was highest at the reference (upland and gully) and CBM affected upland sites. The affected gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the affected gully, implying a potential threat of invasion and competition to established native vegetation. These findings suggest that CBM waters could affect agricultural production operations and long-term water quality.

Wyoming↗
USGS2005

Tar yields from low-temperature carbonization of coal facies from the Powder River Basin, Wyoming, USA

Tar yields from low-temperature carbonization correlate with the amount of crypto-eugelinite in samples selected to represent petrographically distinct coal facies of the Wyodak-Anderson coal zone. Tar yields from Fischer Assay range from <1 to 11 wt.% on a dry basis and correspond ( r = 0.72) to crypto-eugelinite contents of the coal that range from 15 to 60 vol.%. Core and highwall samples were obtained from active surface mines in the Gillette field, Powder River Basin, Wyoming. Because the rank of the samples is essentially the same, differences in low-temperature carbonization yields are interpreted from compositional differences, particularly the crypto-eugelinite content. In the Wyodak-Anderson coal zone, crypto-eugelinite probably was derived from degraded humic matter which absorbed decomposition products from algae, fungi, bacteria, and liptinitic plant parts (materials possibly high in hydrogen). Previous modeling of the distribution of crypto-eugelinite in the discontinuous Wyodak-Anderson coal zone indicated that tar yields should be greater from coal composing the upper part and interior areas than from coal composing the lower parts and margins of the individual coal bodies. It is possible that hydrocarbon yields from natural coalification processes would be similar to yields obtained from laboratory pyrolysis. If so, the amount of crypto-eugelinite may also be an important characteristic when evaluating coal as source rock for migrated hydrocarbons.

Wyoming↗
USGS2005

Hydrologic properties of coal-beds in the Powder River Basin, Montana: II. Aquifer test analysis

A multiple well aquifer test to determine anisotropic transmissivity was conducted on a coal-bed in the Powder River Basin, southeastern Montana, as part of a multidisciplinary investigation to determine hydrologic conditions of coal-beds in the area. For the test, three wells were drilled equidistant from and at different angles to a production well tapping the Flowers–Goodale coal seam, a 7.6-m thick seam confined at a depth of about 110 m. The test was conducted by air-lift pumping for 9 h, and water levels were monitored in the three observation wells using pressure transducers. Drawdown data collected early in the test were affected by interporosity flow between the coal fracture network and the matrix, but later data were suitable to determine aquifer anisotropy, as the slopes of the late-time semilog time-drawdown curves are nearly identical, and the zero-drawdown intercepts are different. The maximum transmissivity, trending N87°E, is 14.9 m 2 /d, and the minimum transmissivity 6.8 m 2 /d, giving an anisotropy ratio of 2.2:1. Combined specific storage of the fractures and matrix is 2×10 −5 /m, and of the fracture network alone 5×10 −6 /m. The principal direction of the anisotropy tensor is not aligned with the face cleats, but instead is aligned with another fracture set and with dominant east–west tectonic compression. Results of the test indicate that the Flowers–Goodale coal-bed is more permeable than many coals in the Powder River Basin, but the anisotropy ratio and specific storage are similar to those found for other coal-beds in the basin.

Montana↗
USGS2005

Hydrologic properties of coal beds in the Powder River Basin, Montana I. Geophysical log analysis

As part of a multidisciplinary investigation designed to assess the implications of coal-bed methane development on water resources for the Powder River Basin of southeastern Montana, six wells were drilled through Paleocene-age coal bedsalong a 31-km east–west transect within the Tongue River drainage basin. Analysis of geophysical logs obtained in these wells provides insight into the hydrostratigraphic characteristics of the coal and interbedded siliciclastic rocks and their possible interaction with the local stress field. Natural gamma and electrical resistivity logs were effective in distinguishing individual coal beds. Full-waveform sonic logs were used to determine elastic properties of the coal and an attendant estimate of aquifer storage is in reasonable agreement with that computed from a pumping test. Inspection of magnetically oriented images of the borehole walls generated from both acoustic and optical televiewers and comparison with coal cores infer a face cleat orientation of approximately N33°E, in close agreement with regional lineament patterns and the northeast trend of the nearby Tongue River. The local tectonic stress field in this physiographic province as inferred from a nearby 1984 earthquake denotes an oblique strike-slip faulting regime with dominant east–west compression and north–south extension. These stress directions are coincident with those of the primary fracture sets identified from the televiewer logs and also with the principle axes of the drawdown ellipse produced from a complementary aquifer test, but oblique to apparent cleat orientation. Consequently, examination of these geophysical logs within the context of local hydrologic characteristics indicates that transverse transmissivity anisotropy in these coals is predominantly controlled by bedding configuration and perhaps a mechanical response to the contemporary stress field rather than solely by cleat structure.

Montana↗
USGS1997

Coal availability in the Hilight Quadrangle, Powder River Basin, Wyoming; a prototype study in a western coal field

The U.S. Geological Survey (USGS), in cooperation with the Bureau of Land Management (BLM), Geological Survey of Wyoming, and U.S. Bureau of Mines (USBM), has produced an estimate of the amount of available coal in an area about 35 miles south of Gillette, Wyo., where the Wyodak coal bed is, in places, more than 100 ft thick. Available coal is the quantity of the total coal resource that is accessible for mine development under current regulatory, land-use, and technologic constraints. This first western coal availability study, of the Hilight 7 1/2-minute quadrangle, indicates that approximately 60 percent (2.7 billion short tons) of the total 4.4 billion tons of coal in-place in the quadrangle is available for development. (There has been no commercial mining in the Hilight quadrangle.) Approximately 67 percent (1.9 billion tons) of the Main Wyodak coal bed is considered available. All tonnage measurements in this report are given in short tons. Coal-development considerations in the quadrangle include dwellings, railroads, pipelines, power lines, wildlife habitat (eagles), alluvial valley floors, cemeteries, and the Hilight oil and gas field and gas plant. Some of these considerations could be mitigated so that surface mining of the coal may proceed; others could not be mitigated and would preclude mining in their vicinity. Other technological constraints that influence the availability of the coal include overburden thickness, coal beds too thin, and areas of clinker.

Montana, Wyoming↗
USGS1989

Comparative facies formation in selected coal beds of the Powder River Basin

Petrologic studies of thick coal beds [Warwick, 1985; Moore, 1986; Moore and others, 1986; Moore and others, 1987; Warwick and Stanton, in press], which build on sedimentological interpretations [Flores, this volume] of associated units, provide data to interpret and contrast the varieties of peat formation in the Powder River Basin. Detailed analyses of the composition of coal beds lead to more complete interpretations regarding the depositional environment on a regional and local scale. Our efforts in the Powder River Basin [areas A-D in fig. 1 of Flores, this volume] have resulted in a series of site-specific studies that interpret the types of peat formation from the arrangement of different facies which comprise the coal beds and from the spatial form of the coal beds. Our approach was to use a combination of megascopic criteria for facies sampling, and where only core was available, to analyze many interval samples to discriminate facies by their maceral composition. Coal beds in the Powder River Basin are composed of laterally continuous, compositional subunits of the bed (facies) that can be discerned most easily in weathered highwall exposures, less readily in fresh highwalls, and very poorly in fresh-cut core surfaces. In general, very low ash (

Montana, Wyoming↗
USGS1988

Petrographic characteristics of the Wyodak-Anderson coal bed (Paleocene), Powder River Basin, Wyoming, U.S.A.

Six lithofacies of the thick ( > 30 m) Wyodak-Anderson subbituminous coal bed of the Fort Union Formation (Paleocene), Powder River Basin, Wyoming, can be delimited using megascopic and petrographic data. Previous lithofacies analysis of the rock types associated with the Wyodak-Anderson bed suggested that raised peat accumulated in restricted parts of an inland flood plain. The peat bodies were separated by deposits of contemporaneous, possibly anastomosed channels. In this study, megascopic descriptions from four mine highwalls of the Wyodak-Anderson coal bed were found to be similar to facies defined by microscopic data from core and highwall samples. The data indicate that the upper and lower parts of the coal bed are rich in preserved wood remains (for instance, humotelinite), whereas the middle part of the bed contains comparatively larger amounts of material that resulted from degradation and comminution of the peat (e.g. eugelinite). The facies are interpreted to be the result of different chemical and biological environments at the time of peat formation.

Wyoming↗
USGS1986

Estimated resources of non-leased federal coal, Powder River Basin, Montana and Wyoming

Maps are generated by combining digital ownership data with geologic resource estimates and other spatial coal data in a geographic information system (GIS). For example, we merged the newly compiled Federal coal ownership files with resource calculations from the 1970's for the Powder River Basin (Trent, 1986). For the first time, we are able to visually display the location of Federally owned coal in each 7.5' quadrangle along with the published coal resource estimates for those areas (fig. 8).

Montana, Wyoming↗
USGS1981

Kriging analysis of mean annual precipitation, Powder River Basin, Montana and Wyoming

Kriging is a statistical estimation technique for regionalized variables which exhibit an autocorrelation structure. Such structure can be described by a semi-variogram of the observed data. The kriging estimate at any point is a weighted average of the data, where the weights are determined using the semi-variogram and an assumed drift, or lack of drift, in the data. Block, or areal, estimates can also be calculated. The kriging algorithm, based on unbiased and minimum-variance estimates, involves a linear system of equations to calculate the weights. Kriging variances can then be used to give confidence intervals of the resulting estimates. Mean annual precipitation in the Powder River basin, Montana and Wyoming, is an important variable when considering restoration of coal-strip-mining lands of the region. Two kriging analyses involving data at 60 stations were made--one assuming no drift in precipitation, and one a partial quadratic drift simulating orographic effects. Contour maps of estimates of mean annual precipitation were similar for both analyses, as were the corresponding contours of kriging variances. Block estimates of mean annual precipitation were made for two subbasins. Runoff estimates were 1-2 percent of the kriged block estimates. (USGS)

Montana, Wyoming↗
USGS1980

Organic composition of some Upper Cretaceous shale, Powder River Basin, Wyoming

The lower Upper Cretaceous strata in northeastern Wyoming, which have yielded major quantities of oil and gas, were sampled at boreholes in Converse, Johnson, and Weston Counties. Cores of noncalcareous shale of largely nearshore-marine origin were obtained from the Frontier Formation and the overlying Cody Shale at depths of 3,780.6 to 3,879.9 m in Converse County, near the axis of the Powder River basin, and at depths of less than 320 m in Johnson County, on the western flank of the basin. Cores of calcareous and noncalcareous shale representing offshore-marine and nearshore-marine environments were acquired from the Belle Fourche Shale, Greenhorn Formation, and Carlile Shale at depths of less than 270 m in Weston County, on the eastern flank of the Powder River basin. Analyses of the shale for organic carbon content, total pyrolytic hydrocarbon yield, volatile hydrocarbon content, temperature of maximum pyrolytic yield, and vitrinite reflectance indicate that the amount and character of the organic matter in the sampled rocks is related to the content of calcium carbonate, the depositional environment, and the burial depth of the strata. On the east flank of the Powder River basin, calcareous shale of offshore-marine origin contains abundant hydrogen-rich organic matter derived mainly from aquatic plants. Noncalcareous shale of largely nearshore-marine origin, on the west flank of the basin, locally contains significant hydrogen-poor organic matter derived mostly from land plants. The noncalcareous, nearshore-marine shale in the middle of the basin probably contained similar amounts of hydrogendeficient organic matter prior to deep burial and thermal alteration. The calcareous shale in Weston County is a potentially rich source of oil and gas, but it is thermally immature and is in a very early stage of the hydrocarbon-generation process. The noncalcareous shale in Johnson County is a potential source rock for gas, but also is in an early stage of thermal alteration. In Converse County, the sampled beds are thermally mature and have generated hydrocarbons. The extent of this contribution of hydrocarbons to the commercial petroleum occurrences of the area can be inferred from the composition of the original organic matter in the beds. Furthermore, the degree of thermal alteration of the organic matter at these localities indicates that the depth of the sampled strata was never as great on the flanks of the Powder River basin as in the basin center.

Wyoming↗