Bureau of Mines Report of Investigations/l986 

Investigation of Similarities Between Methane 

Drainage Potential of Utah's Sunnyside Coalbed 

and Eastern U.S. Coalbeds 

By Gregory M. Molinda, Thomas M. Kohler, and Gerald L. Finfinger 

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

Donald Paul Hodel, Secretary 

BUREAU OF MINES 

Robert C. Horton, Director 
Molinda, G. M. (Gregory M,) 

Investigation of similarities between methane drainage potential of 

Utah's Sunnyside Coalbed and Eastern U.S. coalbeds. 

(Keport of investigations ; 9007) 

Bibliography: p. 9-10. 

Supt. of Docs. no.: I 28.23: 9007. 

1. Coalbed methane drainage-Utah-Carbon County. 2. Coalbed 

methane drainage-Utah-Emery County. 3. Coalbed methane drainagcUnited States. 4. Mine ventilation. 5. Coal mines and mining-Safety 

measures. I. Kohler, Thomas M. 11. Finfinger, Gerald L. 111. Title. 

IV. Series: Report of investigations (United States. Bureau of Mines) ; 

9007. 

TN23.U43 [TN305] 622s [622',42] 85-600275 

t 
CONTENTS 

Page 

Abstract ....................................................................... Introduction ................................................................... Acknowledgments ................................................................ Previous studies at Sunnyside Mines ............................................ Study area ..................................................................... Drilling procedure and results ................................................. Gas flows from individual holes .............................................. Overall reduction of methane emissions ....................................... Physical properties of Sunnyside Coalbed ....................................... Gas content .................................................................. Permeability and geology ..................................................... Projections for potential of future gas drainage at Sunnyside .................. Summary and conclusions ........................................................ References ..................................................................... ILLUSTRATIONS 

1 . Location of Book Cliffs and other Utah coalfields .......................... 3 

2 . Map view of previous methane drainage holes at Sunnyside Mine No . 1. Manshaft Dips section ........................................................ 3 

3 . Outline of Sunnyside Mines showing locations of past and present study 

areas ..................................................................... 3 

4 . Map view of Manshaft Dips section showing horizontal hole locations ........ , 4 

5 . Gas production from horizontal holes at Manshaft Dips section .............. 6 

6 . Methane emissions during key events at Manshaft Dips section ............... 6 

7 . Fence diagram of Sunnyside Coalbed in the Sunnyside No . . 1 and No 3 Mines ... 8 

TABLES 

1 . Gas production data for the four horizontal holes .......................... 5 

2 . Comparison of constituents of coalhed gas from selected coalbeds ........... 7 

3 . Comparison of drainage characteristics of selected coalbeds ................ 9 
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

British thermal unit 

per cubic foot 

centimeter 

cubic centimeter per gram 

foot 

cubic foot 

cubic foot per day 

cubic foot per day 

per foot 

cubic foot per minute 

cubic foot per short ton 

m 

min 

PCt 

hour 

inch 

inch per minute 

pound (force) 

per square inch 

pound (force) per 

square inch, gauge 

meter 

minute 

percent 
INVESTIGATION OF SIMILARITIES BETWEEN METHANE DRAINAGE POTENTIAL 

OF UTAH'S SUNNYSIDE COALBED AND EASTERN U.S. COALBEDS 

By Gregory M. Melinda. Thomas M. Kohler. and Gerald L. ~i nfinger3 

ABSTRACT 

The Bureau of Mines has completed an investigation of the effectiveness of methane drainage in the Lower Sunnyside Coalbed at Kaiser 

Steel Corp.'s Sunnyside No. 1 Mine in Utah. Most of the previous attempts to drain methane gas using long horizontal holes were conducted 

in the Eastern Coal Province. From the high degree of success realized 

in these efforts and the large body of knowledge gained from associated research, it seemed natural to extend the technology to western 

coalfields. 

Previous work had indicated that properties affecting gas drainage 

were variable in the Sunnyside Coalbed. In an attempt to characterize 

these properties, four degasification holes were drilled from the outside entries of an advancing section. The holes were drilled to lengths 

of 780, 1,680, 1,315, and 1,047 ft and produced initial flow rates 

of 50,000, 180,000, 340,000, and 240,000 f t3/d, respectively. A total 

of over 300 million f t3 of commercial-quality gas has been removed from 

the Sunnyside Coalbed. The four holes have reduced face emissions by 

78 pct. 

' ~eologis t.

2~ining engineer. 

3~upervisory geologist. 

Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. 
INTRODUCTION 

The Bureau of Mines began investigating 

methods of controlling gas emissions into 

underground mine workings in 1964. Since 

that time, a number of successful projects in the Pittsburgh Coalbed have shown 

that horizontal gas drainage holes can 

reduce methane gas emissions by as much 

as 70 pct (1).4 

In the present investigation, the Book 

Cliffs coalfield in east-central Utah 

(fig. 1) was selected for several reasons. First, the coalbeds in this area 

closely approximate eastern coals in rank 

and gas content. Second, the strata are 

structurally simple with flat-lying beds. 

Third, the Sunnyside Coalbed presented 

some unique gas reservoir conditions. 

Mines in the Book Cliffs coalfield have 

historically been hazardous workplaces. 

Bumps or small outbursts, which are rare 

in Eastern U.S. coalbeds, are common in 

the Book Cliffs coalfield. The coal in 

the area of Sunnyside Mines is highly 

stressed and tends to fail violently. 

Several major mine explosions have been 

related to sudden releases of gas during face and rib failure (2). Like the - 

eastern mines, the Sunnyside Mines experience persistent methane emissions at the 

face. All these characteristics made the 

Sunnyside Mines an excellent site for the 

study of gas drainage properties. 

Gas emissions in a particular coal mine 

depend primarily on the permeability, gas 

content, and gas pressure of the coalbed. 

Estimated permeability, gas content, and 

gas pressure of the Sunnyside Coalbed are 

2 millidarcies , 160 ft 3/st, and 620 lb/ 

in2, respectively (3). These are approximate figures , subject to wide variation, 

depending on location. 

Because there are some differences in 

characteristics of the Sunnyside Coalbed 

and those of coalbeds in the Eastern 

United States, the effectiveness of horizontal holes for methane control in the 

Sunnyside Coalbed could only be determined by in-mine trials. The purpose of 

the present study was to plan, implement, 

monitor, and evaluate a methane control 

strategy using horizontal holes in the 

Sunnyside Coalbed and to compare the reults with methane control results from 

studies in the Eastern United States. 

ACKNOWLEDGMENTS 

The cooperation of Kaiser Steel Corpmfs Hyita, mining engineer, for their encourSunnyside Mines, Sunnyside, UT, has been agement and assistance in completing the 

greatly appreciated. Special thanks go methane control study at Manshaft Dips. 

to Bret Harvey, mine manager, and Bart 

PREVIOUS STUDIES AT SUNNYSIDE MINES 

Previous studies had indicated the need 

to characterize the gas drainage properties of the Sunnyside Coalbed, where the 

coal characteristics are conducive to 

high stress buildup. The coalbed (both 

upper and lower splits) is hard, brittle, 

relatively unfractured, and exhibits poor 

cleat development. These characteristics 

undoubtedly influence coalbed permeability, and thus gas drainage. 

Perry (1) reported drastic variations 

in drill Fit penetration rates encountered in a previous horizontal methane 

lunderlined numbers in parentheses refer to items in the list of references at 

the end of this report. 

drainage project at the Sunnyside No. 1 

Mine. Drill bit penetration rates varied between 6 and 36 in/min, in holes 

drilled in the same direction and separated by only 350 ft (fig. 2). Variable 

penetration rates from 6 to 18 in/min 

were noted while drilling the four drainage holes for the present study. Hargrove grindability tests performed on 

coal samples collected during drilling 

indicated that coal hardness remained 

constant. The observed variability in 

penetration rates was indicative of rapidly changing stress fields, possibly 

related to mining, which could affect 

permeability and thus drainage effectiveness. Changing stress fields could also 
be caused by rapidly changing local relief, which greatly exceeds the local relief over most Eastern U.S. coalbeds. 

Another indication of variable reservoir conditions was seen in a previous 

Bureau drilling project. Drainage holes 

drilled in the No. 1 and No. 3 Mines 

(fig. 3) showed large differences in productivity. This could have been due to 

several factors, including variable gas 

content, bleedoff of gas due to adjacent mine workings, hole direction, hole 

blockage, variable stress fields, or 

physical properties of the seam and coal, 

such as variable permeability. 

In this earlier degasification project, 

face emissions in the No. 3 Mine were 

roughly one-eighth those in the No. 1 

Mine (Manshaft Dips section), even though 

the No. 3 Mine is under deeper cover 

(1,800 ft versus 1,200 ft). Gas drainage 

holes in the two mines also showed different initial production. Short drainage holes from the No. 3 Mine (180 and 

85 ft long) showed negligible production, 

FIGURE 3. - Outline of Sunnyside Mines showing 

locations of past and present study areas. 

while one hole (95 ft long) from the 

Manshaft Dips section of the No. 1 Mine 

was producing 50,000 ft3/d. This possibly indicated the superior reservoir 

qualities of the Manshaft Dips area, as 

opposed to the No. 3 Mine study area. 

In a later study at the No. 1 Mine, 

Manshaft Dips section, two degasification 

holes, one drilled at 20' off face cleat 

direction (430 ft long) and one drilled 

perpendicular to face cleat (450 ft long) 

(fig. 2), produced 160,000 and 127,000 
ft3/d, respectively. These two holes reasons for the extreme disparities in 

were on production 9 months and produced gas production from drainage holes in the 

over 35 million ft3 of methane. The NO. 1 and NO. 3 Mines are not known. 

STUDY AREA 

The methane drainage site in the Sunnyside NO. 1 Mine, Sunnyside, UT, was in 

the Manshaf t Dips section (fig. 3). Prior to the start of this project, the Manshaft Dips section had been closed to 

mining for 15 months because of excessive 

methane emissions. 

The methane drainage plan was to complete four horizontal holes from the outside entries of the section. Each horizontal hole was to be drilled to a depth 

of at least 1,000 ft (305 m). Two holes 

were drilled perpendicular to face cleat 

and two holes were drilled parallel to 

face cleat (fig. 4). The direction of 

the face cleat is approximately perpendicular to the direction of mining advance of the Manshaft Dips section. The 

Manshaft Dips section slopes downward 

at about 5" in the dircetion of section 

advance. 

- 

LEGEND 

Pipeline - Intake air 

Return air 

-#- Regulator *, Curtain direction 

==.=it= Stopping 

MANSHAFT DIPS 

Vertical borehole 

100 200 

Scale, f t 

FIGURE 4. - Map view of Manshaft Dips section showing horizontal hole locations. 
DRILLING PROCEDURE AND RESULTS 

A rotary drilling technique developed 

by the Bureau in Eastern U.S. coalbeds 

was also successful in the Sunnyside 

Coalbed (4). Each hole was drilled with 

3.5-in-diam drag or diamond bits powered 

by an electrohydraulic drill unit. The 

four holes were drilled to depths of 780, 

1,680, 1,315, and 1,047 ft, respectively. 

(The first hole terminated prematurely 

when it intersected an entry.) 

The results of this drilling project 

are presented in the next two sections. 

Subsequent sections discuss physical 

properties that affect methane drainage 

potential. Then, general projections are 

made concerning the potential for future methane drainage from the Sunnyside 

Coalbed. 

GAS FLOWS FROM INDIVIDUAL HOLES 

The gas flow from the four horizontal 

holes was measured by monitoring pressure differentials on 2-in-diam venturi 

meters and converting the readings to 

flow rates. Hole production was estimated by collecting a series of spot 

readings and preparing graphs over the 

life of the project. Gas flows between 

readings were assumed to be at levels 

determined by drawing a straight line between consecutive readings. This same 

procedure had been used successfully in 

the Eastern U.S. coalbeds. The gas production data in table 1 are based on the 

assumption that production from the horizontal holes was uninterrupted between 

the spot readings. 

Table 1 gives the initial, stabilized, 

and total production, as well as the production life for each of the horizontal 

holes. Initial flows from holes 3 and 4 

were considerably higher than those from 

holes 1 and 2. This was to be expected, 

since holes 3 and 4 were drilled perpendicular to the face cleat, whereas holes 

1 and 2 were more or less parallel to the 

face cleat (fig. 4). The greatest production can be expected from holes 

drilled perpendicular to the direction of 

the face cleat, since holes so oriented 

are most likely to intersect face cleats, 

which can conduct methane gas. Also, 

hole 1 was inadvertently drilled into a 

set of bleeder entries and had a low 

flow rate because of its relatively small 

drainage area. To understand the importance of cleat direction with respect 

to gas production in the Sunnyside Coalbed, hole depth must also be considered. 

Using the hole depth, the gas flow per 

linear foot of horizontal hole can be 

determined. 

Holes 1 and 2 (parallel to the face 

cleat) had initial gas flows of 64 and 

107 (ft3/d)/ft, respectively. Holes 3 

and 4 (perpendicular to the face cleat) 

had initial gas flows of 258 and 229 

(ft3/d)/ft, respectively. Thus, face 

cleat direction was determined to be an 

important consideration in planning a 

horizontal methane drainage program in 

the Sunnyside Coalbed, as had also been 

the case in the Eastern U.S. coalbeds. 

Figure 5 shows the gas production from 

the individual holes thoughout the life 

of the project. The general shape of the 

curves is similar to that of production 

curves from horizontal methane drainage 

holes drilled in Eastern U.S. coalbeds. 

The constituents of the coalbed gas 

drained from the horizontal holes are 

shown in table 2. The gas from the Sunnyside Coalbed was comparable to selected 

TABLE 1. - Gas production data for the 

four horizontal holes 

Hole 

1 ........ 

2 ........ 

3 ........ 

4 ........ 

Production, 

lo3 ft3/d 

Production 

life, days 

640 

670 

7 00 

600 

Initial 

50 

180 

340 

240 

Total 

production, 

lo6 ft3 

5.4 

82.0 

145.0 

69.0 

Stabilized 

10 

120 

200 

110 
1,000 ft, methane that was trapped beyond 

5

1,000 ft was allowed to flow through the 

O 100 200 300 400 500 600 700 800 900 

TIME, days 

FIGURE 5. - Gas production from horizontal holes 

at Manshaft Dips section. 

Predrilling All holes All holes 

completed shut in 

EVENT 

FIGURE 6. - Methane emissions during key events 

at Manshaft Dips section. 
TABLE 2. - Comparison of constituents of coalbed gas 

from selected coalbeds, percent 

Methane (CH4) ............... Ethane (C2H6)~~~~~~~~~~~~... 

Propane (c3H8).............. 

Butane (C4H10)000000000000u 

Carbon dioxide (C02) ........ Nitrogen (N2) ............... Oxygen (02) ................. 

Sunnyside Pittsburgh Pocahontas 

No. 3 

97.07 

1.25 

.0011 

.0001 

020 

2.79 

16 

borehole to the valve without restric- by an underground pipeline and emissions 

tion. With a minimal pressure, methane in the section decreased. This emphabypassed the shut-in valve by flowing sizes the importance of maintaining conthrough the natural fracture system tinuous gas production from the holes to 

(cleat) of the coalbed and into the mine ensure that methane concentrations in the 

workings. However, once the holes were section remain at the lowest possible 

back on production, methane was captured levels. 

Kittanning 

95.47 

ND 

ND 

ND 

010 

3.97 

.47 

~tu/ft~.. ................... I 984 1 989 

PHYSICAL PROPERTIES OF SUNNYSIDE COALBED 

1,005 1 966 

Several physical properties of coalbeds affect their drainage potential. 

These include gas content and in-seam 

permeability. 

ND Not detected. 

GAS CONTENT 

According to the Utah Geological and 

Mineral Survey, Book Cliffs gas contents 

range from 0.0 to 10.0 cm3Ig (6). However, tests performed in this study on the 

Sunnyside Coalbed were inconclusive because of the small number of data points 

obtained. Similar tests on the Pittsburgh Coalbed have shown the gas content 

there to be 6 cm3Ig. 

One factor influencing the gas content 

of coal seams is depth of cover. It has 

been clearly shown that gas content increases with increasing depth of cover 

(I). The rugged canyon terrain of eastern Utah, with its deep canyons and rapid 

relief changes, could explain changes in 

gas content over short distances. 

PERMEABILITY AND GEOLOGY 

In general, coalbed permeability appears to depend on several factors, the 

most important probably being cleat development. Well-developed cleat with 

good permeability provides effective conduits for transporting gas. Consequently, the most efficient and productive 

horizontal methane drainage holes are 

drilled perpendicular to the direction 

of the face cleat so as to intersect the 

greatest number of face cleats per unit 

of hole length. Good cleat development 

includes well-defined, continuous, open 

fractures and dense cleat spacing. The 

upper Sunnyside Coalbed (No. 1 Mine), 

where the drainage holes were drilled, is 

characterized by long splintery fractures 

of rib and pillar that provide excellent 

permeability despite poor cleat development (8). Theissen and Sprunk (8) reported that the lower Sunnyside Coalbed 

(No. 3 Mine) has poorly developed cleat. 

Since it also lacks the long splintery 

fractures of the upper Sunnyside, the 

lower Sunnyside exhibits relatively low 

permeability. 

The Utah Geologic and Mineral Survey 

investigated the possibility of a discontinuity between the No. 1 and No. 3 Mines 

(5). If the coalbed were interrupted 

by discontinuity, such as faulting or 
of methane are thick sandstone units in has been generated in place by organic 

the roof and floor that store gas that inclusions. 

PROJECTIONS FOR POTENTIAL OF FUTURE GAS DRAINAGE AT SUNNYSIDE 

Some general statements can be made 

about reservoir conditions to be anticipated as mining progresses under deeper 

cover. Gas content should increase due 

to the increase in confining pressures 

(which prevents gas escape). Mine emissions should increase due to increased 

gas content and increased confining 

pressure. The time needed to degasify 

coal in advance of mining should also 

increase. Studies have shown that initial gas flows from deeply buried coalbeds have been lower than initial flows 

from shallower beds (10) - because the 

greater confining pressures reduce 

permeability. 

Mine emissions will be greatest in the 

areas where both splits are combined and 

mined as one seam. Scheibner notes that 

when both splits are combined they retain 

their individual characteristics (?), 

that is, the upper split is fractured 

and the lower split is not. In drilling 

drainage holes, it may be advisable to 

confine drilling to the upper s p l i t a s 

much as possible in order to realize optimum drainage. 

In evaluating the effectiveness of the 

four-hole drainage pattern at Sunnyside 

(fig. 4), it was stated that the drainage 

holes reduced face emissions by 78 pct. 

Table 3 gives drainage characteristics 

for several eastern .coalbeds (7). The - 

initial gas flow (per linear foot of 

hole) from the Sunnyside Coalbed compared 

favorably with the initial flows from the 

Pittsburgh, Pocahontas No. 3, and Mary 

Lee Coalbeds. Although comparison between eastern and western coalfields 

based on initial flow per foot of hole 

can be somewhat useful, specific site 

evaluation is necessary to properly evaluate gas drainage potentials. 
TABLE 3. - Comparison of drainage characteristics of selected coalbeds 

SUMMARY AND CONCLUSIONS 

Horizontal gas drainage holes have been 

shown to be as effective in reducing excessive methane emissions in Utah's Sunnyside Coalbed as they have been in many 

Eastern U.S. coalbeds. Four drainage 

holes with an aggregate length of 4,822 

f t produced in excess of 300 million f t3 

of commercial-quality gas from the Manshaft Dips section of the Sunnyside No. 1 

Overburden..........................ft.. 

Gas pressure. .................. .lb/in2.. 

Gas content.. .................. .f t3/st. . Initial gas flow ............ (ft3/d)/ft.. 

properties such as gas production, drill 

penetration rate, fracture development, 

and gas content indicate changing physical properties in the same split of the 

Sunnyside seam, as well as differences 

between the upper and lower splits. 

While both splits exhibit little or no 

cleat development, the upper split is 

vertically broken by irregular fractures. 

NA Not available. 

Pocahontas 

No. 3 

1,600 

650 

430 

170 

Pittsburgh 

500-900 

275 

218 

250 

Mine, Methane emissions in the section This split may have the most potential 

decreased by about 78 pct after the hori- for development of the coal methane rezontal holes were completed. In previous source. The potential for methane reBureau studies, methane emissions had source development at any particular site 

never been reduced by more than 70 pct. depends on physical properties such as 

Previous studies at the Kaiser Steel gas content, permeability, seam pressure, 

Mines in the Sunnyside Coalbed indicated water saturation, and geologic structure, 

differences in reservoir conditions be- which all play a role in the final protween the No. 1 and No. 3 Mines. Varying duction of gas from a drainage hole. 

Mary Lee 

2,100 

830 

512 

200 

REFERENCES 

Sunnyside 

(upper) 

1,200 

NA 

NA 

200 

1. Perry, J. He, G. N. Aul, and J. H. 

Cervik. Methane Drainage Study in the 

Sunnyside Coalbed, Utah. BuMines RI 

8323, 1978, 11 pp. 

2. Osterwald, F. W., J. 0. Mayberry, 

and C. R. Dunrud. Bedrock, Surficial, 

and Economic Geology of the Sunnyside 

Coal-Mining District , Carbon and Emery 

Counties, Utah. U.S. Geol. Surv. Prof. 

Paper 1166, 1981, 68 pp. 

3. Jones, A. H., U. Ahmed, A. S. AbouSayed, A. Mah Yera, and B. Sakashita. 

Fractured Vertical Wells Versus Horizontal Boreholes for Methane Drainage in 

Advance of Mining U.S. Coals. Paper in 

Seam Gas Drainage With Particular Reference to the Working Seam, ed. by A. J. 

Aargraves roc. Symp. Univ. Wollongong, 

Wollongong, Aust., May 11-14, 1982). 

Illawarra Branch Aust. Inst. Min. and 

Metall., 1982, pp. 172-201. 

4. Cervik, J. H., H. H. Fields, and 

G. N. Aul. Rotary Drilling Holes in 

Coalbeds for Degasification. BuMines RI 

8097, 1975, 21 pp. 

5. Fields, H. H., J. Ha Cervik, and 

T. W. Goodman. Degasification and Production of Natural Gas From an Air Shaft 

in the Pittsburgh Coalbed. BuMines RI 

8173, 1976, 22 pp. 

6. Doelling, H. H., A. D. Smith, and 

F. D. Davis. Coal Studies: Methane Content of Utah Coals. UT Geol. and Miner. 

Surv., Spec. Studies 49, Aug. 1979, 

102 pp. 

7. Diamond, W. P. Site-Specific and 

Regional Geologic Considerations for 

Coalbed Gas Drainage. BuMines IC 8898, 

1982, 24 pp. 
8. Theissen, R., and G. C. Sprunk. 10. Cervik, J. H. Experience With 

Origin and Petrographic Composition of Methane Control from Horizontal Borethe Lower Sunnyside Coal of Utah. Bu- holes. Paper in Second International 

Mines TP 573, 1937, 34 pp. Mine Ventilation Congress, ed. by P. 

9. Scheibner, B. J. Geology of the Mousset-Jones. Soc. Min. Eng. AIME, 

Single-Entry Project at Sunnyside Coal 1980, pp. 257-264. 

Mines 1 and 2, Sunnyside, Utah. BuMines 

RI 8402, 1979, 106 pp.