Mission: As the Nation's principal conservation 

agency, the Department of the Interior has responsibility for most of our nationally-owned public 

lands and natural and cultural resources. This 

includes fostering wise use of our landand water 

resources, protecting our fish and wildlife, preserving the environmental and cultural values of 

our national parks and historical places, and providing for the enjoyment of life through outdoor 

recreation. The Department assesses our energy 

and mineral resources and works to assure that 

their development is in the best interests of all 

our people. The Department also promotes the 

goals of the Take Pride in America campaign by 

encouraging stewardship and citizen responsibility for the public lands and promoting citizen participation in their care. The Department also has 

a major responsibility for American Indian reservation communities and for people who live in 

Island Territories under U.S. Administration. 
Report of Investigations 9282 

Pressure Monitoring and Observed Effects 

of Mining at the Oak Grove, AL, Coalbed 

Degasif ication Pattern 

By David C. Oyler 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Manuel Lujan, Jr., Secretary 

BUREAU OF MINES 

T S Ary, Director 
Library of Congress Cataloging in Publication Data: 

Oyler, David C. 

Pressure monitoring and obsemed effects of mining at the Oak Grove, AL, 

coalbed degasification pattern / by David C. Oyler. 

(Report of investigations; 9282) 

Includes bibliographical references. 

Supt. of Docs. no.: I 28.23:9282. 

1. Coalbed methane drainage-Alabama-Oak Grove Region-Evaluation. 

2. Coalbed methane-Alabama-Oak Grove Region-Measurement. I. Title. 

11. Series: Report of investigations (United States. Bureau of Mines); 9282. 

TN23.U43 [TN844.6] 622 S-dc20 [622'.82] 89-600248 
CONTENTS 

Page 

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

Introduction ........................................................................ 2 

Measurement of gas content and gas content reduction ........................................ 3 

Estimated pattern drainage area ......................................................... 3 

Isothermcurve ...................................................................... 5 

Pressuredata ....................................................................... 6 

Productiondata ..................................................................... 7 

Effectsofmining .................................................................... 10 

Gas and water production ............................................................ 12 

Coalbed pressure .................................................................. 12 

Possible causes of observed fluid migration patterns ........................................... 13 

Summary .......................................................................... 14 

~onclusions ........................................................................ 15 

References ......................................................................... 15 

Appendix A..Monitor well pressure data ................................................... 16 

Appendix B..Monitor well core analysis data ................................................ 26 

ILLUSTRATIONS 

Map of monitor and pattern well locations .............................................. Pattern area and estimated area of gas drainage .......................................... Isotherm curve derived from Oak Grove gas content and pressure data ......................... Graph of pressure data for monitor wells MI. M2. and M3 .................................. Daily gas and water production rates for pattern wells 1 through 3 ............................ Daily gas and water production rates for pattern wells 4 through 6 ............................ Daily gas and water production rates for pattern wells 7 through 9 ............................ Daily gas and water production rates for pattern wells 11 through 13 ........................... Daily gas and water production rates for pattern wells 14 through 16 ........................... Daily gas and water production rates for pattern wells 17 through 19 ........................... Daily gas and water production rates for pattern wells 21 through 23 ........................... Daily gas and water production rates for pattern wells 24 and 25 .............................. Isochrone map for mining-induced gas production changes .................................. Isochrone map for mining-induced water production changes ................................ Graph of water and gas production rates. and pressure rates versus time for monitor well M3 and 

patternwell25 ................................................................. Graph of water and gas production rates. and pressure rates versus face position for monitor well M3 

and pattern well 25 .............................................................. 

TABLES 

Measured gas contents and formation pressures at Oak Grove degasification pattern ............... Original Oak Grove pattern in-place gas volume .......................................... Estimated reduction in in-place gas content caused by production through October 1981 ............ Pressure decline equations .......................................................... Joint and cleat orientations ......................................................... Bottom hole pressure data .......................................................... Gas content determination for monitor wells ............................................ Proximate analysis and total sulfur .................................................... Ultimate analysis and calorific value ................................................... Ashcomposition ................................................................. Petrographic entity composition of samples from monitor well M2 ............................ 
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

British thermal unit per pound 

(mass) 

cubic centimeter 

cubic centimeter per gram 

foot 

foot per day 

square foot 

cubic foot 

cubic foot per short ton 

gram 

gallon per day 

in 

lb/ft3 

1bf/in2 

lbf/in2(ga) 

lbf/in2d 

Mstdft3/d 

MMstdft3 

pet 

st 

we pct 

inch 

pound per cubic foot 

pound (force) per square inch 

pound (force) per square inch, gauge 

pound (force) per square inch per day 

thousand standard cubic feet per day 

million standard cubic feet 

percent 

short ton 

weight percent 
PRESSURE MONITORING AND OBSERVED EFFECTS OF MINING 

AT THE OAK GROVE, AL, COALBED DEGASlFlCATlON PAITERN 

By David C. oylerl 

ABSTRACT 

The U.S. Bureau of Mines and the United States Steel Corporation evaluated the progress of methane 

drainage at the Oak Grove, AL, degasification pattern. Coalbed pressures were monitored between 

December 1981 and November 1985. Formation pressures, in the lower bench of the Mary Lee Coalbed, 

were reduced from 400 lbf/in2(ga) in 1977 to 50 lbf/in2(ga) in November 1985. Gas contents of coal 

cores obtained from monitor wells were compared with coalbed gas contents measured in 1976. Data 

indicated a 48- to 56-pct reduction within the pattern and a 29-pct reduction at a point 500 ft outside 

the pattern. 

The effect of the advance of a section of the Oak Grove Mine on changes in gas and water production 

rates in the pattern was evaluated. Gas production increases were noted in 12 wells; water production 

decreases were noted in 6. The times of initial influence indicate the presence of a zone of high 

permeability within the pattern. This zone correlates well in orientation and location with a fracture 

zone mined through at the mine. The existence of such fracture zones could have a significant effect 

on productivity of individual coalbed methane wells. 

l~echanical engineer, Pittsburgh Research Center, U.S. Bureau of Mines, Pittsburgh, PA. 
LEGEND 

Pressure mon~tor well 

MI 

Pattern well 

16 

Pattern well w~lh 

@ desorption data used 

7 to est~mate or~glnal 

coolbed gas content 

Poved highway 

(Wells 10 and 20never dr~lled) 

11'"1' 

0 500 1,000 1,500 

Scale, f t 

Figure 1.-Map of monltor and pattern well locations. 
MEASUREMENT OF GAS CONTENT AND GAS CONTENT REDUCTION 

Gas content data for the pattern area were obtained 

from coal cores from the original pattern wells in 1976 and 

from the monitor wells drilled in 1981. Both sets of gas 

content data were obtained using the Bureau direct 

method (4). No pressure or temperature corrections were 

made to the gas volumes measured from either set of 

samples, or to any of the values computed in this report 

using direct method data. A recent study (4) based upon 

direct method samples from the Oak Grove Mine area (5) 

suggests that uncorrected direct method values average 

about 5 pct higher than measurements corrected to 

standard temperature and pressure. Table B- 1 details the 

computation of gas content for the cores obtained from 

the monitor wells. Four coal samples, together 

representing the entire lower bench of the Mary Lee 

Coalbed, were obtained from each monitor well. A 

separate gas content determination was made for each 

sample, and then the total gas volumes and coal weights 

for the four samples from each well were summed to 

obtain an average gas content for the coalbed at each 

monitor well location. Because only part of the coal from 

each sample was available for residual gas determination, 

it was not possible to directly add the residual gas volume 

to the lost and desorbed volumes, but instead the total gas 

content was determined by adding the residual gas on a 

per unit weight of coal basis. 

The 1976 (original) and the 1981 gas content values 

(table 1) were compared to obtain an estimate of the 

reduction in gas content caused by gas production from 

November 1977 through October 1981. An estimate of the 

original gas content at a particular monitor well location 

was made by averaging the gas content values for those of 

the six production wells closest to that monitor well. 

Comparison of the 1976 and 1981 gas content values 

indicated that the gas content within the pattern had been 

reduced between 48 and 56 pct, while at M3,500 ft outside 

the pattern, the gas content had been reduced by 29 pct 

(3). 

Table 1.-Measured gas contents and formation 

pressures at Oak Grove degasification pattern 

Sample Gas Formation 

location content,' pressure,2 

ft3/st lbf /in2ha) 

Monitor wells:3 

MI ............ M2 . . . . . . . . . . . . M3 . . . . . . . . . . . . Pattern wells:4 

We11 6 . . . . . . . . . We11 7 . . . . . . . . . We11 8 . . . . . . . . . We11 14 . . . . . . . . We11 15 . . . . . . . . We11 25 . . . . . . . . 

'~ot corrected to standard temperature and pressure. 

2~t time of coring. 

3Cored in October or November 1981. 

4Cored in 1976 before gas production initiated. 

ESTIMATED PATTERN DRAINAGE AREA 

The gas content reductions were used to obtain some 

idea of the area affected by the pattern. This was actually 

done by assuming a drainage area, computing the gas 

volume removed from that area, and comparing the computed volume to the known gas volume produced from 

the pattern through October 1981. A simple model was 

chosen assuming two areas of drainage, a central area 

outlined by the pattern perimeter wells, and an area outside the pattern perimeter (shaded in figure 2) to 500 ft 

outside of the central area. 

In the central area the gas content of the lower bench 

of the Mary Lee in October 1981 was assumed to be 227 

ft3/st, based upon an average of the gas content values 

from M1 and M2. The gas content of the outer area was 

assumed to be 352 ft3/st, based upon the gas content at 

M3. 

Table 2 shows the computations made of the estimated 

volumes and weights of coal within these areas and the 

estimated original in-place gas volume. The original gas 

content of the lower bench of the Mary Lee Coalbed was 

assumed to be 480 ft3/st for both areas. The coal thicknesses are based upon data from production wells in the 

pattern. The coal density is based upon data from density 

logs run in the monitor wells. The reduction of in-place 

gas volume is computed in table 3. In both tables two 

estimates are given, the first assuming gas production from 

only the lower bench of the Mary Lee Coalbed and the 

second assuming a contribution from the upper bench in 

addition to that from the lower bench. 

The original estimate given by Oyler (3) assumed 

that the gas produced came only from the lower bench of 

the Mary Lee Coalbed. However, separation of the two 

benches averages about 6 ft and it is likely that the many 

naturally occurring vertical fractures that have been found 

in the rock between the two benches allow gas production 

from the upper bench by way of well completions in the 

lower bench. Where production from the upper bench has 

been assumed, the assumption has also been made that 

the upper bench had the same original gas content as the 

lower bench and that degasification proceeded at the same 

rate in both benches. The original four measurements 

made in 1976 for the upper bench gave an average gas 

content of 449 ft3/st with a standard deviation of 93 fi3/st. 
LEGEND 

$ Pressure monltor well 

Portern we1 I wllh desorptlon 

doto used to esrcmote orlglnol 

coalbed gos contenr 

------ Ponern boundory 

Assumed 1981 outside boundory 

of gas drainage ore0 

I----- 

; I &tlmoTed ov gos conlent 

I ' 227 ft3/st. 10/81 ~----i 

Orlglnol In- lace gas content assumed lo 

be 480 frP/st 

0 1.000 2.000 

Figure 2.-Pattern area and estimated area of gas drainage. 
The two estimates of the reduction in in-place gas 

volume are 1,115 MMstdft3, from the lower bench only, 

and 1,453 MMstdft3, from both benches. These compare 

favorably with the actual gas production of 1,110 MMstdft3. 

Because of the uncertainty in the assumptions made in 

deriving these values it has not been felt worthwhile to 

further refine the estimates. The computations suggest 

that through 1981 the drainage was primarily from the 

lower bench. However, one factor not considered in the 

estimates is that the gas content from M3 may not be 

representative of the coalbed outside of the pattern area. 

Data from a recent publication by Briscoe (6), and production data to be discussed later in this report, suggest that 

M3 lies within the area of influence of a high-permeability 

joint or fracture zone. 

If high-pressure gradients are assumed for the immediate vicinity of this zone, then it is possible that it could 

have caused an anomalously low pressure at M3 and 

therefore a low gas content. A lower than average gas 

content at M3 would incorrectly suggest a greater degree 

of drainage from the coalbed, and that the area required 

to account for the pattern gas production was smaller than 

the actual drainage area. It also suggests that a contribution from the upper bench was unnecessary to account for 

the produced gas. However, the information available 

from the three monitor wells cannot be used to determine 

if drainage took place from the upper bench, although it 

appears likely. 

ISOTHERM CURVE 

The available gas content data were used to develop an 

isotherm curve (fig. 3) for the entire pattern based upon 

field data. Pressure data were available from the monitor 

wells beginning in December 1981 and water levels had 

been measured in a number of production wells in 1-977, 

prior to their stimulation and initial gas production. The 

curve developed from the pressure and gas content data 

allows pressure data from the monitor wells to be used to 

obtain estimates of current gas content and in-place gas 

volumes, and to estimate the current rates of desorption. 

In October 1985 the average formation pressure at 

the Oak Grove pattern had been reduced to about 55 

Ibf/in2(ga), from an original high value of about 420 

Ibf/in2(ga). Based upon the isotherm curve, this suggests 

that the gas content within the pattern area was about 

140 ft3/st by the end of 1985. This is about 30 pct of the 

gas content (480 ft3/st) measured in 1976 when the pattern 

wells were being drilled. 

FORMATION PRESSURE (PI, lbf /in2(ga) 

20 

Figure 3.-Isotherm curve derived from Oak Grove gas content and pressure data. 

I KEY I 1 I 

Mlo Pressure monitor well - 600 
PRESSURE DATA 

Figure 4 shows in graphical form the pressure data 

from the monitor wells. The data are also tabulated in 

appendix A. Dates not shown are days upon which no 

measurements were obtained. Pressure monitoring began 

in December 1981 and continued, with some loss of data 

caused by surface cable breaks and instrument failures, 

until October 31, 1985, the end of the contract period. 

Surface electrical problems prevented obtaining data from 

M2 beginning at the end of June 1985 and from M1 at the 

beginning of October 1985. A final pressure reading was 

obtained manually from M3 on August 14, 1986, long after 

regular pressure monitoring had been discontinued. 

The sensor used to measure pressure was the Lynes 

sentry' tool, a device designed to measure pressure and 

temperature. The tool used a bourdon tube pressure 

sensor, connected to a digitizer, which gave the device a 

resolution of 1 part in 500. Because a 500-lbf/in2 bourdon 

tube was used in all three instruments, each instrument 

could only resolve pressure changes of + 1 lbf/in2. During 

the early data reporting period, the three readings taken 

each day were averaged, and the pressure reported to the 

nearest 0.5 lbf/in2. After April 1982 this practice was 

discontinued and the pressures were reported to the 

nearest 1.0 lbf/in2. 

Before the advance of the Oak Grove Mine began to 

affect them, the rates of pressure decline in all three monitor wells followed stable, linear decline curves. Table 4 

shows the least squares linear equation fit to the pressure 

decline rates at each well. The period used in computing 

the equations is from November 1982 (just after adjustments made to the sensor elevations in the wellbores had 

caused perturbations to the pressure decline curves) until 

June 1984, just before the first mining effects were observed in M3. The equations all have high correlation 

the data. The standard deviations of all three equations 

are close to 1 lbf/in2, which is close to the instrument 

resolution. 

Table 4.-Pressure decline equations 

(November 21, 1982, to June 30, 1984) 

Well Pressure decline equation,' R~ S 

 e east squares fit to pressure data, from day 350 to 937. 

FI2 Correlation coefficient, squared. 

S Standard deviation. 

T Time, in days from December 7, 1981. 

Using the equations in table 4, the formation pressure 

decline at the Oak Grove pattern, due to normal gas and 

water production, may be estimated at between 0.03 and 

0.06 Ibf/in2d. 

The pressure decline rates may be used, along with the 

isotherm curve, to estimate the desorption rates at the 

locations of the monitor wells. When this is done the 

maximum desorption rates for wells MI, M2, and M3, 

between 1982 and 1984, are found to be 1.5, 1.3, and 1.7 

ft3/st per month, respectively.' If the entire pattern area 

shown in figure 2 is assumed to have desorbed gas at the 

highest rate, then the maximum rate of desorption would 

be about 9 MMstdft3 per month for the lower bench only 

and about 12 M~stdft~ for both benches. This is far short 

of the 30.3 ~Mstdft~ actually produced in June 1984. 

These calculations suggest that from 1982 on, most of the 

gas produced, at least 60 to 70 pct, came from outside the 

immediate pattern area. 

coefficients (the R~ valie shown in the table is the square 

of the correlation coefficient), indicating a good T;t to 

'~ven at a constant rate of change in pressure, the desorption rate 

changes with the absolute pressure; increasing as the pressure decreases. 

3~eference to specific products does not imply endorsement by the The values given here are for June 1984, the lowest pressure for the 

U.S. Bureau of Mines. period. 

Hole shut In 

Surface cable 

12-7-81 

oL ,lll,lll,ll Ill1 

200 400 600 800 1,000 1,200 1,400 1,500 

TIME, days 

Figure 4.-Graph of pressure data for monitor wells MI, M2, and M3. 
PRODUCTION DATA 

Figures 5 through 12 show the daily gas and water production rates for the pattern wells. The curves actually 

show the production rates for every third day and have 

been smoothed by taking a 10-point moving average of the 

data (this gives a rough equivalent of a 30-day moving 

average on daily production data). Only every third day 

was plotted because the gas flow rates reported by U.S. 

Steel were obtained by reading totalizing meters every 2 to 

4 days, with the assumption of a constant flow rate during 

the period. The smoothing was done in order to remove 

the effects of minor production changes, especially those 

caused by pump failures, and to allow the major trends to 

become more obvious. The period plotted in the figures 

is from November 6, 1983, to January 14, 1986. This 

period was chosen in order to look at the effects of mining 

upon gas and water production. The period before June 

of 1984 (day 930) was included to give a base period, free 

of mining influence, for comparison. 

About half of the pattern wells show a roughly linear 

decline in gas production, while a linear decline in water 

production was observed in only a few wells. Most of the 

wells exhibiting signs of such trends in water production 

were at the outer edge of the pattern. Wells in the center 

of the pattern generally showed little overall change in 

water production rate during the period. The linear 

decline trends were interrupted when mining approached 

the pattern. 

I I I 500 Water production Lhange: none observed 

Gas production change: none observed 

- 400 

I I I I I I lo 

900 1,100 1,300 1.500 

TIME, days 

Figure 5.-Dally gas and water production rates for pattern 

wells 1 (top), 2 (middle), and 3 (bottom). 

I 1 1 I 

- 

- - 

- Water production change: none observed - 

Gas production change: none observed 

1 I 1 

1 I 1 I I I 1 

- 

- 

- Water production change: none observed 

Gas production change: none observed 1 I 1 I 1 1 

1 I I I 

water lproductibn change: none 'observed 

-Gas production change: day 1,2 59 

Product~on change date ----- Est~mated trend 0 I I I 0 

700 900 1.100 1,300 1,500 

TIME, days 

Figure 6.-Daily gas and water production rates for pattern 

wells 4 (top), 5 (middle), and 6 (bottom). 
Water production change: none observed 1 1 

Gas production change: day 1,187 

- 

60 1 wbter production change: nbne observed ' 1 80 

70 

60 

40 

50 -..- Water 

Production chonge dote 

Estimated trend 1 

700 900 1.100 1,300 1.500 

TIME, days 

Figure 7.-Daily gas and water production rates for pattern 

wells 7 (top), 8 (middle), and 9 (bottom). 

f 

Water production change : none observed I 

Gas production change: none observed 

- 

.. -.. >..\, . {- \

L.. - 

I I 1 I I I 

70 1 Watei ~roduction chariae : none' observed 1 200 i

Gas prbduction chong;: none observed 

70 

~oier production chonge.none obseived 1 300 

h I, Gas production chonge. doy 1,168 4 250 

- Gas -..- Water 

! Pr;$;'on change 

I Est~rnaled trend 

0-I I I, I I 0 

700 900 1.100 1.300 1.500 

TIME, days 

Figure 8.-Daily gas and water production rates for pattern 

wells I 1 (top), 12 (middle), and 13 (bottom). 
lo t Gos production change: 

I,,,, dOY1.069 < 

01 1 1 I 1 I 10 

7 00 900 1.100 1.300 1.500 

TIME, days 

Figure 9.-Daily gas and water production rates for pattern 

wells 14 (top), 15 (middle), and 16 (bottom). 

- 

- 11-6-83 

I - 1-14-56 

I I I 

Figure 10.-Daily gas and water production rates for pattern 

wells 17 (top), 18 (middle), and 19 (bottom). 

6 40 

4 

2 2 0 

0 0 

700 900 1.100 1.300 1.500 

TIME, days 
1 1 1 

- Water production change: none observed 

Gas production change: none observed 

- 

Water production change : none observed 

Gas production change: none observed 

- 

- - 

1 1 I 1 

Water production change: none observed 

- 

, 11-6-83 

0 1 I 1 1 I I 1 0 0 0 

700 900 1,100 1,300 1,500 700 900 1,100 1,300 1.500 

TIME, days TIME, doys 

Figure 11.-Daily gas and water productfon rates for pattern Figure 12.-Daily gas and water production rates for pattern 

wells 21 (top), 22 (middle), and 23 (bottom). weils 24 (top) and 25 (bottom). 

EFFECTS OF MINING 

In late 1983 a section of the nearby Oak Grove Mine 

began to approach the northwestern corner of the Oak 

Grove pattern (figs. 13-14) from the west. The sevenentry, 550-ft-wide section advanced due east beginning in 

December 1983 at 3,180 ft from monitor well M3 and 

3,680 ft from production well 25. Mining continued to 

approach the pattern until May 1985 when the closest mine 

entries were 400 ft from M3. In May 1985 the mine began 

to drive a set of entries south, parallel to the pattern, and 

at a distance of approximately 1,075 ft from the western 

edge of the pattern. Because the contract reporting period 

ended in June 1985 the advance rate of this southern set 

of entries is not known in detail, but they eventually 

extended along most of the western side of the pattern. 

Generally, gas production increased as mining approached the pattern and water production declined. 

Increases in gas production, which appeared to be attributable to the effect of mining, were observed in 12 of the 

23 wells. The area of observable reduction in water production rate was generally smaller than that observed for 

gas production rate increases, so reductions in water production rates were observed in only six wells. The time 

required for a reduction in water production rate to take 

place was also generally longer, for any given well, than 

that required for a gas production change. 
LEGEND 

) Pattern well 

0 Pressure monitor well 

MI 11,0671 Day number for 

water production changes 

',200,woter production isochrone, 

contour interval 50 days 

Approximate location of 

intersection of fracture zone 

Scale. fi 

Figure 14.-isochrone map for mining-Induced water production changes. 
no physical evidence available for the existence of this 

increased permeability zone. Briscoe described the mine 

interception of a fracture zone at the location shown by 

the X's in figures 13 and 14. A more detailed discussion 

of this zone is given in "Possible Causes of Observed Fluid 

Migration Patterns" section. 

COALBED PRESSURE 

No mining-induced changes in formation pressure were 

observed until mining was about 1,500 ft from M3 (day 

1,050), long after gas and water production had been 

affected at wells 14, 17, 24, and 25. Bcfore day 1,050, the 

pressure curve for M3 (fig. 4) showed only the effects of 

pattern gas and water production and the pressure at M3 

declined at an average 0.06 lbf/in2d. Figure 4 shows a 

change in the pressure curve of M3 at about day 1,050. 

The pressure rate curve on figure 15 shows a more rapid 

'~a~ numbers used in this report are referenced to the first day of 

pressure monitoring, December 7, 1981. 

days were required for the pressure wave to travel the 

distance to MI. This gives a rough estimate for the speed 

of the pressure wave of about 300 ft/d. 

W . - ; .. . b~in~ng stopped 

r~ - 

- 

A Pump problems -f. -'..: '- 

-1.0 

700 800 900 1.000 1.100 1.200 1.300 1.400 1.500 

TIME, days 

Figure 15.-Graph of water and gas production rates, and 

pressure rates versus time for monitor well M3 and pattern 

well 25. 
No pressure changes due to mining were ever observed 

in M2. The pressure decline for M2 maintained the same 

slope from day 340 through day 1,300, when the last pressure reading was obtained from the well. The pressure 

decline curve observed in M2 is assumed to have resulted 

solely from the production of water and gas from the 

pattern. Had a surface equipment failure not prevented 

the acquisition of additional data, it is likely that a pressure decline due to mining might have become apparent at 

M2 before the end of the study period. However, it 

appears that M2 was far from both the mine and the 

fracture zone, and the pressure changes caused by mining 

probably would have been small. 

When the time of initial mining effect on M3 is compared to that of the first production changes in well 25 

and similar comparisons are made between wells M1 and 

M2 and the production wells closest to them, the times 

suggest that water and gas production changes take place 

long before any measurable (greater than 1 lbf/in2) change 

in formation pressure occurs. Although M1 might appear 

to be an exception, in this case the pressure wave traveled 

quickly through the fracture zone and actually caught up 

with the changes in the formation associated with the 

changes in gas and water production, which had already 

been observed at well 14 by day 1,015, well before the 

mine intercepted the fracture zone. Prior to the time the 

mine cut into the fracture zone (days 1,030 to 1,060), it is 

assumed that the mine opening had influenced production 

in the pattern by intercepting water that had previously 

flowed from areas northwest of the pattern through coal 

cleat to the fracture zone and then through the fracture 

zone into the center of the pattern. 

POSSIBLE CAUSES OF OBSERVED FLUID MIGRATION PAlTERNS 

Joint and cleat measurements made by U.S. Steel for 

the Gas Research Institute (5) and by the Bureau (3, 

were studied to determine possible sources of the directional permeability observed. Table 5 summarizes the 

work done by the Bureau prior to 1976, and by U.S. Steel 

more recently. The cleat studies showed that the face 

cleat direction was at approximately N 62" E +- 7", and the 

butt cleat, while much less well defined, was approximately 

N 30" W + 12". The surface joint studies indicated that 

the most prominent joint set in the area was oriented at 

between N 62" W and N 65" W. The U.S. Steel and 

Bureau data showed less agreement on other joint sets, 

probably because the Bureau study looked at fewer joints 

over the entire Yolande Northeast, 7-1/2 quadrangle, while 

the U.S. Steel study concentrated upon the area of the 

Oak Grove production pattern and made many more 

measurements in that small area. 

The joint and cleat studies strongly suggest that the 

source of the directional permeability increase was not the 

face cleat, as is often the case, but was generally related to 

the regional joint orientation. The direction of most rapid 

change in production rates was not to be northeast, as 

would be expected if face cleats were the most permeable 

paths for fluid migration, but to the southeast, which 

suggests that naturally occurring joints trending in that 

direction, and presumably in the roof, were of higher 

permeability than the face cleat. In both studies, a prominent set of joints was observed in the same direction 

(N 62" W) as indicated by the production changes. Because no cleat trending in this direction was observed in 

either study, this means that the actual path of fluid movement would have to be along a more localized joint system, in the strata adjacent to the coalbed. However, 

it should be kept in mind that because of the direction 

from which mining was approaching the pattern, highpermeability paths to the southeast would be expected to 

be much more easily observed than those to the northeast 

where there were no wells to allow observation of the 

changes in formation conditions. 

Table 5.-Joint and cleat orientations 

Source and type of data 

Direction 

Coal bed Measurements Primary Secondary 

(face cleat) (butt cleai) 

U.S. Steel (5): 

Surface joints ..... 

Mine cleat ....... Oriented core ..... Do ........... Do ........... BuMines (7): 

Surface joints ..... 

NAp ............... 

Mary Lee, Blue Creek . . Pratt ............... Mary Lee, Blue Creek . . Black Creek ......... 

NAp ............... 

Mine cleat ....... Mary Lee, Blue Creek . . 250 N 64" E 

NAp Not applicable. 

NR Not recorded. 
The conclusion that the face cleat was a much less permeable path is more strongly supported by the fact that 

the earlier times of first increase in gas production continued to occur in wells to the southeast (such as 8,9, and 

13) even after there were wells to the northeast that could 

have been affected. This observation of probable fluid 

flow through rock fractures lends support to the hypothesis 

that gas from the upper bench of the Mary Lee was produced from the well completions in lower bench of the 

Mary Lee. 

As previously discussed, a section of the Oak Grove 

Mine advancing toward the pattern intercepted a set of 

fractures in the roof rock and in the lower bench of the 

Mary Lee Coalbed (6), in October 1984. The data from 

figures 13 and 14 clearly suggested that such a fracture 

system might be present, even before the physical evidence 

proved its existence. This set of fractures apparently 

produced sufficient quantities of gas and water to prevent 

mining for several months, although coal stockpiling and 

market conditions may have contributed to the length of 

the suspension period (the 1981-84 United Mine Workers 

of America contract expired during this period). 

If the line of the permeability increase observed in 

figures 13 and 14 is extended to the mine location where 

the fractures were intercepted, they line up exactly. This 

suggests that the increased permeability zone indicated in 

the figures was caused by an isolated zone of fractures in 

the coalbed or adjacent strata, which have a higher permeability than the coalbed face cleat. 

Briscoe (6) reported that interception of the fractures 

cut off the up-dip source of water to the northwestern portion of the pattern. This in turn would lead to decreased 

water production, decreased pressures, and to increased 

gas desorption rates and gas production in that portion of 

the pattern. Production data from well 25 do not support 

the theory that water production would be reduced immediately upon the interception of the fracture zone. Reductions in the rate of water production began in June 1984, 

well before the fracture zone was mined into. However, 

if it is assumed that a gradual reduction in water production would take place as the mine advanced into portions 

of the coalbed supplying water to the fracture zone, then 

this reduction could be expected to begin before the mine 

Recorder failure\ I \I 1 

u 4.000 3,000 2,000 1,000 0 

FACE DISTANCE. ft 

Figure 16.-Graph of water and gas production rates, and 

pressure rates versus face position for monitor well M3 and 

pattern well 25. 

intercepted the fractures. This hypothesis matches the 

observed water production history of well 25. 

The changes in production rates seemed to travel much 

more slowly along the face cleat direction than along the 

fracture zone direction. The face cleat was estimated to 

be between N 55" E and N 64" E at the Oak Grove site. 

Neither of the isochrones (for water or gas) showed any 

rapid change of production rates to the northeast or southwest along the face cleat direction. Through days 1,100 to 

1,150 the direction of most rapid change was to the 

southeast. After that period the direction of most rapid 

change rotated to the south (between wells 8 and 9) and 

southwest (in the vicinity of well 13). This could indicate 

the termination of the fracture zone allowing the effects 

from the presence of cleat to dominate in that area or 

could indicate an actual rotation of a fracture zone. No 

wells northeast of wells 6, 7, 8, and 9 were observed to be 

affected by mining, but this is likely because the 

production rate changes being observed had been reduced 

below the limits of detection at that distance (wells 3, 4, 

and 5 were about 4,000 ft from the furthest eastern 

advance of the mine) and time. 

SUMMARY 

The U.S. Bureau of Mines and U.S. Steel Corporation 

conducted a 4-year cooperative project to monitor pressures at the Oak Grove, AL, degasification pattern. Three 

monitor wells were drilled to obtain cores to determine 

the change in coalbed gas content from the start of degasification in late 1977 through 1981. The wells were equipped with instruments to measure formation pressure. For 

the period of November 1982 to June 1984 the pressure 

decline curves for the monitor wells followed a nearly 

straight-line decline. The ressure decline rates were P between 0.03 and 0.06 lbf/in d. The gas desorption rates 

obtained from these pressure decline rates are insufficient 

to account for the actual gas production volumes, unless 

production from outside of the pattern area is assumed. 

Estimates were made of the original in-place gas volume and the reduction in in-place gas volume through 

1981. The estimates of original in-place gas were made 

assuming gas production for the lower bench only (2,600 

MMstdft3) and for combined production from the upper 

and lower benches (3,400 MMstdft3), with estimated reductions of in-place gas volume of 1,115 and 1,453 MMstdft3, 

respectively. The actual gas volume produced through 

1981 was 1,110 MMstdft3. 
In late 1983 the Oak Grove Mine began to advance reductions in water production due to the effects of 

toward the northwestern corner of the pattern. By June mining. 

1984 the wells closest to mining had begun to respond to The initial indications of the effects of mining were 

the effects of mining. By the time mining toward the plotted on a map of the pattern and the times were conpattern had been terminated, in May 1985, 12 wells had toured. The contours suggested the presence of a local 

shown increases in gas production and 6 wells had shown area of increased permeability within the pattern. 

CONCLUSIONS 

Data from monitor wells drilled at the Oak Grove 

degasification pattern show that 8 years of gas and water 

production (1978 through 1985) caused a reduction in 

the formation pressure from an original 420 lbf/in2(ga) 

to &bout 55 lbf/in2(ga). During that time, based on an 

isotherm constructed from gas content and pressure data, 

the coalbed gas content is estimated to have dropped an 

average 70 pct from 480 ft3/st to 150 ft3/st, in mid-1985. 

Based upon pressure decline curves and the isotherm 

curve, it appears that since 1982 at least 60 to 70 pct 

of the gas being produced at the Oak Grove pattern 

has come from outside of the immediate pattern area. 

This appears to be the case despite the fact that large 

quantities of gas still remain within the pattern area. 

If the 1981 samples are representative of the coal in 

place, then up to 90 pct of the gas remaining in 1985 was 

desorbable. 

The advance of mining toward the pattern in 1984 

caused a very consistent set of responses. In the wells 

affected, gas production first began to increase for a period of time ranging from 30 to 130 days, followed shortly 

after by decreases in water production over a period of 

from 30 to 150 days. The increases in gas production 

ranged from 10 to 200 pct, while the decrease in water 

production ranged from 50 to 80 pct. Eventually as the 

gas desorbed by the presence of the mine opening was 

produced, either into the mine workings or to production 

wells, gas production leveled off and began to decline 

again. Water production remained at the lower levels, 

reflecting the loss of reservoir area to mining. 

It would be difficult to use this type of information to 

predict the timing or magnitude of the production rate 

changes in other wells in the same coalbed, because the 

ranges of these rate changes were strongly controlled by 

the distances of the wells from the mine opening and the 

fracture zone. However the data do show that the advance 

of the mine opening toward a coalbed methane drainage 

well can cause large, temporary increases in gas production 

and permanent decreases in water production. They also 

suggest that the timing of these changes will vary siMcantly with local geological conditions. 

The time of the initial indications of mining effects on 

the production wells suggested the presence of a localized 

area of high permeability in the northwestern portion of 

the Oak Grove pattern. Study of joint and cleat data 

collected by the Bureau and U.S. Steel suggested that 

this higher permeability was associated with either highpermeability joints or a fault. Physical evidence for a highpermeability fracture zone was finally obtained from 

reports of a zone in the coalbed and roof rock, mined 

through by the Oak Grove Mine. The quantities of gas 

and water reported to be flowing from the fractures shortly after mine-through indicate that the zone is of higher 

permeability than joints or cleat typically existing within 

the Mary Lee Coalbed. Fracture zones of this type could 

have a major effect on the productivity of methane drainage wells and upon mining activity. Knowledge of the 

locations of such features would be of great value, both to 

allow optimization of production well sites, and to minimize the detrimental effects of mining through such zones. 

1. Lambert, S. W., and M. A. Trevits. Methane Drainage Ahead 

of Mining Using Foam Stimulation-Mary Lee Coalbed AL. U.S. Dep. 

Energy RI PMTC-3, Jan. 1979, 22 pp. 

2. Stubbs, P. B., F. X. Dobscha, and J. V. Mahoney. Degasification 

of the Blue Creek Coal Seam at Oak Grove Mine. Paper in Proceedings, Second Annual Methane Recovery for Coalbeds Symposium. 

Morgantown OW) Energy Technol. Center, METC/SP-7919, 1979, 

pp. 96-113. 

3. Oyler, D. C., and P. B. Stubbs. Measuring Formation Pressures 

and the Degree of Gas Drainage in a Large Coalbed Gas Drainage 

Field. BuMines RI 8986, 1985, 15 pp. 

4. Diamond, W. P., J. C. LaScola, and D. M. Hyman. Results of 

Direct-Method Determination of the Gas Content of U.S. Coalbeds. 

BuMines IC 9067, 1986, 95 pp. 

5. Camp, B. S., F. H. Briscoe, P. G. Malone, and C. M. Boycr I1 

(U.S. Steel Corp.). Rock Creek Methane From Multiple Coal Seams 

Completion Project, Special Data Package Preliminary Geologic Report. 

Gas Res. Inst., Chicago, IL, contract 5081214-0847, May 1985, 133 pp. 

6. Briscoe, F. H., B. S. Camp, L. K. Lottman, and P. G. Malone. A 

Study of Coal-Bed Methane Production Trends as Related to Geologic 

Features, Warrior Basin, Alabama. Ch. in Geology and -1-Bed 

Methane Resources of the Northern San Juan Basin, Colorado and 

New Mexico, ed. by J. E. Fassett. Rocky Mountain Assoc. Geol., 

Denver, CO, 1988, pp. 237-246. 

7. Murrie, G. W., W. P. Diamond, and S. W. Lambert. Geology of 

the Mary Lee Group of Coalbeds, Black Warrior Coal Basin, Alabama. 

BuMines RI 8189, 1976, 49 pp. 
APPENDIX 1 ..MONITOR WELL PRESSURE DATA 

Table A-1 . Bottom hole pressure data, pounds (force) per square Inch. gauge 

Presgure. I I Pressure. 

Dec . 7 ...... Dec . 8 ...... Dec . 9 ...... Dec . 10 ..... Dec.11 ..... Dec . 14 ..... Dec . 15 ..... Dec . 28 ..... Dec.29 ..... Dec.30 ..... Dec.31 ..... 1982: 

Jan . 1 ...... Jan . 2 ...... Jan . 3 ...... Jan . 4 ...... Jan . 5 ...... Jan . 6 ...... Jan . 7 ...... Jan . 8 ...... Jan . 9 ...... Jan . 10 ...... Jan . 11 ...... Jan . 12 ...... Jan . 13 ...... Jan . 14 ...... Jan . 15 ...... Jan . 16 ...... Jan . 17 ...... Jan . 18 ...... Jan . 19 ...... Jan . 20 ...... Jan . 21 ...... Jan . 22 ...... Jan . 23 ...... Jan . 24 ...... Jan . 25 ...... Jan . 26 ...... Jan . 27 ...... Jan . 28 ...... Jan . 29 ...... Jan . 30 ...... Jan . 31 ...... Feb . 1 ...... Feb . 2 ...... Feb . 3 ...... Feb . 4 ...... Feb . 5 ...... Feb . 6 ...... Feb . 7 ...... Feb . 8 ...... Feb . 9 ...... Feb . 10 ..... Feb.11 ..... Feb . 12 ..... Feb . 13 ..... Feb . 14 ..... Feb . 15 ..... Feb . 16 ..... Feb . 17 ..... Feb . 18 ..... 

Mar.11 ..... Mar . 12 ..... 

Mar . 13 ..... Mar . 14 ..... Mar . 15 ..... Mar . 16 ..... Mar . 17 ..... Mar . 18 ..... Mar . 19 ..... Mar.20 ..... Mar . 21 ..... Mar.22 ..... Mar . 23 ..... Mar.26 ..... Mar . 27 ..... Mar.28 ..... Mar.29 ..... Mar . 30 ..... Mar.31 ..... Apr . 1 ....... Apr . 2 ....... Apr . 3 ....... Apr . 4 ....... Apr . 5 ....... Apr . 13 ...... Apr . 14 ...... Apr . 15 ...... Apr . 16 ...... Apr . 17 ...... Apr . 18 ...... Apr . 19 ...... Apr . 20 ...... Apr . 21 ...... Apr . 22 ...... Apr . 23 ...... Apr . 24 ...... Apr . 25 ...... Apr . 26 ...... Apr . 27 ...... Apr . 28 ...... Apr . 29 ...... Apr . 30 ...... May1 ...... May2 ...... May3 ...... May4 ...... May5 ...... May6 ...... May7 ...... May8 ...... May9 ...... May10 ...... May11 ...... May12 ...... May13 ...... May14 ...... May15 ...... May16 ...... May17 ...... May18 ...... May19 ...... May20 ...... May21 ...... May22 ...... May 23 ...... 
Table A-1 ..Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Date 

1982.Con . May24 ...... May25 ...... May26 ...... May27 ...... May28 ...... May29 ...... May30 ...... May31 ...... June1 ...... June2 ...... June3 ...... June4 ...... June5 ...... June6 ...... June7 ...... June8 ...... June9 ...... June 10 ..... June11 ..... June 12 ..... June 13 ..... June 14 ..... June 15 ..... June 16 ..... June 17 ..... June 18 ..... June 19 ..... June 20 ..... June 21 ..... June 22 ..... June23 ..... June 24 ..... June 25 ..... June 26 ..... June 27 ..... June 29 ..... June30 ..... July 1 ....... July 2 ....... July 3 ....... July 4 ....... July 5 ....... July 6 ....... July 7 ....... July 8 ....... July 9 ....... July 10 ...... July11 ...... July 12 ...... July 13 ...... July 14 ...... July 15 ...... July 16 ...... July 17 ...... July 18 ...... July 19 ...... July20 ...... July 21 ...... July22 ...... July 23 ...... July 24 ...... July 25 ...... July 26 ...... July 27 ...... July 28 ...... July29 ...... July30 ...... 

July31 ...... Aug . 1 ...... Aug . 2 ...... Aug . 3 ...... Aug . 4 ...... Aug . 5 ...... Aug . 6 ...... Aug . 7 ...... Aug . 8 ...... Aug . 9 ...... Aug . 10 ..... Aug.11 ..... Aug . 12 ..... Aug . 16 ..... Aug . 17 ..... Aug . 18 ..... Aug . 19 ..... Aug.20 ..... Aug . 21 ..... Aug.22 ..... Aug.23 ..... Aug.24 ..... Aug.25 ..... Aug.26 ..... Aug.27 ..... Aug.28 ..... Aug.29 ..... Aug.30 ..... Aug . 31 ..... Sept . 1 ...... Sept . 2 ...... Sept . 3 ...... Sept . 4 ...... Sept . 5 ...... Sept . 6 ...... Sept . 7 ...... Sept . 8 ...... Sept . 9 ...... Sept . 10 ..... Sept . 11 ..... Sept . 12 ..... Sept . 16 ..... Sept . 17 ..... Sept . 18 ..... Sept . 19 ..... Sept . 20 ..... Sept.21 ..... Sept . 22 ..... Sept . 23 ..... Sept . 24 ..... Sept . 25 ..... Sept.26 ..... Sept . 27 ..... Sept . 28 ..... Sept . 29 ..... Sept . 30 ..... Oct . 1 ....... Oct . 2 ....... Oct . 3 ....... Oct . 4 ....... Oct . 5 ....... Oct . 6 ....... Oct . 7 ....... Oct . 8 ....... Oct . 9 ....... Oct . 10 ...... Oct . 11 ...... 

Day Pressure. 

number ~bf/in~(~a) 

MI M2 M3 

Dby Pressure. 

Date number ~bf/in~(~a) 

MI M2 M3 

1982-Con . 
Table A-1 . Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Date 

1 982.Con . Oct . 12 ...... Oct . 13 ...... Oct . 15 ...... Oct . 16 ...... Oct . 17 ...... Oct . 18 ...... Oct . 19 ...... Oct . 20 ...... Oct . 21 ...... Oct . 22 ...... Oct . 23 ...... Oct . 24 ...... Oct . 25 ...... Oct . 26 ...... Oct . 27 ...... Oct . 28 ...... Oct . 29 ...... Oct . 30 ...... Oct . 31 ...... Nov . 1 ...... Nov . 3 ...... Nov . 4 ...... Nov . 5 ...... Nov . 6 ...... Nov . 7 ...... Nov . 8 ...... Nov . 9 ...... Nov . 10 ..... Nov . 11 ..... Nov . 12 ..... Nov . 13 ..... Nov . 14 ..... Nov . 15 ..... Nov . 16 ..... Nov . 17 ..... Nov . 18 ..... Nov . 19 ..... Nov . 20 ..... Nov.21 ..... Nov . 22 ..... Nov . 23 ..... Nov . 24 ..... Nov.25 ..... Nov . 26 ..... Nov . 27 ..... Nov . 28 ..... Nov . 29 ..... Nov . 30 ..... Dec . 1 ...... Dec . 2 ...... Dec . 3 ...... Dec . 4 ...... Dec . 5 ...... Dec . 6 ...... Dec . 7 ...... Dec . 8 ...... Dec . 9 ...... Dec . 10 ..... Dec . 11 ..... Dec . 12 ..... Dec . 13 ..... Dec . 14 ..... Dee. 15 ..... Dec . 16 ..... Dec . 17 ..... Dec . 18 ..... Dec . 19 ..... 

Day Pressure. I I Day Pressure. 

Dec.20 ..... Dec . 21 ..... Dec.22 ..... Dec . 23 ..... Dec . 24 ..... Dec . 25 ..... Dec.26 ..... Dec.27 ..... Dec.28 ..... Dec.29 ..... Dec.30 ..... Dec . 31 ..... 1983: 

Jan . 1 ...... Jan . 2 ...... Jan . 3 ...... Jan . 4 ...... Jan . 5 ...... Jan . 6 ...... Jan . 7 ...... Jan . 8 ...... Jan . 9 ...... Jan . 10 ...... Jan . 11 ...... Jan . 12 ...... Jan . 13 ...... Jan . 14 ...... Jan . 15 ...... Jan . 16 ...... Jan . 17 ...... Jan . 18 ...... Jan . 19 ...... Jan . 20 ...... Jan . 21 ...... Jan . 22 ...... Jan . 23 ...... Jan . 24 ...... Jan . 25 ...... Jan . 26 ...... Jan . 27 ...... Jan . 28 ...... Jan . 29 ...... Jan . 30 ...... Jan . 31 ...... Feb . 1 ...... Feb . 2 ...... Feb . 3 ...... Feb . 4 ...... Feb . 5 ...... Feb . 6 ...... Feb . 7 ...... Feb . 8 ...... Feb . 9 ...... Feb . 10 ..... Feb . 11 ..... Feb . 12 ..... Feb . 13 ..... Feb . 14 ..... Feb . 15 ..... Feb . 16 ..... Feb . 17 ..... Feb . 18 ..... F& . 19 ..... Feb.20 ..... Feb . 21 ..... Feb.22 ..... Feb.23 ..... 

number ~bf/in'(~a) 

MI M2 M3 

Date number ~bf/in'(~a) 

MI M2 M3 
Table A-1.-Bottom hole pressure data, pounds (force) per square inch, gauge-Continued 

Date 

1983-Con. 

Feb. 24 ..... Feb.25 ..... Feb.26 ..... Feb. 27 ..... Feb. 28 ..... Mar. 1 ...... Mar. 2 ...... Mar. 3 ...... Mar. 4 ...... Mar. 5 ...... Mar. 6 ...... Mar. 7 ...... Mar. 8 ...... Mar. 9 ...... Mar. 10 ..... Mar.11 ..... Mar. 12 ..... Mar. 13 ..... Mar. 14 ..... Mar. 15 ..... Mar.16 ..... Mar. 17 ..... Mar. 18 ..... Mar. 19 ..... Mar. 20 ..... Mar.21 ..... Mar. 22 ..... Mar.23 ..... Mar. 24 ..... Mar. 25 ..... Mar. 26 ..... Mar.27 ..... Mar.28 ..... Mar. 29 ..... Mar.30 ..... Mar. 31 ..... Apr. 1 ....... Apr. 2 ....... Apr. 3.. ..... Apr. 4 ....... Apr. 5.. ..... Apr. 6 ....... Apr. 7.. ..... Apr. 8 ....... Apr. 9 ....... Apr. 10.. .... Apr. 11 ...... Apr. 12 ...... Apr. 13.. .... Apr. 14.. .... Apr. 15.. .... Apr. 16 ...... Apr. 17 ...... Apr. 18.. .... Apr. 19.. .... Apr. 20 ...... Apr. 21 ...... Apr. 22 ...... Apr. 23 ...... Apr. 24 ...... Apr. 25 ...... Apr. 26 ...... Apr. 27 ...... Apr. 28 ...... Apr. 29 ...... Apr. 30 ...... May1 ...... 

Day number 

Pressure, 11 

Date 

1983-Con. 

May2 ...... May3 ...... May4 ...... May5 ...... May6 ...... May7 ...... May8 ...... May9 ...... May10 ...... May11 ...... May12 ...... May13 ...... May14 ...... May15 ...... May16 ...... May17 ...... May18 ...... May19 ...... May20 ...... May21 ...... May22.. .... May23.. .... May24.. .... May25 ...... May26 ...... May27 ...... May28 ...... May29 ...... May30 ...... May31 ...... June1 ...... June2 ...... June3 ...... June4 ...... June5 ...... June6 ...... June7 ...... June8 ...... June9 ...... June 10 ..... June11 ..... June 12 ..... June 13 ..... June14 ..... June 15 ..... June 16 ..... June 17 ..... June 18 ..... June 19 ..... June 20 ..... June 21 ..... June 22 ..... June 23 ..... June 24 ..... June 25 ..... June26 ..... June27 ..... June 28 ..... June29 ..... June30 ..... July 1 ....... July 2 ....... July 3 ....... July 4 ....... July 5 ....... July 6 ....... July 7 ....... 

Day 

number 

Pressure, 

~bf/in~(~a) 

M2 
Table A-1 . Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Date 

1983.Con . July 8 ....... July 9 ....... July 10 ...... July 11 ...... July 12 ...... July 13 ...... July 14 ...... July 15 ...... July 16 ...... July 17 ...... July 18 ...... July 19 ...... July 20 ...... July 21 ...... July22 ...... July23 ...... July24 ...... July 25 ...... July 26 ...... July 27 ...... July 28 ...... July29 ...... July30 ...... July 31 ...... Aug . 1 ...... Aug . 2 ...... Aug . 3 ...... Aug . 4 ...... Aug . 5 ...... Aug . 6 ...... Aug . 7 ...... Aug . 8 ...... Aug . 9 ...... Aug . 10 ..... Aug . 11 ..... Aug . 12 ..... Aug . 13 ..... Aug . 14 ..... Aug . 15 ..... Aug . 16 ..... Aug . 17 ..... Aug . 18 ..... Aug . 19 ..... Aug.20 ..... Aug.21 ..... Aug.22 ..... Aug.23 ..... Aug.24 ..... Aug.25 ..... Aug . 26 ..... Aug.27 ..... Aug.28 ..... Aug.29 ..... Aug.30 ..... Aug . 31 ..... Sept . 1 ...... Sept . 2 ...... Sept . 3 ...... Sept . 4 ...... Sept . 5 ...... Sept . 6 ...... Sept . 7 ...... Sept . 8 ...... Sept . 9 ...... Sept . 10 ..... Sept . 11 ..... Sept . 12 ..... 

1 983.Con . Sept . 13 ..... Sept . 14 ..... Sept . 15 ..... Sept . 16 ..... Sept . 17 ..... Sept . 18 ..... Sept . 19 ..... Sept . 20 ..... Sept . 21 ..... Sept . 22 ..... Sept . 23 ..... Sept . 24 ..... Sept . 25 ..... Sept . 26 ..... Sept . 27 ..... Sept . 28 ..... Sept . 29 ..... Sept . 30 ..... Oct . 1 ....... Oct . 2 ....... Oct . 3 ....... Oct . 4 ....... Oct . 5 ....... Oct . 6 ....... Oct . 7 ....... Oct . 8 ....... Oct . 9 ....... Oct . 10 ...... Oct . 11 ...... Oct . 12 ...... Oct . 13 ...... Oct . 14 ...... Oct . 15 ...... Oct . 16 ...... Oct . 17 ...... Oct . 18 ...... Oct . 19 ...... Oct . 20 ...... Oct . 21 ...... Oct . 22 ...... Oct . 23 ...... Oct . 24 ...... Oct . 25 ...... Oct . 26 ...... Oct . 27 ...... Oct . 28 ...... Oct.29. ..... Oct . 30 ...... Oct . 31 ...... Nov . 1 ...... Nov . 2 ...... Nov . 3 ...... Nov . 4 ...... Nov . 5 ...... Nov . 6 ...... Nov . 7 ...... Nov . 8 ...... Nov . 9 ...... Nov . 10 ..... Nov . 11 ..... Nov . 12 ..... Nov . 13 ..... Nov . 14 ..... Nov . 15 ..... Nov . 17 ..... Nov . 18 ..... Nov . 19 ..... 

Day Pressure. 

number ~bf/in~(~a) 

MI M2 M3 

Day Pressure. 

Date number ~bf/in~(~a) 

MI M2 M3 
Table A-1.-Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Date 

1983.Con . Nov.20 ..... Nov.21 ..... Nov . 22 ..... Nov . 23 ..... Nov . 24 ..... Nov . 25 ..... Nov . 26 ..... Nov . 27 ..... Nov . 28 ..... Nov . 29 ..... Nov.30 ..... Dec . 1 ...... Dec . 2 ...... Dec . 3 ...... Dec . 4 ...... Dec . 5 ...... Dec . 6 ...... Dec . 7 ...... Dec . 8 ...... Dec . 9 ...... Dec . 10 ..... Dec . 11 ..... Dec . 12 ..... Dec . 13 ..... Dec . 14 ..... Dec . 15 ..... Dec . 16 ..... Dec . 17 ..... Dec . 18 ..... Dec . 19 ..... Dec . 20 ..... Dec.21 ..... Dec . 22 ..... Dec . 23 ..... Dec . 24 ..... Dec . 25 ..... Dec . 26 ..... Dec . 27 ..... Dec . 28 ..... Dec . 29 ..... Dec . 30 ..... Dec.31 ..... 1984: 

Jan . 1 ...... Jan . 2 ...... Jan . 3 ...... Jan . 4 ...... Jan . 5 ...... Jan . 6 ...... Jan . 7 ...... Jan . 8 ...... Jan . 9 ...... Jan . 10 ...... Jan . 11 ...... Jan . 12 ...... Jan . 13 ...... Jan . 14 ...... Jan . 15 ...... Jan . 16 ...... Jan . 17 ...... Jan . 18 ...... Jan . 19 ...... Jan . 20 ...... Jan . 21 ...... Jan . 22 ...... Jan . 23 ...... Jan . 24 ...... 

Pressure. 11 Pressure. 

Jan . 25 ...... Jan . 26 ...... Jan . 27 ...... Jan . 28 ...... Jan . 29 ...... Jan . 30 ...... Jan 31 ....... Feb . 1 ...... Feb . 2 ...... Feb . 3 ...... Feb . 4 ...... Feb . 5 ...... Feb . 6 ...... Feb . 7 ...... Feb . 8 ...... Feb . 9 ...... Feb . 10 ..... Feb.11 ..... Feb . 12 ..... Feb . 13 ..... Feb . 14 ..... Feb . 15 ..... Feb . 16 ..... Feb . 17 ..... Feb . 18 ..... Feb . 19 ..... Feb . 20 ..... Feb . 21 ..... Feb.22 ..... Feb.23 ..... Feb.24 ..... Feb . 25 ..... Feb.26 ..... Feb.27 ..... Feb . 28 ..... Feb . 29 ..... Mar . 1 ...... Mar . 2 ...... Mar . 3 ...... Mar . 4 ...... Mar . 5 ...... Mar . 6 ...... Mar . 7 ...... Mar . 8 ...... Mar . 9 ...... Mar . 10 ..... Mar.11 ..... Mar . 12 ..... Mar . 13 ..... Mar . 14 ..... Mar . 15 ..... Mar . 16 ..... Mar . 17 ..... Mar . 18 ..... Mar . 19 ..... Mar.20 ..... Mar.21 ..... Mar . 22 ..... Mar . 23 ..... Mar . 24 ..... Mar . 25 ..... Mar . 26 ..... Mar . 27 ..... Mar . 28 ..... Mar . 29 ..... Mar . 30 ..... Mar.31 ..... Apr . 1 ....... 
Table A-1 . Bottom hole pressure data. pounds (force) per square Inch. gauge-Continued 

Date 

1984.Con . Apr . 1 ....... Apr . 2 ....... Apr . 3 ....... Apr . 4 ....... Apr . 5 ....... Apr . 6 ....... Apr . 7 ....... Apr . 8 ....... Apr . 9 ....... Apr . 10 ...... Apr . 11 ...... Apr . 12 ...... Apr . 13 ...... Apr . 14 ...... Apr . 15 ...... Apr . 16 ...... Apr . 17 ...... Apr . 18 ...... Apr . 19 ...... Apr . 20 ...... Apr . 21 ...... Apr . 22 ...... Apr . 23 ...... Apr . 24 ...... Apr . 25 ...... Apr . 26 ...... Apr . 27 ...... Apr . 28 ...... Apr . 29 ...... Apr . 30 ...... May1 ...... May2 ...... May3 ...... May4 ...... May5 ...... May6 ...... May7 ...... May8 ...... May9 ...... May10 ...... May11 ...... May12 ...... May13 ...... May14 ...... May15 ...... May16 ...... May17 ...... May18 ...... May19 ...... May 20 ...... May21 ...... May22 ...... May23 ...... May24 ...... May25 ...... May26 ...... May27 ...... May28 ...... May29 ...... May30 ...... May31 ...... June1 ...... June2 ...... June3 ...... June4 ...... June5 ...... June6 ...... 

June 15 ..... June 16 ..... June 17 ..... June 18 ..... June19 ..... June20 ..... June 21 ..... June22 ..... June 23 ..... June 24 ..... June 25 ..... June26 ..... June27 ..... June 28 ..... June29 ..... June30 ..... Aug.27 ..... Aug.28 ..... Aug . 29 ..... Aug.30 ..... Aug.31 ..... Sept . 1 ...... Sept . 2 ...... Sept . 3 ...... Sept . 4 ...... Sept . 5 ...... Sept . 6 ...... Sept . 7 ...... Sept . 8 ...... Sept . 9 ...... Sept . 10 ..... Sept . 11 ..... Sept . 12 ..... Sept . 13 ..... Sept . 14 ..... Sept . 15 ..... Sept . 16 ..... Sept . 17 ..... Sept . 18 ..... Sept . 19 ..... Sept . 20 ..... Sept . 21 ..... Sept . 22 ..... Sept . 23 ..... Sept . 24 ..... Sept . 25 ..... Sept . 26 ..... Sept . 27 ..... Sept . 28 ..... Sept . 29 ..... Sept . 30 ..... Oct . 1 ....... Oct . 2 ....... Oct . 3 ....... Oct . 4 ....... Oct . 5 ....... Oct . 6 ....... Oct . 7 ....... Oct . 8 ....... Oct . 9 ......a 

Oct . 10 ...... Oct . 11 ...... Oct . 12 ...... Oct . 13 ...... Oct . 14 ...... Oct . 15 ...... Oct . 16 ...... 

Day Pressure. 

number ~bf/in~(~a) 

MI M2 M3 

Day Pressure. 

Date number ~bf/in~(~a) 

MI M2 M3 

1 984-Con . 
Table A-1 ..Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Day Date number 

1984.Con . Oct . 17 ...... Oct . 18 ...... Oct . 19 ...... Oct . 20 ...... Oct . 21 ...... Oct . 22 ...... Oct . 23 ...... Oct . 24 ...... Oct . 25 ...... Oct . 26 ...... Oct . 27 ...... Oct . 28 ...... Oct . 29 ...... Oct . 30 ...... Oct . 31 ...... Nov . 1 ...... Nov . 2 ...... Nov . 3 ...... Nov . 4 ...... Nov . 5 ...... Nov . 6 ...... Nov . 7 ...... Nov . 8 ...... Nov . 9 ...... Nov . 10 ..... Nov . 11 ..... Nov . 12 ..... Nov . 13 ..... Nov . 14 ..... Nov . 15 ..... Nov . 16 ..... Nov . 17 ..... Nov . 18 ..... Nov . 19 ..... Nov . 20 ..... Nov.21 ..... Nov . 22 ..... Nov . 23 ..... Nov . 24 ..... Nov . 25 ..... Nov . 26 ..... Nov . 27 ..... Nov.28 ..... Nov . 29 ..... Nov.30 ..... Dec . 1 ...... Dec . 2 ...... Dec . 3 ...... Dec . 4 ...... Dec . 5 ....a. 

Dec . 6 ...... Dec . 7 ...... Dec . 8 ...... Dec . 9 ...... Dec . 10 ..... Dec . 11 ..... Dec . 12 ..... Dee. 13 ..... Dec . 14 ..... Dec . 15 ..... Dec . 16 ..... Dec . 17 ..... Dec . 18 ..... Dec . 19 ..... Dec.20 ..... Dec . 21 ...a. 1. 111 

Dec . 22 ..... 1. 112 

Pressure. I I 

Date 

1984.Con . Dec.23 ..... Dec.24 ..... Dec . 25 ..... Dec.26 ..... Dec.27 ..... Dec . 28 ..... Dec.29 ..... Dec.30 ..... Dec.31 ..... 1985: 

Jan. 1 ...... Jan . 2 ...... Jan . 3 ...... Jan . 4 ...... Jan . 5 ...... Jan . 6 ...... Jan . 7 ...... Jan . 8 ...... Jan . 9 ...... Jan . 10 ...... Jan . 11 ...... Jan . 12 ...... Jan . 13 ...... Jan . 14 ...... Jan . 15 ...... Jan . 16 ...... Jan . 17 ...... Jan . 18 ...... Jan . 19 ...... Jan . 20 ...... Jan . 21 ...... Jan 22 . ...... Jan . 23 ...... Jan . 24 ...... Jan . 25 ...... Jan . 26 ...... Jan . 27 ...... Jan . 28 ...... Jan . 29 ...... Jan . 30 ...... Jan . 31 ...... Feb . 1 ...... Feb . 2 ...... Feb . 3 ...... Feb . 4 ...... Feb . 5 ...... Feb . 6 ...... Feb . 7 ...... Feb . 8 ...... Feb . 9 ...... Feb . 10 ..... Feb.11 ..... Feb . 12 ..... Feb . 13 ..... Feb . 14 ..... Feb . 15 ..... Feb . 16 ..... Feb . 17 ..... Feb . 18 ..... Feb . 19 ..... Feb . 20 ..... Feb . 21 ..... Feb . 22 ..... Feb.23 ..... Feb.24 ..... Feb . 25 ..... Feb.26 ..... 

Day 

number 

Pressure . 
Table A-1 . Bottom hole pressure data. pounds (force) per square Inch. gauge-Continued 

Date 

1985.Con . Feb 27 . ..... Feb . 28 ..... Mar . 1 ...... Mar . 2 ...... Mar . 3 ...... Mar . 4 ...... Mar . 5 ...... Mar . 6 ...... Mar . 7 ...... Mar . 8 ...... Mar . 9 ...... Mar . 10 ..... Mar . 11 ..... Mar . 12 ..... Mar . 13 ..... Mar . 14 ..... Mar . 15 ..... Mar . 16 ..... Mar . 17 ..... Mar . 18 ..... Mar . 19 ..... Mar . 20 ..... Mar.21 ..... Mar.22 ..... Mar.23 ..... Mar . 24 ..... Mar.25 ..... Mar . 26 ..... Mar.27 ..... Mar . 28 ..... Mar.29 ..... Mar.30 ..... Mar.31 ..... Apr . 1 ....... Apr . 2 ....... Apr . 3 ....... Apr . 4 ....... Apr . 5 ....... Apr . 6 ....... Apr . 7 ....... Apr . 8 ....... Apr . 9 ....... Apr . 10 ...... Apr . 11 ...... Apr . 12 ...... Apr . 13 ...... Apr . 14 ...... Apr . 15 ...... Apr . 16 ...... Apr . 17 ...... Apr . 18 ...... Apr . 19 ...... Apr . 20 ...... Apr . 21 ...... Apr . 22 ...... Apr . 23 ...... Apr . 24 ...... Apr . 25 ...... Apr . 26 ...... Apr . 27 ...... Apr . 28 ...... Apr . 29 ...... Apr . 30 ...... May1 ...... May2 ...... May3 ...... May4 ...... 

Day 

number 

Pressure. 

Date 

1 985.Con . May5 ...... May6 ...... May7 ...... May8 ...... May9 ...... May10 ...... May11 ...... May12 ...... May13 ...... May14 ...... May15 ...... May16 ...... May17 ...... May18 ...... May19 ...... May 20 ...... May21 ...... May22 ...... May23 ...... May24 ...... May25 ...... May26 ...... May27 ...... May28 ...... May29 ...... May30 ...... May31 ...... June1 ...... June2 ...... June3 ...... June4 ...... June5 ...... June6 ...... June7 ...... June8 ...... June9 ...... June 10 ..... June11 ..... June 12 ..... June 13 ..... June 14 ..... June 15 ..... June 16 ..... June 17 ..... June 18 ..... June 19 ..... June20 ..... June 21 ..... June22 ..... June 23 ..... June24 ..... June 26 ..... June27 ..... June 28 ..... July 7 ....... July11 ...... July 13 ...... July 14 ...... July 16 ...... July17 ...... July 18 ...... July 19 ...... July20 ...... July30 ...... Aug . 2 ...... Aug . 5 ...... Aug . 6 ...... 

Day number 

Pressure. 

~bf/in*(~a) 

M2 
Table A-1 . Bottom hole pressure data. pounds (force) per square inch. gauge-Continued 

Day Pressure. 

Date number lbf/in2(aa) 

1985.Con . Aug . 7 ...... Aug . 8 ...... Aug . 12 ..... Aug . 13 ..... Aug . 14 ..... Aug . 15 ..... Aug . 16 ..... Aug . 19 ..... Aug.20 ..... Aug.21 ..... Aug.22 ..... Aug.23 ..... Aug.28 ..... Aug.29 ..... Aug.30 ..... Sept . 1 ...... Sept . 2 ...... Sept . 3 ...... Sept . 4 ...... Sept . 5 ...... Sept . 6 ...... Sept . 7 ...... Sept . 8 ...... Sept . 9 ...... Sept . 10 ..... Sept . 11 ..... Sept . 12 ..... Sept . 13 ..... Sept . 14 ..... Sept . 15 ..... Sept . 16 ..... Sept . 17 ..... Sept . 18 ..... Sept . 19 ..... Sept . 20 ..... Sept . 25 ..... Sept . 27 ..... Sept . 28 ..... Sept 29 . ..... Oct . 2 ....... Oct . 3 .....a. 

Oct . 9 ....... Oct . 11 ...... Oct . 14 ...... Oct . 15 ...... Oct . 16 ...... Oct . 17 ...... Oct . 18 ...... Oct . 22 ....a. 

Oct . 23 ...... Oct . 24 ...... Oct . 28 ...... Oct . 29 ...... Oct . 30 ...... Oct . 31 ...... 1986: 

Aug . 14 ..... NR Not recorded . 
APPENDIX B.-MONITOR WELL CORE ANALYSIS DATA 

Table 6-1 ..Gas content determination for monitor wells 

Laboratory gas content determination 

Monitor Sample Coal sample Gas vol_ume, Estimated 

well interval. dry weight. g cm' Gas content. cm5/g in situ 

and ft Entire Residual Lost and Lost and gas content. 

sample sample gas . desorbed Flesidua12 desorbed Residual ~otal) ft3/st 

MI: 

D ..... 1.077.00-1.078.47 1. 204 382 9. 237 185 7.7 0.5 8.2 263 

C .... 11078.47-11079.94 1. 197 462 9. 137 190 7.6 . 4 8.0 256 

A ..... 1.079.94-1.081.67 1. 309 446 8. 790 360 6.7 . 8 7.5 240 

B ..... 1.081.67-1.082.60 839 378 4. 934 280 5.9 . 7 6.6 211 

Total or average ........ 4. 549 1. 668 32. 098 1. 015 47.~ 4.6 47.6 4244 

M2: 

B ..... 1.086.20-1.087.86 1. 564 56 1 10. 167 200 6.5 . 4 6.9 221 

C .... 1.087.86-1.089.74 1. 753 857 10. 736 350 6.1 . 4 6.5 208 

A ..... 1.089.74-1.09 1.50 1. 575 395 9. 530 340 6.0 . 9 6.9 221 

D ..... 1.091.50-1.093.20 1. 493 564 8. 618 350 5.8 . 6 6.4 205 

Total or average ........ 6. 385 2. 377 39. 051 1. 240 46 . 1 4.5 46.6 4211 

M3: 

A ..... 1.066.60-1.069.20 1. 312 449 13. 136 105 10.0 . 2 10.2 327 

B ..... 1.069.20-1.070.11 696 312 7. 215 230 10.4 . 7 11.1 356 

C .... 1.070.1 1-1.071.61 1. 038 32 1 10. 796 220 10.4 . 7 11.1 356 

D ..... 1.071.61-1.072.50 674 292 7. 473 200 11.1 . 7 11.8 378 

Total or average ........ 3. 720 1. 374 38. 620 755 410.4 4.5 41~.9 4350 

'~esidual gas was measured for only this portion of the entire sample . 2~his gas came from crushing the part of the entire sample indicated in the column labeled "Residual gas portion." 

3~he sum of the lost and desorbed gas content and the residual gas content . 4Computed from totals . 

Table B-2.-Proximate analysis and total sulfur. dry weight percent 

Well and Volatile Fixed Ash-free Total 

sample matter carbon Ash volatile sulfur 

matter 

MI: 

D .................. 19.2 73.7 7.1 20.7 0.52 

C ................. 19.4 71.1 9.5 21.4 .47 

A .................. 18.5 71.6 9.9 20.5 .49 

B .................. 17.9 70.5 11.6 20.2 .48 

~om~osite' .......... 18.7 71.1 10.2 20.8 -44 

M2: 

B .................. 18.9 71.9 9.2 20.8 .47 

C ................. 19.1 71.4 9.5 21.1 .47 

A .................. 19.2 73.2 7.6 20.8 -45 

D .................. 20.1 71.2 8.7 22.0 .46 

Composite1 .......... 19.4 72.0 8.6 21.2 .44 

M3: 

A .................. 19.2 72.0 8.8 21.1 .53 

B .................. 19.8 70.0 10.2 22.0 .45 

C ................. 18.5 70.9 10.6 20.7 .48 

D .................. 20.9 73.3 5.8 22.2 .53 

Composite1 .......... 19.3 70.3 10.4 21.5 .44 

'sample made of coal from samples A through D; not an average of data . 
Table B-3.-Ultimate analysis and calorific value 

Well Ultimate analysis, dry wt pct Calorific value, 

Btu/lb dry wt 

Carbon Hydrogen Nitrogen Oxygen Sulfur Ash 

MI ..... 81.72 4.38 1.66 2.37 0.44 9.43 14,133 

Table B-4.-Ash composition, percent 

Well SiO, A203 MgO P20S TiO, MnO CaO K20s Fe203 Na20 So, 

M 1 ......... 46.35 32.84 1.02 0.54 1.62 0.02 5.65 1.51 5.63 0.44 4.19 

M2 ......... 47.97 34.40 1 -04 .50 1.71 .02 3.36 1.63 6.1 1 .39 2.79 

M3 ......... 45.54 32.50 1.48 .48 1.68 c.02 5.30 1.62 6.12 .44 4.17 

Table B-5.-Petrographic entity composition of samples from monitor well M2, percent 

Technique Mineral Mean maximum 

and sample Vitrinite Exinite lnertinite matter reflectance, 

in oil 

A .................. B.................. 

C ................. D.................. 

composite2 .......... ~eth~lene:~ 

A,................. 

B.................. 

C ................. D .................. ~om~osite~ .......... 

PAp Not applicable. 

Regular immersion lens and oil. 

2~omposite sample made up of coal from samples A, B, C, and D (not an average of data from those samples). 

3~ethylene iodide lens and oil.