Through Slotted Casing 

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

Cecil D. Andrus, Secretary 

BUREAU OF MINES 
I,ambrrt, Stc1)hc.n \\ 

Methane drainage : experience with hydmulic stimulation 

through slotted casing / by S. W. Lambert and M. A. Trevits. 

[Washington] : U.S. Dept. of the Interior, Bureau of Mines, 

1978. 

10 p. : maps, dinprs. : 2; rni. (Kcport of invrstipations - Hureau 

of lines : 8295) 

I3ibli~~riiph.i.: p.1.i" 

1. \iethane, 2. \tine gascs, 3. \line drainage. I. Trevits, 

Xlichael A,, joint author. 11. L'nired States. I3ureau of \lines. 111. 

Title. I\'. Series: Linitcd Srates. Ilureau of \lines. lieport of 

investigations - Ilureau of \lines : 8205. 

TN23.U7 110. 8295 622.06173 

L.S. Ikpt. of rhc Inr. Library 

t 
CONTENTS 

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

Introduction ............................................................ 1 

Drilling. completion. and production .................................... 2 

Mine investigation ...................................................... 3 

Fracture survey .................................................... 3 

Description of m2 ................................................. 5 

Discussion of results ................................................... 7 

Drilling ............................................................ 7 

Cementing .......................................................... 7 

Logging ............................................................ 7 

Jet slotting ....................................................... 8 

Stimulation ........................................................ 9 

Production ......................................................... 12 

Conclusions ............................................................. 13 

References .............................................................. 14 

Appendix.--History of test well No . 2 in the Mary Lee coalbed near 

Oak Grove, Jefferson County, Ala ...................................... 15 

ILLUSTRATIONS 

Hydraulic stimulation pressure and fluid injection chart. TW2 ....... 3 

Daily gas production from m2 ....................................... 3 

Survey stations dividiag area of mine near TW2 ...................... 4 

Roof joint. cleat. and hydraulically induced channel directions 

near m2 .......................................................... 4 

Position of mine face during underground examination of lW2 ......... 5 

Sketch of mine face during underground examination of TW2 ........... 6 

Portion of density log from TW2 compared with rock strata observed 

underground (log run before casing was slotted) ................... 8 

Comparison of density logs run before and after slotting ............ 9 

Comparison of roof joint and cleat directions in mine area with 

fractures induced or extended during drilling, cementing . and 

stimulation of TW1 ................................................ 10 
METHANE DRAINAGE: EXPERIENCE WITH HYDRAULIC STIMULATION 

THROUGH SLOTTED CASING' 

by 

Stephen W. Lambert2 and Michael Am Trevits 2 

ABSTRACT 

The Bureau of Mines examined the wellbore of a vertical gas drainage well 

in the Mary Lee coalbed to determine the results of specific completion procedures in coal. A jet-slotting tool was used to cut four vertical slots 

through the casing about 1 ft below the coalbed. Even though stimulation 

treatment pressure was excessive , hydraulically induced channe 1s were contained entirely within the target coal zone. Sand-filled, induced channels 

were horizontal, inclined, and vertical, and were propagated in directions 

similar to bedding planes, rock joint, and coal cleat directions measured in 

the mine. Variable gas flow rates , recorded during the productive life of the 

well, were attributed to chronic downhole pump malfunction and the slotted 

casing below the production zone. 

INTRODUCTION 

The purpose of this Bureau of Mines research was to test specific hydraulic stimulation procedures in coal by monitoring well production and to later 

inspect the results directly underground in the mine. A vertical degasification borehole that had been drilled in the Mary Lee coalbed and completed 

600 ft ahead of active mining was intercepted on February 15, 1977. The borehole, referred to as test well No. 2 (TW2) , is located in section 35, R 18 S 

R 6 W, near Oak Grove, Ala. ; it is the second such borehole to be examined 

underground in the area. 

A roller bit and foam were used to penetrate the coalbed to minimize 

wellbore damage. After the casing was set in the hole, the coalbed was 

exposed for stimulation using a jet-slotting tool. Density logs were used to 

identify slotted portions of casings and to identify zones withfin the coalbed 

that could have an influence on the geometry of hydraulically induced channels. 

The hydraulic forces used to stimulate the coalbed were diverted several times, 

resulting in numerous short channels. Horizontal channels were propagated 

when injection pressure exceeded effective overburden pressure. 

lThe work described in this report was performed by a component of the Bureau 

of Mines that was transferred to the Department of Energy on Oct. 1, 1977. 
It is indicated that because of the relative softness of coal, the princ ipal mechanism leading to horizonta 1 channel development is compression 

rather than the flexing and lifting of all the overburden. Also, there is a 

direct correlation between propagated vertical channel directions and the 

joint and cleat orientations, and a direct relationship between surface and 

underground fractures. These relationships can be used to determine the 

direction of the vertical channel before stimulation. 

DRILLING, COMPLETION, AND PRODUCTION 

TW2 was rotary-drilled using a 6-114-in-diam air-percussion bit to approximately 235 ft above the 5-ft-thick coal interval. To reduce the possibility 

of formation damage caused by drilling, a 6-118-in-diam roller bit was used to 

drill the remaining distance to 50 ft below the coalbed. TW2 was cased to 

total depth with 4-112-in-outside-diam (OD) pipe. The lower 500 ft of casing 

was set in place using 13.8 lb/gal cement. 

A jet-s lott ing tool was positioned using a geophysica 1 logging device. 

The design called for a water and sand slurry to cut four vertical slots, 

90" apart, from the base of the coalbed to within 1 ft of the top. The coalbed was stimulated using 3,500 gal of a highly viscous fluid containing 

4,000 lb of 10130- and 20140-mesh sand. 

The hydraulic stimulation pressure averaged 2,400 lb/sq in gage with no 

apparent formation "breakdown," the fluid injection rate averaged 8 bbllmin, 

and the instantaneous shut-in pressure was 2,200 lb/sq in gage (fig . 1) . After stimulation, water was circulated in the well removing approximately 

200 lb of propping sand. The well was equipped with a pump to remove water 

and with meters to monitor production.3 

TW2 was put on production November 13, 1976. During successful pumping 

periods, daily gas production averaged about 15,000 cu ft. Sand and other 

foreign material entering the downhole pump mechanism caused chronic malfunction and resulted in overall poor gas production (fig. 2). This malfunction 

made it necessary to dismount the pump and remove the material before water 

production could be resumed. Immediately after servicing the downhole pump 

and after removal of usually less than 5 bbl of water, temporary gas flow 

rates in excess of 80,000 cu ft/day were measured on several occasions. Such 

high gas flows appear to have brought significant amounts of propping sand 

into the wellbore. 

3~or details of drilling and completion of TW2, see the appendix. 
at test well No. 1 (TWl), a 

correlation was made between 

i cleat and joint directions 

and fractures believed to 

have been induced or extended 

by drilling, cementing , and 

stimulation.* 

The area of the mine 

near TW2 is divided into 

seven stations (fig. 3). A 

compass was used to measure 

- the direction of all visible December-~anuar~ -February - 

1976 1977 1977 roof joints and at least 

15 coal cleats within each 

FIGURE 2. - Daily gas production from TW2. station. Directions of all 

observed hydraulically 

induced fractures containing 

prop sand were also measured. All measurements were adjusted for magnetic 

declination and then plotted on rose diagrams (fig. 4). 

4~1, completed approximately 500 ft from active mining, was hydraulically 

stimulated Nov. 23, 1975, using 5,000 gal of fluid and 2,500 lb of sand. 
A 

0 9 18 Mete

Scale 

FIGURE 3. - Survey sta
Crosscut 

Measured direction of packed 

I-', Zone of observed horizonta I I sand-packed channels 

FIGURE .5. - Position of mine face during underground examination of TW2. 
of the 1-in space between the casing and the drill hole in the roof and floor. 

No cement was found in the southern-half of the wellbore; instead prop sand 

and/or gel filled this annular space at both the floor and the roof. 

The casing was expanded outward, where it was pierced by four roughly 

diamond-shaped slots about 5.5 in long and 2 to 2.5 in wide. Five holes 

(0.3-in maximum diameter) in the casing were 5 to 9 in above the slots. The 

tops ofthe slots were about 4 in below the base of the coalbed, and directions 

of the slots were N 60" E and N 15" W. No cement could be found on either 

side of the casing exposed within the coal interval. 

Induced Hydraulic Channels: Three well-defined vertical channels at the 

borehole site were contained in the lower third of the coalbed, and they were 

completely filled with propping sand. The channel sides appeared smooth and 

unabraded, and they followed local vertical fracture planes in the coal. The 

widest channel (4.5 in), located south of TW2, tapered upward gradually; a 

2.0-in-thick channel, north of the borehole, tapered sharply to the floor; the 

remaining vertical channel, located directly behind the exposed casing, was 

0.3 in throughout. All three channels terminated at the base of the coalbed 

with no evidence of fracture continuation into the floor rock. 

Two channels sloped downward to the south and were contained entirely in 

a more friable, soft, and highly slickensided portion of the coalbed. Their 

sides were smooth and unabraded but somewhat irregular; they appeared to 
follow local shear fracture planes in the coal, with minor vertical development along cleat planes. The shape and downward extension of these channels 

indicate direct or inferred continuation with the vertical channels described 

earlier. 

Four horizontal channels appeared at the coal face as extensions of 

either vertical or inclined channel development; all four occurred along bedding planes. Three of the channels were present approximately one-third of 

the distance up from the floor near the line of contact between hard, distinctly cleated coal and soft, friable, sheared coal. The fourth horizontal 

channel ran along a line 6 in below the coal-roof-rock interface; coal imediately surrounding the horizontal channels was very soft and appeared crushed. 

Four small, separate, randomly oriented, sand-filled channels were i-n the 

upper portion of the coal face north of the wellbore. Their locations indicate close association with a system of larger channels trending approximately 

N 65O E. These channels were along shear, cleat, and bedding planes, and thus 

possessed characteristics of all three channel types described earlier. 

DISCUSSION OF RESULTS 

Drilling 

There was no evidence that drilling adversely affected the coalbed or 

surrounding rock strata. Except for hydraulically induced partings in the 

coal, the only opening in rock leading directly from the wellbore was a welldeveloped roof joint which was believed to have opened sometime after TW2 was 

completed because it did not contain cement or propping sand. 

Cement inq 

The lightweight, low-fluid-loss cement mixture, together with the low 

injection rates used to stabilize casing in the borehole (see appendix), prevented excessive permeability damage to the coalbed. No evidence of cement 

infiltration was found in the floor, coal, or roof rock. 

The cement bond to casing was generally poor. For example, the mining 

machine which exposed the borehole never came in direct contact with the 

casing or cement, so the cement, if ever present, must have been pulled from 

the casing leaving no residue as coal surrounding the test well fell away 

under its own weight. The lack of cement within approximately one-half of the 

wellbore annulus in the roof also indicates poor cementing. 

Logging 

A comparison of density logs with underground observations shows the logs 

to be an important tool for predicting coalbed characteristics. All density 

logs clearly indicate two major density zones within the coalbed (fig. 7). 
-Density increase 

FIGURE 7. - Portion of density log from TW2 compared with rock strata observed underground 

(log run before casing was slotted). 

The upper, less dense zone correlates precisely with the friable, highly 

sheared portion of the coalbed containing all induced channels that were 

inclined or horizontal. The denser, lower zone on the log locates the interval of hard, distinctly cleated coal containing induced, vertical channels. 

Jet Slotting 

Using density log information, the base of the coalbed was determined to 

be 1,099.2 ft deep, and four vertical slots, each 48 in long, were to be cut 

at that depth. Subsequent logging revealed that the base of the coalbed was 

actually 1,098.4 ft deep, and that jet slotting had begun below the coal. 

If the casing had been cut throughout the prescribed length, the fact 

that the slots began several inches below the coalbed would have been of 

little consequence. However, as observed underground, the casing had not been 

penetrated throughout the entire coal interval. Factors that may have contributed to poor slotting results include insufficient time allowed to cut the 

casing; slight rotation or twisting of the tool could have occurred as it was 
raised and lowered through the prescribed interval (at least two heavily 

abraded, vertically oriented "tracks" were noted along inner surfaces of 

casing exposed to each jet nozzle), and the very soft, friable nature of the 

coal could have absorbed much of the cutting "energy" (all perf orations 

through casing occurred either in the hard floor rock or in the hard lower 

portion of the coalbed). 

Close examination of density logs taken before and after slotting operations indicated that the small section of pipe successfully cut could have 

been recognized before actual underground observations. Logs taken after 

slotting show a significant density decrease along the interval of borehole 

directly exposed to rock strata (fig. 8). 

Stimulation 

The treatment used to stimulate TW2 was designed to induce vertical, 

1-in-wide , sand-£ illed channels in two directions from the wellbore. Each 

channel was to be approximately 150 ft long and just under 5 ft high. Based 

on prior underground observation at the IW1 site, channels were expected to 

propagate in directions similar to existing natural fractures in the coal. 

- Density increase -0 

Gamma den si ty 

FIGURE 8. - Comparison of density logs run before and after slotting. 
Previous work on stimulating the Mary Lee coalbed (&16 indicated that formation breakdown could be expected to occur below 900 lb/sq in. 

The sand channels hydraulically induced into the coalbed were horizontal, 

inclined, and vertical, making it difficult to determine the complete dimensions of each. However, figure 5 indicates that the maximum length of propagation from the wellbore was 50 ft or less, rather than the maximum 300 ft 

calculated in the original design. 

The underground channels, especially the wide vertical channels, were 

generally composed of several smaller induced sand channels. The number of 

slightly different directions measured along the channel walls; the coal particles contained in these channels; and the number of small, randomly oriented, 

sand-filled channels all indicate a complex system of propagated channels 

204 Readings 

Roof joint and cleat direction 

in mine area of No.1 Test Well. 

Readings 

along closely spaced vertica 1 

planes (as cleat planes). 

Instead of one or two extended 

directions, the hydraulic force 

used to propagate fractures in 

the coal is believed to have 

been diverted several times in 

s lightly different directions 

during high-pressure pumping. 

This apparently resulted innumerous short channels rather than 

in one or two continuous long 

channels as predicted in the 

design. 

Results of the underground 

vertical fracture (fig. 4) show 

a direct correlation between 

propagated channel direction and 

joint and cleat orientation. 

Findings from a previous underground study at TW1 yielded similar results which are shown in 

figure 9. Although sand-filled 

channels were not observed at 

TW1, there is sufficient evidence to indicate that partings 

in the coal and roof rock had 

Partings, induced or extended from been opened during drilling, 

Test Well No. l during drilling, cementing, cementing, and early stages of 

stimulation. 

and stimulation. 

FIGURE 9. - Comparison of roof joint and cleat directions in mine area with fractures bunderlined numbers in Pareninduced or extended during drilling, theses refer to items in the 

cementing, and stimulation of TW1. list of references preceding 

the appendix. 
Surface rock joint and coal cleat directions measured in an area overlying both test well locations (3) indicate a close correlation between the surface and underground fracture orientations of figures 4 and 9. Given the 

observed relationship of induced channel direction with existing underground 

and surface fracture orientation, it may be concluded that the direction of 

induced channel development can be predetermined, thus aiding future placement 

of coal gas wells in the area. 

The most obvious explanation for the initial high treatment pressure during stimulation is that fluid was first exposed to hard fireclay, rather than 

to relatively soft coal. The high pressure that was maintained throughout the 

treatment is attributed primarily to the high viscosity of the treating fluid, 

and second, to the flow resistance created by the small openings in the casing. 

When injection pressures exceed the overburden pressure horizontal channels may develop. Given a mean specific gravity of 2.5, the overburden pressure gradient should be about 1.06 lb/sq in/vertical ft (2). Since the depth 

to the coalbed at 1W2 is 1,093 ft, horizontal channels could be expected to 

develop when injection pressures exceeded 1,160 lb/sq in. Treating pressures 

maintained throughout stimulation of 1W2 were in excess of 2,200 lb/sq in gage 

(fig. 1). 

Horizontally oriented sand-filled channels can result from one of two 

types of rock movement: The compression of rock in the vicinity of the fracture or the flexing and lifting of all or a portion of the overburden (5). 

The crushed appearance of coal surrounding the horizontal channels suggests 

that, in this case, compression of rock was the principal mechanism. 

The loss of treatment fluid during propagation resulting in the premature 

drop of sand proppant is believed to have remained at a minimum during stimulation of TW2. Such "sand-outs" are not indicated on the treatment chart 

(fig. 1 Low fluid loss to the formation is also indicated by the extremely 

high pressures maintained in the wellbore after pumps were shut down. 

Although injection pressures were as high as 2,500 lb/sq in during the 

stimulation treatment, there was no evidence of induced fractures in the roof 

or floor rock. Sand proppant and gel found in the wellbore annulus in the 

floor indicate direct exposure to treatment fluid under high pressure. In 

preference to fracturing the harder floor rock, fluid moved upward, near the 

casing, and into the coal zone before extending outward. A roof joint extending directly from the wellbore was believed to have opened sometime after 

stimulation since it contained no sand or gellike material. 

The stimulation design provided for an enzyme-type breaker to considerably reduce the treatment fluid viscosity within a few days. Gel, however, 

was found around the casing in the roof and floor. The gel in the roof contained no sand and therefore must have been included in the initial fluid pad 

before the proppant was added. The gel around the bottom of the casing did 

contain sand and could have been placed there anytime during treatment. 
Gel presence may be explained in two ways: Either the breaker was not 

added to the stimulation fluid as planned, or the breaker was added throughout 

treatment but chemical factors in both roof and floor prevented gel breakdown. 

The first explanation is unlikely; the second is more probable considering 

temperature variation, possible reaction with pipe, cement, etc. 

Product ion 

Two major factors responsible for the poor production at TW2 are heavy 

grease used to preserve downhole water production equipment was not completely 

removed before installation and repeatedly clogged the pump, and the position 

of slots below the production zone allowed water to drain from the coalbed but 

was not conducive to gas drainage. Since water drains to lower horizons of 

the coalbed, free gas is believed to have accumulated in the upper portions of 

the coal against the overlying impervious roof rock (shale). 

During the first 3 days of successful pumping, TW2 produced no gas, 

although a significant volume of gas is thought to have accumulated in upper 

portions of the coalbed around the wellbore. On the fourth day the pump 

clogged with grease and was dismounted for servicing. The water level rose in 

the borehole as formation pressures partially recovered. Based on previous 

Bureau of Mines studies ,6 it may be assumed that free gas pressure equilibrated with the increasing hydraulic head. 

The pump was repaired and water production resumed on the eighth day, and 

after removing approximately 4.3 bbl of water and measuring no flow through 

gaslines, the well "unloaded," suddenly producing gas at more than 80,000 

cu ft/day. This indicates that the free gas pressure around the wellbore had 

built up during the previous 8 days and that it was suddenly released when 

pumping caused a disequilibrium pressure state between the coalbed and the 

wellbore. This sequence of events was repeated several times during the productive life of the well because the pump became inoperative following each 

unloading. 

Gas production stabilized slightly during a 2-week interval prior to 

underground interception. Given the position of slots in the casing, stabilized gas production could not have been possible while significant amounts of 

water continued to flow through the coalbed. Waterflow from the well did, 

in fact, decrease during this period. Since experience with other coal gas 

wells in the Mary Lee indicates relatively stable waterflow over extended 

periods (I), it is believed that pumping did not significantly "dewater" the 

coalbed around the wellbore and that the reduction of water production rate 

was due to drainage of water into the approaching mine opening. 

' ~ecent laboratory experiments show conclusively that gas desorption from Mary 

Lee coal will continue at pressures in excess of 120 lb/sq in gage. Field 

studies indicate Mary Lee coalbed gas will continue to flow from new wells 

until a static water level is achieved. 
CONCLUS IONS 

1. Rotary drilling using roller bit and foam is an effective technique 

to avoid extensive we llbore and/or coalbed damage. 

2. A lightweight, low-fluid-loss cement mixture can reduce cement infiltration into the floor, coal, and roof rock. 

3. Density logs may be used to identify zones within coalbeds which may 

have a substantial influence on the geometry of hydraulically induced channels. 

Density logs may also be used to identify successfully slotted portions of 

casing. 

4. The hydraulic forces used to stimulate coal may be diverted several 

times, resulting in numerous short channels rather chan one or two continuous 

long channels. Horizontal channels may be propagated when injection pressure 

exceeds effective overburden pressure, but because of the relative softness of 

coal, the principal mechanism leading to horizontal channe 1 development is compression rather than flexing and lifting of the overburden. 

5. Underground fracture studies indicate a direct correlation between 

propagated vertical channel directions and the joint and cleat orientations. 

There is also a direct rela tionship between surface and underground fractures 

which can be used to determine the vertical induced channel direction before 

stimulation. 

6. Ge 1 may not break down sufficiently near the we1 lbore , because of low 

temperatures or adverse chemical reaction with casing materials. 

7. Highly variable gas flow rates may be attributed to downhole water 

pump malfunction and/or to the positioning of production openings (slots or 

perforations) below the productive coal zone. 
REFERENCES 

1. Elder, C. H. , and M. Deul. Degasification of the Mary Lee Coalbed Near 

Oak Grove, Jefferson County, Ala. , by Vertical Boreholes in Advance of 

Mining. BuMines RI 7968, 1974, 21 pp. 

2. Hubbert, M. K., and D. G. Willis. Mechanics of Hydraulic Fracturing. 

Pres. at Ann. Fall Meeting, Soc. Petrol. Eng. , AIME, Los Angeles, Calif., 

Oct. 14-17, 1956, SPE Reprint No. 5, 1970, pp. 241-256. 

3. 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. 

4. Perkins, T. K. , and L. R. Kern. Widths of Hydraulic Fractures. Pres. at 

36th Ann. Fall Meeting, Soc. Petrol. Eng., AIME, Dallas, Tex., Oct. 8-11, 

1961, SPE Reprint No. 5, 1970, pp. 265-277. 
APPENDIX. --HISTORY OF TEST WELL NO. 2 IN THE MARY LEE CQALBED 

NEAR OAK GROVE, JEFFERSON COUNTY, ALA. 

DRILLING 

Drilling depth, ft 

0 to 10.0.. ............. 

Bit type I Bit diameter, I Circulation 

10 to 857.0 ............. 857 to 1,150.6 .......... 

NOTE.--The lower bench of the Mary Lee coalbed is from 1,093.4 to 1,098.4 ft 

deep. 1W2 is in section 35, T 18 S, R 6 W. Drilling was started 

September 26, 1976, and it was completed October 20, 1976, to a total 

depth of 1,150.5 ft. The total depth of the casing was 1,150.0 ft. 

Tricone.. ............ 

- - 

Cement 

CASING 

Air percussion ....... Tricone .............. 

Date. ................................................ Zone cemented ........................................ Number of sacks ...................................... American Petroleum Institute class. .................. 

in 

8.75 

Casing diameter , in 

6.63 

4.50 

Yield ................................................ Mixed weight ......................................... Additives ............................................ 

medium 

Air. 

6.25 

6.13 

Weight , lb/ft 

13.0 

9.5 

Casing, ft 

O to 10 .(I............... 

0 to 1,150 .0............ 

DO ................................................. Circulating pressure ................................. Displacement pressure ................................ Maximum pressure ..................................... Treating rate ........................................ Displacement rate.. .................................. Cement left in casing ................................ 

Air-foam. 

Do. 

Casing type 

Surface pipe ......... K-55 ................. 

October 21, 1976. 

650 to 1,150.5 ft. 

35 

A. 

1.44 cu ft per sack. 

13.8 lb/gal. 

2 pct gel. 

10 lb gilsonite. 

4 lb salt. 

2 pct calcium chloride. 

100 lb/sq in gage. 

150 lb/sq in gage. 

150 lb/sq in gage. 

1 bbl/min. 

1 bbl/min. 

15 ft. 
Geophys ica 1 Logging 

Date .......................................... October 23, 1976. 

Type of log ................................... Natural gamma, gama density. 

Interval logged ............................... 0 to 1,132 ft. 

DO .......................................... 1,012 to 1,130 ft. 

DO ......................................... 1,062 to 1,130 ft. 

Date. ....................................... October 27, 1976. 

Type of log ................................... Gamma density. 

Interval logged ............................... 1,080 to 1,106 ft. 

DO ........................................ 1,066 to 1,105 ft. 

DO. ....................................... 1,084 to 1,101 ft. 

Do. ......................................... 1,082 to 1,105 ft. 

DO .......................................... 1,078 to 1,105 ft. 

Slotting the Casin6 

Date .......................................... October 24, 1976. 

Type of tool used ............................. Jet slotting. 

Abrasive medium.. ............................. 20- to 40-mesh sand. 

Interval treated.. ............................ 1,094.4 to 1,098.4 ft. 

Perf orations, type, spacing. .................. 4 slots, 90° apart. 

Hvdraulic Stimulation 

Date... ....................................... Propping sand ................................. DO .......................................... Treatment fluid ............................... Surfactant concentration. ..................... Fluid-loss additive concentration.. ........... Gelling agent concentration................... 

Breaker concentration ......................... Complexer concentration... .................... Maximum pressure .............................. Average pressure........... ................... Treatment rate, average ....................... Hudraulic horsepawe r.......................... 

October 24, 1976. 

20- to 40-mesh sand, 1,000 lb. 

10- to 20-mesh sand, 3,000 lb . Gelled water, 3,500 gal. 

3 ga1/1,000 gal. 

50 lb/1,000 gal. 

66.7 lb/1,000 gal. 

2 lb/1,000 gal. 

0.4 ga1/1,000 gal. 

2,500 lb/sq in gage. 

2,400 lb/sq in gage8 bbl/min. 

1,000 hp* 

Well Life 

Date production equipment installed. *.*......* November 12, 1976 . Date production began. ........................ November 13, 1976. 

Date production equipment removed.. .......... February 14, 1977- 

Date underground interception ................. February 15, 1977- 

1':U.S. GOVERNMENT PR INTING OFF ICE: 1978-703-103158