OSOOSUGGG 

OF OIL WELLS PENETRATING 

APPALACHIAN COAL MINES 
DEMONSTRATION OF SAFETY PLUGGING OF OIL WELLS 

PENETRATING APPALACHIAN COAL MINES 

G. E. Rennick and J. Pasini 111 

Morgantown Energy Research Center, Morgantown, W. Va. 

F. E. Armstrong and J. R. Abrams 

Bartlesviiie Energy Research Center, Bartlesville, Okla. 

Bureau of Mines Coal Mine Health and Safety Research Program 

Technical Progress Report - 56 

July 1972 

U.S. DEPARTMENT OF THE INTERIOR 

 his report is based on work done under a cooperative agreement between the 

Bureau of Mines, U.S. Department of the Interior, and the Christopher Coal 

Co., a Division of Consolidation Coal Co. 
CONTENTS 

Abstract ................................................................. Introduction ............................................................. Acknowledgments .......................................................... Well-plugging materials .................................................. Well selection ........................................................... Well testing and plugging ................................................ Mining through a plugged well ............................................ Conclusions .............................................................. Appendix.--Detailed summary for plugging wells ........................... 

1. Location of wells with respect to mining operations in Christopher 

Coal Co.'s Osage No. 3 mine, January 1, 1971 ...................... 2. Typical surface equipment on old wells in Clay district, 

Monongalia County, W. Va .......................................... 3. Gamma ray-neutron well log showing location of coalbeds ............. 4. Gamma ray, neutron, caliper, and casing-collar logs showing 

bottom section of plugged well .................................... 5. J. Wildman well 15, before and after partial plugging and 

completion for testing, and after plugging to surface ............. 6. J. Wildman well 16, before and after partial plugging and 

completion for testing, and after plugging to surface ............. 7. S. Barrackman well 5, before and after partial plugging and 

completion for testing, and after plugging to surface ............. 8. Fetty Heirs well 10, before and after partial plugging and 

completion for testing, and after plugging to surface ............. 9. Sampling a plugged well for SF6 tracer .............................. 10. Well at surface after grading and reseeding ......................... 11. Casing from S. Barrackman well 5 after mining through and 

removal from Pittsburgh coalbed ................................... 

1 TABLE 

1. Gas concentrations after mining through S. Barrackman well 5, 

Osage No. 3 mine, Christopher Coal Co ............................. 
DEMONSTRATION OF SAFETY PLUGGING OF OIL WELLS 

PENETRATING APPALACHIAN COAL MINES 

by 

G. E. enn nick,' J. Pasini 11lI2 F. E. ~rrnstronc~,~ and J. R. Abrarns 4 

ABSTRACT 

An oil well penetrating the Pittsburgh bituminous coalbed in northern 

West Virginia was plugged and safely mined through 3 months later. A sensitive chemical tracer, introduced into the oil reservoir before the test, was 

not detected in the mine air following the plugging and during mining of the 

pillar and penetration of the well. Effectiveness of the plugging in preventing reservoir gas from entering the mine through the well hole was verified by 

continuous monitoring of the mine air for indications of sulfur hexafluoride, 

an inert gas detectable in amounts as minute as 112 part per billion. Expandable cement and fly ash-gel-water slurry were utilized to seal the well above 

and below the coal seam. Three other wells were also plugged using various 

techniques. 

1 INTRODUCTION 1 

Plugging of abandoned oil wells is being investigated as a means of solving various problems these wells pose to coal-mining operations. Coalbeds at 

relatively shallow depths are often penetrated by,boreholes drilled into oil 

and gas formations below the coal. In the Appalachian area, thousands of oil 

and gas wells that penetrateminable coalbeds have been abandoned or produce 

only marginal amounts of oil and/or gas. Only about 40 percent of the wells 

are still producing oil or gas; the rest quite likely could be abandoned in 

favor of mining operations. 

The Federal coal-mining regulation5 requires barriers to be established 

and maintained around oil and gas wells in accordance with State laws and regulations. These barriers must be at least 300 feet in diameter, although 

greater or lesser barriers may be permitted by the Secretary of the Interior 

or his authorized representative. The purpose of the barriers is to prevent 1 

Petroleum engineer. 

Research supervisor. 

3~r~ject leader. 

4~ lec tronic development technician. 

5~nterim Mandatory Safety Standard for Underground Mines, section 317(a), 

Federal Coal Mine Health and Safety Act (30 U.S.C. 877(a), 30 CFR 75.1700). 
combustible gases from entering the mine and to prevent accidental shearing of 

wells in mining operations. Many of the wells that intersect coalbeds in the 

Appalachian area enter essentially pressure-depleted reservoirs, and of them, 

many have been plugged and abandoned. A 300-foot pillar around a well represents a quantity of unminable coal and complicates the design of entryways, 

haulageways, and ventilating systems. Areas in which wells are drilled on 

close, irregular spacing (2.5 acres or less) can be completely unminable. 

Also, 300-foot pillars around wells in which the pressures exceed several hundred pounds per square inch would not contain the gas in the event of serious 

leaks. In the case of marginally productive reservoirs, it would be more 

satisfactory to permanently and safely plug the well below the coalbed, 

thereby permitting mining of the pillar. 

Elimination of random well pillars would allow the use of longwall and 

shortwall mining systems (which are inherently safer than conventional mining 

techniques), improve the ventilation system to reduce hazards associated with 

methane, and simplify the haulage system. Additional advantages that increase 

safety include modification of the mining cycle to eliminate abrupt changes 

and improved roof conditions relative to those that exist when there are random pillars. 

ACKNOWLEDGMENTS 

The authors thankJohn L. Rozance, president, Michael O'Brien, vice president of operations, William A. Light, manager, real estate, and Wilbur T. 

Simon, safety director, all with the Christopher Coal Co.; Fred E. Smith, 

Ralph Hicks, and Riley L. Thomas, safety committeemen, Osage Mine No. 3, 

Christopher Coal Co.; and Donald F. Poland, safety coordinator, District 31, 

United Mine Workers of America, for their assistance and cooperation in planning and conducting the mining through of the S. Barrackman well 5, Osage 

No. 3 mine, Consolidation Coal Co. 

Mining through of this well was witnessed by Frank Rutledge, district 

mine inspector, State of West Virginia; Joseph Marshalek and Paul J. 

Componation, Federal coal mine inspectors, Bureau of Mines Coal Mine Health 

and Safety District D; Messrs. Poland, Simon, Smith, Hicks, and Thomas and 

Stanley Hopwood, section foreman, Osage No. 3, Christopher Coal Co.; and 

J. Pasini 111, research supervisor, and G. E. Rennick, petroleum engineer, 

Morgantown Energy Research Center, Bureau of Mines. 

WELL-PLUGGING MATERIALS 

Various cement types and water mixtures were tested in the laboratory to 

determine the properties that could be expected of the cement plugs. Properties of the three cements that were selected for plugging the four test wells 

are as follows: 
Water ..............g al/sack.. 

shrinkage 2..............pct.. 

Sand grain density..g/cu cm.. 

Bulk density ........g/ cu cm.. 

Porosity ................p ct.. 

Effective air permeability 

md.. 

l~eference to specific brands 

.14 I 3.90 I .40 

is made for identification only and does not 

Chem compl 

(expanding cement) 

6.30 

.80 

2.07 

1.71 

17.40 

imply endorsement by the Bureau of Mines. 

"shrinkage is very difficult to determine; therefore, these values show the 

relative shrinkage effect. 

Weight of the fly ash-gel-water slurry used as filler plug was 14.4 pounds per 

gallon when 98 pounds of fly ash and 2 pounds of Aquagel were mixed with 6.3 

gallons of water. 

Pozmixl 

(fly ash and cement) 

5.80 

7.60 

2.12 

1.48 

30.10 

WELL SELECTION 

Port land 

6.30 

5.70 

2.23 

1.53 

31.30 

Several coal companies in the Morgantown, W. Va., area were particularly 

interested in well plugging because they planned to conduct longwall mining in 

certain sections that would necessitate mining through wells rather than pillaring around them. Timing of the work, however, necessitated selection of 

wells in an area that could be mined through within a 1-year period. Also, 

permission of the well owner was required to plug and mine through the wells 

to coincide with mining operations within the 1-year period. Ultimately, four 

wells in Clay district, Monongalia County, W. Va., were selected because at 

least one could be mined through within the necessary time. Figure 1 shows 

the locations of the four wells and the status of mining operations when the 

well owner agreed to let the Bureau of Mines plug the wells. 

WELL TESTING AND PLUGGING 

Three of the four wells selected for plugging had been drilled in the 

early 18901s, and the fourth--Fetty Heirs well 10, a water injection well--was 

drilled in 1965. Two wells still had derricks over them; the engine house, 

belt hall, and band wheel were intact and operative (fig. 2). Fieldwork was 

commenced in the same way operators normally do in this area: The pipe derricks were first cut down; then the engine house, belt halls, and other equipment was dismantled for salvage. A portable drilling rig was then set up over 

the well. 

The rods and tubing were first pulled, and then tools were run to bottom 

to make sure that the well was open to the original productive sand (Big 

Injun). A pressure-recording instrument was run in, and the well was then 

shut in to build up the pressure at the bottom of the hole. 

Gamma ray-neutron and caliper logs were obtained to accurately locate the 

formation and the five coalbeds penetrated by the wells, obtain a record of 

the well casings, and select packer seat locations. Several of the wells were 
FIGURE 1. - Location of Wells With Respect to Mining O
GAMMA 

FIGURE 3. - Gamma Ray-Neutron Well Log Showing 

11111111111 

Location of 

u 

Coalbeds. 
logged two or three times because they had three to four strings of casing. 

In several cases, the presence of gas behind the casing made it difficult to 

interpret the neutron log and accurately locate the coalbeds. Figure 3 illustrates the combination of gamma ray-neutron logs used to detect coalbeds 

through the well casing. Figure 4 shows the caliper log that was used to 

select a packer seat and determine hole and casing size. The casing-collar 

log shows casing collars, bottom of casing, and holes or breaks in the casing. 

The gamma ray-neutron log was used to determine the depth of the petroleumproducing formation, to ascertain lithology (such as sandstone or shale), and 

for correlating with other wells. The caliper log was used to determine the 

condition of the pipe and locate a suitable place in open hole, below the casing and above the producing formation, to set a packer. (Details are given in 

the appendix. ) 

A mechanical packer was set in all four wells--the main deviation from 

normal plugging procedure. A Lynes production-injection packer was used 

because of its expanding feature: the element can pass through the smallest 

well casing but can expand enough to seal against the wall of the open hole, 

thereby preventing leakage. To determine if each well was properly plugged-- 

that is, to establish that there was no communication in the wellbore between 

the oil- and gas-producing formations and the coalbeds--a gas tracer was 

injected into the producing formation before it was plugged. 

Sulfur hexafluoride (SFG) was used as the tracer gas. SF6 is inert, not 

present in the environment, and can be detected with a gas chromatograph in 

quantities as low as 112 part per billion. The S& was injected at pressures 

below 300 psi so it would remain in a gaseous state. Injection of the tracer 

(100 lb--about 250 scf) was followed by injection of enough nitrogen to force 

SF6 from the tubing into the oil and gas formation. A 2-inch bridge plug was 

then set in a tubing nipple at the top of the packer. When the bridge plug 

was run in the tubing, a high-pressure lubricator with grease seals was used 

to prevent the tracer and nitrogen from leaking back into the casing. A 

J-tool in the tubing string above the nipple on the packer released the tubing 

from the packer. An expanding cement plug was then placed on top of the 

packer by pumping the slurry through the tubing. After the cement plug was in 

place, the tubing and the inner (production) string of casing was pulled from 

the well. Field experience in the areas where plugging is being conducted is 

important because the formation can cave in if too much casing is pulled, thus 

preventing reentry to place cement plugs. 

Three wells were plugged back up to the base of the Pittsburgh coalbed 

and the casing was either pulled to expose the coal or ripped opposite the 

coalbed (figs. 5-7). The casing in Fetty Heirs well 10 was only 6 years old 

and had been cemented in. To prevent any possible safety hazard in the mine 

from perforation of the casing opposite the coal, a sand formation below the 

coal was perforated and the well was plugged back up to the base of this perforated zone (fig. 8). This provided test conditions similar to the other 

wells; that is, the annulus could be checked for tracer leaks. After each 

well was ready for testing, a vacuum pump was connected at the top of the well 

and samples were withdrawn daily (fig. 9). Samples were also obtained from 

all wells that are numbered in figure 1, and from two return air shafts 
GAMMA RAY NEUTRON 

SHOT HOLE IN BIG INJUN PAY SAND 

OPEN HOLE 

FIGURE 4. - Gamma Ray, Neutron, Caliper, and Casing-Collar Logs Showing Eottom 

Section of Plugged Well. 
PRESENT WELL STATUS PLUGGING AND COMPLETION 

FOR TESTING 

FINAL 

u 

PLUG 

I CEMENT (NEAT) 

0 

7 

100 200 300 400 TT :l STONE 

VERTICAL SCALE FEET r' TI AQUAGEL 

CLAY 

FIGURE 5. - J. Wildrnan Well 15, 1 to r, Before and After Partial Plugging and Completion 

for Testing, and After Plugging to Surface. 
WELL STATUS PLUGGING AND COMPLETION FINAL PLUG 

PRIOR TO PLUGGING FOR TESTING 

o loo 200 300 400 FZ3 CEMENT (NEAT) 

m EXPANDING CEMENT VERTICAL SCALE, FEET 

U FLY ASH - GEL - WATER SLURRY 

FIGURE 6. - J. Wildman We11 16, 1 to r, Before and After Partial Plugging and Completion 

for Testing, and After Plugging to Surface. 
1,502'-1,505' COAL 

1,559'-1,565'COAL 

1,852' 

2,232' 

WELL 

1 

STATUS 

PRIOR TO PLUGGING 

PLUGGING AND COMPLETION FINAL PLUG 

FOR TESTING 

0 CEMENT INEAT) ,-, 0 100 200 300 400 

EXPANDING CEMENT 

VFRTICAL SCALt FEtT 0 FLY ASH GEL WATER SLURRY 

FIGURE 7. - S. Barrackman Well 5, 1 to r, Before and After Partial Plugging and Completion 

for Testing, and After Plugging to Surface. 
PERFORATED 17 HO 

WELL STATUS PLUGGING AND CJMPLETION FINAL PLUG 

PRIOR TO PLUGGING FOR TESTING 

a CEMENT (NEAT) 

0 - 100 200 300 400 m EXPANDING CEMENT 

VERTICAL SCALE. FEET r POZMIX 

FIGURE 8. - Fetty Heirs Well 10, 1 to r, Before and After Partial Plugging and Completion 

for Testing, and After Plugging to Surface. 
FIGURE 10. - Well at Surface After Grading and Reseeding. 
serving the area of the mine near the plugged wells. Except for two or three 1 

occasions, no SF6 was detected in samples obtained twice daily, including weekends, from March 16 to August 31. Instances in which SF6 was detected can be 

attributed to unavoidable contamination from the mechanics of injection. How- 1 

ever, the real effectiveness of the SF, as a tracer was revealed when it 

migrated through the producing formation and showed in the gas samples from 

S. Barrackman well 9, a producing well, after July 12 inamountsranging up to 

about 200,000 parts per billion. 

Sampling was continued while all four wells were being plugged back to I 

the base of the Pittsburgh coalbed. Plugging to the surface was then com- 1 

pleted and each site was graded to surface specifications and sealed (fig. 10). 1 

Details of the plugging of the four wells are given in the appendix. 

MINING THROUGH A PLUGGED WELL 

S. Barrackman well 5 was the first well plugged and legally mined through 

after passage of the Coal Mine Health and Safety Act of 1969. An agreement 

between the Christopher Coal Co. and the U.S. Department of the Interior, I 

entered into July 31, 1971 (Contract No. 14-09-0070-448), gave the company an 

exception to the mandatory safety standard in section 317(a) of the Federal 

Coal Mine Health and Safety Act of 1969 (30 CFR 75.1700) to remove the entire 

barrier around W. H. Allen well 5 (S. Barrackman) in section 16-A off 12 south, 

Osage No. 3 mine. Section 501(c) of the Federal Coal Mine Health and Safety 

Act authorizes the Secretary of the Interior (delegated to the Director, 

Bureau of Mines, June 25, 1970, 215 DM 9.1L, 9.1P, and 9.1Q) to grant exceptions to the application of mandatory health and safety standards to a coal 1 

mine opera tor who conducts experimental and demonstrat ion projects on behalf 1 

of the Director, Bureau of Mines. 

Before proceeding with the project, Christopher Coal Co. also obtained a 

permit from the State of West Virginia for the company to mine to and through 

the oil well, under the supervision and control of the Bureau of Mines. 

The section crew and others who were to observe the mining through of 

S. Barrackman well 5 entered the mine on the midnight shift, August 7, 1971. 

Section 16-A had been heavily rock dusted by the previous shift, and a methane 

check was made and the accessible roof and ribs around the block of coal containing the well were inspected at time of entry. No methane was detected, 

and the roof and ribs around the well support pillar were in good condition. 

Mining toward the well was started at 1:00 a.m. No methane was detected until 

mining had proceeded to within 29 feet of the well, at which time 0.03 percent 

methane was recorded and crude oil was detected by smell but not by sight. 

Methane concentration when mining reached 14 feet from the well rose to 0.1 

percent and continued at this level until the well was mined into at 4:10 a.m. 

Vacuum-bottle samples taken from around the casing were subsequently analyzed 

for SFG and methane (table 1); methane content of air in the face area was 

0.12 percent (near roof). The crude oil odor was attributed to a 1-112-inch 

hole where the casing had corroded. This hole has probably existed for years 

1 and allowed crude oil to enter the coal around the well. 
Aug. 7 

7 

7 

7 

7 

7 

7 

8 

8 

8 

8 

8 

9 

10 

11 

12 

13 

14 

16 

17 

18 

20 

23 

24 

25 

26 

27 

30 

Nov. 23 

l~ell ir 

TABLE 1. - Gas concentrations after mining through 

S. Barrackman well 5, Osage No. 3 mine, 

Christopher Coal Co., percent 

(Dash indicates no analysis) 

I Time I Location in mine 

04: 10 

04: 42 

04: 45 1 10:48 

10:6 49 32 

16: 33 

08: 10 

08 : 40 

08 : 40 

08: 40 

16: 20 

11: 30 

09: 00 

10: 20 

09: 20 

11:30 

08: 30 

08: 25 

11: 00 

10: 30 

13: 00 

10: 45 

14: 10 

12: 20 

12: 30 

12: 20 

12: 15 - 

"gob. " 

At well casing ..... ....... do .......... ....... do .......... ....... do .......... .... ...do.......... 

....... do .......... - ....... do ........... 0 

Casing in roof ...... - 

Casing in pavement. . 0 

....... do ........... - In entry ............ - ....... do ........... 0 

....... do ...... i"" 0 

At bleeder 16-A .... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

....... do ........... 0 

Methane 1 Oxygen Carbon 

dioxide - 

- 

0 

- 

0 

.05 

- 

0 

- 

0 

.09 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

Nitrogen 

In mining through, the well casing was broken off (the casing had been 

ripped from the surface prior to cementing, fig. ll), by moving the continuous 

miner (ripper) head back and forth. Vacuum-bottle gas samples were taken from 

the well casing after it was removed. Methanometer readings in face area of 

the coal showed 0.1 percent methane. Both the dense cement jacket around the 

casing and the cement within the casing were in excellent condition. Gas 

samples were extracted from the casing until the section became a "gob" area. 

No tracer was detected in samples from the "gob" bleeder ventilating section 16-A through November 1971, thus indicating an excellent well seal. 
rock-dust-supply holes and for methane drainage before mining through, and 

later as "gob" drainage holes, thus offsetting part of the costs of plugging. 
APPENDIX. --DETAILED SUMMARY FOR PLUGGING WELLS 

J. Wildman Well 16 (Fig. 6) 

Operat ion Description 

Geophysical well logs Gamma ray-neutron and caliper (total 

depth) 

Bottom-hole pressure buildup 110 psi after 113 hours' shut-in time 

Production injection packer set 1,845 feet 

Injection test 

Inject ion of SF6 

100,000 scf of nitrogen at 2,200 to 

2,400 psi, shut-in pressure 2,400 psi, 

5-hour shut-in pressure 600 psi, 

19-hour shut-in pressure 350 psi 

Bled wellhead pressure down to 50 psi, 

injected 250 scf SF6 at 94 psi, 

injected 17,000 scf N, at 300 psi, 

injected 53,000 scf N2 at 1,200 psi 

2-inch bridge plug set 1,841 feet 

Placed plug (through tubing) Top of packer to 1,738 feet expanding 

cement (20 sacks) 

Cut 5-3/16-inch casing 1,670 feet (pulled all casing) 

Cut 6-5/8-inch casing 1,361 feet (pulled 131 feet) 

Placedplugs (throughtubing) 1,738to17367feet, flyash-gel-water 

slurry (3 tons fly ash and 125 lb 

Aquage 1) 

1,367 to 1,246 feet expanding cement (38 

sacks) 

Pulled 6-5/8-inch casing to 

558 feet 

Geophysical well logs Gamma ray-neu t ron and caliper 

Placed plugs (through tubing) 1,246 to 825 feet, fly ash-gel-water 

slurry (5.4 tons fly ash and 65 lb 

Aquagel) 

825 to 788 feet expanding cement (14 

sacks) 
Operation Description 

788 to 600 feet fly ash-gel-water slurry 

(2.4 tons fly ash and 35 lb Aquagel) 

600 to 569 feet expanding cement 

(8 sacks) 

14. Moved rig from well and connected vacuum pump for 

samp ling 

15. Collect sample to be analyzed 

for SFG . 

16. Moved rig onto well to complete plugging 

17. Placed cement plug (dump 

bailer) 

18. Cut 6-5/8-inch casing 

19. Placed cement plug (poured 

from surface) 

20. Pulled 6-5/8-inch casing 

21. Placed plug (through tubing) 

22. Set well monument 

23. Graded and seeded area 

80 days 

569 to 501 feet expanding cement (20 

sacks) 

494 feet 

501 to 351 feet neat cement (135 sacks) 

494 feet 

351 feet to surface, neat cement (294 

sacks) 

10 feet below to 30 inches above surface 

(6-5/8-inch casing filled with 15 sacks 

neat cement) 

Grass growing 

Fetty Heirs Well 10 (Fig. 8) 

1. Geophysical well logs Gam ray-neutron and caliper (total 

depth) 

2. Bot tom-hole pressure buildup 131 psi after 68 hours' shut-in time 

3. Production injection packer set 1,923 feet 

4. Injection test 50,000 scf of nitrogen, shut-in pressure 

1,280 psi, 1-hour shut-in pressure 

840 psi 
Operation 

5, Injection of SF6 

Description 

Bled wellhead pressure down to 160 psi 

Injected 2,000 scf nitrogen and 125 lb 

SF6 at 275 psi (Na and SF6 

simultaneously) 

Injected 38,000 scf N, at 1,040 psi 

Shut-in pressure after 16 hours 480 psi 

1 barrel water used to wash down tubing 

6. 2-inch bridge plugs set 1,913 feet 

7. Placed plugs (through tubing) Top of packer to 1,820 feet expanding 

cement (7 sacks) 

1,820 to 1,347 feet, Pozmix cement (22 

sacks) 

1,347 to 1,230 feet, expanding cement 

(8 sacks) 

1,230 to 684 feet, Pozmix cement (24 

sacks) 

8. Perforated casing 20 holes, 664 to 669 feet 

9. collect samples to be analyzed 58 days 

for SF6 

10. Moved rig onto well to complete plugging 

11. Cut 4-112-inch casing 274 feet (pulled from hole) 

12. Placed plug (through tubing) 684 feet to surface, neat cement (150 

sacks) 

13. Set well monument 10 feet below surface to 30 inches above 

(filled 6-inch casing with cement) 

14. Graded and seeded area Grass growing 

S. Barrackman Well 5 (Fig. 7) 

1. Geophysical well logs Gamma ray-neutron and caliper (total 

depth) 
Operation Description 

2. Bottom-hole pressure buildup 48 psi after 46 hours' shut-in time at 

78" F 

3. Production injection packer set 2,185 feet 

4. Injection test 

5. Injection of SF6 

225 scf nitrogen at 110 psi, 12 scf 

nitrogen at 80 psi (14 hours) 

Bled wellhead pressure down to 40 psi, 

injected 325 scf N2 and 125 lb SF6 (N2 

and SF6 injected simultaneously) 

Injected 800 scf nitrogen, shut-in pressure after 14 hours 80 psi 

6. 2-inch bridge plug set 2,180 feet 

7. Placed plugs (through tubing) Top of packer to 2,080 feet, expanding 

cement (10 sacks) 

2,080 to 1,883 feet, fly ash-gel-water 

slurry (1 ton fly ash and 40 lb Aquagel) 

1,883 to 1,843 feet, expanding cement 

(8 sacks) 

8. Cut 5-3116-inch casing 1,831 feet (pulled all casing) 

9. Geophysical well log Gamma ray-neutron and caliper (to 1,843 

feet) 

10. Placed plug (dump bailer) 1,843 to 1,778 feet, expanding cement 

(27 sacks) 

11. Directional survey 1,000 feet, determine exact location of 

well in mine 

12. Placed plugs (through tubing) 1,778 to 1,464 feet, expanding cement 

(58 sacks) 

1,464 to 950 feet, fly ash-gel-water 

slurry (4 tons fly ash and 200 lb 

Aquagel) 

950 to 887 feet, expanding cement 

(13 sacks) 

13. Ripped casing 

1. Cement retainer set 

862 feet, 3 cuts 1 foot long 

853 feet 
Operation Description 

Placed plugs (through tubing) 887 to 853 feet, neat cement (35 sacks) 

864 to 743 feet behind 6-518-inch casing 

(squeezed 16 sacks of neat cement at 

400 psi wellhead pressure) 

853 to 847 feet, neat cement (1 sack) 

Placed cement behind 6-518- 165 feet to surface, neat cement (300 

inch casing sacks) (165 feet of 1-inch pipe run in 

annulus to place cement) 

Ripped casing (to weaken casing 832 to 840 feet, 4 cuts (2 cuts, 4 feet 

and to sample for possible fall into other cuts) 

tracer leaks behind casing) 

Collect samples to be analyzed 73 days 

for SF6 

Placed plug (through tubing) 847 feet to surface, neat cement (200 

sacks) 

Set well monument 10 feet below to 3 feet above surface 

(filled with cement) 

Graded and seeded area See figure 10 

J. Wildman Well 15 (Fig. 5) 

Geophysical well logs Gamma ray-neutron and caliper (total 

depth) 

Bottom-hole pressure buildup 99 psi after 64 hours' shut-in time 

Production injection packer set 1,836 feet 

Injection test 500 scf nitrogen at 60 psi 

Inject ion of SF6 

6. 2-inch bridge plug set 

Injected 250 scf N2 and 125 lb SF6 at 

90 psi (N2 and SF6 injected 

simultaneously) 

Injected 1,000 scf N2, shut-in pressure 

175 psi, shut-in pressure after 13 

hours 110 psi 

1,828 feet 
Operation 

7. Placed plugs 

Description 

Top of packer to 1,819 feet, field stone 

(bridge) 

1,819 to 1,804 feet, neat cement 

(2 sacks) 

1,804 to 1,754 feet, limestone chips 

(bridge) 

1,754 to 1,729 feet, clay 

1,729 to 1,534, gelled water (230 gal 

water and 1 sack Aquagel) 

1,538 feet set brush plug (branch of 

tree) . 

1,538 to 1,536 feet, limestone chips 

(bridge) 

1,536 to 1,523 feet, neat cement 

(3 sacks) 

8. Cut 4-718-inch casing 1,427 feet (pulled all casing) 

9. Placed plugs 1,523 to 1,254 feet, Aquagel and water 

1,254 feet, brush plug 

1,254 to 1,252 feet, limestone chips 

(bridge) 

1,252 to 1,133 feet, neat cement (30 

sacks) 

820 feet, brush plug 

820 to 720 feet, limestone chips (bridge) 

610 feet, brush plug 

610 to 600 feet, limestone chips (bridge) 

600 to 593 feet, neat cement (5 sacks) 

10. Pulled casing 532 feet, 6-518-inch casing cut at 593 

feet (removed 61 feet of casing) 
Operation 

11. Placed plugs 

12. Geophysical well logs 

13. Pulled casing 

14. Geophysical well logs 

15. Placed plugs 

16. Hole caved 

17. Placed plugs 

Description 

593 to 546 feet, limestone chips (bridge) 

546 to 534 feet, neat cement (2 sacks) 

Gamma ray-neutron and caliper (to 534 

feet) 

511 feet, Pittsburgh coalbed exposed 

(pulled casing to 468 feet) 

Gam ray-neutron and caliper (to 534 

feet) 

534 to 487 feet, neat cement (21 sacks) 

472 feet, brush plug 

472 to 470 feet, limestone chips (bridge) 

470 to 413 feet, neat cement (pulled 

casing to 383 feet) 

389 feet, brush plug 

389 to 387, limestone chips (bridge) 

387 to 214 feet, Aquagel and water 

(4 sacks Aquagel) (pulled casing to 189 

feet) 214 feet brush plug 

192 feet bridged 

Drilled out bridge and lost brush plug 

(pulled 6-518-inch casing from well-- 

189 feet) 

214 feet, brush plug 

214 to 208 feet, limestone chips (bridge) 

208 to 151 feet, neat cement (57 sacks) 

151 to 40 feet, Aquagel and water 

40 feet, brush plug 

40 to 17 feet, stone and clay (bridge) 
Operat ion 

18. Set well monument 

19. Graded and seeded area 

Description 

17 feet below to 3 feet above surface, 

neat cement inside and out (13 sacks) 

Grass growing 

IN T.-BU.0 F MIN ES,PGH.,PA. 17790