U.S. Geological Survey -- Science for a Changing World
Selected Presentations on Coal-bed Gas 
in the Eastern United States 
Edited By Peter D. Warwick 
Any use of trade, firm, or product names is for descriptive purposes only and does not 
imply endorsement by the U.S. Government 
Open-File Report 2004-1273 
U.S. Department of the Interior 
U.S. Geological Survey 

U.S. Department of the Interior 
Gale A. Norton, Secretary 
U.S. Geological Survey 
Charles G. Groat, Director 
U.S. Geological Survey, Reston, Virginia 2004 
Revised and reprinted: 2004 
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Contents 
Gas Resource Potential of Cretaceous and Paleogene Coals of the Gulf of Mexico Coastal Plain (including 
a review of the activity in the Appalachian and Warrior basins), by Peter D. Warwick, F. Clayton Breland, 
Jr., M. Edward Ratchford, and Paul C. Hackley  
Abstract  
Acknowledgements 
Outline  
Conclusions 
Literature Cited
Coalbed Methane Potential in Louisiana, by F. Clayton Breland, Jr 
Introduction and discussion  
Literature Cited 
The Pennsylvania Anthracite District Ð a Frontier Area for the Development of Coalbed Methane?, 
by Robert C. Milici  
Abstract 
Appalachian basin CBM Overviewt 
The Anthracite Region 
Potential Problems for CBM Development 
Favorable factors for CBM Development 
Questions  
Literature Cited
Geologic Heterogeneity and Coalbed Methane Production Experience from the Black Warrior Basin, 
by Jack C. Pashin 
Opening Points 
Infrastructure
Geologic Concepts  
Concluding Thoughts 



Warwick, P.D, Breland, F.C., Jr., Ratchford, M.E. and Hackley, P.C., 2004, 
Coal gas resource potential of Cretaceous and Paleogene coals of the 
Gulf of Mexico Coastal Plain (including a review of the activity in the 
Appalachian and Warrior basins), in Warwick, P.D., ed., Selected 
presentations on coal-bed gas in the eastern United States, U.S. 
Geological Survey Open-File Report 2004-1273, p. 1-25. 
Coal Gas Resource Potential of 
Cretaceous and Paleogene Coals 
of the Gulf of Mexico Coastal Plain 
(including a review of the activity in the 
Appalachian and Warrior basins)1 
By Peter D. Warwick2, F. Clayton Breland, Jr.3, M. Edward Ratchford4, and Paul C. Hackley2 

1 Modified from Warwick and others (2004); and unpublished short course notes from Short Course 8: Advances in 
coalbed methane exploration and development: A review of coalbed methane potential and opportunities in North 
America, American Association of Petroleum Geologists Annual Meeting, Dallas, TX, April 18, 2004; and Coalbed 
methane resources in the Southeast, Petroleum Technology Transfer Council, Central Gulf Region, Short Course, 
Lafayette, LA, June 8, 2004 
2 U.S. Geological Survey, Reston, VA 
3 Louisiana Geological Survey, Baton Rouge, LA 
4 Arkansas Geological Commission, Little Rock, AR 


Abstract 
The primary focus of this presentation is on the coal gas resource potential of Lower Cretaceous and 
Wilcox Group (Paleocene-Eocene) coals of the Gulf Coastal Plain. In addition, a brief review of the coalbed 
methane exploration activity and resources of the Appalachian and Black Warrior basin is provided. 
Recent investigations conducted by Federal, State, and industry organizations suggest that significant 
coalbed gas resources may exist in the lower Trinity Group and Hosston Formation (both Lower Cretaceous), 
Midway Group (Paleocene), and Wilcox Group (Paleocene-Eocene) of the Gulf of Mexico Coastal Plain. Drill 
records from Arkansas and Louisiana indicate that there are Cretaceous coal beds greater than 10 ft thick at depths 
of 1,500- 6,000 ft suitable for coalbed gas development. Vitrinite reflectance obtained from Cretaceous coal 
cuttings at these depths indicates that Romax equals up to 0.53%. Available data from conventional oil and gas wells 
in Louisiana indicate that upper, middle, and lower Wilcox Group coal zones have potential for coalbed gas 
accumulations and similar data from Texas, Arkansas, Mississippi, and Alabama indicate that gas may be present in 
coal beds of the lower and middle sections of the Wilcox. In addition, gas accumulations may occur in the coal beds 
of the upper part of the Midway Group in Mississippi and Alabama. Public data from several wells completed in 
Wilcox Group coal zones in north-central Louisiana indicate that initial production ranges from 7 to 122 thousand 
cubic feet (MCF) of gas per day and that production of saline water ranges from 0 to 550 barrels (bbls) per day. 
In Louisiana, the depth to the targeted Wilcox coal beds ranges from 1,500 to 5,000 ft, and individual coal 
beds have a maximum thickness of about 20 ft. The thickest coal beds tend to be in the lower Wilcox coal zone and 
cumulative coal thickness can exceed 100 ft. Although geochemical and petrographic data from Wilcox Group 
coals from across the region indicate that the coal beds are lignite in rank at depths less than 350 ft, they reach a rank 


of subbituminous B, or greater, at depths of approximately 5,000 ft. Preliminary gas isotope data indicate that 
Wilcox coal gas originated from the microbial reduction of CO2 and that in some places, these gases may be mixed 
with migrated thermal gases. Proximity to salt dome structures or buried Late Cretaceous igneous intrusions and 
associated geothermal heat flow may be important exploration tools for finding coal beds with elevated rank and 
potentially increased gas content. More data are needed to better characterize and assess the coalbed gas potential 
for the Cretaceous coal beds in this region. 
Current coal gas production in the Black Warrior basin is primarily located in Tuscaloosa, Jefferson, and 
Walker counties, Alabama. More than 1.5 trillion cubic feet (Tcf) of coal gas has been produced from the Black 
Warrior basin. In the Appalachian basin, current coal gas production is primarily located in southwestern Virginia 
and the adjacent part of southern West Virginia, and in northern West Virginia and adjacent parts of southwestern 
Pennsylvania. Cumulative coal gas production from the Appalachian basin is approximately 0.5 Tcf. 
Acknowledgements 
The U.S. Geological Survey and the Louisiana Geological Survey have Cooperative Research and 
Development Agreements with Devon SFS Operating, Inc., EnerVest Management Partners, Ltd., and Harvest Gas 
Management, L.L.C. Results of this research, which are currently proprietary, will be published in the near future. 
Cooperative research with these companies has led to a better understanding of the coal gas potential of the Gulf 
Coastal region. The Dolet Hills Mining Company provided access for mine coal sample collection and International 
Paper provided assistance in locating information on Cretaceous coal samples, and well logs from Arkansas. 


Outline of presentation. CBM = coalbed methane.


General rank of coal for major coalbed methane areas in the United States. Note that the rank of Gulf Coast coals increase with depth to sub-bituminous or greater. For later 
comparison to the Gulf Coast area, average coal gas and water production data are provided for the Powder River basin (Advanced Resources International [ARI], 2002). 
Note the location of the Appalachian and Black Warrior basins.

 
Major structural features (outlined in blue) of the Louisiana region of the Gulf Coast basin. Modified from Ewing and 
Lopez (1991).


Generalized Jurassic and Cretaceous stratigraphy of the northwestern part of Gulf Coastal Plain. Note the location of the 
Lower Cretaceous Hosston Formation clastic wedge. Modified from Goldhammer and Johnson (2001).


Paleogeographic map of the Lower Cretaceous Hosston Formation clastic wedge. Adapted from Schenk and others (1996) and Goldhammer and 
Johnson (2001). Note the location of the fluvial-deltaic depositional environments proposed by Goldhammer and Johnson (2001) for northern 
Louisiana and southern Arkansas. These were potentially good environments for peat (coal) accumulation. The star indicates the location of the 
Potlatch #1 well in southern Arkansas. The mud log from the Potlatch #1 well reported coal cuttings from intervals within and near the Hosston 
Formation. There are other wells in northern Louisiana that report the occurrence of coal cuttings in the Lower Cretaceous section (Jim York, 
personal communication, 2003).

Portion of the caliper, gamma ray, density, and neutron well logs from the Potlatch #1 well (API # 03011100770000) in Bradley County, 
Arkansas. The red shaded area indicates the probable coal intervals with interpreted thicknesses. Depths are in feet. Coal cuttings were 
recovered from the following intervals 3050-3060 ft, 3060-3070 ft, and 3070-3080 ft. The mud log from this well reported other coal intervals 
from 3440-3460 ft and 3470-3480 ft. Regional correlations with other well logs indicate that the Potlatch #1 coal intervals are within, or are 
associated with, the Hosston Formation (or lower Trinity Group and Travis Peak Formation of Haley, 1993).

Photomicrographs of coal cuttings from the Potlatch #1 well. Photo 14-03-04 08: Vitrinite groundmass with inertodetrinite in the upper left and 
semifusinite showing remnant cell structures in the lower right of the photomicrograph; sample from the 3050-3060 ft interval, 500X magnification 
in reflected white light. Photo 14-03-04 17: Telinite showing well preserved cell structures; sample from the 3060-3070 ft interval, 500X 
magnification in reflected white light. Photo 14-03-04 22: Alginite with exsudatinite filling cracks; sample from the 3070-3080 ft interval, 500X 
magnification in blue light fluorescence. Photo 14-03-04 11: Alginite and resinite filling cell structures; sample from the 3060-3070 ft interval, 
500X magnification in blue light fluorescence.

Summary of findings for Cretaceous age coal from Arkansas and neighboring states. hvCb = high volatile C bituminous.

Generalized coal-bearing stratigraphy of the upper Cretaceous, Paleocene and Eocene of the Gulf Coastal Plain. From Warwick and others (2000b).

Outcrop of Paleocene and Cretaceous coal-bearing units in the Gulf Coastal Plain. The area shaded dark blue shows the area where the depth to 
the top of the Wilcox Group ranges from 1000 to 6000 ft. The heavy solid red line is the line of section on the next illustration. Modified from 
Barker and others (2000).

Generalized cross section showing the major Tertiary aquifers and confining units in the Mississippi Embayment and southern Louisiana. Note 
that much of the aquifer systems are filled with saline water derived from groundwater interaction with salt diapers (Huff and Hanor, 1997). 
Geopressured sediments are found at depth. Diagram modified from Williamson and others (1990). Holo. = Holocene; Mio = Miocene; L = 
Lower; M = Middle; U = Upper.


Review of coal bed methane (CBM) drilling activity in northern Louisiana since 2001. Approximately 15 wells have been drilled specifically for 
coal bed gas exploration or production. Boxes indicate company name, number of wells drilled or producing (prod.), year of first well (in 
parentheses), initial production of gas and water (if available), and total depth (TD) of the wells. Dotted lines indicate 1,000 to 6,000 ft depth range 
to the top of the Wilcox Group. Well data from Louisiana Department of Natural Resources Strategic Online Natural Resources Information System 
[http://sonris-www.dnr.state.la.us/www_root/sonris_portal_1.htm].

Example of well log stratigraphy and coal intervals (shaded in red) in the King Drilling LA Pacific Et Al #1 well in La Salle Parish, Louisiana. 
Note that there are multiple coal zones in the Wilcox and that the thickest coal beds tend to be in the lower part of the Wilcox. The log on the right 
is the expanded Wilcox part of the log on the left. On well logs consisting only of spontaneous potential (SP) and resistivity (Res), coal beds are 
hard to distinguish from limestone beds. Well data from Louisiana Department of Natural Resources Strategic Online Natural Resources 
Information System [http://sonris-www.dnr.state.la.us/www_root/sonris_portal_1.htm]. 

Example of well log stratigraphy with coal (shaded in red) and limestone (shaded in blue) intervals in the Woods Oil and Gas (John B. Company), IPCO #1 well in Caldwell 
Parish, Louisiana. Note that the thickest coal beds are in the lower part of the Wilcox. The log on the right is the expanded Wilcox part of the log on the left. On well logs that 
include gamma ray (GR), sconic (S), and neutron (N), coal and limestone beds are easily distinguished. Formation density curves are also very useful for coal identification. 
Well data from Louisiana Department of Natural Resources Strategic Online Natural Resources Information System [http://sonriswww.
dnr.state.la.us/www_root/sonris_portal_1.htm]. SP = spontaneous potential; Rwa = apparent formation water resistivity, Rt = resistivity. Ro data from J.B. Echols, personal 
communication, 2001.

Plot of public coal reflectance data (Ro %) against depth for the Louisiana area. Vertical dashed lines indicate approximate boundaries between 
lignite (lig), subbituminous (sub), and high-volatile bituminous (hvb) coal ranks. A dashed best-fit line (exponential) is plotted that illustrates the 
approximate change of rank with depth. The trend line is based on public and confidential data. The wide scatter in the data may reflect variable 
heat flow rates and associated maturity in different parts of the basin. Sample states are indicated for each data set. Potlatch #1 data are from this report. Unpub. = unpublished.

Plot of the isotopic values of carbon (C) and hydrogen (D) with fields showing the origin of gases after Whiticar and others (1994). For reference, Powder River (PRB) coals 
primarily plot in the biogenic fermentation field. Wilcox coal gas from north Louisiana (a) plots within the biogenic CO2 reduction field, whereas gas collected from 
conventional Wilcox sandstone reservoirs (b) falls within (near) the transition zone between biogenic and mature thermogenic gases. Coal gas collected from a shallow (380 ft) 
well in northeast Texas also (c) plots within the transition zone indicating that these gases may have originated from mixing of mature gases and gases with a biogenic, CO2 
reduction origin. The red arrow indicates the proposed migration direction and mixing pathway of thermal gas. Sources of data for the PRB = Gorody (1999); North Louisiana 
Wilcox coal = Harry Spooner, written communication, 2001; north Louisiana Wilcox conventional sandstone (SS) reservoir gas = unpublished (unpub.) Louisiana Geological 
Survey (LGS) data; Texas Wilcox coal = Warwick and others (2000b). PDB = Pee Dee Belemnite; SMOW = standard mean ocean water.


Photograph of coal fractures and cleats in the Oxbow Lignite mine in northwestern Louisiana. 


Diagram from Warwick and others (2002) which indicates potential coalbed methane prospects and plays (boxes). Based on the current coal gas 
exploration efforts in north Louisiana and the occurrence of bituminous Cretaceous coal in southern Arkansas, the potential exploration areas have 
been expanded as indicated by the heavy blue lines. Red shaded areas illustrate the depth to the top of the Wilcox Group, and ranges from 500 ft 
(light red) to 6000 ft (dark red). Outcrop of the Wilcox is indicated by the orange color and yellow indicates the location of other coal-bearing 
basins. Base map after Barker and others (2002).



 
Map of Alabama coal fields and coalbed gas production areas. Cumulative gas production (CBM) by county is indicated by color fill. For an 
estimate of the remaining coal gas resources of the Black Warrior basin see Hatch and others (2003). Illustration from Milici, written 
communication, 2004.


USGS coal gas (CBM) assessment map of northern and central Appalachian basin coal fields and coalbed gas production fields. For an estimate of the 
remaining coal gas resources of the Appalachian basin see Milici and others (2003). MPS = Minimum Petroleum System; AU = Assessment Unit. 
Illustration from Milici, written communication, 2004.


Conclusions 
 Cretaceous coals of the northern Gulf Coastal plain 
should be evaluated for their CBM potential 
 Wilcox coals contain saline water; initial gas isotope 
data indicates that Wilcox coal gas originated from 
biogenic reduction of CO2; coal rank increases to near 
hvCb with depth 
 Early production data from Wilcox coals indicate that 
there is a potential resource of coal-bed gas underlying 
a large area in the Gulf Coastal Plain 
 There is potential for enhanced coal-bed methane 
production and CO2 storage in the Gulf Region. This 
may includes the possibility of methane generation from 
reduction of introduced CO2 
Conclusions. CBM = coalbed methane; hvCb = high volatile C bituminous.

 
Literature Cited 
Advanced Resources International, 2002, Powder River basin coalbed methane development and produced water 
management study: U.S. Department of Energy, Office of Fossil Energy and National Energy Technology 
Laboratory Report DOE/NETL-20031184, various pagination, 
http://www.netl.doe.gov/scng/policy/refshelf/PowderRiverBasin.pdf 
Barker, C.E., Biewick, L.R.H., Warwick, P.D., SanFilipo, J.R., 2000, Preliminary Gulf Coast coalbed methane 
exploration maps: depth to Wilcox, apparent Wilcox thickness and vitrinite reflectance: U.S. Geological 
Survey Open-File Report 00-113, 2 sheets. 
Brown, C.S., 1907, The lignite of Mississippi: Mississippi State Geological Survey Bulletin No. 3, 71 p. 
Ewing, T.E., and Lopez, R.F., 1991, Principal structural features, Gulf of Mexico basin, in Salvador, Amos, ed., The 
Gulf of Mexico Basin: The Geological Society of America, The Geology of North America, v. J, Plate 2, 1 
sheet. 
Goddard, Donald, and Echols, John, 1995, Chapter 5-Organic Geochemistry, in Goddard, Donald, ed., Deltaic 
reservoir characterization-geological, petrophysical and engineering applications: Basin Research Institute 
Technical Report No. 5, Louisiana State University, Baton Rouge, p. 78-90. 
Goldhammer, R.K., and Johnson, C.A., 2001, Middle Jurrassic-Upper Cretaceous paleogeographic evolution and 
sequence-stratigraphic framework of the northwest Gulf of Mexico rim, in Bartolini, c. Buffler, R.T., and 
Cantœ ÐChapa, eds., The western Gulf of Mexico Basin: Tectonics, sedimentary basins, an d Petrolum 
systems: American Association of Petroleum Geologists Memoir 75, p. 45-81. 
Gorody, A.W., 1999, The origin of natural gas in the Tertiary coal seams on the eastern margin of the Powder River 
Basin, in Miller, W.R., ed., Coalbed Methane and the Tertiary geology of the Powder River Basin Wyoming 
and Montana: Wyoming Geological Association Fiftieth Field Conference Guidebook, p. 89-101. 
Haley, B.R., comp., 1993, Geologic map of Arkansas: Arkansas Geological Commission and the United States 
Geological Survey, scale 1:500,000, 1 sheet. 
Hatch, J.R., Pawlewicz, M.J., Charpentier, R.R., Cook, T.A., Crovelli, T.R., Klett, R.M., Pollastro, R.M., and Schenk, 
C.J., 2002, Assessment of Undiscovered Oil and Gas Resources of the Black Warrior Basin Province: U.S. 
Geological Survey Fact Sheet 038-03, 2 p. http://pubs.usgs.gov/fs/fs-038-03/ 
Huff, G.F. and Hanor, J.S., 1997, Origin and environmental application of depth-related strontium-isotope ratios in 
brines from the Wilcox Group (middle Wilcox aquifer) of east central Louisiana: Gulf Coast Association of 
Geological Societies Transactions, v. 47, p. 221-229. 
Milici, R.C., Ryder, R.T., Swezey, C.S., Charpentier, R.R., Cook, T.A., Crovelli, R.A., Klett, T.R., Pollastro, R.M., and 
Schenk, C.J., 2002, Assessment of Undiscovered Oil and Gas Resources of the Appalachian Basin 
Province, U.S. Geological Survey Fact Sheet 009-03, 2 p. http://pubs.usgs.gov/fs/fs-009-03/ 
Monroe, W.H., Conant, L.C., and Eargle, D.H., 1946, Pre-Selma Upper Cretaceous stratigraphy of western Alabama: 
American Association of Petroleum Geologists Bulletin, v. 30, no. 2, p. 187-212. 
Mukhopadhyay, P.K., 1989, Organic petrography and organic geochemistry of Texas Tertiary coals in relation to 
depositional environment and hydrocarbon generation: The University of Texas at Austin Bureau of 
Economic Geology Report of Investigations 188, p. 1-118. 
Price, L.C., 1991, On the origin of the Gulf Coast Neogene oils: Transactions-Gulf Cast Association of Geological 
Socities, v. 41, p. 524-541. 
Schenk, C.J., and Viger, R.J., 1996, East Texas Basin Province (048) and Louisiana-Mississippi Salt Basins 
Provinces (049), Region 6; Gulf Coast, Geologic Framework, in Gautier, D. L., Dolton, G.L., Takahashi, K.I., 
and Varnes, K.L., eds., 1995 National assessment of United States oil and gas resources--Results, 
methodology, and supporting data: U.S. Geological Survey Digital Data Series DDS-30, Release 2, one CDROM, 
95 p. 
http://certmapper.cr.usgs.gov/data/noga95/prov49/text/prov49.pdf 
Warwick, P.D., Barker, C.E, and SanFilipo, J.R., 2002, Preliminary evaluation of the coalbed methane potential of the 
Gulf Coastal Plain, USA and Mexico, in Schwochow, S.D., and Nuccio, V.F. (eds.), Coalbed Methane of 
North America II: Rocky Mountain Association of Geologists, p. 99-107. 
Warwick, P.D., Barker, C.E., SanFilipo, J.R., Biewick, L.R.H., 2000a, Preliminary evaluation of the coalbed methane 
resources of the Gulf Coastal Plain: U.S. Geological Survey Open File Report 00-143, 43 p. 
http://pubs.usgs.gov/of/of00-143/ 
Warwick, P.D., Barker, C.E., SanFilipo, J.R., Morris, L.E., 2000b, Preliminary results from coal-bed methane drilling in 
Panola County, Texas: U.S. Geological Survey Open File Report 00-048, 30 p. http://pubs.usgs.gov/of/of00- 
048/ 
Warwick, P.D., Breland, F.C., Ratchford, M.E., Ingram, S.L. Sr, and Pashin, J.C., 2004, Coal gas resource potential 
of Cretaceous and Paleogene coals of the eastern Gulf of Mexico Coastal Plain: Geological Society of 
America Northeast/Southeast Section Meeting, Abstracts with Programs, v. 36, no. 2, p. 53. 
http://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70337.htm 
Williamson, A.K., Grubb, H.F., and Weiss, J.S., 1990, Ground-water flow in the Gulf Coast aquifer systems, south 
central United StatesÑA prelimary analysis: U.S. Geological Survey Water-Resources Investigations Report 
98-4071, 124 p. 
Whiticar, M.J., 1994, Correlation of natural gases with their sources, in Magoon, L.B., and Dow, W.G., eds., The 
petroleum system Ð from source to trap: American Association of Petroleum Geologists Memoir 60, p. 261- 
283. 








Breland, F.C., Jr., 2004, Coalbed methane potential in Louisiana, in 
Warwick, P.D., ed., Selected presentations on coal-bed gas in the 
eastern United States, U.S. Geological Survey Open-File Report 2004- 
1273, p. 27-35. 
Coalbed Methane Potential in Louisiana1 
By F. Clayton Breland, Jr.2 


1 Modified from unpublished short course notes from Short Course #4, Coalbed methane potential in the U.S. and 
Mexican Gulf Coast, Gulf Coast Association of Geological Societies/Gulf Coast Section SEPM Ð 52nd Annual 
Convention, Austin, TX, October 30, 2002. 
2 Louisiana Geological Survey, Baton Rouge, LA 


Introduction and discussion 
Recent reports indicate that while gas resource numbers may be increasing, domestic production has not 
kept pace with domestic demand (Duval and Chabrelle, 2001). Alternative sources of gas including unconventional 
accumulations such as coalbed methane (CBM) must be explored and developed domestically to offset increasing 
demand for natural gas. Most recent estimates of CBM resources of 1,777 trillion cubic feet (Tcf) Gas-In-Place 
(GIP) compared to 1,431 Tcf of U.S. conventional natural gas are indeed impressive (Scott, 2001). Presently, CBM 
supplies more than 7% of total domestic natural gas production and is projected to increase as a percentage of 
domestic production as more producing wells come on line in CBM basins nationally (Scott, 2001). 
CBM production has been established in a number of basins in the U.S., notably from Paleozoic coals in 
the east and from younger, thicker coals in the west. However, very limited drilling activity has been conducted in 
the Gulf Coast Tertiary basin to define the CBM resource specifically. The age, thickness, and quality of the Gulf 
Coast coals have generally been considered a negative contributing factor in the potential development of the 
resource. With the success of CBM in the Tertiary-aged coals of the Powder River basin, a closer look at the CBM 
potential of the Gulf Coast coals is warranted. By way of comparison, according to the Gas Technology Institute 
(2001), the Powder River basin contains 1,300 billion short tons (bst) estimated in-place coal with 39 Tcf estimated 
coalbed GIP and 24 Tcf recoverable gas, and the Gulf Coast Coal Region has 400 bst estimated in-place coal with 8 
Tcf estimated coalbed gas-in-place. 
Initial evaluation of the coal resource in Louisiana was conducted by the Louisiana Geological Survey 
(LGS) (Meager and Aycock, 1942; Roland and others,1976) and focused on the distribution of surface and nearsurface 
coals. Coals are mined at the surface in central northwestern Louisiana, in and around the Dolet Hills 
vicinity in De Soto Parish where the Wilcox Group (Paleocene-Eocene) crops out. The coals are generally confined 
to the lower Tertiary Wilcox Group and to a lesser extent to the overlying Eocene Claiborne and Jackson Groups. 
The coals appear to be widely distributed and some deposits are as thick as 10 ft. The coals are classified as lignites 
based on an average calorific value of 7,480 Btu per pound. Sulfur content is low, averaging 0.91 weight percent as 
received (ar) (Williamson, 1986). 
Coates (1979) and Coates and others (1980) conducted research on the distribution and depositional 
environment of Wilcox lignites in the west-central Louisiana subsurface using well logs. These studies indicated 
that in the study area, the Lower Wilcox is a progradational delta complex to the east and a marginal delta plain to 
the west. They also noted that the Lower Wilcox is the major lignite-bearing interval containing as many as 35 coal 
seams (fig. 2). In an adjacent area with abundant subsurface data to the east, LGS has recognized the presence of 
numerous coal beds in the Lower Wilcox, with total coal thickness of a little more than 100 ft (fig. 3). 
Warwick and others (2000) drilled two CBM test wells in Panola County, Texas, near Dolet Hills and 
reported calorific values above 8,300 Btu/lb, the boundary between lignite and subbituminous coal from shallow 
samples collected from 350 ft to 370 ft. Sulfur content averaged 0.52 percent (ar). Desorption analysis of the 


samples yielded an average gas content of 11 scf/ton dry-ash free (daf). Published adsorption values (Pratt and 
others, 1999) from the Powder River basin have similar adsorption values as those obtained from samples from the 
Texas wells. Isotope work on the Texas gas samples indicated a transitional biogenic/thermogenic mixed origin for 
the coal gases. Echols (1995) reported that analysis of gas samples from Paleocene-Eocene Wilcox conventional gas 
reservoirs in Winn Parish, Louisiana, believed to be sourced by CBM, were 99.94 percent methane and biogenic in 
origin. 
Drilling in central North Louisiana in the prolific conventional Paleocene-Eocene Wilcox trend established 
the presence of numerous coal beds (fig. 4). Investigations by LGS initially defined a Central Louisiana Coalbed 
Methane basin (CELCOM), from detailed study of Caldwell and LaSalle, Parishes, Louisiana (Echols, 2000). There 
is every indication, based on previous work, (such as Coates and others, 1980; Rogers, 1983), that CELCOM 
extends to the southwest and northeast portions of North Louisiana (fig. 2). In fact, the name CELCOM was used for 
reference purposes only and is actually only a small portion of the entirety of the Gulf Coast Tertiary Coalbed 
Methane Basin which covers parts of seven southeastern states. 
The first CBM production in Louisiana (and the Gulf Coast Tertiary CBM basin) was established in the 
Russell coal bed in April 1989 in Section 21, T14N, R4E, Caldwell Parish with the Torch Operating Co. #3 Greer 
well (figs. 2 and 5). The Torch #3 Greer came in flowing at 50 thousand cubic feet of gas per day (Mcfg/d) and 65 
barrels of water per day (bblw/d) but was plugged and abandoned in 1989. More recently and in the same coal, the 
Woods Oil and Gas Co. IPCO #1 (completed 3/9/01) in Section 5, T11N, R3E, produced 15 Mcfg/d and almost no 
water (figs. 2 and 6). In an effort to stimulate gas flow, the IPCO #1 was water fraced approximately five months 
after completion. The procedure had the opposite effect of reducing gas flow and the well was later plugged and 
abandoned. In the area of detailed study in Caldwell and LaSalle Parishes, LGS has determined that the Russell coal 
is generally between 12 and 15 ft thick and calculated (using 13.5 ft as average thickness, coal specific gravity of 
1.30, and 115 standard cubic ft of gas per ton of coal) an estimate of 63.3 billion cubic ft of coalbed methane gas 
GIP for the Russell coal in T11N-R3E. Based on other coalbed studies in east Texas (Griffiths and Pilcher, 2000), 
this GIP may be relatively low. More knowledge gained from tests and production from coalbed methane wells in 
the North-Central Louisiana should, however, provide more reliable estimates. 


Figure 1. Coal map of the United States with Gas-In-Place (GIP) estimates in trillions of cubic feet (Tcf). Base map from USGS 
unpublished data; GIP estimates from Gas Technology Institute (2001).



Figure 2. Structure map showing top (elevation below sea level; contour interval = 200 ft) of the Wilcox Group and location of existing oil and gas 
fields. The potential outline (red line) of a coalbed methane basin is indicated (from Echols, 2000). The distributions of Wilcox coal-bearing facies 
(1-5, modified from Coates and others, 1980) in North-Central Louisiana are also shown. The locations of two wells that have produced coal gas 
are indicated. Blue grid lines indicate Township and Range (red labels).



Figure 3. Histograms showing cumulative thickness of coal beds in each 100 ft interval below the top of the 
Wilcox Group (resistivity > 50 ohms). All wells are in LaSalle Parish, Township 10 N, Range 3 E (see fig. 2). 
SN = Louisiana well serial number. 



Figure 4. Type well logs (spontaneous potential, SP, and resistivity, Res.) for the coal-bearing Wilcox Group in Caldwell 
and LaSalle parishes in north Louisiana. Type log selected for the area is the Placid Oil Co., #214 Louisiana O&G Co., 
sec 15, T10N, R3E, LaSalle Parish (Olla Field), modified from Echols (2001).


Figure 5. Portion of the electric log showing the Russell coal zone in the Greer # 3 well.



Figure 6. Portion of the electric log showing the Russell coal zone in the IPCO #1 well. GR = gamma ray; SP = 
spontaneous potential; RWA = apparent formation water resistivity; SN = short normal log; ILD = deep induction log



Literature Cited 
Coates, E.J. , 1979, The Occurrence of Wilcox Lignite in West-Central Louisiana: Baton Rouge, Louisiana State 
University, M.S. thesis, 249 p. 
Coates, E.J., Groat, C.G., Hart, G.F., 1980, Subsurface Wilcox Lignite in West-Central Louisiana, Transactions Gulf 
Coast Association of Geological Societies, v. 30, p. 309-332. 
Duval, B. and Chabrelle, M..F., 2001, Strategic Trends and Challenges in Gas Exploration, 2001 American 
Association of Petroleum Geologists Annual Convention, June 3-6, 2001, Denver, Colorado, Official 
Program, v. 10, p. A54. 
Echols, J.B., 1995, Coalbed Methane--A Production Energy Source in the Paleocene-Eocene Wilcox of Central 
Louisiana and Southwest Mississippi, Basin Research Institute Bulletin, v. 5, p. 3-6. 
Echols, J.B., 2000, Coalbed Methane--LouisianaÕs Unexplored Energy Resources, Basin Research Institute Bulletin, 
v. 9, p. 18-27. 
Echols, J.B., 2001, The producibility of coalbed methane from Wilcox coals in Louisiana: Gulf Coast Association of 
Geological Societies Transactions, v. 51, p. 75-84. 
Gas Research Institute, 1999, North American coalbed methane resource map: Gas Research Institute Gas Tips, 
Chicago, Illinois, vol. 5, no. 2, 1 sheet. 
Gas Research Institute, 2001, North American coalbed methane resource map: Gas Research Institute Gas Tips, 
Chicago, Illinois, 1 sheet. 
Griffiths, J.C., and Pilcher, R.C., 2000, Coalbed methane potential of the upper Texas Gulf Coast, in Coalbed and 
Coal Mine Methane Conference, Denver, Colorado, March 27-28, 2000 [Proceedings]: New York, Strategic 
Research Institute, unpaginated. 
Meager, D.P. and Aycock, L.C., 1942, Louisiana Lignite, Louisiana Geological Survey Pamphlet., no. 3, 56 p. 
Pratt, T.J., Mavor, M.J., and DeBruyn, R.P., 1999, Coal gas resource and production potential of subbituminous coal 
in the Powder River Basin: 1999 International Coalbed Methane Symposium Proceedings, Tuscaloosa, p. 
23-34. 
Roland, H.L., Jr., Jenkins, G.M., and Pope, D.E., 1976, Lignite--evaluation of near-surface deposits in northwest 
Louisiana, Louisiana Geological Survey, Department of Conservation, Mineral Resources Bulletin no. 2., 39 
p. 
Rogers, J.S., 1983, The occurrence of deep basin lignite in the Wilcox Group of northeast Louisiana: Baton Rouge, 
Louisiana State University, M.S. thesis, 165 p. 
Scott, A., 2001, EMD Takes Unconventional Role: American Association of Petroleum Geologists Explorer, August, 
2001, p. 55. 
Warwick, P.D., Barker, C.E., SanFilipo, J.R., and Morris, L.E., 2000, Preliminary results from the coal-bed methane 
drilling in Panola County, Texas: U.S. Geological Survey Open File Report 00-0048, 30 p. 
Williamson, D.R., 1986, Lignites of northwest Louisiana and the Dolet Hills lignite mine, in Finkelman, R.B., and 
Casagrande, D.J., eds., Geology of Gulf Coast lignites: Houston, Environmental and Coal Associates, p. 
13-28. 

 
 
 
 

Milici, R.C., 2004, The Pennsylvania Anthracite District Ð a frontier area for 
the development of coalbed methane?, in Warwick, P.D., ed., Selected 
presentations on coal-bed gas in the eastern United States, U.S. 
Geological Survey Open-File Report 2004-1273, p. 37-59. 
The Pennsylvania Anthracite District Ð 
a Frontier Area for the Development of 
Coalbed Methane?1 
By Robert C. Milici2 
Abstract3 


1 Presented at 2004 combined annual meeting of the NE/SE Section of the Geological Society of America 
2 U.S. Geological Survey, Reston, VA 
3 Reprinted from Milici (2004) 



The anthracite region of eastern Pennsylvania consists of four major coal fields that are within the folded 
and faulted Appalachians, in the Valley and Ridge and Appalachian Plateaus physiographic provinces. These are, 
from south to north, the Southern Anthracite field, the Western Middle Anthracite field, the Eastern Middle 
Anthracite field, and the Northern Anthracite field. Rank of the coal ranges from semi-anthracite to anthracite. In 
general, the anthracite fields consist of Pennsylvanian strata that are complexly folded, faulted, and preserved in 
structural synclines within older Paleozoic strata. 
Published gas-in-place (GIP) data for Pennsylvania anthracite range from 6.4 SCF/ton (0.2 cc/g) for the 
Orchard coal bed to a high of 691.2 SCF/ton (21.6 cc/g) from a sample of the Peach Mountain coal bed that was 
collected in the Southern Anthracite field at a depth of 685 feet. This is the largest GIP value that the U.S. Bureau of 
Mines (USBM) (Diamond et al, 1986) reported for coalbed methane (CBM) nationwide. Of the 11 CBM analyses 
reported for the Southern Field by USBM, seven exceed 396 SCF/ton (12.4 cc/g) (average of 11 samples: 325.8 
SCF/ton [10.2 cc/g]). In addition, adsorption isotherms for the Mammoth, Seven-Foot, and Buck Mountain coal 
beds in the Southern Field indicate that these beds have a very high capacity to hold methane under pressure (Lyons 
et al, 2003), with values that range from about 320 to 850 SCF/ton (10 to 27 cc/g). 
In spite of the complex geologic structures, there are several areas in the Southern Anthracite field where 
subhorizontal to moderately inclined coal beds may be accessed by the drill. For example, a detailed map and 
sections by Wood (1972) in Schuylkill County, Pennsylvania, has defined several areas of subhorizontal to gently 
inclined strata that contain 10 or more coal beds at depths of 500 to 2000 feet (150 to 600m), and with a cumulative 
coal thickness of 50 feet (15m), or more. 
These data suggest that the Pennsylvania anthracite district is, at least, worthy of testing for CBM, using 
current desorption methodology and with coal samples collected from several coal beds in a single core hole. 
 
Appalachian Basin CBM Appalachian Basin CBM 
Overview Overview


Cumulative coalbed methane (CBM) production by county in the northern and central Appalachian coal fields as of 
2003. MM = million; B = billion; T = trillion. See next slide for data sources.

 


Cumulative production of CBM from the Appalachian Basin (1999-2003 data). Source of data: Alabama State Oil and Gas Board (2004); Kentucky 
Division of Gas and Oil (2004); Markowski (2004); Virginia Center for Coal and Energy Research (2004), and Avary (2004).




In-place gas values by county in cubic feet per ton (Diamond and others, 1986; in CF/TON). N = number of samples in the 
county; the values presented are the largest for each county represented. USBM = U.S. Bureau of Mines. Vitrinite reflectance 
line of 0.8 %Ro separates relatively immature region on the west from mature region on the east, similar to thermal maturation 
patterns in Alabama (Pashin and Hinkle, 1997).

 
Location and vitrinite reflectance values (%Ro) for coal samples studied courtesy of Leslie Ruppert, USGS. Illustration shows the 
minimum petroleum system boundaries for the Dunkard (Northern Appalachian) and Pocahontas basins, the folded and unfolded 
parts of the Dunkard basin, and a generalized boundary between thermally mature and immature coal beds. C. = Central, N. = 
Northern, App. = Appalachian, MPS = Minimum Petroleum System.

 
The Anthracite Region

 
Map 11, Pennsylvania Bureau of Topographic and Geologic Survey, http://www.dcnr.state.pa.us/topogeo/maps/map11.pd.


Although there is a great deal of difference, geologically, between the Pocahontas basin and the Pennsylvania anthracite district, the 
regions do exhibit some common characteristics. Gas-in-place data, the maximum for each basin (Diamond and others, 1986), in 
cubic feet per ton (cf/ton) were obtained from desorbing coal core samples under ambient conditions. Max = maximum. 

 
Data from Diamond and others (1986). Gas-in-place data were measured under ambient conditions. See earlier slide for number 
of samples per county.


The slide shows increase of thermal maturity from west to east across the northern part of the Appalachian coalfields. %Ro 
values range from about 2 on the western side of the anthracite region to 5, or more, in the Southern Anthracite Coalfield (data 
from Ruppert, written communication, 2002, and Hower and others, 1993).

 
CBM desorption values, in ambient cubic feet per ton, obtained by the U.S. Bureau of Mines for the Northern and 
Southern Anthracite fields in Pennsylvania (Diamond and others, 1986).

 
Generalized stratigraphic column for the Northern and Southern Anthracite fields (adapted from Arndt and others, 1968; gas Arndt and others, 1968; gas 
data from Diamond and others, 1986). Coal bed names are shown g data from Diamond and others, 1986). Coal bed names are shown generally on right of column, together with maximum tested enerally on right of column, together with maximum tested 
values for gas content; names or numbers in red are for coal bed values for gas content; names or numbers in red are for coal beds for which there is gas s for which there is gas-in in-place data. Numbers on the left side place data. Numbers on the left side 
of columns show the average thicknesses of the coal beds. of columns show the average thicknesses of the coal beds.

 
Part of Pennsylvania Topographic and Geologic Survey Map 11, showing the general location of the Schuylkill quadrangle (Wood, 
1972) and two closely spaced USBM core holes (Trevits, and others, 1988). See earlier slide for explanation of colors.

In this illustration, the faults are shown in red and the coal beds in black, except for Coal bed 23, which is colored blue and 
yellow. Synclinal axes are shown in blue and anticlinal axes in green. The location of the cross section partly illustrated in the 
following slide (WoodÕs Section H) is shown by the straight blue line. The part of the section shown is indicated by the solid line. 
Note that the mapped area may be divided into an imbricate thrust-faulted zone, with strata that are moderately inclined to the 
southwest, and the Llewellyn syncline, which contains beds that are tightly folded. The scale of WoodÕs (1972) published map is 
1:12,000.


Note that the Pottsville Formation (Pp) is shown in yellow, and the Llewellyn Formation (Pl) with vertical ruled lines. The 
Primrose (Pr), Orchard (O), Peach Mountain (PM), and Tunnel (TU) coal beds are high-lighted in dashed green. Solid greencolored 
coal beds along the surface of the section have been mined. Section G is one mile northeast of section H.


USBM Boreholes USBM Boreholes 
 Two holes drilled in Minersville 
Quadrangle in 1975 (Trevits and others, 
1988) 
Ð 1. Drilled to 1,948 feet, stuck, flooded; 6 coal 
beds perforated, stimulated; Peach Mountain 
had 640 cu ft/ton, low porosity and 
permeability; little gas. 
Ð 2. Drilled to 2,355 feet; 8 coal beds perforated 
and stimulated; Tunnel coal 482 cu ft/ton, low 
porosity and permeability; little gas. 


Cross section from Trevits and others, 1988, Figure 9-17.


Is there gas?
Explosions of fire-damp (CH4) in Anthracite coal mines 1870 to 1880

YEAR NUMBER 
1879 100 
1878 29 
1877 71 
1876 65 
1875 59 
1874 77 
1873 74 
1872 81 
1871 83 
1870 40 
Total 679 
Casualties 1127; deaths 225 
Data from Chance (1883). 


Potential Problems for CBM Potential Problems for CBM 
Development Development 
¥ Complex geologic structure; subsurface geology 
may not be as shown in cross Ðsections. 
¥ Many surface and deep mines. 
¥ Adequate seals, gas leakage? 
¥ USBM Well, Minersville quadrangle, low porosity 
and permeability? 
¥ Development of drilling units in areas of complex 
structure. 
¥ Water disposal amounts and quality unknown. 
Potential problems for CBM development.

 
Favorable factors for CBM Favorable factors for CBM 
Development Development 
¥ Detailed Geologic studies. 
¥ Many thick coal beds Ð great cumulative 
coal thickness, perhaps up to 100 feet 
locally. 
¥ High GIP values. 
¥ Good fractures, porosity, permeability? 
¥ Thermally mature or post mature. 
¥ Close to local markets. 
Favorable factors for CBM development. GIP = Gas-in-Place.

 
Questions Questions 
¥ Does the coal have sufficient 
microporosity and permeability to store 
and release gas at economically sufficient 
rates to warrant development? 
¥ Can we dewater the coal beds sufficiently 
to improve permeability and release 
methane to the well bore? 
A major question for CBM development.


Literature Cited 
Arndt, H.H., Averitt, Paul, Dowd, James, Frendzel, D.J., and Gallo, P.A., 1968, Coal, in U.S. Geological Survey and 
U.S. Bureau of Mines, Mineral Resources of the Appalachian region: U.S. Geological Survey Professional 
Paper 580, p. 102-133. 
Avary, K.L. 2004, Coal-bed methane (CBM) wells: http://www.wvgs.wvnet.edu/www/datastat/datastat.htm 
Alabama State Oil and Gas Board, 2004, Coalbed methane resources of Alabama: (http://www.ogb.state.al.us/). 
Chance, H.M., 1883, Report on the mining methods and appliances used in the anthracite coal fields: Second 
Geological Survey of Pennsylvania, Harrisburg, 574p. 
Diamond, W.P., LaScola, and Hyman, D.M., 1986, Results of direct-method determination of the gas content of U.S. 
coalbeds: U.S. Bureau of Mines Information Circular 9067, 95 p 
Hower, J.C., Levine, J.R., Skehan, J.W., Daniels, E.J., Lewis, S.E., Davis, Alan, Gray, R.J., and Altaner, S.P., 1993, 
Appalachian anthracites: Organic Geochemistry, v. 20, no. 6, p. 619-642. 
Kentucky Division of Oil and Gas 2004, http://dmm.ppr.ky.gov/OilandGas.htm. 
Markowski, A.K., 2004, Coalbed Methane: http://www.dcnr.state.pa.us/topogeo/cbm/index.aspx 
Milici, R.C., 2004, The Pennsylvania anthracite district Ð a frontier area for the development of coalbed methane?: 
Geological Society of America Northeast/Southeast Section Meeting, Abstracts with Programs, v. 36, no. 2, 
p. 54. http://gsa.confex.com/gsa/2004NE/finalprogram/abstract_69425.htm 
Pashin, J.C., and Hinkle, Frank, 1997, Coalbed methane in Alabama: Geological Survey of Alabama Circular 192, 71 
p. 
Trevits, M.A., Lambert, S.W., Steidl, P.F., and Elder, C.H., 1988, Chapter 9. Methane drainage through small 
diameter vertical boreholes, in Methane control research: summary of results, 1964-1980: U.S. Bureau of 
Mines Bulletin 687, p. 106-127. 
Virginia Center for Coal and Energy Research, 2004, http://www.energy.vt.edu/ 
Wood, G.H., 1972, Geologic map of anthracite-bearing rocks in the Pottsville quadrangle, Schuylkill county, 
Pennsylvania: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-681, scale 1:12,000 





 

Pashin, J.C., 2004, Geologic heterogeneity and coalbed methane 
production - experience from the Black Warrior Basin, in Warwick, 
P.D., ed., Selected presentations on coal-bed gas in the eastern 
United States, U.S. Geological Survey Open-File Report 2004-1273, p. 
61-92. 
Geologic Heterogeneity and Coalbed 
Methane Production Ð Experience from 
the Black Warrior Basin1 
By Jack C. Pashin2 


1 Modified from unpublished short course notes from Short Course #4, Coalbed methane potential in the U.S. and 
Mexican Gulf Coast, Gulf Coast Association of Geological Societies/Gulf Coast Section SEPM Ð 52nd Annual 
Convention, Austin, TX, October 30, 2002. 
2 Geological Survey of Alabama, Tuscaloosa, AL 


Opening Points 
á Numerous geologic factors, including stratigraphy, structure, coal quality, and hydrology influence 
coalbed methane production in the Black Warrior basin of Alabama. 
á Producing coalbed methane requires a different paradigm that is used for conventional reservoirs. 
á The Black Warrior basin is an operationally mature basin in which extreme geologic heterogeneity 
influences gas and water production from coal. 


Figure 1. Infrastructure associated with coalbed methane fields in the Black Warrior basin of west-central Alabama. 

Figure 2. Major geologic concepts associated with coalbed methane production. 

Figure 3. The Blue Creek coal bed is the principal mining target in the Black Warrior basin and was the original focus of coalbed methane operations. 

Figure 4. Graphic log of the Duncanville core showing upper Pottsville coal zones from which coalbed gas is produced. 

Figure 5. Stratigraphic model of an idealized Pottsville depositional cycle in the Black Warrior basin. 

Figure 6. Cycle stacking patterns in the Pottsville Formation of the Black Warrior basin in Alabama. 

Figure 7. Flow of water in Pottsville coalbed methane reservoirs is exclusively through natural fractures, including cleats, joints, and shear fractures. 

Figure 8. Structural contour map of the top of the Pratt coal zone in the Black Warrior coalbed methane fields. See Figure 3 for index map. 
Contours relative to mean sea level. 

Figure 9. Structural cross section of thin-skinned horst-and-graben system in Deerlick Creek Field. 

Figure 10. Isotherms showing variable sorption performance of Pottsville coal for three gases. Isotherms run by University of British Columbia. 

Figure 11. Plots of gas content versus depth showing heterogeneous distribution of coalbed gas in the Black Warrior basin. 

Figure 12. Intensely pyritized coal with mineralized fractures suggests that coal quality affects reservoir properties. 

Figure 13. Map of coal rank in the Black Warrior coalbed methane fields. 

Figure 14. Cross sections showing coal rank in the Black Warrior basin. See Figure 15 for location. 

Figure 15. Relationship between coal rank and sorption capacity in the Black Warrior basin. 

Figure 16. Maps of ash content contrasting the Mary Lee and Utley coal beds in Blue Creek Field. 

Figure 17. Relationship between sorption capacity and ash content and sorption capacity of coal in the Black Warrior basin. 

Figure 18. Relationship of methane sorption to temperature in a San Juan basin coal. 

Figure 19. Temperature-depth plot for coalbed methane wells in the Black Warrior basin showing variation of geothermal gradient. 

Figure 20. Map of geothermal gradient in the Black Warrior coalbed methane fields. 

Figure 21. Location of fresh-water plumes in the Mary Lee coal zone, which are fed by recharge along the upturned southeast basin margin. 

Figure 22. Comparison of composition of conventional and coalbed gas in the Black Warrior basin. 

Figure 23. Pressure-depth plot showing bimodal pressure regime in the Black Warrior coalbed methane fields. 

Figure 24. Map of hydrostatic pressure gradient determined from water levels in gas wells of the Black Warrior coalbed methane fields. 

Figure 25. Relationship of peak and cumulative fluid production values in the Black Warrior coalbed methane fields. 

Figure 26. Scatterplot showing lack of correlation between peak and gas water production in the Black Warrior coalbed methane fields. 

Figure 27. Scatterplot showing lack of correlation between peak gas production and net completed coal thickness in the Black Warrior basin. 

Figure 28. Map showing concentration of productive gas wells along a synclinal axis in Oak Grove Field. Structure contours (ft below sea level) on 
top of Mary Lee coal bed. 

Figure 29. Map showing concentration of exceptional gas-producing wells in two half grabens in Deerlick Creek Field. Structure contours on top of 
Gwin coal zone. 

Figure 30. Map showing concentration of exceptional water-producing wells in two half grabens in Deerlick Creek Field. Structure contours on top 
of Gwin coal zone. Compare with Figure 29. 

Figure 31. Concluding thoughts.  
CBM reservoirs in the Black Warrior basin are CBM reservoirs in the Black Warrior basin are 
characterized by heterogeneous stratigraphy, structure, characterized by heterogeneous stratigraphy, structure, 
and coal quality. and coal quality. 
This heterogeneity has a strong effect on sorption This heterogeneity has a strong effect on sorption 
capacity, gas content, basin hydrology, and reservoir capacity, gas content, basin hydrology, and reservoir 
performance. performance. 
Similar factors affect CBM potential in other Similar factors affect CBM potential in other 
sedimentary basins, but differing geologic factors pose sedimentary basins, but differing geologic factors pose 
basin-specific challenges. basin-specific challenges. 
 
End of file.