SAND78:::2342'uNLIMITED RELEASE

HIGH ENERGY

R. WARPINSI<I; R. A. SCHMIDT; H. C, WALLU'IlG;

W. COOPER AND S, J. FINLEY

SF 2900.oQ9(3-

SAND78-2342Unlimited Release

High Energy GaS Frac*

N. R. Warpinski, R. A. Schmidt, H. C. Walling,P. W. Cooper, and S. J. Finley

Sandia LaboratoriesAlbuquerque, NM 87185

ABSTRACT

A High Energy Gas Frac field test has been conducted at DOE's Nevada Test

Site, Nevada. The Gas Frac utilizes a controlled propellant def1agration to

initiate and extend multiple fractures in a borehole. Three different propellants

were tested in a volcanic ash fall tuff medium and resulted in phenomenologically

different behavior. Mineback of the experiments provided direct observational

evidence to characterize the results. The slowest propellant (burn time == 0.9 sec)

had a pressure loading rate (0.09 psi/jlsec) and a peak pressure (6250 psi) that

were relatively low and resulted in a single fracture that was similar in appearance

to a hydraulic fracture. The fast propellant (burn time - 1 msec) had a pressure

loading rate (> 1500 psi/jJsec) and a peak pressure (> 20,000 psi) that were so

large that, although multiple fractures were initiated, considerable crushing

near the we11bore was observed and only one fracture was extended more than 6 in

from the we11bore. The intermediate propellant (burn time = 9.4 msec)

had a pressure loading rate (20 psi/jJsec) and a peak pressure (13,800 psi) suffi-

cient to initiate and extend 12 separate fractures in random radial directions.

Lengths of these fractures varied from 6 in to 8 ft for 20 1b of propellant in an

8 in borehole. This technique provides an attractive method to alleviate

we11bore damage for other in situ technology applications.

*This work was supported by the U. S. Department of Energy (DOE) under contractAT(29-1)789.

1-2

Introduction

The High Energy Gas Frac isa wellbore fracturing technique designed to in­

crease the permeability of a formation near the wellbore. With tnis method,

multiple fractures are created and extended in a pay zone by imparting a controlled

high intensity and short term pressure load to the borehole. This technique can

be applied to the Eastern Devonian shales as well as to many tight gas sands to

overcome wellbore damage that occurs during drilling. It can also be useful for

solution mining and other in situ technologies.

The concept of High Energy Gas Frac is to tailor the pressure-time behavior

of the deflagration of a suitable propellant to create multiple fractures and

avoid limitations inherent in both hydraulic fracturing and explosive fracturing.

Hydraulic fractures, which are propagated at pressures that are slightly higher

than the minimum in situ stress and for pumping times that are on the order of

hundreds of seconds, typically produce only a single fracture whose orientation is

aligned with the in situ stresses. Detonations, which usually have peak pressures

that are orders of magnitude above the in situ stresses and occur in microseconds,

often cause considerable crushing of the rock and leave a residual compressive

stress zone around the wellbore. (1-3) This results in wellbore damage, and may seal

off any cracks that are formed. The High Energy Gas Frac imparts a controlled

pressure load about one order of magnitude above the in situ stress level but be­

low the flow stress of the rock. This pressure load is applied over an interval

on the order of milliseconds to c:teate and extend multiple fractures radially

from the borehole. The initial loading rate must be large enough to initiate

multiple fractures. The number of fractures appears to be rate dependent and is

probably influenced by the velocity of sound in the rock, the size of the borehole,

the in situ stresses and the number of available flaw sites for crack nucleation.

The propellant must continue to burn for a short period so that the hot, high

pressure gasses will enter the created fractures and extend them~ the crack size

will be limited if the fluid does not penetrate into the cracks. The pressure

must be considerably above the in situ stresses so that the near wellbore stress

field is dominated by the effect of the pressure in the cracks and wellbore, re­

sulting in fractures which propagate radially. However, if the pressure is too

large and results in crushing, small particles may enter the cracks and seal them

off. Under these conditions of elevated temperature, pressure and gas velocity

it is also expected that the fractures will be somewhat self-propping and a number

of high conductivity paths will remain after the pressure has decayed.

3

There are other techniques that utilize a number of the same concepts as the

High Energy Gas Frac. The "Controlled Explosive Rock. Break.er" (CERB) (4) detonates

a fuel-air mixture to produce high pressure and temperature gasses to fracture rock.

for mining. "Dynafrac" (5,6) combines the pressure loading rates typical of explosive

fracturing techniques with peak. pressures that are associated with hydraulic frac­

turing by using a controlled explosive source to generate a shock wave in a fluid

in the borehole and induce mUltiple fractures. Although they are not yet discussed

in the literature, "Kine-Frac" by Kinetech Corporation and a stanford Research

Institute-Thiolkol process are also similar to Gas Frac. However, it is believed

that the work. presented in this report is the first time that multiple fracture

initiation and propagation have been observed directly under realistic in situ

conditions.

Field Test

In order to test the concept over a range of experiment conditions, three

different gas frac experiments were conducted in G tunnel at the Nevada Test Site,

where mineback facilities provide the opportunity to observe the results. (2,3) G

tunnel is driven into a volcanic ash fall tuff having the properties shown in Table 1.

The location where the experiment was performed has approximately 1400 ft of over-

burden. Three different propellants having different burn rates and, therefore,

different pressure-time (p-t) profiles were utilized for the experiments. These

propellants were off-the-shelf materials having the properties shown in Table 2.

Table 1

Ash Fall Tuff Properties

4

Density

Porosity

Permeability

Elastic Modulus

Poisson's Ratio

Compressional Wave Velocity

Shear Wave Velocity

Tensile Strength

Compressive Strength (Unconfined)

Fracture Toughness

Calculated Terminal Crack Velocity

1. 8 gm/cc

40 %

0.01 md

0.6 x 10 6 psi

0.2

7000 ft/sec

4000 ft/sec

400 psi

5000 psi

450 psi~

1500 ft/sec

Table 2

Description of Gas Frac propellants

Material Designation

Composition (percent)

Nitrocellulose

Nitroglycerine

Binders

Burning ~ate (apn)*

a (in/sec)

n

~elatively

GF#l

JPN

52

43

5

55.3 x 10-4

0.69

"slow"

GF#2

M-26

75

20

5

-48.28 x 10

0.87

"medium"

GF#3

M-5

82

15

3

6.64 x 10-4

0.91

"fast"

*Rate is a function of pressure; P in psia. Manufacturers data

M-5 which is used for small armS ammunition, has a relativelY fast burn rate (~l

millisecond under the assumed experiment conditions). M-26, which is a large bore

gun ammunition, has an intermediate burn rate (-10 milliseconds). JPN, which is used

as a rocket propellant has a very slow burn rate (~l second). Twenty pounds of each

propellant were used and a small amount of carbon black was added to each propellant

to facilitate identification of the created fractures during mineback.

As shown in Fig. 1, three 3 in pilot holes were drilled in the ash fall tuff of

side drift U12g.l0HFS#18 of G tunnel and then reamed to 8 in. The holes were drilled

at -100, 20 ft deep and spaced 15 ft apart. The propellant canisters shown in Fig. 2

were inserted into the holes. These canisters contained (1) the propellant, which was

jacketed inside the porous plate cylinder; (2) two dual channel ignitors, one at each

end of the charge; (3) a fluid coupled plate (FCS) pressure transducer (7) which provides

high frequency response pressure measurements under harsh conditions; (4) thermocouples;

(5) instrumentation and detonation cables, wiring and gas blocks to prevent leakage;

and (6) a grout plug to prevent the grout from surrounding the device during stemming.

Figure 3 shows the configuration of the canisters in the borehole. All three

canisters were stemmed in the borehole with a high strength cement having a cure

time of 28 days. Gas frac #1 (GF#l) contained the canister with the slow propellant,

GF#2 contained the intermediate propellant and GF#3 contained the fast propellant.

GF#3 was the first propellant ignited. An intercom was turned on prior to the

tests and considerable rumbling was heard at ignition. The pressure data from the

fluid coupled plate (FCP) pressure transducer are shown in Fig. 4. The propellant

5

tIV

/

GF#3

-_ ....._:_---.I

IIIIII

___I

Proposed Mineoack Drift

I+- 8" Borehole

r Pilot Hole:;1

GF#2

-------------~

GF#l

Propellant Canister

- .......- -.- ~ - .....-- --

U12g.10 HFS#l8

U12gPortal

o 10 ft

Figure 1. Gas Frac Experiment Drift.

slowly built up pressure until 0.12725 seconds after ignition when it rapidly

deflagrated. This delay is caused by the relatively slow surface flame spreading

rates and large chamber-to-grain volume ratio. The latter permits the grain

surfaces to burn very slowly until sufficient chamber pressure is built up; at that

time the burning rate increases rapidly. The pressure rise shown in Fig. 4 is the

maximum that can be measured by the FCP and it is estimated that the peak pressure

was actually about 30,000 psi and the loading rate was greater than 1500 psi/~sec. The

signal from the rcp was lost at this point and the subsequent data is meaningless.

Later analysis of metal that was recovered from the canister indicated that the

propellant did not detonate. Analysis of the p-t record to determine the length

of the burn is impossible due to the incomplete record.

6

N

7

Figure 3. Gas Frac Canisters and Instrumentation Location.

8 in Borehole20 ft deep

-100 incline

20000

DetonationCables

III I

PropellantCanister

Grout Barrier

Pressure Transducer

---..:""--__ Ga s Blocks

I II I I

j i'-';-'0---1

10000

Lt I I I I I I In IIIIII1-----+----1 11-'-1-'-1-1-': I-11111111 '_I

, I I III I I1III1 n I

I I I II I I 1

1··: ~H~+'~+t1~JI~I--1I II I I . I I I

.1268 .1270

TIME {SEC} FROM IGNITION

.1272

8

Figure 4. GF#3 Pressure Record

The intermediate propellant burn, GFi2, was conducted second. Moments after

ignition, a whistling sound was heard over the intercom, indicating that some of the

gasses may have vented into the tunnel. The pressure data are .stiown in Fig. 5.

Again, the pressure rose slowly until 0.241 seconds after ignition, at which time it

entered the rapid burn mode. The pressure loading rate between 3000 and 11,000 psi was

....... 20 psi/jlsec. After rising to near 12,000 psi (tl in Fig. 5) the pressure decreased

somewhat (t2)

and then increased again, peaking at 13,800 psi (t3) before declining.

Analysis of this record shows that the propellant stopped burning at about 0.251

sec (t4)

after ignition, at the time when the oscillations started. This can be

calculated from the rate equation in Table 2 and the measured P-t curve by inte­

grating and determining the time at which the propellant graL1s were completelY

consumed. The signal from the FCP was lost at 0.255 sec and no further data were

obtained.

15000

10000

~

H[J:lIII

~i:J[J:ltn

i2III

5000

o

r-: ....r·T-r-]·'-r-'l-n-ilt-r'-rT-r-'- lIT:.I-'i--·I-'--I-!-~~-lf,-l.-!-!I I I I I 'j l l fl I I I I I Ii

II i ! I i I I j I ! i i l!j-r-t"--i'- "-+'+~'i l-~A!· ..· +-1'1rl·-..t-1- ·r +._+__.jt4~··_+·_·_~V\ 1_JI! i I I ._,..,__....;.._.1.;;.....1 ! i I I I ~r\IJ1! I--•.•- .._.... . '-'.- - ... . . ! . ", .,

.240 .245 .250 .255TIME (SEC) FROM IGNITION

Figure 5. GF#2 Pressure Record

9

The slow propellant, GF#l, was ignited last. As shown in its p-t curve in

Fig. 6, the loading rate (""".09 psi/\lsec) and peak pressures (6250 psi) are much

lower than GF#2. The oscillations are 60 cycle noise. Analysis of thi~ record

indicates that the propellant stopped burning 0.9 sec after ignition.

Mineback

Direct observations of the created fractures were made possible by mineback

with a. rotating drum Alpine mining machine. This miner provides a clean face cut

so that fractures and geologic details can be easily identified. Both photography

and standard geologic mapping techniques were used for data acquisition. Particular

attention was paid to the length a.nd the number of the fractures that emanated from

the borehole. The carbon black that was added to the propellant coated the sides

of the fracture so that identification of the created fractures was simplified.

GF#l, which was the slowest burn test, was entirely mined back and a single

fracture was observed to extend"" 3 ft to the southwest and"" 2 ft to the northeast

of the location in the borehole were the canister was situated. This direction

0.80.2 0.4 0.6TIME (SEC) FROM IGNITION

Figure 6. GF#l Pressure Record

nJ III J_I_.

o

6'>00

o

4000

~ 2000ptr.ltr.l

~Po<

10

is approximately perpendicular to the minimum compressive principal in situ stress.

The fracture also extended -- 3 1/2 ft above and 2 ft below the canister site.

From~ 2 1/2 ft above to ~1 ft below the borehole, stranding of the~£racture was

very common. The fracture strike and dip, respectively, ranged from N28oW,

550_60oW at the lower extremity to due North, 70 0W at the upper tip. At the approxi­

mate location of the canister, the strike was N200E and was approximately vertical.

In general, the fracture resulting from GF*l was very similar to a typical small

hydraulic fracture near this tunnel location.

In GF*2, the intermediate burn rate test, 12 different fractures were observed.

Five of the fractures were small with lengths less than 1 ft, but seven of the

fractures were from 2 to 8 ftlong. All 12 fractures apparently originated

from the top half of the borehole, but this may be due to the grout stemming.

Apparently, the grout broke through the seal and filled much of the cavity, re­

sulting in a significant amount of high strength grout covering the bottom of the

cavity. The widths of the fractures during the test must have been considerable

since pieces of detonation cable (~3/l6 in diameter) were found wedged into one

fracture 2-3 ft from the borehole and chunks of grout were forced out into other

fractures. Most of the fractures broke out parallel to the borehole, although a

few are perpendicular to it. The borehole showed no apparent enlargement nor a

crushed zone. Figure 7 shows a photograph of one face of the GF*2 mineback.

The numbered pieces of paper have been inserted into individual fracture planes.

The cavity area is darkened and the grout fi.l1ed pilot hole is adjacent to the

pick handle. The arrow at the right shows one location where a piece of detonation

cable was found in a fracture. Figures 8 and 9 show the side and top views, re­

spectively, of a computer facsimile of the fractures based upon observed fracture

orientations and extents. A square, 3 in grid has been drawn on each fracture so that

distortions of that grid will help indicate the orientation of the frac plane. All the

fractures originate in the bottom 2 ft of the borehole, where the canister was situated.

The mineback of GF*3, the fast propellant, revealed a single prominent fracture

that was observed to extend - 4 ft radially from the borehole. The strike and dip,

respectively, of the fracture were N70 0W and vertical near the canister and N55 0W

and 7loN away from the canister. Stranding was very common along the fracture.

There was also a crumbled zone about 2-4 in thick around the wellbore that is

typical of high explosive detonations conducted in the ash fall tuffs. (5) A

number of small «6 in) incipient fractures were also found around the borehole.

11

12

Figure 7. GF*2 Cavity and Fractures

Figure 8. GF#2 Computer FaGsimile Side View

Figure 9. GF#2 Computer Facsimile ~op View

13

14

Discussion

Results from the first High Energy Gas Frac experiments are encouraging in that

the phenomenological behavior of the three tests differed considerably. The experi­

ment of most interest is GF#2 since this one produced 12 approximately radial frac­

tures ranging from 0.5 toB ft in length with no evidence of rock crushing at the

cavity wall.

The lack of crushing at the cavity wall indicates that the peak pressure of

l3,BOO psi was below the flow stress of the ash fall tuff. However, indications

from triaxial compression data and estimates of the stress state at the cavity wall

indicate that the flow streSs is probably not much above 14,000 psi. (B)

The fracture lengths will be strongly dependent on the extent of gas penetra­

tion and the resulting pressure distribution on the cracks presents a highly compli­

cated problem that couples gas dynamics with solid mechanics. However, upper and

lower bounds on this problem can be obtained by assuming, first, total gas pene~

tration with no pressure losses, then no penetration resulting in no pressure on

the crack faces.

If the high temperature gas was able to enter the cracks as fast as they

propagate, without any pressure losses due to cooling or viscous drag, then the

cracks would be expected to propagate during all times in which the pressure re­

mained above the "fracturing pressure". The fracturing pressure is approximately

1000 psi. (9) Unfortunately, the pressure record of GF#2 ends with transducer

failure after 13 msec when the pressure had dropped to 6000 psi, but extrapolating

the fairly linear pressure decay indicates that the pressure reached 1000 psi in

approximately 20 msec. Assuming that the cracks travel at the maximum velocity

for ash fall tuff of approximately 1500 ft/sec, each fracture would have a

maximum length of 30 ft.

A lower bound on crack lengths can be obtained if it is assumed that no gas

penetrates the cracks. This case is more complex in that the time at which the

crack growth is arrested depends on the stress analysis as well as the pressure­

time record. The first pressure peak on the p-t record occurs at 12,000 psi and

it seems natural to assume that "breal<:down" or initial crack growth begins at this

point. The fractures will then propagate until the stress intensity, K, at the

cracl<: tip falls below the material's critical value known as its fracture tough-

ness, KI C'

There are two contributions to the calculation of the stress intensity factor­

the gas pressure in the hole which is counteracted by the in situ stresses.

Ouchterlony(lO) indicates that the stresS intensity for radial cracks emanating from

a pressurized circular hole is

7f PD-----2vn rn

where

n number of cracks (n ~ 3)

P pressure

D diameter of hole

a crack length as measured from hole center (a> D).

The closing (negative) stress intensity due to in situ streSs is

2~ a ,I7fan

where

a = in situ stress acting perpendicular to crack of interest.

(1)

(2)

Adding these two contributions one can obtain the total stress intensity which is

then set equal to KI c as the condition for crack arrest.

7f PD

2vn rn2~ a ITIa

n (3)

Since it is desired to solve for the crack length, a, this equation is recognized

as quadratic in la, which yields a solution of a given by

47fIn - 1 PDa - Kn n Ic

4v"Il=l an

(4)

n ~ 3.

Careful examination of this equation indicates that for many realistic problems

the results are fairly insensitive to the actual value of Kr c and the equation can

be greatly simplified

For the case of two cracks, n

vn PO, n ~ 3 •

4~a

2, the equation is

a::::: 1:. PO7f a

(5)

(6)

Note that equation 5 is quite insensitive as to the number of cracks, n.

15

(

16

For the particular case of GF#2 it is estimated that

Kr c 500 psi lin [Ref. llJ

p 12,000 psi, [from the p-t recordJ

a = 1,000 psi

D a in.

n 12

Substituting these values into equation 4 yields

a 1.9 ft.

(The estimate based on the simplified form of Equation 4, namely, Equation 5 is

a= 2.1 ft.). This, then, is a lower bound on the estimated crack lengths.

Note that this estimated crack length of 1.9 ft is 1.6 ft when measured from

the cavity wall rather than the center of the borehole. Using the previously

assumed crack velocity of 1500 ft/sec, this crack growth of 1.6 ft will take place

in 1.0 msec. Referring to the p-t record in Fig. 5, the 1.0 msec corresponds

nicely to the time from the first peak, tl,

to the time that pressure begins to

rise again, t2•

This suggests the following proposed scenario.

At time tl

many cracks (appro}{imately twelve) nucleate and begin to propagate

simultaneously* at the maximum crack velocity with no gas penetration. During

this stage, the hole is expanding in size causing the press1,lre to drop, even though

the propellant is still burning. After 1.0 msec, at time t 2, the cracks have

grown approximately 1.6 ft from the wall of the hole and the stress intensity at

the crack tip drops below the critical value of K r c ' which causes the cracks to

arrest. The cavity stops expanding and pressure begins to rise again.

The pressure rises now, but at a reduced rate compared with initial rise

since gas pressure is now entering the cracks which effectively increases the cavity

volume. At time t3

some of the cracks begin to propagate again, due to the gas

penetration, but the pressure in the cracks remains less than in the cavity so

the final crack lengths are less than the theoretical lengths of 30 ft. The crack

growth is arrested finally when the stress intensity again falls below Kr c' but

realistic calculations for this final crack length will require knowledge of the

gas dynamics and the actual pressure loading in the cracks. The pressure oscillations

*Simultaneous propagation is expected at this stage siDce, according to calculationsby Ouchterlony (a), a single well-established crack will "clamp" the surroundingregion making additional crack nucleation unlikely. If a single crack were establishedfirst, then crack branching rather than additional nucleation would be favored.

that occur abruptly at time t4

are probably not related to the fracture process.

GF#3 is also quite interesting phenomenologically. Although it did not detonate,

the loading rate was extrem§ly high and the peak pressure was undoub~~dly well above

the flow stress. One would expect that the fast pressure rise would induce mUltiple

fractures but, as stated by Bligh, (4) the crushing of the rock at the wellbore would

promote sealing of the cracks due to the small particles entering the fractures.

Indeed, many incipient cracks were observed at the wellbore, yet one main fracture

did propagate a significant distance.

GF#l is similar in appearance to hydraulic fractures observed in G tunnel.

The peak pressure was too low to induce crushing around the wellbore and the

loading rate was too low to initiate multiple fractures. Essentially, GF#land

GF#3 bracket the region of interest as typified by GF#2.

Conclusions

The High Energy Gas Frac has been shown to be a viable technique for creating

multiple fractures ina borehole. This field test has demonstrated that a propellant's

burn characteristics can be suitably tailored to provide (1) a high enough loading

rate to initiate multiple fractures, (2) high enough pressures to extend fractures

radially, but not so high as to exceed the flow stress of the rock and (3) sufficient

gas generation to allow most of the fractures to be pressurized and propagated further.

In GF#2, twelve separate fractures were initiated and at least seven of these were

propagated a significant distance. The GF#l and GF#3 tests resembling a hydraulic

fracture and a detonation, respectively, have effectively bracketed the region of

interest.

Acknowledgements

The authors would like to acknowledge the efforts of George B. Griswold who

encouraged and initiated these studies. Many thanks are given to William C. Vollendorf,

many other Sandia personnel, and the skilled mining crew who conducted these tests,

evaluations and mining operations at G tunnel. This project is sponsored by the

Department of Energy, Division of Fossil Fuel Extraction.

References

1. C.VI. Smith, R. C. Bass and L. D. Tyler, "Puff 'n Tuff, A Residual Stress ­

Gas Fracturing Experiment," presented at 19th U. S. National Symposium in

Rock Mechanics, May 1-3, 1978.

2. D. A. Northrop and C. L. Schuster, Editors, "Enhanced Gas Recovery Program,

Second Annual Report, October 1976 through September 1977," Sandia Laboratories

Report, SAND77-1992, April 1978.

17

18

3. D. A. Northrop, N. R. Warpinski, R. A. Schmidt andC. W. S;nlith, "Stimulation

and Mineback Experiment Project - The Direct Observation of Hydraulic and Ex­

plosive Fracturing Tests," Proceedings of the Fourth Annual DOE-Symposium on

Enhanced Oil and Gas Recovery, Tulsa, OK, August 1978.

4. T. P. Bligh, "Principles of Breaking Rock Using High Pressure Gases," Advances

in Rock Mechanics, Proceedings of the Third Congress of the International

Society for Rock Mechanics, Denver, 1974, Vol. II, Part B, p. 1421.

5. E. T. Moore, D. M. Mumma and K. D. Seifert, "Dynafrac-Application of a Novel

Rock Fracturing Method to Oil and Gas Recovery," Physics International Final

Report 827, April 1977.

6. E. T. Moore and D. M. Mumma, "Application of a Novel Rock Fracturing Method

to Oil and Gas Recovery," Proceedings of ERDA Symposium on Enhanced Oil and

Gas Recovery, Tulsa, OK, September 1976, Vol. 2.

7. C. W. Cook and E. S. Ames, "The Fluid Coupled Plate (FCP) Gage," Sandia

Laboratories Report, SAND78-0698, August 1978.

8. W. R. Wawersik, private conununication.

9. L. D. TYler and W. C. Vollendorf, "Physical Observations and Mapping of Cracks

Resulting from Hydraulic Fracturing In Situ Stress Measurements," SPE 5542,

Dallas, TX, September 28 - October I, 1975.

10. F. Ouchterlony, "Fracture Mechanics Applied to Rock Blasting,"Proceedings of

the Third Congress of the International Society for Rock Mechanics, Vol. II,

parts B, p. 1377.

11. R. Weisinger, L. S. Costin, and T. J. Lutz, "KI C and J - Resistance Curve

Measurements on Nevada Tuff," Submitted for presentation at SESA Spring meeting,

1979.

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Mr. John L. GidleyExxon Company, USAP. O. Box 2180Houston, TX 77001

R. C.G. E.H. E.Attn:

A. B.P. W.J. H.H. C.T. L.A. W.E. H.L. D.J. H.G. E.V. L.H. M.R. K.D. A.N. R.R. A.S. J.C. L.A. L.S. G.A. F.O. E.T. B,.Attn:

M. SparksG. A. FowlerC. D. BroylesJ. D. KennedyAttn: C. R. Mehl, 1111

C. W. Smith, 1111ShearHanscheViney

W. D. Statler, 1133W. C. Vollendorf, 1133

ChurchCooper (10)DavisWalling (10)PaceSnyderBecknerTylerScottBrandvoldDuganStollerTraegerN"orthrop (25)Warpinski (10)Schmidt (10)Finley (10)SchusterStevensVarnadoVenerusoJonesLane

S. W. Key, 5521T. G. Priddy, 5522

5530 W. HerrmannAttn: B. M. Butcher, 5532

5800 R. S. Claassen8266 E. A. Aas (1)3141 T. Werner (5)3151 W. L. Garner (3)3172-3 R. P. Campbell

for DOE/TIC (25)

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