By Anthony T. Iannacchione and Donald G. Puglio 

UNITED STATES DEPARTMENT OF THE INTERIOR 
UNITED STATES DEPARTMENT OF THE INTERIOR 

Cecil D. Andrus, Secretary 

BUREAU OF MINES 

Lindsay D. Norman, Acting Director 
lannacchionc, Anthonj- 'I' 

Methane content and geology of the IIartshorne coalbed 

in IIaskell and Le Flore Counties, Okla. 

(Kcport of investigations) 

Bibliography p. 1.4. 

Supt. of 1)ocs. no: 1 28.23. 

1. C.u.11-(;cology-Oklahoma-llaskell (10. 2. Coal-(;eologyOklahoma-lde Flor? (;o. 3. (:oal-Oklahoma-llaskell (10.-\lethanc 

content. 4. Coal-Oklahoma-Le Flore Co.-Methanc content. I. 

Puglio, I). G., joint author. 11. Title. 111. Series llnited States, 

Bureau of ,\lines. Report of investigations. 

TN23.U43 LTN805.05) 622l.08~ [662'.622g176677] 79-607051 
CONTENTS 

Page 

Abstract ................................................................ 1 

Introduction ............................................................ 1 

Acknowledgments ......................................................... 3 

Geology ................................................................. 3 

Stratigraphy ........................................................ 3 

Structure .......................................................... 8 

Cleat .............................................................. 9 

Methane content ......................................................... 9 

Method of calculations ............................................. 10 

Results ............................................................ 12 

Summary and conclusions ................................................. 13 

References .......................................................... 14 

ILLUSTRATIONS 

Location map of study area showing topographic quadrangles. towns. 

and major roads .................................................. Mined-out -area map and overburden map of the Hartshorne coalbed .... Generalized stratigraphic column of exposed rocks in the study area 

Isopach map of interval between Lower and Upper Hartshorne coalbeds 

Isopach map of the undivided Hartshorne and of the Lower Hartshorne 

coalbeds ......................................................... Isopach map of the Upper Hartshorne coalbed ........................ Generalized cross section of the Hartshorne Formation through 

Haskell and Le Flore Counties .................................... Structure contours on the base of the Hartshorne coalbed in Haskell 

and Le Flore Counties ............................................ Coal cleat orientations of the Hartshorne coalbed inLeFlore County 

Graph showing changes in gas content of the Hartshorne coalbed with 

changes in depth ................................................. Overburden above the Hartshorne coalbed ............................ 

TABLES 

1. Coal in place .................................................... 11 

2 . Methane content versus overburden .................................. 13 

3 . Distribution of methane in the Hartshorne coalbed .................. 13 
METHANE CONTENT AND GEOLOGY OF THE HARTSHORNE COALBED 

IN HASKELL AND LE FL-ORE COUNTIES, OKLA. 

by 

Anthony T. lannacchione and Donald G. Puglio2 

ABSTRACT 

The Bureau of Mines developed data on the methane content of the 

Hartshorne coalbed, Haskell and Le Flore Counties, Okla. The methane content 

is calculated to be between 1.1 and 1.5 trillion cubic feet, based on an 

estimate of total coal in place of 2.4 to 3.2 billion short tons. Methane 

increases with depth, but the rate of increase decreases with greater depths. 

Degasification in advance of mining is recommended for all mines operating 

at depths greater than 500 feet to reduce hazards and methane explosions, 

decrease mine ventilation costs, and conserve the natural gas that would be 

otherwise wasted. 

INTRODUCTION 

As part of the Bureau of Mines methane control program, a study was conducted to determine the geology and methane content of the Hartshorne coalbed 

in an approximately 1,500-square-mile area in Le Flore and Haskell Counties, 

Okla. (fig. 1). Underground mines operating in the Hartshorne coalbed have 

had a long history of high methane emissions. Recently, two mines (Howe mine, 

Le Flore County, Okla., and Choctaw mine, Haskell County, Okla.) closed down 

completely or suspended mining owing to a combination of high methane emissions and roof control problems. 

The purpose of this study is to establish a scientific basis for planning 

the degasification that will be essential for mining the coal safely. Approximately 900 data points were used to interpret the geology of the Hartshorne 

coalbed and to estimate the total coal in place. Gas resources estimated were 

calculated using direct-method analyses (913 of 16 coal cores sampled between 

1976 and 1978 from depths of 200 to 1,500-feet. 

IGeologist, ~ittsburgh Research Center, Bureau of Mines, Pittsburgh, Pa. 

2 ~eologist, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, Pa. (now 

with ~ichael Baker, Jr., Inc., Consulting Engineers and Surveyors, Beaver, 

Pa.). 

3~nderlined numbers in parentheses refer to items in the list of references at 

the end of this report. 
FIGURE 1. - Location map of study area showing topographic quadrangles, towns, and major 

roads. 

The Hartshorne coalbed in the study area is a high-volatile A bituminous 

to semianthracite coal, which has been used for making coke in Indiana, 

Illinois, Texas, and Colorado. It is generally friable, has closely spaced 

cleat, and contains many inclined (shear) fractures that dip 45" to 55". 

Individual coalbed thickness ranges from zero to approximately 6 feet, averaging 3 to 5 feet. Overburden ranges from zero at outcrop to almost 7,000 feet 

under Cavanal Mountain in Le Flore County. 

In the past, the coal was mined close to the outcrop, as shown on the 

mined-out-area map (fig. 2). However, two newer operations err-~c~ee's 

Choctaw mine, 1,200 to 1,400 feet deep; and Armco's Experimental Mine No. 1, 

a drift mine that will eventually be under 1,500 feet of overburden) will be 

mining down to and at the bottom of major synclinal structures, where most of 

the leased remaining coal resources lie. 
16BokaIm SmoWIS CodCo.,OldOlirNaImi 

I7Brrntalschas Gad Co. I8 Untm 

19Ocbshe GadU,Na8,8M,9,10,U,~Vr,md16mia 

20 Darn md Srindk No. l mh 

21 ~qtmGadCo.,No.lmdL2~ 

22 Supera Smd:eb% Cad Co., No. 29 mir 

38Heovaa Sdmbs Gad Co. 

39ChDmvGadmd Mbiq Co. 

lCTNE DEEPms 

40 Em Gad Co., E-l No. I mi* 

41 Kcrr-UMe Gad Co. Cho*a mi* 

FIGURE 2. - Mined-out-area mop and overburden map of 

the Hartshorne coalbed. 

Stratigraphy 

regional splitting of the 

Hartshorne into an upper 

and lower coalbed. All of 

these geologic factors 

should be considered in the 

design of degasification 

programs in this area. 

The Hartshorne coalbed is contained within the tiartshorne Formation 

(fig. 3) and is stratigraphically the lowest minable coalbed in the Arkoma 

basin. The coalbed is commonly overlain and/or underlain by the Hartshorne 

Sandstone (5, 8, 11). 
Atoka 

Formation 

In the eastern and southern portions of the study area, the Hartshorne 

coalbed is divided into two beds known 

as the Upper and Lower Harts,horne (8). 

The Hartshorne is considered divided 

wherever the parting within the coala 

E 

P! 

cn 

.- 6 

c 

- e 

% 

cn 

C 

C 

8 

bed exceeds 1 foot in thickness (4). 

Figure 4 shows the separation between 

4 

2 

(3 

8, 

cn 

.- 0, 

5 

c 

.e 

*- g %Of! 

V)$Y 

23 

I 

these two important coal units. Areal 

distribution and coalbed thickness of 

the undivided Hartshorne, the Lower 

Hartshorne, and the Upper Hartshorne 

are shown in figures 5 and 6. 

Boggy 

Formation 

I I 

Savanna 

Formation 

a 

Mc Alester 

For mat ion 

I I 

Hartshorne 

Format ion 

The coalbed splits along an irregular northeast -southwes t "hinge" line, 

with the interval between the two 

benches thickening to the southwest 

(fig. 4). The maximum separation 

between the Lower and Upper Hartshorne 

coalbeds is approximately 115 feet 

within the Heavener 15-minute quadrangle, Le Flore County (figs. 1 and 4). 

Three coreholes in this same area 

indicate the presence of a 1 -foot -thick, 

shaley "wild" coalbed approximately 

70 to 90 feet above the Lower Hartshorne coalbed. 

The Hartshorne Formation is comprised of complex layers of coal, 

shale, siltstone, and sandstone 

(fig. 7). We believe these sediments 

are part of a prograding deltaic complex that contains a distributary 

channel system, levee and overbank 

deposits, interdistributary bay sediments, crevasse splays, and peat 

swamps much like the environments 

FIGURE 3. - Generalized stratigraphic col- found today on the River 

lJrnn of exposed rocks in the study area. Delta complex as described by Fisk (3). - 

The Hartshorne Formation is overlain by the McCurtain Shale Members of 

the McAlester Formation and is underlain by the shales, siltstone, and sandstones of the Atoka Formation. The Hartshorne Formation ranges in thickness 

from a minimum of 35 feet in the Lafayette 7-112-minute quadrangle to approximately 300 feet in portions of the northern Poteau East and southern Spiro 

7-112-minute quadrangles (fig. 1). The base of the Hartshorne Sandstone 

defines the base of the formation, and the top of the undivided Hartshorne 

coalbed or of the Upper Hartshorne coalbed defines the top of the formation. 

V~goo

-1 I to 2 f

Bmj2 o3fe

Drill hole lo

_,-- Dividing line 

and Upper 

Note : 

Solid pattern icoalbed,and st

FIG
FIGURE 6. - lsopach map of the Upper Hortshorne coalbed. 

A A' 

McAlester 

Formation 

Harts tame 

brmatii 

Atoka 

Formation 

McAWr Formation I 

Atoka 

Formation 

LEGEND 

coal 

Shale 

a Sandstone 

HASKEU 

COUNTY 

cross section th&h study area 

FIGURE 7. - Generalized cross section of the Hartshorne Formation through Haskell and 

Le Flore Counties. 
Localized thickening of the Hartshorne Formation is generally associated 

with the thickening of the Hartshorne Sandstone. In the Poteau East and southern Spiro 7-1/2-minute quadrangles, this sandstone comprises the entire Hartshorne Formation, where ancient fluvial channels apparently eroded away the 

Hartshorne coalbed (figs. 5-6). Regional thickening of the Hartshorne Formation is generally associated with the thickening of the interval between the 

Lower and Upper Hartshorne coalbeds (fig. 4). 

Structure 

The study area is located within the Arkoma basin. This large synclinorium is comprised of synclines and faulted anticlines. The most prominent 

synclinal folds in the study area include the Cavanal, Panther Mountain, and 

Sans Bois (fig. 8), which form broad synclinal mountains. Dominant anticlinal 

axes folds are the Milton, Backbone, and Kinta (fig. 8). There are largedisplacement faults paralleling the axes of these anticlines. The synclinal 

and anticlinal axes trend in easterly and northeasterly directions. Dips 

FIGURE 8. - Structure contours on the base of the Hartshorne coalbed in Haskell and Le Flore 

Counties. 
range from nearly horizontal at the bottom of the Cowlington syncline at the 

site of the Choctaw mine, to steeply dipping beds that approach the vertical 

in places along the Milton anticline as observed at Great ~ational's strip 

mine near McCurtain (fig. 1). 

Intense faulting occurs along major anticlinal structures and within the 

complex Whitefield uplift (11) of north-central Haskell County (fig. 8). The 

Whitefield uplift, a broad anticlinorium, includes several small folds and 

faults. The oldest strata in the study area belong to the Atoka Formation and 

are exposed within the Whitefield uplift and along the axes of the Milton and 

Backbone anticlines. 

Cleat 

Cleat directions were measured at strip min 

LEENO 

2 Anticline 1 Mib strip mirs 

x Syncbe 28okm NaK)stripmins 

4Fadtwnhdiectmddp 3 outcrop 

-O'Outcrop lire d limtsbm F6nmth 4 Rock k&md No. I strip mine 

1 Primary diion 5 Howe deep mine 

1 Secondary diection 6Roodart 

FIGURE 9. - Coal cleat orientations of the Hartshorne 

s and surface exposures of 

coal (fig. 9). Cleat data 

were then analyzed using a 

method devised by Diamond 

(2). Results of these analyses show that the direction 

of face cleat ranges from 

N 32" W to N 17" W, which 

is perpendicular to structural trends in the area. 

The friability of the Hartshorne coalbed is due to 

close spacing of cleat and 

the frequent occurrence of 

shear fractures with dips of 

45" to 55" within the coalbed. Directional permeability characteristics of 

coalbeds are generally 

dependent on the orientation 

of these cleat fractures (7). - 

METHANE CONTENT 

Methane is always 

present in coal. Within the 

study area, methane gas constitutes a serious potential 

safety hazard for all future 

deep mining. Methane content of coalbeds is a function of depth and rank (6, 

- 12). Methane emissions xn 

coal mines are controlled by 

porosity, fracture permeability, and gas pressure. 

coalbed in Le Flore County. 
Method of Calcualtions 

Sixteen desorption samples from different coal cores collected within the 

study area were analyzed for methane content using the Bureau of Mines directmethod technique. This information was then used to construct the graph shown 

in figure 10. Equation 1 is the linear least-squares equation representing 

the changes in gas content with depth for this coalbed in the study area. 

A 

Y = -27.88 + 6.25 (In X), (1) 

where X = overburden (feet) 

and ? = expected methane content (~rn~/~). 

This equation has a correlation coefficient of 0.908 with the data. The area 

between the dashed lines shown in figure 10 indicates the range of expected 

gas content, using the direct method, of coals collected at various depths at 

the 95-pct confidence level. 

h 

Y.27.882 + 6.251 (log x) 

R* = 0.908 

22 

20 

FIGURE 10. - Graph showing changes in gas content of the Hartshorne coalbed with changes 

in depth. R~ = correlation coefficient. 

1 I I I I 1 1 I 1 I I I I 1 ( 

- I/&& - 

- // - / 

/( 

- I / - 

18- I 

/ 

- 

16 - 

0 - 

\ 

14- 

0 - - 

'2- - 

W - - 

lo- - 

8 - 

v, 8- - 

a - 

u 

6- - - 

4- - - 

2- - - 

J 

0 200 400 600 800 F0 1,600 

DEPTH, feet 
/ To calculate the total volume of methane contained within the coalbed 

in the study area, it was necessary to estimate the amount of total coal in 

place within the various depth intervals indicated in table 1. This was accomlplished by overlaying the overburden map (fig. 11) with the coal isopach maps 

of the Hartshorne coalbed (figs. 6-7). 

TABLE 1. - Coal in place 

The different methane contents for the various depth intervals were calculated by plugging the median depth value for each overburden interval into 

the X variable of equation 1. The Y variable of this equation is the gas content of the coal in cubic centimeters of methane per gram of coal. The equivalent cubic feet of methane per ton of coal is obtained by multiplying the Y 

value by 32. Minimum and maximum methane contents were obtained by multiplying the minimum and maximum tonnages of coal times the methane content for 

each of the various overburden intervals (equations 2 and 3). 

Overburden, feet 

0 -500. ............. 

500-1,000. ......... 

1,000-1,500 ........ 

1,500-2,000.. ...... 

2,000-3,000 ........ 

Total. ........ 

( Minimum methane content (ft3) at XX = [min coalbed thickness of ax] 

I 

x [acreage within XX] 

x [z,aoo ft3/ton] x [YxJ. (2) 

( Maximum methane content (ft3) at XX = [max coalbed thickness of Zx] 

Percent of 

total coal 

19 

29 

27 

15 

10 

100 

Million short tons 

I 

x [acreage within XX] 

x [1,800 ft3/ton] x [YX]. (3) 

Hartshorne 

(undivided) 

Min 149 

Max 221 

Min 368 

Max 487 

Min 365 

Max 475 

Min 158 

Max 204 

Min 49 

Max 61 

Min 1,089 

Max1,448 

In these equations, Xx = overburden interval (0 to 500 = XI, 500 to 1,000 = X2, 

1,000 to 1,500 = X,, 1,500 to 2,000 = X,, and 2,000 to 3,000 = X,); Yx = average methane content of Xx; and Z = coalbed thickness in feet (1 to 2 feet = Z1, 1 2 to 3 feet = Z2, 3 to 4 feet = Z,, 4 to 5 feet = Z,, and 5 to 6 feet = 2,). 

Upper 

Hartshorne 

Min 122 

Max 178 

Min 108 

Max 165 

Min 76 

Max120 

Min 37 

Max 60 

Min 48 

Max 75 

Min 391 

Max598 

Lower 

Hartshorne 

Min 174 

Max. 238 

Min 228 

Max 290 

Min 198 

Max 252 

Min 160 

Max 198 

Min 141 

Max 176 

Min 901 

Max1,154 
FIGURE 11. - Overburden above the Hartshorne coalbed. 

Results 

The Hartshorne coalbed in Haskell and Le Flore Counties is estimated to 

contain 1.1 to 1.5 trillion cubic feet of methane. Table 2 lists the gas 

potential for the Hartshorne coalbed at various overburden intervals within 

the study area. Methane distribution within each of the various overburden 

intervals (table 3) indicates that 58 pct of the total gas in the coalbed 

occurs at depths from 500 to 1,500 feet. This interval also contains approximately 56 pct of the total coal in place (table 1) and is the expected depth 

range of most future underground mining operations. 
TABLE 2. - Methane content versus overburden 

Overburden, feet 

0-500 ........... 

500-1,000.. ..... 

1,000-1,500 ..... 

TABLE 3. - Distribution of methane in the Hartshorne coalbed 

Average 1 Estimated methane content, 

1,500-2,000.. ... 

2,000-3,000. .... 

13.5 

16.7 

SUMMARY AND CONCLUSIONS 

Methane content 

18.8 

21.0 

Overburden, feet 

0-500 ........... 500 -1,000. ...... 1,000-1,500.. ... 1,500 -2,000. .... 2,000-3,000.. ... 

Using data gathered from core logs, mine maps, outcrops, and desorbed 

cm3Ig 

6.6 

billion cubic feet 

432 

534 

coal core samples, the gas resources of the Hartshorne coalbed in Haskell and 

Le Flore Counties are calculated to be between 1.1 and 1.5 trillion cubic feet. 

~t~ /ton 

211 

Undivided 

Hartshorne 

Min 32 ( Max 47 

602 

672 

Methane distribution, pct 

These data were based on an estimated total coal in place of between 2.4 to 

3.2 billion tons. 

Min 47 

Max 71 

 in 195 Min 40 

IMax 253 1 Max 64 

Undivided 

Hartshorne 

6 

31 

38 

18 

6 

The Hartshorne coalbed has indicated dips ranging from horizontal to 

vertical and is intensely faulted. Overburden ranges from zero at the outcrop to nearly 7,000 feet. The coalbed is friable with principal cleat 

orientations developed parallel and perpendicular to regional structural 

trends, and it also contains a secondary shear cleat system. Stratigraphically, the Hartshorne coalbed splits into an upper and lower coalbed and 

ranges in thickness from zero to approximately 6 feet. 

Upper 

Hartshorne 

Min 26 

Max 37 

Min 99 

Max 125 

Min 106 

Max 135 iMin 95 

Max 123 

2: 

Methane content of the Hartshorne coalbed increases with depth, but at a 

decreasing logarithmic rate so that the maximum methane content will probably 

not exceed approximately 700 ft3 /ton at 3,000 feet of overburden. Degasification in advance of mining is recommended as part of a complete mine development plan for mines operating at depths greater than 500 feet to reduce 

methane emissions in mine workings. Also, there is the added possibility of 

commercial gas production from a degasification system (I), - conserving this 

gas that would otherwise be vented into the atmosphere. 

Lower 

Hartshorne 

Min 37 

Max 50 

Upper 

Hartshorne 

15 

28 

24 

14 

19 

Min 23 

Max 36 

Min 32 

Max 51 

Min 96 

Max 119 

Min 95 

Max 119 

Lower 

Hartshorne 

9 

23 

24 

22 

22 

Total 

9 

27 

31 

19 

4 
REFERENCES 

1. ~eul, M., M. L. Skow, and A. G. Kim. Helping Finance New Mines With 

Revenues From Coalbed Degasification. Proc. 3d NCA/BCR Coal Conf. and 

Expo IV on underground Mining, Louisville, Ky., Oct. 18-20, 1977, 

pp. 25-41. 

2. Diamond, W. P., C. M. McCulloch, and B. M. Bench. Use of Surface Joint 

and photolinear Data for Predicting Subsurface Coal Cleat Orientation. 

BuMines RI 8120, 1976, 13 pp. 

3. ~isk, H. N., E. ~c~arland, Jr., C. D. Kolb, and L. T. Wilbert, Jr. 

sedimentary Framework of the Modern Mississippi Delta. J. Sedimentary 

~etrology, v. 24, No. 2, June 1954, pp. 76-99. 

4. Friedman, S. A. Investigation of Coal Reserves in the Ozark Section of 

Oklahoma and Their Potential Uses. Final Report to the Ozark Regional 

Commission, July 10, 1974, 117 pp. 

5. Hendricks, T. A., C. H. Dane, and M. M. Knechtel. Stratigraphy of 

Arkansas-Oklahoma Coal Basin. Am. Assoc. Petrol. Geol. Bull, v. 20, 

No. 10, October 1936, pp. 1342 1356. 

6. Kim, A. G. Estimating Methane Content of Bituminous Coalbeds From 

Adsorption Data. BuMines RI 8245, 1977, 22 pp. 

7. Kissell, F. N. The Methane Migration and Storage Characteristics of the 

Pittsburgh, Pocahontas No. 3, and Oklahoma Hartshorne Coalbeds. 

BuMines RI 7767, 1972, 22 pp. 

8. ~nechtel, M. M. ~eology and Coal and Natural Gas Resources of Northern 

Le lore County, Oklahoma. Okla. Geol. Survey Bull. 68, 1949, 76 pp. 

9. Mc~ulloch, C. M., J. R. Levine, F. N. Kissell, and M. Deul. Measuring 

the Methane Content of Bituminous Coalbeds. BuMines RI 8043, 1975, 

22 PP 

10. Murrie, G. W. Coal and Gas Resources of the Lower Hartshorne Coalbed in 

Le Flore and Haskell Counties, Oklahoma. Abs. with Programs, 11th Ann. 

Meeting, South-Central Sec., Geol. Soc. America, v. 9, No. 1, March 

1977, p. 80. 

11. Oakes, M. C., and M. M. Knechtel. Geology and Mineral Resources of 

Haskell County, Oklahoma. Okla. Geol. Survey Bull. 67, 1948, 99 pp. 

12. Stach, E., M.-Th. Machowsky, T. Teichmuler, G. H. Taylor, D. Chandra, and 

R. ~eichmuler. tach's Textbook of Coal Petrology. Gebruder Borntraegar, Berlin-Stuttgart, 2d ed., 1975, pp. 40, 200, 329. 

i2U.S. GOVERNMENT PRINTING OFFICE: 1979-603-00211 17 lNT.-BU.OF MlN ES,PGH.,PA. 24 174