AXON, ALLAN G., and D.L. CROWELL, Ohio Department of Natural Resources, Division of Geological Survey, Columbus, OH

Implementation of geographic-information-system technology for use in coal geology investigations at the Ohio Department of Natural Resources, Division of Geological Survey

Geographic information system technology is being used by the Ohio Division of Geological Survey to link project-specific databases to avoid unnecessary duplication of effort and equipment. Descriptive geologic data from measured sections, drill holes, and geochemical analyses are being computerized in cooperation with the U. S. Geological Survey National Coal Resources Data System. Line and area data, including coal croplines, surface mines, and underground mines, are being digitized into computer-aided mapping systems and transferred to the geographic information system. Computer-generated maps of coal thickness, elevation, and quality also are being integrated into the geographic information system.

The Ohio Division of Geological Survey maintains a series of 1:24,000-scale mylar maps showing the outlines of abandoned underground mines. During 1995, these maps were digitized by Ohio Department of Natural Resources, Division of Real Estate and Land Management into a geographic information system. The construction of a database containing geologic and mine information which will be linked to these digitized outlines is a priority of the Ohio Survey.

The Ohio Division of Geological Survey's Coal Availability cooperative program with the U.S. Geological Survey illustrates the utility of geographic information systems for performing complex analyses of the natural resources in specific areas. Regional databases (nine-quadrangle areas) were created to estimate the coal resources for eight 7.5-minute quadrangles. These databases will be the basis for additional regional coal resource estimations. Stratigraphic data computerized for Coal Availability investigations are also being used for the statewide bedrock geologic mapping program (STATEMAP).

BARANOSKI, MARK T., RONALD A. RILEY, AND LAWRENCE H. WICKSTROM, Ohio Department of Natural Resources, Division of Geological Survey, Columbus, OH

New Ohio Oil and Gas Pools and Fields Map Series

Ohio has not had an updated oil and gas fields map since 1974. Since then, significant development of fields has taken place and numerous new fields and pools have been discovered and developed. The Ohio Divisions of Geological Survey and Oil and Gas recently completed work for the U.S. Department of Energy to document all major gas plays and 80% of the original oil in place for Ohio. This work, which utilized county and township well-spot maps, forms the foundation for a new series of maps illustrating the productive oil and gas areas of the state.

A generalized map has been compiled at 1:500,000 scale showing all oil, gas, and storage fields from all geologic units. Extensive development from formations such as the "Clinton" sand and Berea Sandstone has virtually covered the eastern half of Ohio with oil and gas fields. In order to more easily discern productive areas of each producing formation, we are creating a series of fields maps, each showing production from selected stratigraphic intervals. This series is being compiled using computer cartographic techniques, thereby allowing easy customization of scale and content. Use of this methodology should also aid future updating of these maps. The maps will be available at scales of 1:2,100,000 (page size), 1:500,000, and 1:250,000. The map series should prove useful as a reconnaissance tool for oil and gas exploration, enhanced recovery, environmental assessments, and planning issues.

BARNHILL, MARK A., Eastern American Energy Corporation, Charleston, WV

The Corbin Sandstone of Eastern Kentucky: Outcrop and Subsurface Analysis of a Pennsylvanian Age Big Braided River

A combined outcrop and subsurface study of the Pennsylvanian age Corbin Sandstone Member (Lee Formation) of eastern Kentucky was undertaken. The Lee Formation has been variously interpreted as barrier island, fluvial or tidal in origin.

The objectives of this study were threefold: 1) to determine the origin of the Corbin Sandstone, 2) to ascertain the influence of intrabasinal tectonics on the unit, and, 3) to develop a comprehensive depositional model.

The Corbin Sandstone consists, predominantly, of medium grained sandstone composed of planar tabular and trough crossbedding. Planar crossbeds are interpreted as transverse bars deposited in a low-sinuosity or braided river. Trough crossbedding is primarily associated with braid channel deposition. A fourfold hierarchy of braid channels was observed: 1) a first order channel consisting of an alluvial braidplain up to 60 kilometers wide, 2) second order channels the margins of which are observable at outcrop scale, 3) third order channels which scoured the flanks of transverse bars, and 4) fourth order channels which scoured transverse bar tops. A marine tidal sandstone caps the vertical succession in some outcrops.

Isopach mapping demonstrates that intrabasinal tectonic elements influenced basin evolution by controlling sediment thickness patterns, paleodispersal trends and paleocurrent directions within the Corbin Sandstone.

Outcrop and subsurface data suggest that the Corbin Sandstone represents a multilateral, multistory fluvial sheet sandstone deposited across a broad alluvial braidplain. Rising sea level halted sandstone deposition and resulted in tide-dominated estuarine and marine shale deposition which cap the Corbin Sandstone.

BOORSE, SCOTT C., LORAL Environmental Systems, Paoli, PA

Rapid In-Situ Subsurface Characterization of a Petroleum- Contaminated Site Using Laser Induced Fluorescence and Cone Penetrometer Testing

In-situ sampling techniques used to characterize the stratigraphy and extent of subsurface contamination are becoming increasingly common in environmental site investigations. Laser Induced Fluorescence (LIF) combined with Cone Penetrometer Testing (CPT) is a new in-situ technology that provides real-time data on the extent of Aromatic Petroleum Hydrocarbons and stratigraphy in the subsurface. Integrated LIF/CPT data can rapidly provide contaminant and geologic information necessary to define plume boundaries and design efficient and effective remediation plans.

The Rapid Optical Screening Tool (ROST^tm, a trademark of the Loral Corporation) combines state-of-the-art LIF technology in conjunction with CPT equipment. The combined ROST^tm/CPT system provides a two centimeter resolution which quickly and accurately delineates the vertical and horizontal extent of petroleum contamination. The system distinguishes between specific fuel types by obtaining wavelength-time matrices, which are three-dimensional representations of the fluorescence data. By performing the test in-situ, the combined system eliminates cuttings disposal and the cost and time of extensive laboratory analysis associated with other subsurface screening techniques.

The ROST^tm/CPT system was used at a former refinery to investigate the extent of petroleum hydrocarbons in the subsurface. The ROST^tm/CPT tool was hydraulically advanced to an average depth of 30 feet below grade at 150 grid locations in two separate areas. The results provided a clear real-time characterization of the vertical and horizontal extent of three separate plumes and the potential contamination migration pathways. Due to the rapid, continuous subsurface characterization, on-site decision making enabled a 50% reduction in the planned scope of work and significantly reduced the investigation costs to the client.

CATANZANO, MARK A., Columbia Gas Transmission Corporation, Charleston, WV

An Introduction to Gridding and Contouring Geologic Surfaces with a Computer

Many geoscientists are now using inexpensive mapping programs and fast personal computers to create contour maps. Those geoscientists new to computer-assisted mapping often accept the program defaults and allow the program to control the mapping process. This paper provides inexperienced users with a basic understanding of what the mapping program is doing and how to include their geologic knowledge and expertise into the resulting map.

One of the most important aspects of computer-assisted mapping is an understanding and knowledge of gridding. Gridding is the conversion of irregularly-distributed data points into an ordered array(grid) of calculated values. The grid is what the mapping program uses to produce a contour map. It is when the geoscientist is defining the grid, choosing the appropriate gridding algorithm, and selecting the gridding parameters that personal geologic expertise can be directly input into the mapping process. There are five main types of gridding algorithms: independent node, node spreading convergence, polygonal, curve fitting, and triangulation. Kriging can be viewed as a geostatistical version of the independent node type algorithm. Some general properties of grids and gridding parameters will be illustrated with examples. In addition, opportunities for the geoscientist to provide geologic direction to the gridding algorithm and the data populations where the algorithm works most effectively will be considered for selected gridding algorithms.

CAVALLO, LARRY J., Dominion Appalachian Development, Inc., Jane Lew, WV; and RICHARD A. SMOSNA*, West Virginia University Department of Geology and Geography, Morgantown, WV

Predicting Porosity Distribution within Oolitic Tidal Bars

The Mississippian Greenbrier Limestone is a major gas reservoir in the Appalachian basin, but its complex porosity patterns often deter active exploration. In southern West Virginia, the reservoir consists of oolitic tidal bars which are composites of smaller shoals. Porosity trends closely follow the ooid-grainstone facies which occupied shoal crests, where coarse-grained, well-sorted ooid sand was generated with either unidirectional or bidirectional cross-beds. Nonporous packstone occurred in adjacent tidal channels, and a transitional grainstone/packstone facies of marginal porosity was situated along the flanks of the shoals. The key to drilling successful wells is in understanding the complex internal geometry of Greenbrier ooid shoals. A well penetrating the oolite with good porosity and bimodal cross-beds should be offset perpendicular to the dip directions,that is, parallel to the shoal axis. However, a well penetrating thin, porous limestone with one dominant cross-bed azimuth should be offset opposite to that dip direction, that is, up the flank of the ooid shoal. Shaly interbeds characterize the edges of the shoals and mark the limit of productive wells. Schlumberger's Formation MicroScanner (FMS) log, which provides data on both lithology and cross-bedding, has proven to be a useful tool in predicting the distribution of oolite porosity.

COOGAN, ALAN H., Kent State University, Department of Geology, Kent, OH

Subsurface Siluro-Devonian Carbonate Interval (Bass Islands-Columbus/Onondaga and Oriskany in Ohio

Siluro-Devonian dolomite and limestone strata in the subsurface of Ohio consist of zero to 650 feet of late Bass Islands dolomite, Devonian Helderberg (Keyser) limestones, Oriskany sandstone (of Ohio), and the Columbus and Delaware (Onondaga) limestones. The sequence is ripped up by unconformities causing the Silurian Salina and Bass Islands dolomites to toplap below the Columbus Limestone on the "Bass Islands platform". The gas-producing Oriskany sandstone is limited to the "Helderberg basin" northeast of the Cambridge Arch. In that basin, Oriskany strata are absent over the Silurian Niagaran reef. In contrast, the Columbus Limestone thickens over the Niagaran reef. In the northeastern portion of the "Helderberg basin", Oriskany and Helderberg strata are preserved like the Salina B salt; i.e. they occur north of a line marked by the Smith-Suffield-Akron fault zone. Southwest of the Cambridge Arch, the Silurian Bass Islands Dolomite is beveled by erosion, then onlapped by the Columbus Limestone. At the wedge edge just north of the Rome Trough in Kentucky, all Salina strata are removed by subaerial erosion and then onlapped by the Devonian shale. From the wedge edge, the Devonian limestone depocenter is northeast, a departure from the southeast direction of the depocenter of earlier Silurian deposition.

COOK, THOMAS P., JOHN J. RENTON, RONALD R. MCDOWELL, and MICHAEL ED. HOHN, West Virginia Geological and Economic Survey, Morgantown, WV

An Evaluation of the Minimum Required Sampling Density of Middle Pennsylvanian Interburdens at a Typical Southern West Virginia Surface Mine; A Preliminary Study

The goal of this project is to establish the minimum sampling density required to accurately characterize a volume of Middle Pennsylvanian interburden. This project is significant to the coal industry of West Virginia in that it will allow mining operators to more precisely predict acid mine drainage (AMD) potential of interburdens and overburdens.

The field area for this project is located at an active surface mine in southern West Virginia. Samples were collected from air rotary drill cuttings during the drilling of shot holes. Representative samples were taken of continuous 1.2 m (4 ft.) intervals down each drill hole. Three analyses were performed on all samples: Total percent sulfur by total combustion, X-ray diffractometry, and elemental analysis by X-ray fluorescence. The known elements and minerals that have the greatest effect on AMD were used in the interpretations. Those elements and minerals are total percents of: sulfur, calcite, pyrite, siderite, calcium oxide, and ferric oxide.

Through the use of a FORTRAN program called PIKSAMP4, holes were randomly excluded from the data sets. This was systematically done in one-hole intervals starting with the complete data set and continuing until only one hole remained. The process of excluding individual holes was repeated a minimum of one hundred times for each data set. The mean, standard deviation and coefficient of variation were calculated for each chemical parameter as sample density varied. These graphs were then interpreted to determine how many data points (holes) were required to accurately predict the AMD potential of the sample site.

DEAN, STUART L., University of Toledo, Department of Geology, Toledo, OH; PETER LESSING, West Virginia Geological and Economic Survey, Morgantown, WV; and BYRON R. KULANDER, Wright State University, Department of Geological Sciences, Dayton, OH

The Cacapon River Fault, Morgan County, West Virginia

Cacapon Mountain anticlinorium is one of the major positive structures west of the Great Valley in West Virginia and extends from Fulton County, Pennsylvania to Rockingham County, Virginia. The anticlinorium is asymmetrical to the west, with numerous folds and faults in Silurian and Devonian strata superimposed on it. Typical of these structures are Piney Ridge anticline, South Fork anticline, and Cacapon River fault. Cacapon Mountain anticlinorium developed as major folding proceeded westward of the Great Valley, first with development of Ferrel Ridge anticlinorium, then Sleepy Creek anticlinorium, and finally the Cacapon Mountain structure.

Early faulting above the Martinsburg detachment horizon generated complex folds and faults in the overlying Silurian, Devonian, and Mississippian section, with development of the Cacapon River splay fault from the Martinsburg detachment. Development of Cacapon Mountain anticlinorium as a fault bend anticline occurred through longitudinal ramping from a décollement horizon in Lower Cambrian Waynesboro Formation shales to the upper detachment level seated in shales of the Upper Ordovician Martinsburg Formation. Emplacement of the Cacapon Mountain structure folded the previously formed Cacapon River fault, with subsequent erosion exposing this feature in a narrow window on the northwest flank of the mountain in the Ridge quadrangle. Cacapon River fault re-emerges west of the window and its trace trends southwest to northeast close to the outcrop of Devonian Oriskany Sandstone across Morgan County.

DEVER, GARLAND R., JR., Kentucky Geological Survey, Lexington, KY

Evidence for Mississippian Structural Activity Above a Precambrian Rift System, South-Central Kentucky

Erosional and depositional features in Mississippian limestones of south-central Kentucky suggest the influence of coeval structural activity. The Greenwood Anomaly, a large north-trending gravity anomaly, underlies Paleozoic rocks in the area. It is considered to be part of a Precambrian rift system. The Grenville Front, identified as the western margin of a Proterozoic Grenville allochthon, extends along the west side of the Greenwood Anomaly.

Several lines of evidence, mainly involving the St. Louis Limestone and Ste. Genevieve Limestone Member of the Monteagle Limestone, suggest Mississippian reactivation of faults associated with the Greenwood Anomaly and the Grenville Front. Subaerial exposure of St. Louis sediments and depositional thinning of lower Ste. Genevieve sediments apparently resulted from local uplifts produced by reactivation of rift-related faults. Broader uplift later interrupted Ste. Genevieve deposition across the Greenwood Anomaly and was followed by development of an extensive erosional surface cut into lower Ste. Genevieve and upper St. Louis deposits. Faulting also is indicated by thickness variations in Mississippian units across the Greenwood Anomaly and Grenville Front, including growth faulting off the western flank of the anomaly and front.

DICKAS, ALBERT B., University of Wisconsin, Department of Geology, Superior, WI

New Structural and Stratigraphic Interpretation of Lake Superior Basin from Hydrocarbon Exploration Geophysics and Geology

Between October 1987 and April 1992, two deep boreholes were drilled along the south shore of Lake Superior in a test of the hydrocarbon potential of the conglomerate, sandstone and shale composing the Middle Proterozoic Oronto Group (~1 billion years). These drilling ventures, preceded by geophysical programs, and combined with wireline and core information, support new interpretations of the structural and stratigraphic geology associated with the Midcontinent Rift System in the Lake Superior district.

#7-22 Terra-Patrick: A stratigraphic, but not structural fit. This borehole in Bayfield County, Wisconsin, drilled an expected sequence of Oronto Group clastic red-beds. No viable hydrocarbon shows were encountered. Six second reflection seismology profiles collected in northwestern Wisconsin indicate the Douglas Fault decreases in throw in an easterly direction, changing to a fold northeast of the borehole. This termination is associated with the south flank of White's Ridge, a pre-rift residual high identified through modeling studies and seismic interpretations by local absence of Midcontinent Rift volcanics and overlying strata. To the southwest of Isle Royale, the pre-rift Grand Marias Ridge exhibits similar characteristics.

#1-29 St. Amour: A structural, but not stratigraphic, fit. Drilled in Alger County, Michigan, the St. Amour well appears to bottom in pre-rift metamorphic basement rocks. This hole was 100% cored. No hydrocarbon shows were reported. Reflection seismology profile analyses verify a change in strike, from northeast to southeast, of the Keweenaw Fault in the eastern Lake Superior Basin. The drilled section included 6,000 feet of pre-Paleozoic red-beds containing cross-bedding, ripple marks, and multiple fining-upward strata.

DOMINIC, J. B., K. A. DONALDSON, T. H. WILSON, and R. C. SHUMAKER, West Virginia University, Department of Geology and Geography, Morgantown, WV

Differences in Structural Characteristics and Historical Development of the Rome Trough

Regional seismic analysis of the Rome trough in West Virginia indicates an overall change in deformation of the trough from north to south. Basic geometry of the southern trough is marked by faulted west and east margins. In contrast, the northern part of the trough has a faulted eastern margin whereas subsidence across the western margin takes place primarily through rotation. The trough interior of southern West Virginia is divided by four smaller faults, each with an average offset of 200 meters, while in the north, the trough is offset by two interior faults that have displacements of 1 km and 0.8 km respectively. In both areas interior faults step down to the west.

Reactivation history diagrams for the two areas are similar during the Cambrian Period (>510 Ma), however during the remainder of the Paleozoic significant differences are observed. In the north, inversion is a common occurrence after 450 Ma, while inversion is not observed in the seismic lines close to the southern border of West Virginia. Cumulative displacement across the west margin fault in the south is less than 1 km compared to cumulative rotation of 2.2 km experienced on the western margin in the northern trough. In the northern part of the trough the East-Margin fault has an average displacement of 1.6 km and experienced 0.1 km of inversion, however in the southern part of the trough the East-Margin fault has a cumulative displacement of 700 meters with no significant inversion. Along with the differences in displacement history, extension in the southern part of the trough is dominated by faulting whereas to the north extension is accommodated by a combination of rotational collapse and fault displacement.

The distinct structural differences between the northern and southern parts of the trough, along with evidence of complex rift geometries of central West Virginia, suggest that the central trough region is a transfer zone. To understand more about this postulated transfer zone, a detailed geologic study will analyze a diversity of surface and subsurface data to characterize the interior fault geometry and reactivation history of this critical region.

DONALDSON, KURT, PADMA MEDURY, and JOE DONOVAN, West Virginia University, Department of Geology and Geography, Morgantown, WV

Relative Age Dating Courseware

Multimedia courseware entitled Geohistory incorporates sound, animated illustrations, and a high degree of interactivity to explain and review basic relative age dating concepts, and then tests the user's knowledge with four comprehensive exercises. The topic relative age dating was chosen because it is an important component of instruction for introductory geologic classes. The relative age dating courseware Geohistory is an excellent educational tool for explaining dynamic geological processes that otherwise would not be possible from reading a textbook. Currently Geohistory has eighty-six illustrated animations, seven colored photographs, four colored schematics, and twelve sound files to help students learn how the rocks of the earth are created, deformed, and eroded. Unlike other geologic courseware packages, Geohistory juxtaposes animated illustrations with photographs so that students can better visualize how specific geological principles evolved. Because Geohistory concentrates on explaining one subject thoroughly, the courseware can be completed by most students during their class period. This software is unique in that students can choose different levels of difficulty for the exercise portion of Geohistory to evaluate effectively their knowledge of relative age dating concepts. With this approach, both beginning and advanced students are challenged during their learning process. Another strong point for using Geohistory is that because it covers basic geologic principles, anyone wanting to learn something about geology for the first time can enjoy using this educational courseware. Just as important, this multimedia software has a variety of applications, from supplemental courseware for earth science labs, or multimedia presentations by teachers during their lectures, to students who need additional instruction outside the classroom.

DRAHOVZAL, JAMES A., Kentucky Geological Survey, University of Kentucky, Lexington, KY

Cambrian and Precambrian Rifting in Central and Western Kentucky: Evidence from Reflection-Seismic Data

Newly available reflection-seismic and age-dating data confirm the existence of two and possibly three major, early rifting events in central and western Kentucky that are separated by angular unconformities: Middle Proterozoic, Late Proterozoic(?), and Cambrian. The Middle Proterozoic rifting event is associated with the East Continent Rift Basin (ECRB). This basin is dominated by terrigenous siliciclastic and volcanic rocks and extends from northwestern Ohio to south-central Kentucky. Some of the newly available seismic-reflection data suggest that these rocks extend at least to Union County in western Kentucky. The precise age of the basin is unknown, but based on age-dating data from several wells, it appears to be between 1.02 and 1.5 Ga. Basin fill in the ECRB just west of the Grenville allochthon is more than 5 km thick, thinning westward onto adjacent zones of older silicic and mafic Granite-Rhyolite Province (GRP) rocks, and thickening again in western Kentucky. The subsequent Grenville compressional event thrusted and folded the ECRB and GRP rocks, resulting in a marked angular unconformity of these rocks with younger units. Cambrian rifting in Kentucky is part of a larger rift system that extends from Pennsylvania to Arkansas. The Rough Creek Graben (RCG) in western Kentucky is a deep, north-tilted, Cambrian half-graben. Within the graben, the Cambrian rift sequence ranges in thickness from nearly 5.5 km near the northern boundary fault to about 1.5 km to the south. The rift fill is dominated by marine carbonate and siliciclastic rocks, with some possible siliciclastic fan complexes in parts. The rift sequence onlaps Precambrian rocks beneath.

FAUSNAUGH, JAMES M., Gallagher Research and Development Company, Lakewood, CO

Survey Design and Data Integration When Using Surface Geochemistry

Surface geochemistry can be a valuable extension to any exploration project when applied properly. Staging the exploration program so that samples are acquired judiciously is the most often prescribed survey practice. This minimizes cost while maximizing sample placement. However, due to the noisy nature of geochemical data, staging sample collection can present some problems. How can separate data sets, both reconnaissance and detailed, be integrated into one cohesive sample population?

Many of the geochemical methods currently in use can yield spurious anomalies. False anomalies can be detected if 1) the sample spacing is sufficiently close to determine the discontinuous nature of the anomaly, 2) a sufficient number of samples are taken to obtain an adequate population to differentiate an anomaly from background, 3) the method used meets or exceeds an expected signal to background ratio.

There are several statistical options available to test the significance of geochemical anomalies. Significance testing is related to frequency distribution and probability. Because geochemical data is usually log-normally distributed, data transformations are required so that inferences regarding a survey can be easily interpreted. Normalization procedures allow the integration of multiple data sets. Parametric statistical methods, such as z-transforms and linear regression, are often used so that the magnitude of the data is retained. Non-parametric methods, such as data ranking, can also be utilized and performs satisfactorily when delineating general trends of anomalies.

FEDORKO, NICK, BASCOMBE M. BLAKE JR., GAYLE H. McCOLLOCH, and KIMBERLY J. TIMBERLAKE, West Virginia Geological and Economic Survey, Morgantown, WV

Creating a Geographic Information System (GIS)-Based Inventory of Coal for West Virginia

The goal of the Coal Bed Mapping Project at the West Virginia Geological and Economic Survey is to produce an accurate Geographic Information System (GIS)-based inventory of the coal beds of West Virginia. GIS computer technology provides new and powerful ways to create, display, and analyze coal information. Geologists are creating maps depicting various aspects of West Virginia coal beds using a system of networked PCs and engineering workstations, coupled with manual map-making methods. The maps created for each coal bed and converted to GIS "layers" or coverages, include: a structural model, the outcrop, the areas mined by surface, auger, and underground methods, coal isopach, and locations of samples taken for chemical analysis.

Mapping is organized around the 7.5-minute quadrangles. Once significant numbers of contiguous quadrangles are mapped, GIS gives the users flexibility to view the information in different combinations of coverages, for any desired geographic window, at any scale. Coverages are designed to take advantage of the analytical capabilities inherent in GIS technology. The coal bed coverages will have significant value to West Virginia and its citizens. Potential uses include a compliance tool for the mineral lands tax program, coal resource estimates, abandoned mine lands risk assessment and amelioration such as mine subsidence, planning and development, and mine permitting.

FINKELMAN,R., U.S. Geological Survey, Reston, VA; G. BREIT, U.S. Geological Survey, Denver, CO; C. EBLE, Kentucky Geological Survey, Lexington, KY; R. AFFOLTER, U.S. Geological Survey, Denver, CO; H. BELKIN, U.S. Geological Survey, Reston, VA; M. BROWNFIELD and J. CATHCART, U.S. Geological Survey, Denver, CO; S. CROWLEY, U.S. Geological Survey, Reston, VA; J. HOWER, Center for Applied Energy Research, Lexington, KY; J. LEVENTHAL, U.S. Geological Survey, Denver, CO; J. MCGEE and C. PALMER, U.S. Geological Survey, Reston, VA; R. REYNOLDS, U.S. Geological Survey, Denver, CO; C. RICE, U.S. Geological Survey, Reston, VA; and R. ZIELINSKI, U.S. Geological Survey, Denver, CO

Systematic investigation of the compositional variations in solid waste products from coal combustion

A systematic study of the chemical and physical characteristics of feed coal, fly ash, bottom ash, feed limestone, and flue gas desulfurization sludge has been initiated at a Kentucky power plant.

Two units at the power plant are sampled monthly for a two-year period. One unit burns a high-sulfur coal (3 wt % total S); the other unit burns a low-sulfur coal (<1 wt % total S). One focus of the study is to evaluate the variability in feed coal compositions and resulting variability in the composition of combustion solids. Major, minor, and trace element composition and mineralogy are determined on most samples. In addition, modes of occurrence, magnetic properties, stable and radiogenic isotopic composition, organic chemistry, and leachability under different conditions are determined on selected samples. Mass balance calculations show that most elements (data for Hg are not available) are retained in the solid waste products except for Se. The ratios of trace elements in the fly ash to bottom ash for both units are very similar to the order of element volatility reported in the literature. Ni, Cr, and Co show substantial enrichment in the magnetic fraction of the fly ash from the low-sulfur unit. Laboratory leaching of the fly ash and bottom ash shows that the magnetic particles are very rapidly dissolved by mild acids. Fission track results indicate that U is uniformly distributed within some fly ash cenospheres. Dark, iron-rich glass may have higher concentrations of U than does clear glass. The distribution of As appears to be uniform at low levels in most fly ash particles.

FOWLER, MICHAEL L., MARK A. YOUNG, E. LANCE COLE, and MICHAEL P. MADDEN, BDM-Oklahoma, Bartlesville, OK

Some Practical Aspects of Reservoir Management

The practical essence of reservoir management is the optimal application of available resources--people, equipment, technology, and money- to maximize profitability and recovery. Success must include knowledge and consideration of 1) the reservoir system, 2) the technologies available, and 3) the reservoir management business environment.

Two Reservoir Management Demonstration projects (one in a small, newly-discovered field and one in a large, mature waterflood) implemented by the Department of Energy through BDM-Oklahoma illustrate the diversity of situations suited for reservoir management efforts. Project teams made up of experienced engineers, geoscientists, and other professionals arrived at an overall reservoir management strategy for each field.

In 1993, Belden & Blake Corporation discovered a regionally significant oil reservoir (East Randolph Field) in the Cambrian Rose Run formation in Portage County, Ohio. Project objectives are to improve field operational economics and optimize oil recovery. The team focused on characterizing the reservoir geology and analyzing primary production and reservoir data to develop simulation models. Historical performance was simulated and predictions were made to assess infill drilling, water flooding, and gas repressurization.

The Citronelle Field, discovered in 1955 in Mobile County, Alabama, has produced 160 million barrels from fluvial sandstones of the Cretaceous Rodessa formation. Project objectives are to address improving recovery through waterflood optimization and problems related to drilling, recompletions, production operations, and regulatory and environmental issues. Initial efforts focused on defining specific problems and on defining a geographic area within the field where solutions might best be pursued. Geologic and reservoir models were used to evaluate past performance and to investigate improved recovery operations.

GREB, STEPHEN F. and CORTLAND F. EBLE, Kentucky Geological Survey, Lexington, KY; and JAMES C. HOWER, Center for Applied Research, Lexington, KY

Coal-Bench Architecture as a Means of Understanding Regional Changes in Coal Thickness and Quality

Analysis of the Fire Creek (Westphalian B), Pond Creek (lower Westphalian B), and Stockton (Westphalian C) coals, three of the most heavily mined coals in the Central Appalachian Basin, shows that all have a similar multiple-bench architecture of at least two benches split by a regional clastic parting or durain. Coal benches beneath regionally extensive partings are generally less continuous, thinner, more palynologically variable, higher in ash yield, and higher in sulfur content than coal benches above regional partings in all three coals. Where thick, benches above regional partings tend to exhibit temporal palynological changes from lycopod- to fern-dominant. Where inertinite-rich/fern-dominant benches are overlain by additional benches, the upper benches are limited in extent, variable in thickness, high in sulfur content and ash yield, and split away from the coal.

The multiple-bench architecture exhibited by these coals is interpreted to represent a cyclic mire succession that was common in the Middle Pennsylvanian. Peats began as planar mires infilling an irregular topography during rising base level. When the topography was infilled, unconfined flooding was possible and resulted in widespread partings. Ponding above these clay-rich flood deposits led to re-establishment of new planar mires with greater continuity than the underlying mires. The extent of these mires provided buffers to clastic influx and, in many cases, allowed domed conditions to develop. Doming resulted in thick, high-quality coal benches. In some cases, a third stage of planar peats, with similar characteristics to the planar peats at the base of the beds, developed on the unevenly distributed clastics that buried underlying mires during continued base-level rise.

Because a mined seam at any location is typically a product of several benches, coal-bench architectural analysis provides a useful tool for understanding, and predicting, lateral variation in coal characteristics. This type of analysis also explains why thick, multiple-bench coals often have poorer quality than laterally equivalent, thinner coals that are not composed of lower and rider benches. This approach can also aid in delineating structural influences on peat accumulation.

GREB, STEPHEN F. and CORTLAND F. EBLE, Kentucky Geological Survey, Lexington, KY; JAMES C. HOWER, Center for Applied Research, Lexington, KY; and THOMAS L. PHILLIPS, University of Illinois, Urbana, IL

Mining Conditions and Deposition of the Amburgy (Westphalian B) Coal, Breathitt Group, Central Appalachian Basin

Carbonate concretions called clay balls are rare in the Central Appalachian Basin, but were found in the Amburgy coal overlain by the Kendrick Shale Member. In the study area, the Amburgy coal is 0.7 to 0.9 meters thick, moderate to high in sulfur content, moderate to high in ash yield, and mostly bright clarain, except at the top near the area of coal balls, where durain of limited extent occurs. The coal is co-dominated by lycopod and cordaites tree spores, with subordinate Calamites. The local durain layer is dominated by Densosporites, produced by the shrubby lycopod Omphalophloios. Coal balls were encountered where the durain is immediately overlain by a coquinoid hash of broken and whole marine fossils, along a trend of coal thinning. The coal balls contain permineralized cordaites, lycopods, calamites, and ferns.

The Amburgy coal accumulated as a succession of planar mires. Local splits in the seam are common, indicating contemporaneous clastic influx. The abundance of Cordaites may indicate brackish mire waters related to a coastal position and initial eustatic rise of the marginal Kendrick seas. Near the end of the Amburgy mires, the high ash-Omphalophloios association is interpreted as a local area that was being drowned by the Kendrick transgression. Ravinement within this local embayment, rapid inundation by marine waters, and concentration of carbonate-bearing waters within transgressive scours may have contributed to the formation of coal balls and pyritic concretions in the upper part of the coal bed.

Although the rarity of coal balls in the basin makes them scientifically important, from a mining perspective they resulted in decreased coal quality, increased extraction costs, and abandonment of part of the mine in which they were found. A comparison with other coal-ball locations in the basin shows that all have been associated with fossil shell debris at the coal/roof contact. This lithology could be identified in cores, and should be looked for in coals underlain by widespread marine zones.

GUILER, RICHARD W., MICHAEL A. MILLER, and ROBERT F. KLEINSCHMIDT, Blake & August Environmental, Inc., Morgantown, WV.

A Case Study: Dual Phase Recovery of Petroleum Hydrocarbon Contaminants from the Subsurface

Due to the well-documented limitations of traditional pump and treatment, alternate technologies for reducing subsurface contaminants including dual phase recovery via high vacuum liquid ring pumps (LRP) have been investigated. The LRP is capable of producing air flow rates up to 250 CFM, water flow rates up to 20 GPM, and attains a maximum vacuum of 28 inches of mercury to effectively recover both fluids (NAPL and dissolved phase) and vapors from the shallow subsurface.

The LRP has proven to be an effective technology to recover volatile organic compounds in a variety of geologic settings throughout the Appalachian Basin. Throughout the Valley and Ridge physiographic province of western Virginia, competent limestone bedrock is often encountered at depths as shallow as one foot below grade and recovery of contaminants is primarily through pre-existing pathways including bedding planes and orogenically-induced fracture systems. Effective rates of recovery have also been attained utilizing a LRP in silty and clayey subsurface materials found in the residuum throughout West Virginia.

This paper presents evidence indicating that LRPs have drastically reduced clean-up time whereby case closure may be attained in a fraction of the time required by more traditional remedial technologies.

HAMILTON-SMITH, TERRENCE, Applied Earth Science, Lexington, KY

Fractured Shale Reservoirs: Towards a Realistic Model

Fractured shale reservoirs are fundamentally unconventional, which is to say that their behavior is qualitatively different from

reservoirs characterized by intergranular pore space. Attempts to analyze fractured shale reservoirs are essentially misleading. Reliance on such models can have only negative results for fractured shale oil and gas exploration and development. A realistic model of fractured shale reservoirs begins with the history of the shale as a hydrocarbon source rock. Minimum levels of both kerogen concentration and thermal maturity are required for effective hydrocarbon generation. Hydrocarbon generation results in overpressuring of the shale. At some critical level of repressuring, the shale fractures in the ambient stress field. This primary natural fracture system is fundamental to the future behavior of the fractured shale gas reservoir. The fractures facilitate primary migration of oil and gas out of the shale and into the basin. In this process, all connate water is expelled, leaving the fractured shale oil-wet and saturated with oil and gas. What fluids are eventually produced from the fractured shale depends on the consequent structural and geochemical history. As long as the shale remains hot, oil production may be obtained. (e.g. Bakken Shale, Green River Shale). If the shale is significantly cooled, mainly gas will be produced (e.g. Antrim Shale, Ohio Shale, New Albany Shale). Where secondary natural fracture systems are developed and connect the shale to aquifers or to surface recharge, the fractured shale will also produce water (e.g. Antrim Shale, Indiana New Albany Shale).

HARRIS, DAVID C., and JAMES A. DRAHOVZAL, Kentucky Geological Survey, University of Kentucky, Lexington, KY

Gas Potential of the Rome Trough in Kentucky: Results of Recent Cambrian Exploration

A recent gas discovery in the Rome Trough suggests the need to re-evaluate the deep Cambrian potential of eastern Kentucky. A new phase of Cambrian exploration began in mid-1994 with a new pool discovery by the Carson Associates No. 1 Kazee well in Elliott County, KY. This well blew out and initially flowed 11 MMcfd of gas from the upper Conasauga Group/Rome Formation at 6,258 to 6,270 feet. After this discovery, a second exploratory well (the Blue Ridge No. 1 Greene) was drilled on a separate structure in Elliott County in late 1995. The Blue Ridge well was temporarily abandoned, but had shows of gas and condensate. In early 1996, Carson Associates offset their initial discovery well with the No. 33 Lawson Heirs well. This activity follows a frustrating exploration history in the Rome Trough that is marked by numerous gas and oil shows, but rare commercial production. Only three single-well pools have produced commercial gas from the trough, including the recent Kazee well.

Stratigraphic units below the Cambrian-Ordovician Knox Group in the Rome Trough are dramatically thicker than their equivalents on the shelf to the north. The interval in the trough is thought to include rocks as old as Early Cambrian, consisting of a basal sandstone, equivalents of the Shady/Tomstown Dolomite, the Rome Formation, and the Conasauga Formation. Sandstones and fractured shales have been responsible for most of the production to date, but dolostone intervals may also have potential. Limited seismic data indicate possible fan-delta and basin-floor fan deposits that may have reservoir potential. The trough has been interpreted as a failed Cambrian continental rift basin, and structural traps have been the exploration target to date. Structural mapping of the basement surface in eastern Kentucky indicates greater than 13,000 feet of structural relief across its northern boundary, and about 7,000 to 8,000 feet along the southern boundary. The dominant normal faults are oriented east-northeast, but two north-south-oriented faults bound the Floyd County Channel in southeastern Kentucky. North of this feature is a north-south-trending surface structure, the Paint Creek Uplift. It is along this uplift and its flanks that the two recent wells were drilled. Interpretation of recently reprocessed seismic data was a key factor in the recent Carson Associates discovery. Future exploration will depend heavily on enhanced seismic interpretation of complex structures in the graben. High-quality seismic data will also be required to define potential stratigraphic traps in the trough.

HOHN, MICHAEL ED., RONALD R. MCDOWELL, and DAVID L. MATCHEN, West Virginia Geological and Economic Survey, Morgantown, WV; and THOMAS J. WOODS, Gas Research Institute, Washington, D.C.

Did Devonian shale wells drilled during the 1980's and early 1990's in West Virginia measure up to

expectations?

In the mid-1980's, a model of future Devonian shale drilling and production was prepared for the Gas Research Institute (GRI). In late 1995, the West Virginia Geological and Economic Survey (WVGES) was contracted by GRI to evaluate actual drilling and production in the 1980's and early 1990's and compare these data to the predictions made in the existing model. Drilling activity data were compiled for the years 1979-1993 for all wells drilled, and for all Devonian shale wells drilled. Monthly and annual production data were summarized for both categories. The Devonian shale wells were subdivided into two subsets: 1) the western black shales trend and 2) the eastern black and gray shales and siltstones trend, according to the play definitions used in the "Atlas of Major Appalachian Gas Reservoirs". Devonian shale wells were subdivided into vintages by completion year. Finally, each Devonian shale well was assigned to a 30 minute geographic grid or "cell" and production data were compiled and compared between cells.

Analysis of the data led to the following conclusions: fewer shale wells were being drilled in the early 1990s, but these wells had better recoveries than the wells drilled in the 1980s. Some grid cells showed higher recoveries for the black and gray shales and siltstones play than in cells with black shale reservoirs alone. These higher recoveries perhaps can be attributed to the common practice of completing and producing shallower zones (i.e. Mississippian sandstones) in addition to the Devonian shales.

HOWER, JAMES C., University of Kentucky Center for Applied Energy Research, Lexington, KY; JOHN H. CALDER, Nova Scotia Department of Natural Resources, Halifax, NS, CANADA; CORTLAND F. EBLE, Kentucky Geological Survey, Lexington, KY; ANDREW C. SCOTT, Department of Geology, Royal Holloway University of London, Egham, Surrey, UK; J. DAVID ROBERTSON and LORI J. BLANCHARD, Department of Chemistry, University of Kentucky, Lexington, KY

Petrology, Geochemistry, and Palynology of Joggins Formation (Westphalian A) coals, Cumberland Basin, Nova Scotia

Five Westphalian A coals were collected from the Joggins Formation section exposed along Chignecto Bay at Joggins, Nova Scotia. Several of the coal beds along the bay were mined beginning in the early 17th century. There has been little detailed investigation of the coal beds of this classic section.

The lowermost coal, the Upper Coal 29 (Fundy), is a high-vitrinite coal with a spore assemblage dominated by arboreous lycopod spores with tree ferns subdominant. The upper portions of the coal bed have the highest ratio of well-preserved to poorly-preserved telinite of any of the coals investigated. Coal 19 (Forty Brine) has 88% total vitrinite but, unlike the Fundy coal bed, the telinite has a poor preservation ratio and half of the total vitrinite population comprises gelocollinite and vitrodetrinite. The latter coal bed is directly overlain by a basin-wide limestone bed. The Lower Kimberly (Coal 15) shows good preservation of vitrinite with relatively abundant telinite among the total vitrinite. The Upper Kimberly, which underlies the tetrapod-bearing lycopsid trees found by Lyell and Dawson in 1852, exhibits an upward decrease in arboreous lycopod spores and an increase in the tree fern spore Punctatisporites minutus. The megaspore record is similarly dominated by Lagenicularugosa paralycopodites and tree fern spores. Telinite preservation increases upwards in the Upper Kimberly but overall is well below the preservation ratio of the Fundy coal bed.

The coals are all high sulfur, up to 13.7% total sulfur for the lower lithotype of the Fundy coal bed. The Kimberly coals are not only high in total and pyritic sulfur, but also have high concentrations of chalcophile elements.

JOHNS,PATRICIA J., LARRY D. WOODFORK, DOUGLAS G. PATCHEN, and KATHARINE LEE AVARY, West Virginia Geological and Economic Survey, Morgantown, WV

Sistersville, West Virginia: 1893 Oil Capital of the World

By the early 1890's, production had peaked and was declining in the Pennsylvania oil fields. Drilling activity shifted south into West Virginia. The Sistersville oil field, discovered in 1891, became the "oil capital of the world" in 1893. For a brief period of time, Sistersville, West Virginia experienced its "moment of fame" with all of the attendant growth, excitement, glamour, prosperity, turmoil, rowdiness, disillusionment and eventual decline typical of "oil booms".

The geology of the Sistersville pool as well as aspects of the history and culture of the town during the boom are portrayed on the poster by maps, photographs and narrative. The history and heritage of that bygone era are also celebrated annually at the Sistersville Oil and Gas Festival and memorialized in The Oil and Gas Museum, Parkersburg, WV.

KIGER, CARA B., and PAUL D. HOWELL, Department of Geological Sciences, University of Kentucky, Lexington KY

Truth or Dare: The Maquoketa-Trenton(!) Petroleum System

Middle Ordovician carbonates produce hydrocarbons in many portions of the Illinois, Michigan and Appalachian basins. Although both reservoir and source potential of the superjacent Upper Ordovician shales are well characterized, little published work has combined these into a coherent description of this petroleum system. Building on the approach suggested by Magoon and Dow (AAPG Memoir 60, 1994), we are developing a comprehensive petroleum system model for these reservoirs, their proven and potential source rocks, and the timing and style of hydrocarbon generation, migration and entrapment. We refer to this as the Maquoketa-Trenton(!) petroleum system, following the notation of Magoon and Dow for a proven oil-source correlation with "Maquoketa" representing the Upper Ordovician source rocks and "Trenton" referring to Middle Ordovician carbonate reservoirs, regardless of their local stratigraphic nomenclature.

Recent published work has established the signature of at least two source rocks contributing to Trenton production; one is compatible with the Type II kerogen dominating the Maquoketa, and the other has Type I kerogen indicators, suggesting a possible New Albany (Upper Devonian) source. Our preliminary quantification of this petroleum system yields a source potential index of 0.75 metric tons/square meter and a generative potential for the Illinois basin alone of ~1,011 metric tons (1012 Barrels of oil equivalent). Given total Trenton production in the Illinois and Michigan region of ~108 metric tons, this yields a generation-accumulation efficiency (GAE) of ~0.1%. This low GAE, coupled with low exploration well density in prospective areas, suggests that significant hydrocarbon reserves remain in this petroleum system.

Petrophysical Characteristics of the Subsurface Sauk Sequence (Cambro-Ordovician) of Western New York

KOLKAS, MOSSBAH M., and GERALD M. FRIEDMAN, Brooklyn College and Graduate School of the City University of New York, Department of Geology, Brooklyn, NY, and Northeastern Science Foundation, Rensselaer Center of Applied Geology, Troy, NY

Petrographic analyses of selected core- and well-cutting samples from Niagara, Steuben and Wyoming counties, western New York, indicate that the Beekmantown Group (Sauk Sequence) was deposited in a shallow, tidally-influenced marine environment. Three major facies have been recognized: 1) sandstone, 2) sandy dolostone, and 3) dolostone. These facies have been divided into several lithofacies based on lithology, sedimentary microstructure, texture, and fabric.

Petrophysical analyses of some selected core plugs and well cuttings, using a mercury porosimeter, indicate that the sandstone facies has high quality reservoir parameters (porosity, recovery efficiency, and fluid saturation) compared to the other facies. Four types of capillary-pressure curves have been recognized from porosimetric studies: convex capillary-pressure curve (low porosity and high recovery efficiency), concave capillary-pressure curve (high porosity and low recovery efficiency), gently sloping capillary-pressure curve (intermediate porosity and intermediate recovery efficiency), and polymodal capillary-pressure curve (low porosity and low recovery efficiency). The petrophysical parameters (porosity, recovery efficiency, and fluid saturation) throughout the different lithofacies are controlled by different degrees of diagenetic modification.

LENTZ, LEONARD J. and JOHN C. NEUBAUM, Pennsylvania Department of Conservation and Natural Resources-Bureau of Topographic and Geologic Survey, Harrisburg, PA

Availability of Coal in the Hackett 7.5-minute quadrangle, Washington County, Pennsylvania

Coal has been extensively mined in Pennsylvania and elsewhere in the Appalachian Basin over the last 100 years. In an attempt to better define what coal is left, a new approach to quantifying resources, rooted in modern environmental and technological constraints, was needed. The Bureau of Topographic and Geologic Survey in cooperation with the United States Geological Survey, embarked in 1993 upon a series of six quadrangle studies for Pennsylvania to provide information about coal resources still accessible to mining. Using our data residing on the United States Geological Survey's National Coal Resources Data System computer to compute resources for the Hackett 7.5-minute quadrangle, the available coal for the four principally mined seams in the area (the Pittsburgh, Redstone, Waynesburg, and Waynesburg A coals) could be determined by subtracting out mined-out areas from in-place coal to give remaining coal, and then subtracting land-use and technological restrictions to mining, such as wetlands, and subsidence waivers, respectively, from the remaining coal. Results of the study found that the amount of coal available for mining varied from 26 to 70 percent. It is felt by the authors that this quadrangle is typical of the mature nature of this mining region for this part of the geologic section, and that similar results might be expected for the other quadrangles to be studied in southwestern Pennsylvania.

LESSING, PETER, West Virginia Geological and Economic Survey, Morgantown, WV

Geological maps, regarded as the dynamic force in geology, illustrate the distribution, configuration, succession, and interpretation of rock units at the earth's surface. Their origins can be traced back to 1150 B.C., but the modern geological map only emerged in the early 1800s, primarily because fossils were recognized for correlation and age purposes; geology became a widely accepted academic discipline; chromolithography was developed; topographic base maps became available; and there was near agreement on stratigraphic and structural concepts. An examination of their history exposes plagiarism, raw speculation, political back-stabbing, old ideas somehow very modern, repeated repetition, major geological advances, and major geological blunders.

The oldest geological map in the world is the Turin Papyrus (circa 1150 B.C.). The oldest cross section is credited to Strachey (1719). The oldest map of North America was completed by the Frenchman, Guettard (1752). The earliest known colored map is by Charpentier (1778). The first map of the U.S. printed in the U.S. is Maclure's (1809). The first recognition of fossils for correlation was Smith's map of England (1815). The first to use modern stratigraphic names in the U.S. was Hall (1843). The first published map of Virginia [and West Virginia] was by Rogers (1874). The earliest known use of contour lines in the U.S. was by Hayden (1878) on his Yellowstone map. And the first publication of the West Virginia Geological Survey [naturally, a geological map] was produced by Morris and White (1899).

MANGER, KATHERINE C., The Cadmus Group, Alexandria, VA; THOMAS J. WOODS, Gas Research Institute, Washington, DC; JOHN B. CURTIS, Colorado School of Mines, Golden, CO; and MICHAEL D. ZUBER, S. A. Holditch & Associates, Inc., Pittsburgh, PA

Antrim Shale Fractured Reservoirs:

Their Potential Throughout the Michigan Basin

Antrim shale gas production grew from 0.4 Bcf in 1987 to 156 Bcf in 1994, causing record gas production in Michigan. Recent industry activity suggests the play will continue to expand.

The GRI Hydrocarbon Model contains an Antrim resource base description that was developed in 1991. It was based on industry activity through 1990 and only covered the northern extent of the Antrim surrounding the current play. Significant technological improvements since then have resulted in projected near-term production lagging actual production by one to two years. Even so, the 1996 Edition of the GRI Baseline Projection predicts Antrim production will reach 1 Tcf by the year 2015.

Given the 1996 projection results, a reassessment of the potential for producing gas from Antrim shale-type fractured reservoirs was initiated. The analysis identified general geological characteristics that appear to contribute to successful wells and extrapolated them to the rest of the Michigan Basin. Data used included production and well data through 1995, GRI-funded studies, and proprietary studies and data on the Antrim and deeper formations significant to gas origin and thermal maturity.

Initial results suggest four "Resource Areas" based on comparison to the existing play using the following geological factors: 1) extent and thicknesses of the Lachine and Norwood organic shales; 2) regional structural expression of potential fracturing; 3) total depth relating to probability of open fractures; and 4) probability of biogenic gas contribution.

MARKOWSKI, ANTONETTE K., Pennsylvania Department of Conservation and Natural Resources-Bureau of Topographic and Geologic Survey, Harrisburg, PA

Subsurface Definition of the Allegheny Group Coalbed Methane Prospect Interval in Southwestern Pennsylvania and New Gas Content Results

A preliminary reconnaissance of coalbed methane gas content data from exploratory coal cores and pre-existing data implies that the greater the depth and rank, the greater the total and cumulative gas content. The coal seams studied, ranging in age from the Pennsylvanian-Permian Dunkard Group to the Middle Pennsylvanian Allegheny Group, are from the Main Bituminous Field and two of the anthracite fields.

Consequently, the Pennsylvania Geological Survey and the West Virginia Geological and Economic Survey conducted a mapping investigation to evaluate the regional geology of the coal-bearing intervals and its influence on coalbed methane potential. Phase I of this study involved the entire Pennsylvanian coal-bearing interval; Phase II focused on a stratigraphic delineation and evaluation of Allegheny coalbeds and associated sandstones. A variety of cross sections and isopach maps show several prospective coalbeds and facies relationships with channel-fill sandstones. This suggests that some of these sandstones may be traps for coalbed methane.

Often overlooked in reservoir characterization is the quality of a coal seam. Coal rank, grade, and type influence the reserves and production of coalbed methane; the higher the rank, the greater adsorptive capacity of the coal. The integration of coal quality with other critical tools of exploration may increase the success rate of finding "sweet spots." Additional Pennsylvania Geological Survey drilling occurred in Beaver, Lawrence, Somerset, and Washington counties. Gas contents were graphically displayed against depth, thickness, and time for a variety of samples from 21 coal seams; average gas composition and Btu values were determined for selected samples.

MARTIN, PHILIP L., Consultant, Retired CNG, Bridgeport, WV

Detailed Surface Structure Yields Clues to Deep Structure

The unique three-dimensional perspective afforded by the stereoscopic viewing of aerial photos permits the accurate outcrop tracing of many exposed Appalachian bedrock units. When carefully drawn on 7.5 minute topographic maps, the intersections of these outcrop traces yield a dense network of elevation control points. Contouring these data produces a detailed surface structure map which neither overemphasizes micro-geology nor glosses over structural detail which could have more significance than first meets the eye. Often structural features are revealed which never have been mapped before, simply because the geomorphic expression of certain units can be followed in stereo on aerial photos, while the accurate and continuous field mapping of the same units, by conventional methods, is obstructed by the naturally-concealing products of humid climates, such as soil and vegetation.

Such maps, when overlain on well- or seismic-controlled subsurface maps, exhibit some dramatic, if not always direct, overprinting of deep features. These analogs reinforce the concept of the upward, modified, transfer of discrete pre-Alleghenian structural features, probably through sporadic reactivation along already-weakened zones. It also is highly probable that this process produced some depositional surface topography which strongly influenced depositional patterns and facies, especially in Lower Devonian time.

MCCLURE, MICHAEL and MARSHALL S. MILLER, Marshall Miller and Associates, Bluefield, VA

Trace Element Concentration of Central Appalachian Coal Beds

As a result of more stringent environmental regulations, there is increasing demand for coal beds with lower sulfur and trace element concentrations. Unfortunately, due to technical difficulties associated with the detection of elemental composition in parts-per-million, reliable trace element data are scarce. Examination of the U.S.G.S. COALQUAL database of Appalachian coals was conducted for the following metals: antimony, arsenic, chromium, lead, and mercury. Within an area of approximately 14,000 square miles, 1,500 raw (core, underground and surface mine) coal samples with geographic coordinates were examined, and more than 100 named coal seams from Tennessee, southern West Virginia, eastern Kentucky, and southwestern Virginia were investigated. Some samples were obtained from formerly active mines which have since been depleted. Researchers have identified approximately 80 coal-related minerals including clays, carbonates, phosphates, chlorides, silicates, sulfates, and sulfides and, of these, sulfides have been found in chemical association with some trace elements. Quality trends over a broad region provide insights into geochemical and depositional processes which may have influenced trace element content. Furthermore, recently published E.P.R.I. data from "as-shipped" coal samples (located by state only) demonstrate similar patterns at the state level. Analysis of these data generally indicates a geographic and stratigraphic preference for coal beds with lower levels of trace elements along the southern edge of the Appalachian coal fields. While these quality trends may be a reasonably good first approximation, additional sampling is needed in minable reserve areas to further identify coal seams which possess favorable trace metal concentrations.

MCKOY, MARK L., and W. NEAL SAMS, EG&G Technical Services of West Virginia, Inc., Morgantown, WV

New Tools for Modeling Fracture Networks and Simulating Gas Flow in Low-Permeability Sand and Shale Reservoirs.

The U.S. Department of Energy, Morgantown Energy Technology Center, has an on-going project to model and simulate gas flow in low-permeability sands and shales that contain irregular, sometimes discontinuous, fracture networks (i.e., the types of networks not adequately represented by existing models/simulators). A FORTRAN code and methodology for modeling and simulating flow in these fracture networks has been developed. The goal was to convert the locations and orientations of fractures, as observed along a horizontal well bore, into two-dimensional, geometrically and hydraulically equivalent networks, which can be used to study variability in yield and drainage pattern. The fracture network generator implements four models of increasing complexity through a Monte Carlo process of selecting fracture network attributes from fitted statistical distributions. A process of shifting fracture end-point locations along the axes of fractures provides a partial control of fracture intersection/termination frequencies. Output consists of fracture end-points and apertures. The flow simulator divides each fracture-bounded matrix block into subregions that drain to the midpoint of the adjacent fracture segment in accordance with a one-dimensional, unsteady idealization. The idealization approximates both the volume and the mean flow path length of each subregion. Volumetric flow rate in the fractures is modeled as a linear function of the pressure difference between the recharge points and the fracture intersections. The requirement of material balance between all intersections couples the individual recharge models together, and the resulting equations are solved by a Newton-Raphson technique.

MILICI, ROBERT C., U.S. Geological Survey, Reston, VA and ELIZABETH

V. M. CAMPBELL, Virginia Division of Mineral Resources, Charlottesville, VA

Virginia's Coal Resources - An Update

In the mature coal mining regions of the Appalachian basin, state production statistics and preliminary reserve figures can be used to model future production rates and to estimate the time of ultimate depletion of the resource. These projections are more accurate if the production data are analyzed by bed, by county. In the absence of the resource data necessary to calculate coal reserves, the remaining recoverable coal can be estimated by extrapolating current production decline rates into the future.

In 1989, the Virginia Division of Mineral Resources, calculated remaining reserves to be between 1.9 and 4.1 billion tons and concluded that a general production decline would occur between 1995 and 2011, when half of the original reserve (cumulative production plus remaining reserve) would be mined. Subsequently, Virginia's coal production peaked at 46.5 million tons in 1990 and has declined to 37.6 million tons in 1995. The current cumulative production, nearly 2.1 billion tons, is about half of an ultimate recoverable resource of 4.2 billion tons. Extrapolation of current production decline rates of 2.4% per year into the next century indicates that Virginia's annual coal production will fall to 25 million tons within 25 years and to 11 million tons within 50 years.

Of the 43 beds mined for coal in Virginia, thirteen commonly produce 1 million tons or more annually. The decline is related chiefly to reduced production from the Dorchester, Lower Banner, Pocahontas No. 3, Raven, Splash Dam, and Upper Banner coal beds. Pocahontas No. 3 production, the largest in the state, has declined from about 9.8 million tons in 1990, to about 7 million tons in 1995.

MILLER, MARK B., DENNIS A. CLARK, MAUREEN HANDLER, AND ZHING-MING HUANG, Marion Environmental, Inc., Chattanooga, TN

In-situ Bioremediation of Groundwater Using a Horizontal Injection Well in Clay Soil, Madisonville, TN

Tennessee's first horizontal groundwater remediation well was installed at Madisonville located in the eastern Valley and Ridge Province. The open-ended well, drilled through clay soil, is constructed of 280 feet HDPE pipe, 2 inches in diameter, with a screen length of 100 feet at 18 feet below ground surface. The purpose of the well is to remediate gasoline contaminated groundwater that resulted from a leaking underground storage tank (UST) system. The groundwater benzene and TPH plumes covered an area of one-half acre and extended beneath a rural grocery store.

Remediation is achieved by injecting aerated water, nutrients and microbes to reduce contaminant levels to drinking water standards. MODFLOW was utilized to computer-model the development of the groundwater mound that would result from injection. It was calculated that one horizontal injection well would equal the efficiency of 80 vertical injection wells. Benzene and TPH masses have been reduced by 92% and 95% respectively. BIOTRANS calculated the bio-decay rate to determine remediation time.

This system will reduce project life and eliminate additional costs associated with: operations and maintenance (versus vertical pump and treat), water disposal, emissions controls, well installations, and site disturbance. A "Minimum Economic Plume Size", the minimum plume volume required to support a horizontal system has been developed. Although costs per foot are greater for horizontal drilling than vertical drilling, project costs savings are realized later in the project.

MORGAN, J. F., and T.H. WILSON, West Virginia University, Department of Geology and Geography, Morgantown, WV

Crustal scale gravity and magnetic models along a transect across the central Appalachians of West Virginia

The origins of gravity and magnetic anomalies along a transect across the central Appalachian foreland of West Virginia are evaluated through inverse modeling. The gravitational influence of basement geometry and Paleozoic sediment distribution was incorporated in the gravity models using published surface geologic maps, limited borehole data, and nearby seismic profiles. The transect is dominated by a major regional scale gravity anomaly that rises from approximately -80 milligals along the West Virginia/Virginia border to a high of -46 milligals in central West Virginia and drops farther northwest to approximately -60 milligals. Several magnetic anomalies of up to 600 nanoteslas in magnitude occur along the profile.

Calculations reveal that gravity anomalies along the profile are not simply related to the distribution of Paleozoic sediments. Gravity models derived from the data indicate that gravity anomalies are due in large part to variations in the thickness of the crust from 55 km to just under 30 km. The potential role of intra-crustal layering interpreted from seismic refraction data collected in the Appalachians is also modeled. The magnetic model indicates that the major linear anomaly associated with the New York-Alabama Lineament can be explained by susceptibility contrasts concentrated in the lower half to lower two-thirds of the crust. Anomalies with more limited strike lengths are modeled by more localized regions of susceptibility contrast in lower and mid-crustal levels. Magnetic bodies are generally not associated with specific bodies in the gravity model suggesting that they result from different episodes of magnetization in rocks of similar lithology.

MORSE, DAVID G., Illinois State Geological Survey, Champaign, IL

Sedimentology, Diagenesis, and Trapping Style, Chesterian Tar Springs Sandstone at Inman Field, Gallatin County, Illinois

The Tar Springs Sandstone in southern Illinois is often overlooked as a pay, yet it can be a prolific producer. The Inman Field, discovered in 1940, produces from several cyclic Chesterian sandstones from structural-stratigraphic traps in the Wabash Valley Fault System of southeastern Illinois. The oil was sourced from the Devonian New Albany Shale and apparently migrated vertically along the Wabash Valley faults to its present location, thus charging many of the Chesterian and lower Pennsylvanian sands in the field. The Tar Springs Sandstone produces from stacked distributary channel sand reservoirs up to 125 feet thick which have cut up to 40 feet into laterally equivalent, non-reservoir, delta-fringe facies and the underlying Glen Dean Limestone. The reservoir sands are well-sorted, fine- to medium-grained quartz arenites with less than 5% feldspar and chert. Quartz grains have quartz overgrowths. Feldspar grains are clouded in thin-section and show pronounced etching and dissolution in SEM. Diagenetic kaolinite and small amounts of illite and magnesium-rich chlorite occur in intergranular pores. Sparry, iron-rich dolomite or ankerite that fills pores in irregular millimeter-size patches, occupies up to 10% of the reservoir rock. Typical reservoir porosity ranges from 16 to 19 percent and permeability ranges from 60 to 700 md. By contrast non-reservoir delta-fringe sands typically have porosities of 6 to 12 percent and permeabilities of 1 to 20 md. Delta-fringe Tar Springs shales act as impermeable lateral and vertical seals, aiding in stratigraphic trapping.

MOYER, CHARLES C., Lomak Petroleum, Hartville, OH

Geology and Log Responses of the Rose Run Sandstone in Randolph Township, Portage County, Ohio

Approximately 75 wells have penetrated the Cambrian Rose Run sandstone in Randolph Township, Portage County, Ohio, about half of which should produce well beyond economic payout. Only one deep test (to the Rose Run or deeper) was drilled in this Township prior to 1990. Two separate and distinct Rose Run producing fields exist in the Township; the western field is predominately gas-productive and the east is predominantly oil-productive. Both fields are on the north side of the Akron-Suffield Fault Zone, which is part of a regional cross-strike structural discontinuity extending from the Pittsburgh, Pennsylvania area northwestward to Lake Erie (Gray and others, 1982; Riley and others, 1993). This feature exhibits control over Berea, Oriskany, Newburg, Clinton, and Rose Run production.

MUSHRUSH, GEORGE W. and DOUGLAS G. MOSE, George Mason University, Chemistry Department, Fairfax, VA

The Chemical Characterization and Instability of Shale Derived Middle Distillate Fuels

Changes in fuel properties with time in storage have been a continuing problem in the use of shale-derived middle distillate fuels. The storage stability of middle distillate fuels is usually defined in terms of the formation of sediment, gum, color, and peroxides. A shale-derived fuel of marginal stability has been used as a source of nitrogen-rich polar extracts. These polar nitrogen heteroatoms were isolated by mild acid extraction followed by silica gel adsorption and were identified by combined capillary column GC/MS. Alkyl substituted pyridines were the prevalent class of compounds present. Other nitrogen functional groups present included the alkyl substituted: tetrahydroquinolines, quinolines, indoles, and carbazoles. This fuel was also analyzed for the metal ions content by ICP. The effect of adding these shale extract fractions as dopants to a stable shale diesel fuel were examined in terms of sediment formation, and peroxide number under accelerated storage stability test conditions. We have developed a 16 hour test method that predict accurately fuel behavior over a two year period. The activities of the extracts in inducing fuel instability were correlated with their chemical composition and will be reported.

NEIDIG, CRAIG A., Office of State GIS Coordinator, Charleston, WV; NICK FEDORKO, West Virginia Geological and Economic Survey, Morgantown, WV; ED MAKI, WV Department of Tax and Revenue, Charleston, WV; and GREGORY ELMES, West Virginia University, Morgantown, WV

The West Virginia Mineral Lands Mapping Program: Statewide GIS Resource Evaluation and Assessment

In 1995, the West Virginia legislature enacted H.B. 2222 that provided a mandate and funding for a statewide evaluation of mineral resources, specifically coal, to promote a more open and equitable means to assess the taxable value of mineral holdings by West Virginia property owners. Written into the legislation was an appropriation for the initial development of a Geographic Information System (GIS) to integrate the work. Designated as the Mineral Lands Mapping Program, the lead agencies are the WV Geological and Economic Survey, the WV Department of Tax and Revenue, and the State GIS Technical Support Center at West Virginia University. The complex topography and geology of West Virginia require that large volumes of two- and three-dimensional spatial data be created to support the identification, mapping, and evaluation of coal resources for improved tax assessment of land parcels. The political and economic context of the project, data requirements and sources, inputs and digital conversion procedures, adoption of metadata and data standards, geological base mapping, coal resource modeling methods, tax parcel reconciliation, and integration of the various data sets are all important issues for this program.

PASHIN, JACK C., Geological Survey of Alabama, Tuscaloosa, AL, and RICHARD H. GROSHONG, JR., University of Alabama, Tuscaloosa, AL

Area Balance and Strain in Coalbed Methane Reservoirs of the Black Warrior Basin

Investigation of coalbed methane reservoirs in the Black Warrior basin of Alabama has established a correspondence between productivity and structural position, but the reasons for this correspondence remain uncertain. In Cedar Cove field, for example, exceptionally productive wells are concentrated in a rollover anticline, whereas in Oak Grove field, exceptionally productive wells are aligned along a synclinal axis. This suggests that factors controlling gas production are a derivative of the structural geometry, and not the geometry by itself.

Natural fractures and a low state of in-situ stress facilitate depressurization of coalbed reservoirs by dewatering, and hence, desorption and production of coalbed gas. Our hypothesis is that the abundance and openness of natural fractures in the Black Warrior basin are a direct expression of the layer-parallel strain dictated by map-scale structural geometry. Area balancing techniques can be used to quantify requisite strain, which is the homogeneous layer-parallel strain required for local area balance, and can also be used to constrain and verify structural cross sections.

Application of area balancing techniques to extensional structures in the Black Warrior basin indicates that coalbed gas is produced from thin-skinned structures detached within the coal-bearing Pottsville Formation. Within reservoir intervals, requisite strain values are as high as 10 percent and increase downward toward the basal detachment. Mapping structure and production indicates that some productivity sweet spots correlate with enhanced bed curvature. Whereas requisite strain is the homogeneous strain calculated for discrete bed segments, curvature affects the distribution of strain within those segments. Recognizing this, our research is now focused on integrating area balancing techniques with curvature analysis to explain production patterns in coalbed methane reservoirs.

RAMIREZ, J. RAUL, and ERIC CORDLE*, The Ohio State University Center for Mapping, Columbus, OH

The Conversion of 7.5' Quadrangles to DLG-3 Files for the State of Ohio : A Project Overview

In October 1993, The Ohio State University, several Ohio state agencies, the U.S. Geological Survey (USGS) and representatives of the private sector began a four-year cooperative agreement to convert 700 of the 793 7.5' (1:24,000 scale) quadrangles covering the State of Ohio to the USGS Digital Line Graphic 3 (DLG-3) Standard form. Ninety-three quadrangles already had partial to complete DLG-3 coverage.

Information layers being converted include boundaries, hydrography, hypsography, public land survey system and transportation (roads, railroads and miscellaneous transportation). At the end of the agreement, Ohio will be the first state in the nation with such coverage. This project is known as Generating Information from Scanning Ohio Maps (GISOM).

This paper describes the project background, organization, conversion model, and implementation. A discussion of results and experiences after the first two years of the project are also presented.

RICHERS, DAVID M, and DOUGLAS E. WYATT, Westinghouse Savannah River Company, Aiken, SC

Evidence of Thermogenic Hydrocarbon in the Central Savannah River Area, South Carolina and Georgia

Soil gas data collected from 1993 through 1996 from the area in and around the U. S. Department of Energy Savannah River Site, located in the Central Savannah River Area of South Carolina and Georgia, suggests a regional potential for thermogenic hydrocarbons. Toluene and light saturated soil gas data suggest that an organic source is present either in the Triassic basins of the region, or possibly from other pre-Cretaceous sediments.

High values in soil gas samples were found along the surface expressions of regional faults. These faults are felt to be steeply dipping features that become listric with depth and are basement involved. Therefore these faults are in contact with all subsequent sediments and it is postulated that they are serving as conduits for the upward migration of hydrocarbons from deeply buried material from the Riddlesville and Dunbarton Basins or possibly from other Triassic terrain coastward. The presence of isolated regional soil gas anomalies may suggest deeper sources and outcrop samples of Tertiary limestone also support this possibility.

ROBERTSON, GEORGE A., Huntington, WV

Field Descriptions of Unconsolidated Clastic Sediments for Environmental Investigations

Complete field lithologic descriptions of field samples collected from unconsolidated clastic sediments during environmental investigations provide the primary source of data for hydrogeological characterization of the site and surrounding area.

Most environmental site investigations are performed in unindurated sediments and soil. Thus, the focus of this paper addresses lithologic descriptions of unconsolidated clastic sediments. Due to the multidisciplinary composition of environmental professionals, this study reiterates the basic field skills required to adequately investigate the geological setting and discusses their applications in combination with geotechnical engineering field descriptions.

Complete lithologic descriptions provide the data needed to interpret and understand lithofacies and predict changes in hydraulic parameters across an aquifer. Additionally, lithofacies data are needed to determine the shape and boundary characteristics of an aquifer. Once the depositional environment is understood, it is possible to begin to model aquifer characteristics and aquifer geometry. Lithofacies mapping provides a method to advance beyond treating aquifers as homogenous, isotonic bodies and produce more realistic environmental site assessments resulting in more effective remedial action plans.

The procedure for describing "soils" for engineering purposes is found under the fixed American Society for Testing and Materials (ASTM) designation D 2488-84. This system applies to soil mechanics and may be of use to characterize naturally occurring "soils" for construction purposes. The ASTM system is designed for engineering purposes only and should not be considered in lieu of a more rigorous interpretative lithologic description from which a depositional environment can be interpreted.

ROSE, PETER R., Telegraph Exploration, Inc., Austin, TX

Risk Analysis of Prospects Versus Plays: The Play's the Thing!

The most difficult and crucial decision in petroleum exploration is not which prospect to drill, but rather, which new play to enter. Such a decision, whether ultimately profitable or not, commits the organization to years of involvement, expenditures of millions of dollars, and hundreds of man-years of effort. Even though uncertainties and risks are high, organizations commonly make the new-play decision in a disjointed, non-analytic, even superficial way. The economic consequences of a bad play choice can be disastrous.

Using established principles of prospect risk analysis, modern petroleum exploration organizations routinely assign economic value to individual prospects, but they actually operate via exploration programs in plays and trends. Accordingly, the prospect is the economic unit of exploration, whereas the play is the operational unit.

Plays can be successfully analyzed as full-cycle economic risk ventures, however, using many principles of prospect risk analysis. Economic measures such as Expected Present Value, Discounted Cash Flow Rate of Return (DCFROR), etc. apply equally to plays or prospects. The predicted field-size distribution of the play is analogous to the forecast prospect reserves distribution. Economic truncation applies to both. Variance of play reserves is usually much greater than for prospect reserves. Geologic chance factors such as P_reservoir, P_generation, etc., must be distinguished as independent or shared among prospects in the play, so they should be defined so as to apply as well to the play as to its constituent prospects. They are analogous to multiple objectives on a prospect, and are handled differently in performing the risk analysis.

RUPPERT, LESLIE, LINDA BRAGG, and SUSAN TEWALT, U.S. Geological Survey, Reston, VA

The U.S. Geological Survey's National Coal Resource Assessment: The northern and central Appalachian Basin

The U.S. Geological Survey (USGS) Energy Resource Surveys Program is currently conducting a five-year National Coal Resource Assessment project. Primary focus is on the quality and quantity of top-producing coal beds and coal zones in five of the nine major coal producing regions in the U.S. These regions include the (1) Northern and Central Appalachian Basin, (2) Gulf Coastal Plain, (3) Illinois Basin, (4) Colorado Plateau, and (5) Powder River Basin and the Northern Great Plains.

In the northern and central parts of the Appalachian Basin there are 10 top-producing coal beds and coal zones that account for approximately 26% of the Nation's annual coal production and 61% of the Appalachian production. We will be assessing most of the top-producing coal beds over their areal extent. Top producers include seven coal beds -- the Pittsburgh, Upper Freeport, Hazard No. 5A, Hazard No.4, Lower Elkhorn, Pocahontas No. 3, and the Stockton-Lewis - and three coal zones - the Kittannings, Upper Elkhorn No. 1 and No. 2, and the Upper Elkhorn No. 3. Digital products will include stratigraphic and geochemical databases, original and remaining resource tonnage, and comprehensive bed-scale maps (crop-line, coal thickness, coal structure, overburden thickness, and mined-out areas). The maps will be at a scale of 1:250,000 or 1:500,000. Geochemical parameters, including calorific value (BTU's), moisture, ash yield, sulfur, and potentially hazardous chemical elements will be mapped or presented in tabular form.

The Upper Pennsylvanian Pittsburgh Coal bed assessment will be completed in mid-1996. The stratigraphic database for the Pittsburgh currently consists of approximately 5000 point-locations.

RYDER, R.T., J.R. SANFILIPO, U.S. Geological Survey, Reston, VA; R.D. HETTINGER, C.W. KEIGHIN, B.E. LAW, V.F. NUCCIO, W.J. PERRY, JR., and C.J. WANDREY, U.S. Geological Survey, Denver, CO

Continuous-type (basin-centered) gas accumulation in the Lower Silurian "Clinton" sands, Medina Group, and Tuscarora Sandstone in the Appalachian basin

Following earlier interpretations by Davis (1984), Zagorski (1988,1991), and Law and Spencer (1993), investigations at the U.S. Geological Survey (USGS) suggest that natural gas trapped in the Lower Silurian "Clinton" sands, Medina Group, and Tuscarora Sandstone of the Appalachian basin constitute a regionally extensive continuous-type (basin-centered) gas accumulation. Based on the USGS 1995 National Assessment of United States oil and gas resources (Gautier and others, 1995, USGS DDS-30), this accumulation contains, at a mean value, several tens of trillion cubic feet of recoverable gas estimated as undiscovered.

Important characteristics of continuous-type (basin-centered) gas accumulations, such as low-permeability reservoir, abnormal formation pressure, gas fields that tend to coalesce with additional exploration, gas shows or production in most holes drilled, low water yield, lack of well-defined downdip gas-water contacts, production "sweet spots", and a general lack of structural control on entrapment are all present in the proposed "Clinton"/Medina/Tuscarora gas accumulation. A 17,000 square mile region of western New York, northwestern Pennsylvania, eastern Ohio, and a small area of westernmost West Virginia--part of which is already gas productive in the "Clinton" sands and Medina Group--is the most favorable corridor for future continuous-type gas resources. Oil and gas produced in east-central Ohio from "Clinton" sands since the early 1880's, located updip from the most favorable corridor of continuous-type gas resources, are considered conventional-type hydrocarbon accumulations because of their tendency to exist as discrete fields with well-defined oil- and gas-water contacts. The boundary between the conventional- and continuous-type accumulations is transitional and poorly defined.

SAFLEY, L. EUGENE, BDM-Oklahoma, Bartlesville, OK; and JOHN B. THOMAS, Belden & Blake Corporation, North Canton, OH

Improved Reservoir Characterization of the Rose Run Sandstone in the East Randolph Field, Portage County, Ohio

The East Randolph Field, located in Randolph Township, Portage County, Ohio, produces oil and gas from the Cambrian Rose Run sandstone unit, a member of the Knox Supergroup. Field development and infill drilling opportunities illustrate the need for improved reservoir characterization of the hydrocarbon productive intervals. This reservoir study is conducted under the Department of Energy's Reservoir Management Program with professionals from BDM-Oklahoma and Belden & Blake Corporation.

Well log and core analyses were conducted to determine the reservoir distribution, the heterogeneity of the hydrocarbon producing intervals, and the effects of faulting and fracturing on well productivity. The Rose Run sandstones and interbedded dolomites were subdivided into three productive intervals. Cross sections were constructed for correlation of individual layers and identification of localized faulting. The geologic data was input into GeoGraphix software for construction of structure, net pay, production, and gas- and water-oil ratio maps.

Rotary sidewall cores and core plugs were analyzed to determine porosity, relative permeability, fluid saturation, and capillary pressures. Detailed core descriptions provided information on lithologies, depositional environments, diagenesis, and fracture density. Core to log relationships were used to refine geologic mapping.

Relationships between well production and reservoir parameters, such as structure, net sandstone thickness, and porosity were investigated. Volumetric calculations using the new geologic model increased original oil-in-place estimates to over 11 million stock tank barrels, more than doubling the original estimate. Reservoir simulation will be used to optimize locations of infill wells, and determine waterflood and/or pressure maintenance feasibility.

SATHAYE, J.,A and D.E. GRANDSTAFF, Temple University, Department of Geology, Philadelphia, PA

Water Rock Interaction and the Distribution of Salinity in the Illinois Basin

Available data on the chemical composition of Illinois Basin formation waters were analyzed to identify the diagenetic reactions that are occurring in the basin. The distribution of salinity was visualized in three dimensions and correlated with the present day groundwater flow system in the basin. Formation waters in the entire basin are enriched in calcium and depleted in magnesium, sodium, potassium and sulfate, relative to the seawater evaporation trend. However, there are different compositional trends in waters from Devonian-Silurian and Mississippian-Pennsylvanian strata which are probably maintained by the regional aquitard separating them. Extensive analysis of brines reveals that their composition is influenced to a large degree by processes such as seawater evaporation, halite dissolution, ion-exchange on clays, dolomitization, authigenic magnesium-silicate formation, and bacterial sulfate reduction. Groundwater salinity generally increases with depth, and towards the southern and eastern regions of the basin. Freshwater recharge occurs along the basin's northern and western margins.

TREWORGY, COLIN G. and CHERI A. CHENOWETH, Illinois State Geological Survey, Champaign, IL

Development of a Statewide, GIS-Based Inventory of Coal Resources for Illinois

A statewide, GIS-based (geographic information system) inventory of coal resources in Illinois has been developed to provide information on the quality, availability, and recoverability of the state's resources. The new database was assembled over a 9-month period from pre-existing digital data, newly digitized maps, and computer-contoured point-source data. The database contains resource information for 26 coal seams in 75 counties. The data include thickness, depth, mining status (minable, mined-out, inaccessible), sulfur content, heating value, and rank of the coal. Processing efficiency was enhanced by having individual staff members focus on specialized tasks (e.g. processing mine maps versus coal thickness maps). Detailed, on-line documentation was maintained to track and record the status of each component of information. Development of the GIS database revealed irregularities inherent in many paper-based resource inventories: some older base maps differed from newer ones digitized from more recent 7.5-minute quadrangles; depth and thickness contours on maps of adjoining areas commonly did not match and, in some cases, older boundaries of mined areas extended beyond more recent boundaries. Conversion of all the data to the new GIS resulted in some changes in volumetric values for coal seams in areas that had been neither re-mapped nor mined since the previous resource estimate. These volumetric changes were caused by improvements in base maps or differences between the algorithms used for volume calculations in the current vector-based GIS and earlier methods used to compute areas (e.g. grid-based GIS, hand planimetering, and dot-counting).

WARNER, TIMOTHY, West Virginia University, Department of Geology and Geography, Morgantown, WV

Integration of structural and geobotanical remote sensing for hydrocarbon microseep identification - preliminary results

WEGWEISER, MARILYN D., The Ohio State University, Department of Geological Sciences, Columbus, OH

Integration of Photomosaics and stratigraphy in the western Appalachian Basin as an Aid to Identify Potential Hydrocarbon Reservoirs

Paleozoic stratigraphy of the southern Lake Erie region is commonly interpreted as being dominated by flat-lying sedimentary rocks. Recent surface stratigraphic studies in New York, Pennsylvania, and Ohio have revealed the widespread presence of NW- and NE-trending folds and faults exposed along stream beds, and in bluffs along the southern Lake Erie shoreline. A black shale unit, previously unknown in northwestern Pennsylvania, was also discovered and its lateral continuity mapped. The shale forms a disconformable contact with the overlying Northeast Shale.

Ship-based photomosaics were made of bluffs along Lake Erie, and integrated with land-based stratigraphic sections to map the continuity of units, identify displacement zones, and identify low amplitude folds. The black shale unit aided identification of offset and folding. Faults observed at the surface offset Devonian and Mississippian rocks, and unconsolidated Quaternary sediments. Subsurface wrench faults, apparently extending into Precambrian rocks, have been identified by others. These wrench faults are generally perpendicular to the strike of the Appalachian Mountains, and are known as cross-strike discontinuities (CSDs). Principle zones of displacement associated with the CSDs can be recognized at the surface by numerous fractures having little offset, aligned drainage systems, and zones of increased hydrocarbon productivity and fluid migration. Increased hydrocarbon production occurs where reservoirs are cross-cut by the faults. The faults offset various reservoirs in Pennsylvania and Ohio in the subsurface. Identifying the location of these faults at the surface may provide information that leads to the discovery of new potential reservoirs.

WILSON, T. H., J. DOMINIC, J. HALVERSON, A. BURNS, and J. HOLMES, West Virginia University, Department of Geology and Geography, Morgantown, WV

Applications of fractals in the characterization of geologic data in the central Appalachians of West Virginia

This study evaluates the fractal characteristics of topographic and structural relief, drainage, and topographic contours, and examines the possibility of using fractals to quantify interrelationships between them. Local studies in a total of four areas extending from the Valley and Ridge across the Appalachian Plateau reveal significant differences in the fractal dimension of surface topography and suggest that fractals may provide a quantitative measure of structural control on topographic development.

A detailed study in the Valley and Ridge reveals systematic changes in the fractal dimension of topography along major structures where they cross the Parsons cross-strike discontinuity (CSD). The fractal dimension of structural relief was computed for several cross sections through the area, and a linear correlation was obtained between the fractal dimensions of topographic and structural relief.

The east margin of the Rome trough is defined by a major normal fault with several thousand feet of displacement. Fractal analysis of seismic profiles across the east margin of the trough reveal abrupt increases in fractal dimension between Precambrian basement and top of the Rome Formation, and between the Devonian Onondaga Limestone and Huron Shales. These differences are associated with Cambrian rifting and Alleghenian detachment, respectively. The east-margin fault was relatively inactive following the early Paleozoic and variation in the fractal dimension of surface topography is not observed locally across it; however, a significant difference is observed between the east and west margins of the trough suggesting the presence of possible regional influence of trough structure on topography.

In general our research indicates that fractals are a useful tool for quantifying interrelationships between various geological variables. More comprehensive studies are in progress.

WYATT, DOUGLAS E., Westinghouse Savannah River Company, Aiken, SC; and TOM J. TEMPLES, U. S. Department of Energy, Aiken, SC

Environmental Characterization of Shallow Channels, Joints and Faults in Unconsolidated Sediments using Ground Penetrating Radar

Environmental and geological characterization of the shallow subsurface in unconsolidated sediments may involve structures not readily detectable by conventional drilling and mapping techniques. A knowledge of these structures is required in environmental and geotechnical studies related to characterization, remediation and risk assessment programs. These features may act as preferential pathways for groundwater flow or as direct conduits to the water table. Ground Penetrating Radar (GPR) may be used to map these structures in favorable sediments.

Three principal shallow subsurface features are readily detectable using GPR: paleochannels, joints or fractures, and faults. The detection of paleochannels is dependent on the scale of the GPR survey and the attitude of the channel within the survey area. Channel morphological features such as scour surfaces, point bars and thalwegs are observable. Joints and fractures are more difficult to detect depending upon size, patterns, orientation and fill material. Vertical joints may not be visible to radar unless they are wider than the sampling interval or are filled with radar opaque materials such as limonite. Angled joints or fractures may be distinguished by an apparent continuous reflector on the radar profile. Faulting on radar profiles may be observed by the offset of reflectors, the image of the fault plane or the coherent interpretation of a fault system.

YEDLOSKY, ROBERT J., Consulting Geologist, Fairmont, WV

Concepts Relating Reservoir Mineralogy to Reservoir Interpretation, Completion and Economics

Reservoir interpretation using electric logs is affected by grain density and "irreducible water" saturation values. Standard assumptions used without direct well sample information are often dangerous and misleading. The grain density for "sandstone" is assumed to be 2.68 g/cc, but it may vary from 2.63 g/cc to 2.85 g/cc for Appalachian "sandstones". Examples are shown for various reservoirs.

Porosity/permeability relationships are determined by both pore size and shape. Examples of various Appalachian reservoirs are shown, demonstrating effects of diagenesis on pore sizes and shapes and the resultant permeability and irreducible water.

Reservoir composition and pore size are extremely important in determining completion methods. Examples of good and poor completion methods and the resultant well production (economics) are shown for some Appalachian Basin reservoirs.

Reservoir permeability as well as reservoir continuity and gas/fluid ratios are directly related to well drainage and thus well economics. Examples are shown.

Reservoir type and mineralogy are sometimes consistent within a given formation, but often are quite variable. The use of an average value for reserve interpretation or average type completion for a given formation is often dangerous. Examples are shown.

Electric logs have improved greatly over the past four decades, but studies of well samples and cores are still an extremely important aspect of reservoir analysis, well completion and well economics, and thus the success and economic stability of an oil and gas company.

ZHOU, GUOJUN, Houston, TX; ROBERT C. SHUMAKER*, West Virginia University Department of Geology and Geography, Morgantown, WV; and WILLIAM K. STAUB, Consolidated Gas Transmission Co., Clarksburg, WV

Subsurface Structure of the North Summit Gas Field, Chestnut Ridge Anticline of the Appalachian Basin

The Chestnut Ridge anticline is the westernmost of the High Plateau folds in southwestern Pennsylvania and north-central West Virginia that are detached primarily in the Marcellus Shale, and the Martinsburg, Salina, and Rome Formations. The primary, basal detachment at the Summit field occurs in the Salina salt. Production from fracture porosity in the Devonian Oriskany Sandstone commenced in 1936. During the late 1980s and early 1990s, 14 wells were drilled preparatory to conversion of the reservoir to gas storage. Schlumberger's Formation MicroScanner (FMS) logs were run in each of these wells to provide information on the structural configuration and fracture patterns of the reservoir. These data indicate that two inward-facing, tight folds at the Oriskany level form the upper flanks and core of the anticline at the northern end of the field, whereas the main part of the field to the south is a comparatively simple, broad closure at the Oriskany level. The structure is a broad, slightly asymmetric open fold in the Mississippian Greenbrier Formation at the surface.

Fracture patterns mapped using FMS logs indicate a complex fracture system which varies slightly along the trend of the fold and among the units analyzed, including the Helderberg Formation, Huntersville Chert, Oriskany Sandstone, and Onondaga Formation. An orthogonal joint system strikes toward the northwest and northeast slightly askew to the trend of the fold's crestal trace. A similar, but more complex fracture pattern is found in an oriented core of these units.