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

Cecil D. Andrus, Secretary 

BUREAU OF MINES 

Roger A. Markle, Director 
This publication has been cataloged as follows: 

Perry, John H 

Methane drainage study in the Sunnyside coalbed, Utah / 

by J. H. Perry, G. N. Aul, and Joseph Cervik. [Washington] : 

U.S. Dept. of the Interior, Bureau of Mines, 1978. 

11 p. : ill., diagrs. ; 27 cm. (Report of investigations - Bureau of 

Mines ; 8323) 

Bibliography: p. 11. 

1. Methane. 2. Mine gases. 3. Coal mines and mining -Utah. 

I. Aul, George N., joint author. 11. Cervik, Joseph, joint author. 

111. United States. Bureau of Mines. IV. Title. V. Series: 

United States. Bureau of Mines. Report of investigations - Bureau 

of Mines ; 8323. 

TN23.U7 no. 8323 622.06173 

U.S. Dept, of the Int. Library 

2 A 

A 
CONTENTS 

Abstract ....... .......................................................... Introduction ............................................................ Acknowledgments ......................................................... Drill site . ............................................................. Drilling procedure ...................................................... Methane flow from the holes ............................................. Hole 1 ............................................................. Hole 2 ......... .................................................... Gas emissions from faces ................................................ Sumary .................................................................. References .... .................................................*........ 

ILLUSTRATIONS 

1 . Location of study area at the Sunnyside No . 1 mine .................. 2 . Location of holes drilled in 18 Dips section ........................ 3 . Horizontal drilling at Sunnyside No . 1 mine ......................... 4 . Stuffing box and 4-inch valve on grouted pipe ....................... 5 . Completed hole .... .................................................. 6 . Ventilation diagram of the face of 18 Dips .......................... 7 . Methane decline curves for holes 1 and 2 ............................ 8 . Methane flows through face .......................................... 

TABLES 

1. Ventilation data. station 1 ......................................... 2 . Analyses of gas from holes 1 and 2 at 18 Dips . ...................... 
METHANE DRAINAGE STUDY IN THE SUNNYSIDE COALBED, UTAH 

by 

Jw Hw Perry, Gw Nw Aul, 2 and Joseph Cervi k 3 

ABSTRACT 

The Bureau of Mines is conducting research to determine the effectiveness 

of long holes in degasifying an area of the Upper Split of the Lower Sunnyside 

coalbed at Kaiser Steel CO.'s Sunnyside No. 1 mine. These holes were drilled 

from the two outside entries of a section that was closed to mining because of 

excessive methane emissions. 

Two holes drilled to 430 and 450 feet produced initial gas flows of 

160,000 and 127,000 cfd, respectively. Sixteen days after the completion of 

the second hole, the total gas production declined to just over 144,000 cfd. 

In 9 months of degasification, over 35 MMcf of commercial-quality gas has been 

removed from the coalbed. The combined gas flows declined to 106,000 cfd in 

the 9-month period. The two holes have reduced face emissions by about 40 pct. 

INTRODUCT I ON 

The Bureau of Mines has demonstrated that removing methane from virgin 

coal by use of long holes in advance of mining reduces the amount of gas entering the mine during advancement (L).~ To date, most of this research has been 

concentrated in the Eastern United States (6). 

The rate at which gas flows through coal into either the mine entry or a 

horizontal hole depends on the gas pressure in the coalbed, fracture permeability and porosity, and diffusivity coefficient. The Pittsburgh coalbed, 

which has a relatively high permeability, has a measured in situ pressure of 

275 psi (1). This means that large amounts of gas can be removed from the 

coal through long holes drilled in the seam. Two demonstration projects conducted in the Pittsburgh coalbed have removed more than 1.8 billion cubic feet 

of methane. Methane flows through faces of a section have been reduced by 

70 pct, and about 700 MMcf of the gas has been sold cmercially (2-4). 

Physicist. 

2~eologist. 

Supervisory geophysicist . All authors are with the Pittsburgh Mining and Safety Research Center, Bureau 

of Mines, Pittsburgh, Pa. 

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

the end of this report. 
The objectives of this test are to drill two long holes to determine the 

methane flow potential of the Upper Split of the Lower Sunnyside coalbed, to 

establish a decline curve for the two holes, and to observe the effects of 

degasification on methane flows through the faces of the section. 

ACKNOWLEDGMENTS 

The cooperation of the management of Kaiser Steel Co.'s Sunnyside No. 1 

and No. 3 mines and of the Utah Geological and Mineral Survey is greatly 

apprec ia ted . 

DRILL SITE 

This project was designed to degasify the 18 Dips section of Kaiser 

steel's Sunnyside No. 1 mine, Sunnyside, Utah (fig. 1). The coalbed in the 

area of 18 Dips is gassy and has been closed to mining for more than a year. 

0 

Scale, feet 

FIGURE 1. - Location of study area at the Sunnyside No. 1 mine. 
Mine personnel tried to degasify the area with two short holes. These holes, 

85 and 95 feet deep, were drilled perpendicular to the face cleat (fig. 2). 

The combined gas flow from these two holes over a period of 1 year averaged 

55,000 cfd. 

Figure 2 shows the location of the two long horizontal holes. Hole 1 was 

started 30 feet outby the face of the rightmost entry and was drilled at an 

angle of about 20° off the entry's heading. Hole 2 was located in an offset 

in the left outside return, about 110 feet outby the face, and was drilled 

directly in line with the entry heading. This section of the mine dips about 

5" below horizontal in the direction of section advance. The face cleat direction is at 90° to the direction of section advance. 

LEGEND 

D Stopping 

ff Stopping 

Face cleat Scale, ft 

FIGURE 2. - Location of holes drilled in 18 Dips section. 
DRILLING PROCEDURE 

A 30-hp electrohydraulic horizontal drill was used to drill the holes 

(fig. 3). For each hole, a 6-inch-diam hole was drilled to a depth of 22 feet, 

and a 20-foot length of 4-inch schedule 40 pipe was grouted in place. When 

grouting was completed, a Bureau-designed stuffing box and a 4-inch fullported valve were attached to the pipe (fig. 4). The stuffing box is designed 

to separate the gas from water and drill cuttings during drilling. Either a 

three-bladed , 3-518-inch-diam drag bit or a 3-518-inch roller bit was used, 

followed by a check valve, a 3-7116-inch centralizer, a 20-foot-long NQ drill 

collar, another 3-7116-inch centralizer, and BQ drill rods (2). 

A Sperry-Sun single-shot survey instrument was used to determine the 

inclination of the hole (1). Initially, surveys were taken every 20 feet to 

determine the proper drilling parameters. Thereafter, survey intervals were 

increased to 30 feet, and then to 50 feet. 

During drilling, the inclination of the hole could be changed by changing 

the amount of thrust applied to the drill string. A thrust of 1,800 pounds 

would drop the bit lo every 40 feet. A thrust of 2,400 pounds would raise the 

bit lo every 50 feet. 

A drastic difference in the penetration rates was observed between the 

two holes. For hole 1, bit penetration rate averaged 36 ipm; for hole 2, it 

averaged only 6 ipm. Hole 1 was drilled with one drag bit. A roller bit had 

to be used in hole 2 after only 200 feet of drilling with a drag bit. No 

noticeable difference in the penetration rates was observed between the two 

types of bits in hole 2. Apparently, the hardness of the coalbed changed 

drastically over the distance of 350 feet that separated the holes. Samples 

of coal were taken from each drilling site to test for hardness. The Hardgrove Grindability Index for samples taken from both sites was the same. To 

date, we have been unable to explain the difference in penetration rates. 

When drilling of each hole was completed, about 400 feet of 1-112-inch 

plastic pipe was inserted, which will be used to grout the hole in the future. 

Then the stuffing box was removed, and each hole was connected directly to a 

4-inch pipeline (fig. 5). 
FIGURE 4. - Stuffing box and 4-inch valve on grouted pipe. 
FIGURE 5, - Completed hole. 

METHANE FLOW FROM THE HOLES 

All methane and air volume flows are reported at conditions existing at 

the mine. The elevation of the mine is about 6,150 feet abwe sea level, and 

the temperature of methane in the coalbed is about 52' I?. 

Hole 1 

The quantity of methane produced from the first 180 feet of hole 1 was 

determined by measuring the increase in methane concentration in the return air 

(table 1). During the interval of drilling, methane was being diffused across 

the return entry. Measurements were made at ventilation station 1 (fig. 6). 

Prior to drilling, the methane concentration in the return was about 0.9 pct. 

TABLE 1. - Ventilation data, station 1 

(37,500 cfm air, 62.5-sq-ft area) 
FIGURE 6. - Ventilation diagram of the face of 18 Dips. 

A small quantity of methane was produced during the first 150 feet of 

drilling. The flow rate from the hole was 18,900 cfd (491,000 minus 472,500 

cfd). During the next 30 feet of drilling, the methane flow rate increased 

dramatically from 18,900 to 108,000 cfd. The low flow from the first 150 feet 

of the hole is probably due to degasification by holes drilled earlier by the 

company. At 180 feet, drilling was suspended because the concentration of 

methane in the return had reached 1 pct. By increasing the flow of air to the 

section from 37,000 to 53,000 cfm and by ducting methane from the stuffing box 

directly into the 4-inch pipeline, the methane concentration in the return was 

reduced to about 0.8 pct. Drilling was resumed and continued to a depth of 

430 feet. At this time, methane was leaking from the stuffing box, because 

the frictional resistance to flow in the 4-inch pipeline increased back pressure at the stuffing box. This leakage raised the methane levels in the 

return to 1 pct , and drilling was therefore terminated. 

\/ 

Station 1 

h V \ 

Hole 1 was closed in for 3 hours to monitor its gas pressure buildup. 

The maximum pressure was 13.5 psig. Immediately after the hole was permanently connected to the 4-inch pipeline, its initial flow was 160,000 cfd. 

After 34 days, the flow had declined to 69,000 cfd; after 5 months it was 

60,000 cfd (fig. 7). Methane flows from the hole were determined by measuring 

the discharge velocity at the end of the pipeline in the return air shaft with 

an anemometer. This measured velocity was corrected to a true average velocity 

which was determined by a laboratory test with air flowing through a 4-inchdiam pipe. Because the anemometer is calibrated for air measurements, the 

pipeline flow measurements were also corrected for gas density (0.55 specific 

gravity) (I). 

/\ 

/ 

A' \ I 

I 

\I I 

/\ 

1- 

I \ \ \ I 

, Hole1 I 

I 

I 

Station 2 I 

I Hole 2 

/ / / 

I 

I 
40L I I I I I I I I I I I I 

0 20 40 60 80 100 120 140 160 180 200 220 240 2L 

TIME, days 

1 60L 1 1 1 I I 

FIGURE 7. - Methane decline curves for holes 1 and 2. 

140: u 'z = 

J 120-1 

$ 

Hole 2 

Before hole 2 could be drilled, a second 4-inch-diam pipeline was laid 

from the drill site to the return air shaft. During the drilling phase, 

methane flow from the hole was discharged from the stuffing box directly into 

the pipeline. 

- 

LL Hole 2 - W $ 80- - 

t; - 2 -. w-4- 

60 - 

I 

I - 

J 

\ * 

Flows from this hole were measured in the same way as for hole 1. The 

first 100 feet of hole produced little gas because it parallels an adjacent 

entry (fig. 2). At a depth of 190 feet, gas production increased to 49,000 cfd 

and at 360 feet it was 58,000 cfd. At the final depth of 450 feet, the gas 

flow was 127,000 cfd. 

I 

-I 

Fourteen days after completion of hole 2, its flow declined from 127,000 

to 77,000 cfd. For 5 months the flow has remained near 77,000 cfd (fig. 7). 

Waterflow from hole 2 is negligible. Table 2 gives the composition of the gas 

from both holes. 

- 

- 

TABLE 2. - Analyses of gas from holes 1 and 2 at 18 Dips 

ND Not determined. 

Composition 

Methane ........................... pet*. 

Ethane ............................p ct.. 

Propane ...........................p ct.. 

Oxygen ............................ pct. 

Nitrogen .......................... pct.. 

Carbon dioxide. ................... pct 

Btu .................................... Specific gravity ....................... 

Hole 1 

99.24 

0.28 

0.03 

0 

0.65 

0 

1,005 

0.56 

Hole 2 

99.24 

0.08 

0.03 

0.60 

0.30 

0 

1,009 

ND 
GAS EMISS IONS FROM FACES 

The two holes drilled in advance of the section isolate the coal between 

them and prevent methane from entering this region from the left and right. 

In the direction of the holes, methane that is flowing toward the faces will 

be diverted to one of the holes before reaching the mine opening (2). Consequently, gas flow through the faces of the section declines (fig. 8), but not 

as dramatically as expected. 

After completion of hole 1, face flows declined rapidly from a value of 

about 160 to 100 cfm af ter 15 days (fig . 8) . Hole 2 appears to have had 

little or no effect on methane face flows. Over a 4-month period, face flows 

have remained between 90 and 100 cfm. This lack of effect is difficult to 

explain. 

Gas-bearing strata are known to exist above and below the Upper Split of 

the Lower Sunnyside coalbed. A gassy 2-foot-thick rider seam exists within 

2 feet of this coalbed. Methane is encountered during roof bolting. In the 

floor, the Lower Split of the coalbed (4 to 5 feet thick) is within 2 to 

3 feet of the Upper Split of the coalbed. Methane has been observed bubbling 

through water near the faces of the section. The effect of these methane 

sources on flows at the faces of the section is unknown. Geological studies 

are being conducted to obtain a better understanding of the location and 

effects of the gas-bearing strata. 

TIME,doys 

FIGURE 8. - Methane flows through face. 
SUMMARY 

The two holes drilled in 18 Dips have proved effective in draining 

commercial-quality methane from the Upper Split of the Lower Sunnyside coalbed. 

During 9 months of degasification 35 MMcf of methane, with an average heat 

value of 1,007 Btu, has been removed from the coalbed. Kaiser Steel Co. is 

now making plans to utilize this gas at its facilities. 

The 40-pct reduction in the emission of methane from the face was not as 

great as expected. Additional methane is entering 18 Dips from coalbeds above 

and below the Upper Split of the Lower Sunnyside coalbed. The geology of 

these coalbeds is under investigation, and the results may clarify the effects 

of these methane-bearing strata on face flows. 
REFERENCES 

1. Cervik, J. , H. H. Fields, and G. N. Aul. Rotary Drilling Holes in Coalbeds for Degasification. BuMines RI 8097, 1975, 21 pp. 

2. Deul, M., and J. Cervik. Methane Drainage in the Pittsburgh Coalbed. 

Proc. 17th Internat. Conf. Min. Res., Varna, Bulgaria, Oct. 3-7, 1977, 

pp. 9-15; available from Joseph Cervik, Bureau of Mines, 4800 Forbes 

Ave., Pittsburgh, Pa. 15213. 

3. Fields, H. H., J. Cervik, and T. W. Goodman. Degasification and Production of Natural Gas From an Air Shaft in the Pittsburgh Coalbed. 

BuMines RI 8173, 1976, 23 pp. 

4. Fields, H. H. , J. Ha Perry, and M. Deul. Commercial-Quality Gas From a 

Multipurpose Borehole Located in the Pittsburgh Coalbed. BuMines 

RI 8025, 1975, 14 pp 

5. Ower , E . The Measurement of Air Flow. Chapman and Hall, Ltd. , London, 

3d ed., 1949, pp. 146-184. 

6. U.S. Bureau of Mines, Staff--Mining Research. Methane Control in Eastern 

U.S. Coal Mines. Proc. of the Symposium of the Bureau of ~ines/~ndustry 

Technology Transfer Seminar, Morgantown, W. Va. , May 30-31, 1973. 

U.S. GOVERNMENT PRINTING OFFICE: 1978-603-00216