UNITED STATES DEPARTMIENT OF THE INTERIOR 

BUREAU OF MINES 

1962 
UNITED STATES DEPARTMEN'T OF THE INTERIOR 

Stewart L. Udall, Secretary 

BUREAU OF MINES 

Marling J. Ankeny, Director 
Merritts, William M 

Removing methane (degasification) from the Pittsburgh 

coalbed in northern West Virginia, by W. M. Merritts, W. N. 

Poundstone, and B. A. Light. [Washington] U. S. Dept. of 

the Interior, Bureau of Mines [1962] 

v, 39 p. illus., tables. 27 cm. (U. S. Bureau of Mines. Report 

of investigations, 5977) 

1. Methane. 2. Coal preparation. I. Title. (Series) 

TN23.U7 no. 5977 622.06173 

U. S. Dept. of the Int. Library 
PRE FAC IE 

Explosions caused by ignitions of methane accumulations in coal mines 

have resulted in loss of life and property. In gaseous mines, methane accumulations can be anticipated by periodical1;y checking the ventilating air. 

Possibly, many explosions may have been prevented by stopping mining operations whenever large methane emissions have been encountered and by allowing 

the ventilating air to dilute the gas. Stopping operations, however, results 

in loss of time and increased production costs. 

As the more accessible high-quality coalbeds become depleted, and coal 

must be obtained from the deeper and usually more gaseous coalbeds, the methane hazard encountered during mining probably will increase. Also, the mining 

industry undoubtedly will expand the use of continuous-mining equipment to 

recover these coals. Since most gaseous coals emit more methane when they are 

reduced in size, the equipment and mining methods used are expected to contribute further to methane emission problems. Therefore, to continue capacity 

production, techniques must be developed to degasify these coalbeds before and 

during mining operations. 

In the United States, several techniques have been used to remove methane 

from coalbeds, such as drainage by free flow and by vacuum pumping through 

vertical drillholes from the surface; free- flow drainage from horizontal holes 

in the coalbed; and free flow from holes drilled into the mine roof and mine 

floor. 

The Bureau of Mines, reviewing the methane problem with coal-mining officials, learned that faces and ribs of entries advancing into virgin coal emit 

more gas than those of other mine workings. Further, ribs of the outside 

entries emit more gas than inside entries intersected by crosscuts, and continue to give off gas as the faces advance. 

Based upon earlier tests that were conducted to allay coal dust, it 

appeared possible that methane could be removed from coalbeds by infusing 

water into holes drilled in the advancing, faces. If the process proves successful, hazards created by methane accur~ulations may be reduced, and a 

reduction in dust at the working face may also be expected. 
CONTENTS 

Preface ............. Surmnary and introduction ................................... Acknawledgments ...................I.......e................ 

Test site .................................................. Location ............................................. Coalbed ............................................... Mine development ..................................... Previous degasification experiments ....................... Recent degasification experiments ......................... Horizontal drill holes ............................... Equipment ....................................... Procedure ....................................... Results of degasification with horizontal 

boreholes ...................................... Water infusion of horizontal drill holes ............. Equipment used .................................. Pump ....................................... Continuous methane .recorders ............... Miscellaneous .............................. Procedure ..............................m........ 

Infusion in 4 South entries ..................... NO . 7 entry ................................ NO . 1 entry ................................ Discussion of infusion results, 4 South entries . Infusions in Main entries ....................... NO . 9 entry ................................ Crosscut between the 5 and 6 entries ....... Infusions in 5 South entries .................... Crosscut outby clay vein ................... Crosscut inby clay vein .................... Discussion of infusion results, Main and 5 

South entries .................................. Degasification through vertical borehole .................. Free flow of methane ................................. Flaw by vacuum .................................m..... 

Flaw by vacuum through horizontal drill hole in face . Migration tests, anhydrous ammonia ........................ Conclusions ............................................... 
5 South ............................................ 28 

Bottom-hole pump installation at BH26 ............... 31 

Veeco MS-9A helium-leak detector .................... 34 

Connection of BH26 with horizontal borehole, 

5 South ............................................ 35 

Spacing of holes in coal face for migration tests ... 38 
TABLES 

Page 

Cumulative actual drilling time and methane released 

during drilling of a bleeder hole at face No. 1 

Main entry.......................................... 10 

Summary of free- flow drainage data from horizontal 

bleeder holes..............aa.a..a..a.aa..aO....m... 11 

Methane released in 4 South before, during, and 

after infusion of hole L in. entry 7.. . . . . . . . . . . . . . . . 22 

Methane content of air at 5 South regulators before, 

during, and after water-infusion tests in entry 1, 

4 S~~th~~~~~~m~~~~aa~~am22 

Methane released from 5 South before and after 

infusions in 4 So~th...........~....~~........~~.... 24 

Mass spectrometer analysis of gas from horizontal 

boreholes, 4 South entries.......................... 25 

Composition of gas from boreholes N during water 

infusion of borehole L.........~.................... 25 

Methane drainage data for borehole BH26.............. 30 

Summary of data on helium releases, 5 South.......... 32 

Gas composition and flow under vacuum through drill 

hole in face................................^...... 36 
REMOVING METHANE (DEGASIFICATION) FROM THE PITTSBURGH 

COALBED IN NORTHERN WEST VIRGINIA ' 

by 

W. M. ~erritts,~ W. N. ~oundstone,~ and B. A. ~i~ht~ 

SUMMARY AND INTRODUCT ION 

A joint investigation by the Bureau of Mines and the Christopher Coal 

Co. at the Humphrey No. 7 mine, operating in the Pittsburgh coalbed in northern West Virginia, was undertaken to gain more insight concerning the hazardous emission of methane gas in mining. This report describes the equipment, 

procedure, and results. 

Horizontal bleeder holes drilled in the faces drained large quantities of 

methane, eliminating downtime of mining equipment. Also, larger quantities of 

methane were removed by forcing 14 to 25 g,.p.m. water at 25 to 200 p.s.i. 5 

pressure into the bleeder holes. In one infusion test a fluorescein dye was 

added to the infusion water; in later mining operations, the infusion water 

was traced for a distance of 1,500 feet. With vacuum pump applied to the 

horizontal hole the gas-flow rate increased, and the methane content decreased. 

Tests indicated that methane and water infused in bleeder holes traveled 

along the bedding planes of the Pittsburgh coalbed at a faster rate than 

across the planes. 

Methane associated with coalbeds is produced by the slow decomposition of 

carbonaceous material in the absence of ai.r and the presence of water. It is 

lighter than air and, depending on its concentration, forms an inflammable or 

explosive mixture with air. It is believed that methane is entrapped in and 

around the pores of the coal and adjacent strata--often under great pressure. 

In many cases where the strata have been disturbed by geologic movements the 

'work on manuscript completed September 1961. 

 i in in^ methods research engineer, Coal Mining Research Center, Bureau of 

Mines, Pittsburgh, Pa. 

3~eneral superintendent, Christopher Coal Co., Osage, W. Va. 

4~roject engineer, Humphrey No. 7 mine, Christopher Coal Co., Osage, W. Va. 5 All pressures given throughout this report are gage pressures, 
sae e atospee coud be ataed, oweve, by appoacg te 

problem in another manner. Instead of allowing the methane to drain into the 

mine atmosphere during mining, it could be removed before mining, thus avoiding the necessity of large volumes of ventilating air. 

Degasification, the extraction of methane from coal-bearing formations 

before and during mining, has been well received in the United Kingdom, 

Europe, and other major coal-producing countries. A survey of foreign literature shows that the techniques of draining methane from coal-bearing formations has been thoroughly investigated and has proven to be both practical and 

economical. In a recent report,6 it was stated that 135 collieries removed 

more than 17 billion cubic feet of methane in 1958 for use as town gas, for 

automotive and gas-turbine fuel, and for steam generation. The various 

degasification techniques may be classified generally as: 

6 Boyd, W. T., and Perry, Harry, Degasification of Coalbeds in Advance of 

Mining: Pres. 47th Nat. Safety Cong. and Exposition, Chicago, Ill., Oct. 

20, 1959, Trans. Nat. Safety Cong., vol. 7, 1959, pp. 21-34. 
1. Cross-measure borehole method: Boreholes are drilled through overlying beds or into the floor strata from the working areas. 

2. The Hirschbach method: Superjacent entries are developed over the 

working areas. 

3. Packed- cavity method: Drainage of methane is controlled as mining 

progresses. 

4. Surface and underground borehole drainage. 

5. Drainage from virgin coalbeds by collecting gas from pockets. 

The cross-measure borehole method is the most widely used for removing 

methane from the coal formations. In this method, the gas is collected by 

free flow and vacuum pumping from boreholes and is piped to the surface, 

Analysis of the literature indicates that European degasification techniques would not be adaptable to existing natural conditions or mining methods 

used by the U. S. coal industry. Longwall mining is practiced extensively in 

Europe, while room-ando pillar mining predominates in the United States . In 

longwall mining the roof subsides as mining progresses, resulting abutment 

pressures at and ahead of the longwall fisce breaking and cracking the overlying strata. In room-and-pillar mining,, the roof is supported and generally 

remains undisturbed until the pillars are removed during retreat mining. The 

effect of the longwall-mining method on inethane liberation is that when the 

pressure on the longwall face is relieveld, much of the gas in the coalbed is 

liberated and is trapped in the overlyin,g strata. In room-and-pillar mining 

the overburden pressure is not relieved and the gas enters the mine workings 

or remains in the coal pillars and immediate adjacent strata. Other differences in mining conditions and practices such as the number beds worked simultaneously, interval between workable coalbeds, attitude of the beds, and the 

character of the adjacent strata have a marked effect on the success of 

degasification techniques. 

Increased use of continuous-mining equipment and the encouraging results 

obtained by the degasification techniques being used in foreign countries 

prompted the Bureau of Mines to initiate laboratory and field studies to 

determine the feasibility of degasifying coalbeds before and during mining 

and to develop techniques applicable to U. S. mining conditions and practices. 

The laboratory phase of the work was to determine the sorption characteristics of coal, while the field investigations were to study migration of 

methane in the coalbed, use of surface boreholes and long underground horizontal drill holes in advance of mining, and water-infusion technique for 

degasification. 

AC KN(XJ LED) GMENT S 

The cooperation and assistance of the late G. R. Spindler, director, and 

G. W. Campbell, oil and gas research engineer, School of Mines, West Virginia 

University, is gratefully acknowledged, 
u TEST SITE 1-1 Dark shale 

Location 

Coal 

Carbonaceous 

Coal 

Carbonaceous 

Coal 

Splint coal 

Coal 

Shale 

FIGURE 1. - Section of Pittsburgh Coalbed 

of Humphrey No. 7 Mine. 

shale 

shale 

The degasification 

experiments were conducted 

at the Humphrey No. 7 mine, 

Christopher Coal Co., near 

Osage, Monongalia County, 

W. Va., operating in the 

Pittsburgh coalbed, 

Coalbed 

The Pittsburgh coalbed 

is the basal stratum of the 

Monongahela series of the 

Pennsylvanian period. This 

series is composed chiefly 

of limestones, interstratified sandstones, shales, and 

coal; of these the Pittsburgh 

coalbed is of greatest economic importance. Figure 1 

shows a columnar section of 

the immediate roof, the coalbed, and the bottom. The 

coalbed outcrops along the 

Monongahela River and dips 

gradually N. 75O W. The westward extension of the bed from the area contiguous to the Monongahela River has been mined extensively and constitutes the 

principal reserves which are below drainage--depth of cover increasing away 

from the river. 

The coalbed in this area averages 90 inches in thickness and has a blocky 

structure, resulting from well-defined butt and face cleats at approximately 

right angles to each other. About 5 feet from the bottom, 2 inches of splinty 

coal occurs, and two shale partings just above the splinty coal are known 

locally as the 6-foot and 7-foot binders. The coalbed is intersected by 

numerous clay veins of various thickness, which may extend over large areas. 

Immediately overlying the coalbed is a foot or more of shale that disintegrates readily upon exposure to the mine atmosphere. To protect this 

immediate roof 1 foot or more of top coal is left during mining. 

A typical analysis of coal at this mine on the as-received basis is as 

follows : 
=isture................................percent 3.2 

Volatile matter...........................do. 37 .O 

Fixed carbon....,.........................do. 53.2 

A~h.......................................do. 6.6 

S~lf~r....................................do~ 1.45 

Calorific value, B,t,u. per pou:nd,............. 14,000 

Mine Development 

The coalbed was entered through two drifts and four shafts--the latter 

ranging from 325 to 568 feet in depth. A multiple-entry block system was used 

to develop the coalbed. The main entries were developed in sets of nine or 

more and the panel entries in sets of seven or more; all were driven 14 to 17 

feet in width on 50- or 70- foot centers. Crosscuts were driven on approximately 80-foot centers. Pillars were recovered on retreat by the pocket-andfender method, Figure 2 shows the plan of developing the main and 4 and 5 

South entry groups; contour lines show the elevation of the bed. 

One ripper-type continuous-mining machine was used in each set of entries, 

and the coal was first discharged onto the mine floor and then loaded into 

shuttle cars by a conventional loading machine. The shuttle cars discharged 

the coal onto an extensible-belt intermed.iatew haulage system, which, in turn, 

discharged it into mine cars for haulage to the surface, 

Roof bolting was the predominant roof support method, but in areas of 

dangerous roof conditions the roof bolts were supplemented with crossbars and 

posts. Yielding steel arch supports were used along main haulage roads that 

had heavy or squeezing roof. 

The mine was classed as gassy by the! West Virginia Department of Mines 

and was liberating about 8 million cubic feet of methane per day. About 

915,000 cubic feet of air per minute was circulated through the mine by three 

exhaust fans. A split system of ventilatlion, using noncombustible permanent 

stoppings, overcasts, and regulators, coursed the air to the active sections 

of the mine. Intake air in each set of developing entries was coursed through 

the center entries, split near the active faces, and returned through the 

outside entries, 

Air currents were directed to the working faces by means of brattice 

cloth faced with a thin sheet of plastic on the higher pressure side of the 

cloth to minimize leakage. By installing the line brattice on the return side 

of a working place, mining equipment coulld travel to and from the working face 

without passing under a line brattice or check curtain. Figure 3 shows the 

ventilating system and the general arrangement of equipment used in development. Figure 4 shows the sequence of advancing a set of seven entries. By 

following this sequence of mining it was possible to advance all working 

places under positive ventilation. 
FIGURE 2. Pla
Loader miner 

LEGEND 

- 1-7 Entry numbers --- -- Line brattice 

- Intake air # Permanant stopping Return air - Curtain 

PREVIOUS DEGAS IF ICAT ION 

EXPERIMENTS 

As early as 1952, the 

School of Mines and the Engineering Experiment Station 

of West Virginia University 

and the Christopher Coal Co. 

started experimental degasification work at an adjoining mine. The purpose was 

to investigate the characteristics of the Pittsburgh 

coalbed with respect to the 

liberation of methane and to 

study various techniques for 

degasifying the coalbed in 

advance of and during mining. 

This early work centered 

mainly around the use of 

vertical boreholes for methane drainage. The findings 

were that this method had 

only limited application, 

unless the drainage zone FIGURE 3, - Face Venti lotion System and Gjeneral could be extended by hydrau- Arrangement of Mining Equipment. lic fracturing. 7 

RECENT DEGAS IF ICATION EXPERIMENTS 

Horizontal Drill Holes 

Following these early experiments, the company began a study using horizontal drill holes in advance of the working faces for controlling methane 

drainage. General test procedures followed, and some early results have been 

published.8 As the drilling methods for horizontal free-flow holes and 

those used for water-infusion purposes are similar, only a brief description 

of horizontal-drill-hole procedure and results will be included in this report. 

7 Spindler, G. R., Degasification of Coal Seams: Coal Mine Modernization, Am. 

Min. Cong., 1953, pp. 206-220; West Virginia Eng. Exp. Sta. Tech. Paper 46, 

1953, 15 pp. 

8 Spindler, G. R., and Poundstone, W. N., Experimental Work in the Degasification of the Pittsburgh Coal Seam by Horizontal and Vertical Drilling: 

Preprint 60-F106 of paper pres. Ann. Meeting AIME, New York, February 1960, 

28 PP 

"~i~ht, B. A*, Recent Experiments in Degasification of the Pittsburgh Coal 

Seam in Northern West Virginia: Paper pre. 50th Conv. Mine Inspectors' 

Inst. of Am., Louisville, Ky., June 13- 15, 1961, 16 pp . 
Figure 5 illustrates the plan of spacing the bleeder holes. Most of the 

holes were 100 to 150 feet deep, although a few were 230 feet deep. They 

were so collared that when the connecting crosscuts between entries were completed and line brattices placed in the outside entries, gas would be liberated directly into the return air. As each entry adjacent to the virgin coal 

was advanced far enough for the succeeding crosscut, another bleeder hole was 

drilled in each outside entry. The holes were 2 inches in diameter although 

some holes up to 4 inches in diameter were tested. Horizontal holes at various angles to the entry were drilled as well as several in the roof and bottom. 

Drilling was done on the intake air through a prepared opening in the 

line brattice, and therefore all gas emitted during drilling was released into 

the return-air current. As a precaution, the amount of air passing the drill 

hole was increased during drilling to keep the concentration low in the event 

of a sudden outburst of gas. Gas pressures, flows, and methane concentrations 

were measured repeatedly to record the production of gas from the holes. 
,211 bleeder holes \ 

Fire-resistant belt 

-. 

LlEGEND 

- 1-7 Entry numbers Intake air 

-- -----.I Return air ----- Line brattice 

# Permanant stopping 

Curtain 

'2" bleeder holes' 

FIGURE 5. - Spacing of 2-Inch Bleeder Holes 

in Solid Ribs. 

Results of Degasif ication 

With Horizontal 

Boreholes 

Before January 1960, 

240 horizontal boreholes 

were drilled in developing 

14,000 feet of main- and 

cross-entry sets, Observations made during and after 

drilling indicated that the 

holes could be spaced further apart and still obtain 

satisfactory results, As a 

result, from January to 

September 1960, only 24 ribline holes were drilled to 

develop 8,000 feet of entry. 

As might have been 

expected, there were variations in: (1) Drilling time; 

(2) methane emission from 

the holes; (3) shut-in pressures; and (4) total time 

holes emitted gas. 

During the first 5 feet 

of drilling little gas was 

encountered, but the emission increased generally 

with hole depth. Table 1 

summarizes the actual drilling time and the amount of methane released during 

drilling of a hole in No. 1, Main. The face area was 98 square feet, and from 

the velocities of the ventilation current measured at intervals, the air volumes were computed. While air velocities were being measured, readings were 

being taken wit11 a Riken gas indicator to determine the percent of methane in 

the ventilating air from which the cubic feet of methane was computed. In 

these calculations it was assumed that increases in methane emission were 

entirely the result of drilling and that the volume of intake air, percent 

methane, and volume of methane remained substantially constant between 

measurements . 

Practically all holes emitted gas during drilling and continued to do so 

for lengths of time varying up to several months. Shortly after a hole was 

completed, the velocity and volume of gas issuing from it was measured, and 

the methane concentration was determined from bottle samples and checked by 

Riken readings, Shut-in pressure also was determined. 
the velocity of the gas was 8,900 £.p.m. The hole emitted 193 cubic feet of 

methane per minute with a shut-in pressure of 60 p.s.i., despite a considerable leakage through cracks in the coal at the collar of the hole. 

Although the volume of methane produced from bleeder holes was not uniform, the volumes usually were greater after penetrating clay veins. 

When a long hole was sealed, and provided no mining was done in the imediate area, the time required for the gas to reach maximum shut-in pressure 

ranged from several minutes to several weeks. After maximum pressure was 

reached it was possible to open the seal, bleed off the gas, reseal the hole, 

and regain the previous shut-in pressure. A pressure gage connected to the 

seal in the hole fluctuated continuously until the maximum pressure was 

reached; these fluctuations were greater with deeper seals. 
TABLE 2. - Summary of free-flow drainage data from horizontal bleeder holes 

Location of 

drill hole 

No. 1, 3 West 

No. 6, 3 West 

No. 1, 5 South 

DO . . . . . . . 

No. 1, Mains.. 

No. 9, Mains.. 

DO . . . . . . . 

Depth, 

feet 

Locat ion 

of face, 

inby drill 

hole, feet 

Time 

interval 

after 

drilling, 

days 

- 

14 

30 

38 

43 

- 

10 

16 

23 

- 

4 

39 

76 

256 

- 

39 

0 

.6 

- 

. 5 

- 

. 5 

-- - 

Velocity 

of gas, 

f .p .ma 

Remark

Shut- in 

pressure, 

Penetrated a 2

vein. 

Me thane 

Volume, [purity, 

Penetrated thr

clay veins. 

Drilled into 

thick clay v

siderable lea

collar of ho

Hole drilled 

12- foot- thick

Inby end of h

j roof to drai

 to^ of bed. --- - -- - - -- 

l~rilled at an angle bf 45O to direction of entry. 

2~ri11ed at an angle of 5O to direction of entry. 
Steel washer 

Nuts. 1" NPT (3 required) 55,. ID OD I,, 5 sCh 80 s&f p

2 x 1:" hex. crs. \,< / I 

. - 

A" -10'8 threaded 8" NPT 
the 1/2-inch pipe 

from turning when 

the inby nut is 

turned to release 

the rubber washers 

and to remove the 

FIGURE 7. - Maihok Mono-Methane Analyzer and Recorder. seal. 

Continuous Methane Recorders 

The company had a German Kaihak Mono-Methane unit that required cornpressed air for operation. (See fig. 7 .) This recorder was used almost exclusively in the water- infusion experiments. By checking the record periodically 

'~ackson, E. O., and Merritts, W. M., Water Infusion of Coal Pillars Before 

Mining, Kenilworth Mine, Independent Coal & Coke Co ., Kenilworth, Utah: 

Bureau of Mines Rept. of Investigations 4836, 1951, 25 pp. 
While the details of infusion procedure had to be varied to suit condi

tions, the general approach was as follows: 

The pump was placed in an intake-air course and connected to waterlines, 

and 3/4-inch heavy-duty hose connected the pump discharge with the infusion 

equipment at the infused face. A typical arrangement of equipment is shown in 

figure 9 with the watermeter in the hose line leading from the infusion pump. 

The hose with an intervening valve and pressure gage was connected to the 

infusion seal. The orifice meter in the inclined pipe was sealed in a hole 

near the top of the coalbed to measure the flow of gas from that part of the 

bed during the infusion, and the flow measurements were continuously recorded. 

Figure 10 is a closeup of the face showing the water trap in the orifice-meter 

pipe, the infusion seal, and, in the upper left corner of the face, a pressure 

gage and pipe sealed in another hole to indicate pressure developed at that 

part of the coalbed by gas, water, or both during infusion of the face bleeder 

hole. 
FIGURE 8. - Bureau of Mines Continuous Methane Analyzer and Recorder. 
of an approved ultraviolet light it was possible to identify and trace the 

progress of the infusion water. 

During infusions, the path and distribution of the water could be traced 

by sweating of the coal. Small gas-water bubbles would appear on the coal 

surface at the face being infused and spread gradually to other adjacent faces 

and ribs. (See fig. 11.) Usually the seal was set 3 feet in the hole from 

the collar, but if the infusion water oozed too rapidly at the face being 

infused, the seal was reset deeper in the hole. 

Infusions in 4 South Entries 

This set of entries, driven on the face cleats, had been idle 3 months 

before infusions were started. Methane bleeder holes already had been drilled 

in the solid coal at the faces of the outside entries, and these bleeder holes 

were used for the infusions. 
FIGURE 10. - Closeup of Orifice-Meter Piping at Face. 

No. 7 Entry 

Figure 12 shms the locations of the face bleeder holes, two rib bleeder 

holes, and three roof-bolt holes inby the last open crosscut in entry 7. 

Water under pressure of 60 p.s.i. and at a rate of 15 g.p.m. was injected 

into hole L for several hours; within 1 hour, water seepage on the coal surface was noted. As infusion continued, the seepage extended across the entire 

section and along the outside ribs of entries 1 and 7. After 8 hours of water 

injection, the amount of methane in the immediate right return-air course 

decreased 28 c.f.m., but there was an increase of 84 c.f.m. in the immediate 

left return--a net increased release of 56 c.f.m. 

It had not been realized then that the changes in methane content of the 

air at the return regulators would differ from changes at the immediate 
FIGURE 11. - Dark Streaks Are Water and Gas Oozing From Coal Face During Infusion. 

returns. The immediate return samples accounted only for changes in methane 

content at the immediate face; samples taken at the return regulators included, 

in addition, the gas forced from the ribs outby the immediate returns. Had 

the methane content at the return regulators been taken during these initial 

infusions, they probably would have shown an increase at each return regulator. 

Six additional infusions of hole L were made. The total injection time 

for the seven infusions was 44 hours-- the longest single infusion period being 

18 hours. Figure 13 shows the relationship between water pressures and hours 

during infusions. The maximum water pressure was 125 p.s .i., and a total of 

36,400 gallons of water was injected. 

During one of these infusions, water mixed with fluorescein dye traveled 

along the coal bedding planes 64 f.p.h. (feet per hour) and moved vertically 

across the bedding planes at a rate of 0.5 f.p.h. 
RB4 I " 1 7 1 Vertical 

RB5 1 " 1 7 1 Vertical 

FIGURE 12. - Face Area of No. 7 Entry, 4 South, During Water Infusions. 
shown in figure 14. The methane content of the air was measured at each location before, during, and after infusions to determine the amount of methane 

released in the section. The percentage of methane in the air at locations 1 

and 20 was read from the recorder charts; methane content at the other locations was taken by Riken readings or from analyses of bottle samples. Table 3 

summarizes the available data regarding methane released in 4 South before, 

during, and after infusion into hole L in entry 7. 

No. 1 Entry 

Figure 15 is a sketch of the face area of No. 1 entry 4 South. Borehole 

C was infused six times, during which 29,880 gallons of water with dye added 

were injected at maximum pressure of 50 p.s.i. The longest infusion period 

was 11 hours. (See fig. 16.J 
LEGEND 

o 1 23 Location of air 

measurements 

Intake air 

Return air 

CC Canvas check 

PC Plastic check 

# Cement block stopping 

GR German-type methane 

recorder 

SP Return-air sampling 

point for continuous 

methane recorder 

SH Sampling hose for 

continuous methane 

recorder 

- R Return air Line brattice 

I h h 

1 L 

tYl I' 

22 

0 

Intake air 

FIGURE 14. - Locations Where Air Measurements Were Taken in 4 South. 

Discussion of Infusion Results, 4 South Entries 

While the results of the infusion in 4 South varied, the effects were 

more widespread than had been anticipated, being noted not only in the 4 South 

entries but also in the parallel 5 South. 

Soon after water infusion was started. in No. 1 entry, 4 South, the section foreman of the 5 South section report.ed abnormal changes in the methane 

emission. After this report additional re.adings were taken in 5 South to 

determine me thane liberations before, duri.ng, and after succeeding water infusions of 4 South. Table 4 sumarizes thesle results and shows that methane 

concentration in 5 South increased during each infusion and decreased 

afterward. 

The quantity of methane removed from the 5 South section before and after 

infusions in 4 South is given in table 5. 
Date, 1959 

September : 

25............... 

October : 

3............... 

5............... 

6............... 

8............... 

9 ............... 14............... 

lg............... 

21............... 

3 1. .............. November I............ 

Do. 

Infusing. 

After in fusing . In£ using. 

After infusing. 

Do. 

In £us ing . Do. 

After infusing. 

Do. 

Remarks 

38,000 

37,400 

Right regulator 

Air, 

c.f .m. 

Left repulator 

0.05 

.06 

Methane, 

percent 

Air, 

c. f .m. 

Methane, 

percent 

58,000 

57,600 

0.05 

.05 

Before infusing. 

DO. 
FIGURE 15. - Face Area No. 1 Entry, 4 South, During Water Infusions. 
FIGURE 16. - Graph of Water-Infusion Pressure Versus Time, No. 1 Entry, 4 South. 

'- 60 4 I I I I I I I I I I n Typical for five 

-+- ---- + ----- 4- ----+-----+-------o 

- 

Represents longest period 

of continuous infusion - 

- 

TABU 5. - Methane released from 5 South before 

and after infusions in 4 South 

LL 

f 

E 

W 

k 

- - 

During some infusions in 4 South a dye mixed with the infusion water traveled through 1,500 feet of solid coal to and across the faces of 5 South. 

Also, when mining was resumed in 4 South, the dye was detected by the use of 

an ultraviolet light for 1,500 feet ahead of the infusion point. 

I O 

I I I I I I I 1 I 1 

1 2 3 4 5 6 7 8 9 10 11 

WATER-INFUSION TIME, hours 

Location of 

infusion 

hole 

No. 7 entry 

Do 

Doo 

Do 

No. 1 entry 

Do . 

The quality of gas draining from the horizontal drill holes changed materially during water infusions. Table 6 shows the composition of gas from 

boreholes in 4 South before water infusions were started; table 7 shuws the 

composition of gas from borehole N during an infusion of borehole L. During 

this infusion the gas emission increased from 15 to 20 c.f.m, Repeated infusions of borehole L produced similar results in gas emission rates and quality 

from borehole N. The temperature of water seeping from hole N during infusions was 57O to 58O F., and that of the infusion water was lo to 2' F. higher. 

During infusion of borehole L in No. 7 entry, 4 South, the gas velocity 

from holes in No. 1 entry, 4 South, increased as folluws: Zero to 250 £.p.m. 

from A; 600 to 800 f,p ,mo from B; 400 to 500 f.p ,m. from C; and 50 to 200 

f .p.m. from Y. Borehole X was sealed. The flow of gas from roof-bolt holes 

RBI and RB2 also increased considerably, The rib of borehole X exuded water 

freely and was covered with gas-water bubbles during these infusions. Several 

hours after infusions were completed, the gas being liberated from this rib 

created a loud hissing sound. These results were obtained after each infusion. 

, Methane, c,f.m, 

Left re~ulator 

Increase 

126 

90 

10 5 

134 

180 

116 

Before 

46 

29 

0 

0 

0 

0 

Ri~ht regulator 

After 

172 

119 

105 

134 

180 

116 

Before 

0 

23 

0 

0 

0 

0 

Total section 

Before 

46 

52 

0 

0 

0 

0 

After 

57 

90 

40 

83 

76 

79 

Increase 

57 

67 

40 

83 

76 

79 

After 

229 

209 

145 

217 

256 

195 

Increase 

183 

157 

145 

217 

256 

195 
TABLE 6. - Mass spectrometer analysis of gas from horizontal 

boreholes, 4 South entries 

'see figure 12. 

2~ee figure 15. 

Hole sampled 

L' ................. N1 ................. B~ ........... .. .... c2 ................. 

TABLE 7. - Comosition of gas from borehole N during 

water infusion of borehole L 

Elapsed time, 

minutes 

Percent 

During the infusion of borehole C in No. 1 entry, the gas emission rates 

from borehole A increased from nearly zero to 400 f.p.m,; borehole B increased 

from 600 to 800 fapame; and borehole Y increased from 50 to 300 fap.m. A considerable volume of gas was suddenly emitted from roof-bolt holes RBI and RB2, 

and the left rib at borehole X again exuded water, freely covering the rib 

with gas-water bubbles. After each infusion the liberating gas from the rib 

created a loud hissing sound. Also, the gas emission rate from borehole L was 

increased from nearly zero to 700 fapame As the gas emission rates increased, 

the methane content decreased, 

Percent 

Infusions in Main Entries 

ca% 

0.01 

.01 

.02 

.O2 

c% 

90.00 

92.40 

94.00 

90.50 

No. 9 Entry 

C3% 

0.03 

.03 

.03 

.03 

Ar 

0.02 

.O2 

.04 

.01 

02 

0.20 

4.10 

5.00 

16.80 

20.80 

N2 

1.20 

16.60 

19.10 

53.80 

62.60 

The Mains were developed in a group of nine entries on the butt cleats. 

Figure 17 is a plan of the Main entries during two water infusions showing 

locations of methane drainage holes. 

& 

0.30 

20 

.50 

90 

N2 

1.60 

1.20 

2.30 

4.20 

co2 

6.10 

7.10 

7.20 

7.10 

7.10 

Hole No, 1 was infused for 9 hours, and 10 minutes at water pressures 

ranging from 30 to 118 pasmi., using two pumps in parallel capable of delivering 25 g,p.m. A total of 13,650 gallons of water was infused. During the 

last 30 minutes a wetting agent was added to the water, and within a few minutes after the infusion hole No. 2 was discharging water colored by the 

wetting agent, 

C& 

8.00 

6.10 

3.10 

4.20 
Drill hole 4, 120' 

Drill hole 2, 100' 

Drill hole 5, 120' 

infusion 

1, 100' 

infusion 

FIGURE 17. - Plan of Main Entry Faces During Two Infusions. 

Less dust became airborne during mining operations in the section infused 

with a wetting agent solution than in those sections where water alone was 

used. 

Air measurements before and during this infusion at the right and left 

return regulators were 54,400 and 63,000 c.f.m,, respectively. The methane 

content of the air after infusion increased 0.28 percentage point at the left 

regulator and 0.17 percentage point at the right regulator. Thus, the total 

methane liberation from the Mains as a result of infusion was 268 c .fama 

Crosscut Between the 5 and 6 Entries 

Figure 17 shows horizontal borehole No. 3 drilled in the pillar between 

projected 5 and 6 entries, the face of Mains when the hole was drilled, and 
the bleeder holes 4 and 5. Hole No. 3 was infused at the same time the continuous-mining machine was being operated in No. 3 entry. Pressure of infusion water ranged from 100 to 150 p .s .i. at the beginning of the infusion; 

later it was reduced to 50 p.s.i. and then to 25 p.s.i. to prevent the release 

of an excessive amount of methane. 

Air measurements at the right and left return regulators before and during this infusion were 55,600 and 44,200 c.f.m., respectively. The methane 

content of the air after the infusion increased 0.14 percentage point at the 

left regulator and 0.13 percentage point at the right regulator. Thus, the 

total methane liberation from the Mains as a result of infusion was 134 c.f.m. 

Lnfusions in 5 South Entries 

Crosscut Outby Clay Vein 

Entries 1 through 4 had been driven through a clay vein that was exposed 

at the face of entry 5. (See fig. 18.) Holes 2 and 3 terminated in the clay 

vein. Hole No. 3 was infused for 21 hours and 10 minutes. During the first 

7 hours, water at pressures ranging from 50 to 110 p.s.i. was injected. During the last 14 hours and 10 minutes of the infusion, water at 100 p.s.i. was 

supplied from a pipeline at a static pressure of 225 p.s.i. Water, totalling 

14,560 gallons, and wetting agent soluticln were used at the rate of 11.5 g.p.m. 

Air measurements before and during the infusions at the right and left 

return regulators were 80,100 and 65,900 c. f.m., respectively. Methane content of the air after infusion increased 0.9 percentage point at the right 

regulator and 0.6 percentage point at the left. Thus, the total methane liberation from 5 South as a result of the f.irst infusion was 1,116 c.f.m. 

After 5 hours, hole No. 3 again was infused for 1 hour and 15 minutes 

with water at pump pressures ranging from 70 to 140 p.s.i. The flow rate was 

14 g.p.m. The flow of air at the left and right return regulators was 58,500 

and 83,300 c.f.m., respectively. There bras no increase in methane content at 

the left regulator, but there was an increase of 0.2 percentage point at the 

right regulator. Thus, total methane liberation from 5 South as a result of 

the second infusion was 167 c.f.m. 

During subsequent mining in the 5 South entries, the mine officials and 

workmen reported that there was a substantial decrease in airborne dust. 

Crosscut Inby Clay Vein 

After the entries had been mined four crosscuts past the clay vein, 

bleeder holes 5, 6, and 7 were drilled. (See fig. 18.) Hole 6 was infused 

for 13.5 hours. Water at pump pressure of 250 p.s.i. and a rate of 15 g.p.m. 

was injected into the hole for 12 hours and 10 minutes. Water at a pressure 

of 200 p.s.i. was supplied from a static pipeline for 1 hour and 10 minutes at 

the rate of 11.5 g.p.m. 
FIGURE 18. - Clay Vein and Face Areas During Two Infusions, 5 South. 

Air measurements before and during the infusion at the right and left 

return regulators were 64,300 and 63,100 c.f.m., respectively. The methane 

content of the air after infusion increased 0.65 percentage point at the right 

regulator and 0.3 percentage point at the left. Thus, the total methane liberated from 5 South as a result of the infusion was 607 c.f.m. 

When the faces had advanced another crosscut, hole 7 was drilled in the 

pillar between 5 and 6 entries. It was fitted with a water-infusion seal, a 

pressure gage, and a shutoff valve. When the valve was closed for 1 minute, 

the shut-in pressure was 0.5 p.s.i., and after 4 hours the pressure was 

5 p.s.i. 
Discussion of Infusion Results, Main and 5 South Entries 

The results of infusion in the Mains and the 5 South entries were similar 

to those in the 4 South. The Mains were driven on butt cleats, and although 

higher pressures were needed to force the water into the boreholes, there is 

no conclusive proof that the cleats were wholly responsible for pressure 

differences. 

As in 4 South, there was no indication of damage to the floor or roof as 

a result of water infusion. 

DEGAS IFICATION TMZWGH VERTICAL BOREHOLE 

Free Flow of Methane 

A power-drop borehole, BH26 (fig. I),, was drilled from the surface to the 

top of the coalbed ahead of the 5 South eintries. Before completing the drilling through the coalbed, the hole was cased with 6- 5/8- inch standard casing 

and grouted to the surface. The total depth of the hole was 455 feet. Both 

gas and water entered the hole, but the gas flow stopped when water reached a 

static level of 365 feet. 

A bottom-hole pump (fig. 19) was installed, and when water was removed, 

24,000 cubic feet per day of gas was emitted. The hole developed a shut-in 

pressure of 28 p.s.i. 

Flow by Vacuum 

Two months after the pump was installed the free flow of gas from the 

hole, when dewatered, decreased to 17,000 cubic feet per day. A rotary vacuum 

pump with a capacity of 53 c.f .me was connected to the casing, and the flow of 

gas was increased to 29,200 cubic feet per day. The installation of a vacuum 

pump with a capacity of 115 c.f.m. at a vacuum of 13.5 inches of mercury 

increased the gas flow further to 82,200 cubic feet per day. 

Samples of gas were taken from the borehole during free flow and while 

the vacuum pump was being operated. After the larger vacuum pump was connected, the gas samples showed an increase of air content. Although the 5 

South entries were 800 feet from the borehole, the increased air content probably was coming from the mine ventilating currents, 

Table 8 summarizes drainage data and gas analyses of samples taken from 

BH26. Gas samples were taken periodicallly from the hole at free flaw by 

stopping the vacuum pump. After each sample, orifice readings showed that the 

gas quantity decreased; likewise the methane content decreased. 

To determine if mine ventilating air was passing through the 800 feet of 

coal between the 5 South entries and the borehole, a Veeco Ms-9A helium-leak 

detector was installed on the surface. (See fig. 20.) Helium emission readings were taken for several days before helium was released in 5 South. The 

accuracy of the leak detector permits measurement of 1 part helium in 10 

million parts of gas, 
Ac cumulated 

producing 

time of 

hole, days 

0 ....... 

51. ...... 

Ill....... 

145....... 

15 1. ...... 158.. ..... 164....... 16 5.. ..... 216....... 244....... 256....... 258. ...... 

264.. ..... 266.. ..... 

26 7. ...... 

271....... 

275.. ..... 

284....... 

290....... 

29 3. ...... 

 ole dry. 

Temperature, 

Atmosphere 

- - 

t: 

- 

- 

32 

{ 

32 

30 35 

{ 6! 

40 

46 46 

26 

{ 6; 

49 

{ z: 

40 

- 

" F, 

Gas 

- 

- 

- - 

- - 

78 

88 91 

82 

84 82 

110 

- 

80 

86 

89 

102 

6 1 

84 

80 

51 

70 

65 

- 
ypp

mine atmosphere at the face of No. 1 entry, 5 South. A substantial increase 

in heliumwas detected at the borehole 3 hours and 20 minutes after release. 

The following day, helium under pressure of 50 p.s .i. was released through an 

infusion seal into a bleeder hole in the No. 1 entry. One hour after the 

release it was detected on. the surface. Three more releases, on successive 

days, were made: (1) At the face of No. 1 entry, 5 South; (2) at the face of 

No. 4 entry, 5 South; and (3) in the intak.e air of No. 4 entry, 5 South. Two 

hours after each release a substantial increase in helium was detected on the 

surface. 

Table 9 sunnnarizes data for the five helium releases in the mine. 
TABLE 9. 

Days 

operating 

helium leak 

detector 

1st day.... 

2d day. .... 

3d day.. . . . 

Time of 

readings 

3:30 p.m. 8:30a.m. 

9:30a.m. 

10:OO a.m. 

2:OO p.m. 

2:15 p.m. 

3:00 p.m. 5:00 p.m. 5:50 p.m. 

6:15p.m. 6:35 p.m. 9:50 p.m. 

10:03 p.m. 10:21 p.m. 10:30p.m. 

12:OO a.m. 

8:00 a.m. 

10:OO a.m. 

10:30a.m. 

11:OO a.m. 

12:30 p.m. 

2:00 p.m. 

2:30p.m. 

4:00 p.m. 4:30p.m. 

\7:05p.m. 

Top of 

BH26, 

oF 

40 

14 

20 

25 

35 35 35 30 

25 

22 

22 18 18 

17 17 17 17 18 20 25 

32 

36 

38 

45 

50 

43 

ro

d
- 

- 

- 

- 

- 

- 

From cylinde

mine atmosp

- 

- 

- 

- 

- 

From cylinde

mine atmosp

- 

- 

- 

- 

- 

- 

- 

- 

From cylinde

mine atmos

- 

- 

- 

- 

- 

- 

- 

- 

first met

ing in table, 1.80, times 0.00122 (constant) equals 0.002196 micron cubic feet of helium per h

"~eadin~s taken before helium was released underground to establish normal helium emission for the 

borehole. 

- 

- 

o 

- 

- 

- 

Face of No. 1 entry 

- 

o 

- 

- 

- 

Face of No. 4 entry 

- 

- 

- 

o 

- 

- 

- 

- 

Intake of No. 4 entry. 

- 

o 

- 

- 

- 

- 

- 

- 

feet per hour; for example, 

4th day.. .. 

5th day .... 

34 

45 

41 

42 

42 

42 

44 

44 

45 

46 

47 

47 

40 

41 

42 

39 

40 

37 

30 

30 

30 

32 

33 

35 

40 

41 

40 

37 

35 

40 

0.00122 

12:30 a.m. 

7:00 p.m. 

2:OOa.m. 

/7:30a.m. 

8:OOa.m. 

9:OOa.m. 

10:OOa.m. 

11:OO a.m. 

12:00 n. 

1:00 p.m. 

2:30 p.m. 

3:OOp.m. 

8:OOa.m. 

2 .OO 

1.90 

1.80 

1.60 

1.50 

1.30 

1.45 

1.45 

2 .OO 

2.00 

1.90 

1.80 

1.60 

1.60 

1.95 

2 .OO 

1.90 

1.80 

1.70 

1.50 

1.40 

1.20 

1.30 

2.00 

2.20 

2.05 

1.50 

1.40 

1.20 

1.30 

(constant) 

9:OOa.m. 

10:OOa.m. 

12:00 n. 

1:OOp.m. 

- 

- 

- 

o 

- 

- 

10:OO to 10:15 a.m. 

o 

- 

- 

- 

- 

8:00 to 8:05 a.m. 

- 

- 

- 

- 

- 

- 

- 

- 

8:00 to 8:03 a.m. 

- 

- 

- 

- 

- 

- 

- 

- 

equals micron cubic 

7thday.... 

8th day .... 

6:00 p.m. 

/ 4:00 a.m. 

5:OOa.m. 

7:OOa.m. 

8:OOa.m. 

9:OOa.m. 

10:OO a.m. 

12:30p,m, 

2:OOp.m. 

3:00 p.m. 

12:OOa.m. 

I 8:00 a.m. 

9:30a.m. 

l~etereading times 
FIGURE 20. - Veeco MS-9A Helium-Leak Detector. 
A~,n",n",n",~",~",~",A",~",n",~,", 9 ‘infusion plug L~educedl tozff to fit I 

- - - - - - - - - - - - - - - - 

FIGURE 21. - Connection of BH26 With Horizontal Borehole, 5 South. 
9:OOa.m. 55 95 11.0 

9:30 a.m. 55 100 11.0 

7:25 p.m. 66 60 - 

7:30 p.m. 66 75 11.0 

7:35 p.m. 66 75 11.0 

7:37 p.m. 66 75 11.0 2d..... 7 :39 p.m. 66 75 11.0 

7:41p.m. 66 75 11.0 

7:44p.m. 65 80 - 

7:47 p.m. 65 80 11.0 

7 :50 p.m. 65 80 11.0 

7:52 p.m. 65 86 11.0 

7:57 p.m. 64 91 11.0 

7:59p.m. 64 100 11.0 

8:00 p.m. 64 105 11.0 

See footnotes at end of table, p. 37. 
TABLE 10. - Gas composition and flow under vacuum 

through drill hole in face (Con,) 

suction Atmosapplied 

* 

Water 

gage, 

inches 

Analyses of gas, 

inc he:; 

l~ottom of No. 26 surface borehole was intersected by 5 South workings. 

. 'capacity of gas vacuum pump was 115 c.f.m. 

A piece of litmus paper was attached to the free ends of the tubes, and 

they were held by one observer together with a piece of cloth soaked in a weak 

solution of hydrochloric acid. While this observer sniffed the handheld 

tubes, another released the ammonia from a cylinder through an infusion seal. 

As the gasified ammonia migrated through the bed, the pungent odor was 

detected by fuming of the acid-soaked cloth and the change in color of the 

litmus paper from pink to blue. 

It required 21 seconds for amuonia to migrate from hole 2 to hole 1, 27 

seconds from hole 2 to hole 3, and 31 seconds from hole 2 to hole 5. No gas 
y g

gas per minute. Since horizontal holes in the coalbed drained gas longer and 

at a faster rate than holes in the roof, it appeared that most of the methane 

was held in the coalbed rather than in the adjacent strata. 

Vacuum applied to a drainage hole increased the flow rate of gas. Drainage from a 20-foot horizontal hole in the coal was increased twentyfold by 

vacuum applied to a surface borehole connected with the horizontal hole. 

By controlling the water-infusion rate applied to bleeder holes, release 

of methane from the coalbed ahead of mining faces can be regulated. During 

one idle period, as much as 1,600,000 cubic feet of methane was removed; when 

mining was resumed, the methane content was less than normal. 

Lnfusion water did not penetrate the 7-foot binder of the coalbed and no 

ill effects of the water were noticed on either the roof or floor of the mine. 

Water infusion, especially with a wetting agent added to the solution, reduced 

the amount of dust at the face. 
A vertical borehole from the surface to the bottom of the coalbed drained 

methane from the bed by free flow, With a -vacuum pump connected on the surface, the emission rate increased, but the percentage of methane decreased, 

The total volume of gas removed by free flow and vacuum pumping was 8 million 

cubic feet, The shut-in pressure ranged from 28 to 100 p,s,i. 

Experiments with tracers introduced into the infusion water and the 

ventilating-air current proved that water, helium, and anhydrous ammonia 

travel through solid coal, Infusion water mixed with fluorescein dye traveled 

1,500 feet through coal, 

Helium under vacuum traveled 800 feet through the coalbed and through a 

455-foot borehole to surface in 1 to 3 hours. 

Anhydrous ammonia under pressure released into horizontal boreholes 

traveled 4 feet in 21 seconds horizontally,, 4 feet in 27 seconds vertically, 

and 7 feet in 31 seconds diagonally across the bedding planes.