Geology topics

William C. Grady

Publications and source records attributed to William C. Grady.

6 recordsLinked to original sources

USGS2014

Thermal maturity patterns in Pennsylvanian coal-bearing rocks in Alabama, Tennessee, Kentucky, Virginia, West Virginia, Ohio, Maryland, and Pennsylvania

Thermal maturation patterns of Pennsylvanian strata in the Appalachian basin and part of the Black Warrior basin were determined by compiling previously published and unpublished percent-vitrinite-reflectance (%R 0 ) measurements and preparing isograd maps on the basis of the measurements. The isograd values range from 0.6 %R 0 in Ohio and the western side of the Eastern Kentucky coal field to 5.5 %R 0 in the Southern field in the Pennsylvania Anthracite region, Schuylkill County, Pa. The vitrinite-reflectance values correspond to the American Society of Testing Materials (ASTM) coal-rank classes of high-volatile C bituminous to meta-anthracite, respectively. In general, the isograds show that thermal maturity patterns of Pennsylvanian coals within the Appalachian basin generally decrease from east to west. In the Black Warrior basin of Alabama, the isograds show a circular pattern with the highest values (greater than 1.6 %R 0 ) centered in Jefferson County, Ala. Most of the observed patterns can be explained by variations in the depth of burial, variations in geothermal gradient, or a combination of both; however, there are at least four areas of higher ranking coal in the Appalachian basin that are difficult to explain by these two processes alone: (1) a set of west- to northwest-trending salients centered in Somerset, Cambria, and Fayette Counties, Pa.; (2) an elliptically shaped, northeast-trending area centered in southern West Virginia and western Virginia; (3) the Pennsylvania Anthracite region in eastern Pennsylvania; and (4) the eastern part of the Black Warrior coal field in Alabama. The areas of high-ranking coal in southwestern Pennsylvania, the Black Warrior coal field, and the Pennsylvania Anthracite region are interpreted here to represent areas of higher paleo-heat flow related to syntectonic movement of hot fluids towards the foreland associated with Alleghanian deformation. In addition to the higher heat flow from these fluids, the Pennsylvania Anthracite region also was buried more deeply than other parts of the Appalachian basin. The area of high rank coal in southwestern Virginia probably was controlled primarily by overburden thickness, but may also have been influenced by higher geothermal gradients.

Appalacian basin↗

USGS2014

Results of coalbed-methane drilling, Mylan Park, Monongalia County, West Virginia

The Department of Energy National Energy Technology Laboratory funded drilling of a borehole (39.64378°N., 80.04376°W.) to evaluate the potential for coalbed-methane and carbon-dioxide sequestration at Mylan Park, a public park in Monongalia County, W. Va. The total depth of the borehole was 2,525 feet (ft) and contained 1,483.41 ft of Pennsylvanian coal-bearing strata, 739.67 ft of Mississippian strata, and 301.93 ft of Devonian strata. The drill site was located directly over abandoned mines in the Pittsburgh and Sewickley coal beds. Coal cores from remaining Pittsburgh and Sewickley coal-bed-mine pillars were cut and retrieved for desorption from both mines. In addition, coals were cored and desorbed from the Redstone, Pittsburgh roof coal interval, Little Pittsburgh, Elk Lick, Brush Creek, Upper Kittanning, Middle Kittanning, Clarion, Upper Mercer, Lower Mercer, and Quakertown coal beds and coal zones. All coals are Pennsylvanian in age and are high-volatile A bituminous in rank. A total of 34.75 ft of coal was desorbed over a maximum period of 662 days, although most of the coal was desorbed for about 275 days. Measured raw-total-gas contents ranged from 0.43 standard cubic feet per ton (SCF/ton, an industry abbreviation) for the mined Sewickley coal bed to 130.98 SCF/ton for the Upper Kittanning coal bed. Volumes of residual gas were not measured; therefore, the gas volumes reported here should be regarded as minimum volumes. The amount of oxygen in the gas samples collected from the desorption canisters ranged from 2.55 to 20.13 percent. Methane contents ranged from 0 percent for one single canister from the Pittsburgh (WV–02–B3–4) and Little Pittsburgh (WV–02–CB3–2) coal beds to almost 81 percent for two canisters from the Clarion coal zone (WV–02–B3–16 and WV–02–B3–17), which suggests that all of the gas samples were contaminated to some degree by air. Therefore, all gas compositions reported have been normalized to remove the air. With a single exception (the Quakertown coal zone), the coals from the Mylan Park study area are thermogenic in origin with the isotopic composition of carbon (carbon 13, 13 C) in methane (expressed as δ 13 C in units of parts per thousand (per mil) relative to the Vienna Peedee belemnite (VPDB) standard) ranging from -32.39 to -50.66 per mil and ratios of methane to hydrocarbons of higher molecular weight ranging from 10 to 53. The Quakertown coal zone has a C 1 /C 2+ ratio of 913, suggesting that it contains some microbial gas. High-pressure carbon-dioxide adsorption isotherms were measured on composite coal samples of the Upper Kittanning coal bed and the Middle Kittanning and Clarion coal zones. Assuming that the reservoir pressure in the Mylan Park coals is equivalent to the normal hydrostatic pressure, the estimated maximum carbon-dioxide adsorption pressures range from a low of about 300 pounds per square inch (lb/in 2 ) in coals from the Clarion coal zone to 500 lb/in 2 for coals from the Upper Kittanning coal bed. The estimated maximum methane adsorption isotherms show that the coals from the Upper Kittanning coal bed and the Middle Kittanning coal zone are undersaturated in methane, but coals from the Clarion coal zone are close to saturation.

West Virginia↗

USGS2014

Results of coalbed-methane drilling, Meadowfill Landfill, Harrison County, West Virginia

The U.S. Environmental Protection Agency funded drilling of a borehole (39.33889°N., 80.26542°W.) to evaluate the potential of enhanced coalbed-methane production from unminable Pennsylvanian coal beds at the Meadowfill Landfill near Bridgeport, Harrison County, W. Va. The drilling commenced on June 17, 2004, and was completed on July 1, 2004. The total depth of the borehole was 1,081 feet (ft) and contained 1,053.95 ft of Pennsylvanian coal-bearing strata, and 27.05 ft of Mississippian strata. A total of 37.02 ft of high-volatile A and B bituminous Pennsylvanian coal was cored and desorbed from the Harlem, Brush Creek, Upper Freeport, Upper Kittanning upper split, and Upper Kittanning coal beds and the Clarion coal zone. Intact coal intervals were desorbed for a maximum period of 92 days before they were crushed to approximately 10-mesh to determine residual gas amounts. Crushed coal was desorbed for a period of 36 days. Measured gas content, on a dry, ash-free basis, ranged from 79.69 standard cubic feet per ton (SCF/ton), or 2.49 cubic centimeters per gram (cc/g), for the Harlem coal bed to 223.21 SCF/ton, or 6.98 cc/g, for the Clarion coal zone. Methane contents of desorbed gas from coal samples in the Meadowfill Landfill study area ranged from 14.87 to 98.73 percent (corrected for air contamination) for the Harlem coal bed and Clarion coal zone, respectively. Proportions of methane to the sum of the higher molecular weight hydrocarbons ranged from about 40 to 340 as the desorbed gas contained only a small percentage of higher weight hydrocarbons. Coalbed methane from the Upper Kittanning upper split and the Upper Kittanning coal beds is thermogenic in origin with isotopic composition of carbon (carbon 13, 13 C) in methane (expressed as δ 13 C in units of parts per thousand (per mil) relative to the Vienna Peedee belemnite (VPDB) standard) ranging from -46.6 to -48.7 per mil. Coalbed methane from the Brush Creek and Upper Freeport coal beds and the Clarion coal zone contains some biogenic methane with δ 13 C values ranging from -51.05 to -51.56 per mil.

West Virginia↗

USGS2010

Geologic controls on thermal maturity patterns in Pennsylvanian coal-bearing rocks in the Appalachian basin

Thermal maturation patterns of Pennsylvanian strata in the Appalachian basin were determined by compiling and contouring published and unpublished vitrinite reflectance (VR) measurements. VR isograd values range from 0.6% in eastern Ohio and eastern Kentucky (western side of the East Kentucky coal field) to greater than 5.5% in eastern Pennsylvania (Southern Anthracite field, Schuylkill County), corresponding to ASTM coal rank classes of high volatile C bituminous to meta-anthracite. VR isograds show that thermal maturity of Pennsylvanian coals generally increases from west to east across the basin. The isograds patterns, which are indicative of maximum temperatures during burial, can be explained by variations in paleodepth of burial, paleogeothermal gradient, or a combination of both. However, there are at least four areas of unusually high-rank coal in the Appalachian basin that depart from the regional trends and are difficult to explain by depth of burial alone: 1) a west-northwestward salient centered in southwestern Pennsylvania; 2) an elliptically-shaped, northeast-trending area centered in southern West Virginia and western Virginia; 3) the eastern part of Black Warrior coal field, Alabama; and 4) the Pennsylvania Anthracite region, in eastern Pennsylvania. High-rank excursions in southwest Pennsylvania, the Black Warrior coal field, and the Pennsylvania Anthracite region are interpreted here to represent areas of higher paleo-heat flow related to syntectonic movement of hot fluids towards the foreland, associated with Alleghanian deformation. In addition to higher heat flow from fluids, the Pennsylvania Anthracite region also experienced greater depth of burial. The high-rank excursion in southwest Virginia was probably primarily controlled by overburden thickness, but may also have been influenced by higher geothermal gradients.

Appalachian basin↗

USGS2004

Results of coal bed methane drilling, Mylan Park, Monongalia County, West Virginia

The Department of Energy National Energy Technology Laboratory funded drilling of a borehole (39.64378 deg E , -80.04376 deg N) to evaluate the potential for coal bed methane and carbon dioxide sequestration at Mylan Park, Monongalia County, West Virginia. The drilling commenced on September 23, 2002 and was completed on November 14, 2002. The 2,525 ft deep hole contained 1,483.41 ft of Pennsylvanian coal-bearing strata, 739.67 feet of Mississippian strata, and 301.93 ft. of Devonian strata. The drill site was located directly over abandoned Pittsburgh and Sewickley coal mines. Coal cores from remaining mine pillars were cut and retrieved for desorption from both mines. In addition, coals were cored and desorbed from the Pittsburgh Roof, Little Pittsburgh, Elk Lick, Brush Creek, Upper Kittanning, Middle Kittanning, Clarion, Upper Mercer, Lower Mercer, and Quakertown coal beds. All coals are Pennsylvanian in age and are high-volatile-A bituminous in rank. A total of 34.75 ft of coal was desorbed over a maximum period of 662 days, although most of the coal was desorbed for about 275 days. This report is provided in Adobe Acrobat format. Appendix 3 is provided in Excel format.

Open-File Report↗

USGS1993

Brown coal maceral distributions in a modern domed tropical Indonesian peat and a comparison with maceral distributions in Middle Pennsylvanian–age Appalachian bituminous coal beds

Analyses of modern Indonesian peat samples reveal that the optical characteristics of peat constituents are consistent with the characteristics of macerals observed in brown coal and, as found by previous workers, brown-coal maceral terminology can be used in the analysis of modern peat. A core from the margin and one from near the center of a domed peat deposit in Riau Province, Sumatra, reveal that the volume of huminite macerals representing well-preserved cell structures (red, red-gray, and gray textinite; ulminite; and corpo/textinite) decreases upward. Huminite macerals representing severely degraded (<20 microns) cellular debris (degraded textinite, attrinite, and densinite) increase uniformly from the base to the surface. Greater degradation of the huminite macerals in the upper peat layers in the interior of the deposit is interpreted to be the result of fungal activity that increased in response to increasingly aerobic conditions associated with the doming of the peat deposit. Aerobic conditions concurrent with the activities of fungi may result in incipient oxidation of the severely degraded huminite macerals. This oxidation could lead to the formation of degradosemifusinite, micrinite, and macrinite maceral precursors in the peat, which may become evident only upon coalification. The core at the margin was petrographically more homogeneous than the core from the center and was dominated by well-preserved huminite macerals except in the upper 1 m, which showed signs of aerobic degradation and was similar to the upper 1 m of the peat in the interior of the deposit. The Stockton and other Middle Pennsylvanian Appalachian coal beds show analogous vertical trends in vitrinite maceral composition. The succession from telocollinite-rich, bright coal lithotypes in the lower benches upward to thin-banded/matrix collinite and desmocollinite in higher splint coal benches is believed to reflect a progression similar to that from the well-preserved textinite macerals in the lower portions of the peat cores to severely fragmented and degraded cellular materials (degraded textinite, attrinite, and densinite) in the upper portions of the cores. This petrographic sequence from bright to splint coal in the Stockton and other Middle Pennsylvanian coal beds supports previous interpretations of an upward transition from planar to domed swamp accumulations.

Special Paper of the Geological Society of America↗