Testing Geothermal-Well Cements:

Strength Measurements Following

Hydrothermal Exposures

Ralph F. Krause, Jr. Edwin R. Fuller, Jr.

Fracture and Deformation Division

Center for Materials Science

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

April 1979

Interim Report

Issued July 1980

-QCPrepared forof Geothermal Energy

100

.1156

80- 2099-1

1980

c.2

Department of Energy

hington, DC 20461

NBSIR 80-2099-1

NATIONAL BUREAU

Of STANDARDS

LIBRARY SEP 1 9 1980

TESTING GEOTHERMAL-WELL CEMENTS:

STRENGTH MEASUREMENTS FOLLOWING

HYDROTHERMAL EXPOSURES

, (JJ> ®

Ralph F. Krause, Jr. Edwin R. Fuller, Jr.

Fracture and Deformation Division

Center for Materials Science

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

April 1979

Interim Report

Issued July 1 980

Prepared for Division of Geothermal Energy

U.S. Department of Energy

Washington, DC 20461

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity, Technology, and Innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Abstract

Laboratory data were obtained for the compressive and tensile

strength of some candidate cements for geothermal wells after they were

exposed to water at a temperature of 195°C and a pressure of 17 to 21

MPa for various periods. Some of these cements were being considered

for use in the remedial cenenting of a hot-dry-rock well at Los Alamos

Scientific Laboratory. The shear-bond strength to steel of the prime

candidate for this remedial cementing was also examined. The methods

used are preliminary to a standard property verification program, now

being developed at the National Bureau of Standards.

Introduction

In an earlier report [1] the results of compressive and tensile

strength tests at room temperature and pressure were given for five

cements which had been treated according to a certain procedure in water

at 195°C and 21 MPa. The cements were first cured in molds for about 40

h and then were exposed out of the molds for about another 136 h.

Additional tests have since been made on these same cements after a succession of even longer periods of exposure, extending up to a total

of 950 h for some cements.

Due to specimen numbers and size restrictions, these tests did not

specifically follow recommended practice of the American Petroleum

Institute [2] for testing oil-well cements. Instead, specimens were

molded into 18 mm diameter rods rather than the standard two inch cubes.

These smaller specimens were chosen because a large number of specimens

had to be handled in a short time under the space restraints of our equipment. In addition, inordinate delays often occurred between the

time specimens were removed from the autoclave, detached from their

molds, cut to size, and eventually tested in a compressive strength

test. In an effort at giving a clear history of all specimens tested,

the earlier results are repeated here along with the recent results.

Major emphasis was given to testing cements which consisted of

sodium silicate, silica, and either ZnO or A1(0H)

3 (cementing materials

C and D, respectively, in Table 1) because these cements were prime

candidates for the remedial cementing of a hot-dry-rock well at Los

Alamos Scientific Laboratory. Initial tests [1] on these cements indicated

strengths which were less than those reported by another laboratory [3].

Newly formulated batches of these cements were tested to determine the

influences of segregation of dry components, mold material, release

agent, curing in a mold under saturated steam versus liquid water, and

the wetness or dryness of the test specimens. In addition, specimens

of the ZnO cement which had been cured elsewhere [3] were tested for

comparison. Prior to the remedial cementing, a measure of the shearbond strength to steel was attempted for the AHOH)^ cement.

- 1 -
After completing the work of interest to the remedial cementing,

two additional cements (cementing materials F and G, Table 1) were

tested for compressive and tensile strengths. In these two cases,

techniques were modified so that freshly molded specimens were cut to

size and tested wet without undue delay.

Compressive and Tensile Strength Tests

SI urries

The cementing materials that have been used thus far are listed in

Table 1. Batches of 0.6 to 1.0 kg were weighed in the proportions

prescribed. Slurries of cementing materials A, B, F, and G were prepared

by the API recomnended practice [2] except that a two liter high-speed

blender was used. Cementing material G was very difficult to blend with

water because its slurry was very viscous. Cementing materials C and D were blended with water in a paddle mixer for 10 min, resulting in a workable mortar. The components of cementing material E were preheated

separately to 55°C and mixed by hand; this slurry also seemed very

viscous.

Molds

Molds for the majority of the tests described below were 20 mm diameter Pyrex tubes with a one mm wall thickness and 150 mm length.

Silicone grease, Kraxo, or Teflon powder was used as a mold release.

Slurries of the cementing materials were placed into these tubes and

puddled; the tubes were then capped with Teflon plugs, which had a one mm leak hole. In addition, slurries of cementing material D were placed

into similarly-sized brass tubes with a thin-walled teflon tube lining

because this cementing material was suspected to react with Pyrex.

Set-Cure

All of the cementing materials except E were set-cured in their

molds for nominally 40 h under autoclave conditions. Usually nine molds

of two cementing materials were submerged together in water at 25°C in a stirred autoclave. At the start of the cure the autoclave was pressurized

to 8 MPa, and automatic heating brought the contents up to 195°C and 21 MPa in 75 min. These conditions were maintained for the remainder of

the curing period. At the end of the cure the inside of the autoclave

was water-cooled gradually to about 50°C in 45 min and then depressurized

slowly. In contrast the setting of cementing material E was done at one atmosphere in an oven: first, for four h at 55°C; then, for 18 h at

110°C. The set-cure time for a batch of a given cementing material is the

first entry of each group of exposure times in Table 2.

- 2 -
The formulations used in preparing the first and second batches of

cementing material B did not yield set cements. After each unsuccessfully

set batch, the formulation mix was altered as described in Table 1 at

the advice of the supplier. Finally, the third formulation provided

adequate firmness, for all except approximately the upper ten percent of

the material in the mold.

The volume of a set rod of cementing material F appeared about 15

percent smaller than the original volume of its slurry, perhaps due to

segregation of water. The corresponding volume change for the other

cementing materials appeared slight.

Specimen Sizes

Upon cooling to room temperature, the Pyrex tubes were carefully

fractured and broken away from the set cement. The resulting rods of

nominally 18 mm diameter were sawed perpendicular to their longitudinal

axes into several pieces. Generally, the rods of a given set cement

yielded 20 specimens of 36 mm length for compressive strength tests and

20 specimens of 9 mm length for tensile strength tests. The batches

prepared prior to the last report [1] encountered considerable delays

between the time of removal from the autoclave and testing. These

delays have since been brought under control so that specimens from the

recent batches were tested wet within 2 to 4 h after the end of their cures.

When cementing materials C and D were first removed wet from the

autoclave, they were so friable that specimens of appropriate length

were difficult to obtain without fracturing. When they were dried in

the room for awhile, these two materials were sufficiently stronger that

less breakage was incurred upon the removal of their molds. Even so,

several of the rods of cementing material D had to be sawed to size

within their molds to provide enough specimens.

Two two-inch cubes of cementing material C which had been set-cured

elswhere [3], were sawed into smaller pieces (15 mm by 15 mm by 23 mm)

to provide enough specimens for statistically meaningful test results.

Both cubes had been cured initially in saturated steam at 120°C for 6 h;

then one cube was cured further in an open autoclave at the same temperature

for another 6 h. Both cubes had been received dry with no history of

the time between curing and receipt.

Load Tests

Generally, five compressive specimens and five tensile specimens of

each set cement were used for the respective strength tests. In the

case of a compressive strength test, the diameter (d) of a rod specimen

(or the sides of a rectangular specimen) were measured, and its sawed

faces were carefully aligned parallel to the bearing blocks of a strength

testing machine. The machine was operated at a displacement rate of 0.5

- 3 -
mm/min to determine the force (F ) required to crush the specimen. In

the case of a tensile strength test, both the diameter (d) and the

length (L) of a rod specimen were measured; then the test machine was used at the same displacement rate to apply diametral compression to the

specimen, until the force (F.) required to break the specimen was observed.

Cardboard cushions were usedTM these diametral tests to distribute

evenly the applied load. The compressive strength (a) and the tensile

strength («r.) of the rod specimens were calculated fr8m 4F /^d 2 and

F./irdL, respectively. Values of these strengths for the various set

cements are given in Table 2.

Extended Exposures

The remainder of the sawed specimens were exposed to liquid water

for extended periods under the same autoclave conditions as used in the

set-cure. The autoclave was occasionally depressurized and cooled so that selected specimens could be removed for testing. The remaining

specimens were then subjected to another exposure period. Table 2 gives

the accumulated time that specimens of each batch of cement was exposed

to the autoclave conditions, including the initial cure in the mold,

before the strength tests were conducted. Because only one autoclave of

a limited capacity was available for either curing specimens in their

molds or exposing them out of the molds, several of the set cements were

kept at room temperature and pressure for many days before the strength

tests. These interim times are also given in Table 2.

During one period of exposure, the specimens were subjected to a sudden loss of pressure due to the fatigue of a safety rupture disc.

Consequently the specimens were cooled suddenly and eventually dried

upon being reheated automatically to 195°C for an unknown duration over

a weekend. All of the specimens which had been prepared from cementing

material A, Table 1, and which had been cut to size for compressive

strength tests broke apart as a result of this abnormal exposure condition.

In contrast almost all the specimens of the other four cementing materials

(B, C, D, and E) survived without breaking apart.

Strength Retrogression

The strength of set cement C retrogressed significantly when it was exposed to liquid water at the autoclave conditions. Even the strength

of the freshly set cement did not develop adequately despite the time of

cure, the wet rods being too fragile to withstand removal of the Pyrex

molds. A drying period after the set-cure facilitated the removal of

the mold. In our first formulations of this cement only a portion of a large powder supply was used to prepare the batches. Since the observed

strength retrogression could have been caused by a segregation of components

in the powder mixture, a second shipment was sent from which the entire

contents of a one kg package could be prepared. Since the strength of

specimens regressed in both instances, possible segregation of the

components in the powder mixture appeared to have a negligible influence.
When the abrupt depressurization and drying occurred near the end of

the 130 h exposure, the decrease in strength was not as serious as before; but became worse upon subsequent exposure to liquid water at the

autoclave conditions. This strength retrogression behavior was also

observed for specimens which were prepared from cubes that had been setcured elsewhere [3].

When set cement D was exposed to liquid water at the autoclave

conditions, its strength did not retrogress proportionately as much as that of cement C; but neither was cement D ever as strong as cement C.

Even though cement D was allowed to dry after the set-cure, sufficient

strength did not develop to withstand removal of the Pyrex without

breaking many of the rods. In order to prepare specimens for the

extended exposures, they had to be sawed while in their molds. Their

strength appeared to increase somewhat after subsequent exposure in

their molds. When the abrupt depressurization and drying occurred near

the end of 456 h of exposure, the Pyrex molds cracked and were removed

before continuing the exposure. After 814 h of exposure, the strength

decreased by almost half. Table 2 shows that specimens, which were

prepared by different methods to examine possible influences on strength

development, were all weak iimediately after the set-cure; however, when

the specimens were allowed to dry for several days at room temperature,

they strengthened considerably.

Some retrogression in strength of set cements A and B was observed

upon extended exposures; however, their strengths remained relatively

high. The strength of set cement E remained very high throughout all

the tests. The strength of set cements F and G were moderately high,

although exposures have not been conducted sufficiently long to date to

test for any retrogression in strength.

Shear-Bond Strength Tests

Cementing Material

Since a limited time was available prior to the remedial cementing

at Los Alamos, the shear bond strength to steel was examined only for

cementing material D, the prime candidate.

Molds

Commercial one inch pipe couplings of 316 stainless steel were used

to mold the test specimens. Stainless steel end plates were fabricated

to center a steel rod (’19 mm diameter by 48 mm length) within each

coupling. The couplings and rods were cleaned with trichloroethylene

and dried. Teflon sheet (0.2 mm) was used as a release agent at the end

plates. The cement slurry was poured into and puddled within the molds,

and the molds were then stacked inside a pressure vessel.

- 5 -
Thermal Cycling

The cement was cured near 200°C with saturated steam and nitrogen

at pressures from 6 to 13 MPa. About 75 min was required to heat the

previously pressurized vessel to the operating temperature. The curing

conditions were maintained for about two days; then, the vessel and

contents were cooled by compressed air to about 60°C in 2 h. The vessel was opened, one specimen was removed, and the above process was repeated

with the other specimens for a total of four cycles.

Load Tests

After a specimen was cooled to room temperature, the diameter (d)

of the steel rod and the height (l) of the cement and steel rod interface

were measured. Then a strength testing machine was used at the displacement

rate of 0.5 mm/min to determine the force (F ) required to displace the

steel rod in the cementing-material . Because the cementing -material

itself failed near the boundary of the coupling, only a minimum value of

the shear-bond strength (O could be calculated from F /udL. Table 2

gives these values which were obtained after each cycles in a series of

four cycles.

X-Ray Diffraction Examinations

In order to obtain a better understanding of the mineral and microstructural changes that might be accompanying the observed strength

development of the set cement, D, x-ray diffraction patterns were obtained

for specimens which had been subjected to the select autoclave and room exposure periods. The results are listed in Table 4 with the corresponding

compressive strengths. These preliminary results indicate that the

strength of this cement is related to the formation of a series of

zeolites which range from analcime with a Si/Al ratio of 2:1 to those

with Si/Al ratios of 5:3 and 1:1. The water content of the zeolite

increases concurrent with this decreasing silica content.

Acknowl edgement

We wish to thank C. R. Robbins for his assistance both in obtaining

and in interpreting the x-ray diffraction patterns.

- 6 -
Table 1. Cementing-materials with mass proportions of components.

Code Mass proportions

A 1.00 class G cement,

0.40 silica flour, and

0.60 water.

B 1.00 class H cement,

0.35 silica flour,

0.045 lignin,

0.015 borax, and

0.56 water, (a)

C 1.00 cement (ZnO, sodium

silicate, and silica) and

0.18 water, (b)

D 1.00 cement [A1 (OH

)

3 , sodium

silicate, and silica] and

0.18 water, (b)

E 0.30 class C cement;

0.70 silica (0.35 mesh 16,

0.175 mesh 30, and 0.175 mesh

100); 0.13 liquid monomers

(0.065 styrene, 0.0455

acrylonitrile, 0.013 divinyl

benzene, and 0.0065 acrylamide);

0.0013 silane A-174; and 0.00065

catalyst AIBN.

F 1.00 cement (B-2Ca0-Si02 and

silica with 0.65 mole ratio

Ca0/Si0 2 , 0.03 bwc A1 2 0 3 , and

0.0225 bwc CaS04 .2H 2 0); 0.045

bwc perlite; 0.011 bwc bentonite;

and 0.85 bwc water.

G 1.00 cement (0.3 class J cement,

0.4 pozzolan, and 0.3 blast furnace

slag); 0.005 car boxy methyl

cellulose; and 0.50 water.

(a) Two other formulations were also used; firstly, the mix was altered

to have 0.40 bwc water; and secondly, the mix was further altered

to have 0.025 bwc lignin, 0.025 bwc borax, and 0.45 bwc water.

(b) Two other formulations in which the mix was altered to have 0.19

and 0.205 bwc water were also used. This cement was received in

three separate shipments.

- 7 -

Reference

6, 7

8

3

3

9

4

5
Table 2. Compressive strength ( g ) and tensile strength (crt

) of selected

geothermal c ementing -mater ia 1 s after exposure under liquid

water in an autoclave at 195°C and 17 to 21 MPa for various

accumulated times. Entries for c and o. are the mean value

and standard deviation for the N samples.

Cementing

materials (a)

Exposure

time (h)

Interim

(da)

A 40 (f)

176

592 (n)

950

3 (dry)

4(dry)

22(dry)

1 6(wet)

B 24 (f) 0.1 (wet)

B (b) 40 (f) 0.1 (wet)

B (c) 40 (f)

178

456 (n)

814

4(dry)

0.2(wet)

22 (dry)

16(wet)

Cl 24 (f) 0.1 (wet)

Cl 40 (f)

176

502

8 (dry)

4(dry)

63(wet)

C2 40 (f)

130 (n)

488

3 (dry)

22(dry)

1 6 (wet)

C2 (d) 70 (g) 0. 1 (wet)

C3 6 (k)

166

?(dry)

0. 1 (wet)

C3 12 (JO

166

?(dry)

0.1 (wet)

D1 40 (f)

176

592 (n)

950

3(dry)

4(dry)

22(dry)

1 6(wet)

D1 40 (f)

456 (n)

814

4(dry)

22(dry)

16(wet)

D2 40 (f) 30(dry)

02 (d) 70 (g)

158 (j)

32(dry)

0.1 (wet)

N a

c /MPa N a

t

/MPa

5 90 + 8 5 9.4 + 1 .0

5 64 + 6 5 7.8 + 0.4

4 10.7 + 1 .9

3 11.6 + 0.5

5 102 + 10 5 12.5 + 0.3

5 71 + 5 5 9.8 + 1 .0

3 88 + 5 2 12.3 + 0.7

3 58 + 12 1 12.9

5 34 + 3 5

[ 5.0 + 0.6

5 4.0 + 1 .4 5 0.83+ 0.15 I 4 4.6 + 1.2 4 0.74+ 0.06

5 35 + 8 5 7.1 + 1 .2

4 11 .0 + 1 .7 5 1 .80+ 0.13

4 3.2 + 0.3 4 0.54+ 0.10

4 27 + 4

4 3.5 + 0.4

4 23 + 4

4 3.6 + 0.5

2 13.2 + 2.4 5 2.6 + 0.6

8 20.3 + 6.3 5 3.0 + 0.7

5 3.3 + 0.4

4 2.6 + 0.4

3 17.5 + 3.7

5 17.1 + 1.8

3 9.8 + 1 .3

4 8.6 + 0.3

5 9.8 + 2.3 5 1 .71+ 0.27

5 7.2 + 2.6 5 1.42+ 0.44

8 - 1

4
Cementing

materials (a)

Exposure

time (h)

Interim

(da) N <rc /MPa N a

t

/MPa

D3 (e) 36 (i) 0. 2(wet) 1 0.9

36 (i) 3(dry) 1 7.8

101 (l) 0.2(wet) 3 2.4 + 1 .6

101 (i) 9(wet) 5 2.3 + 0.7

101 (i) 9(dry) 5 6.1 + 1.3

D3 (e) 65 (i,j) 0. 2(wet) 5 1 .3 + 0.2

65 (h, j) 0.2(wet) 2 6.0 + 1.5

153 (j) 0.1 (wet) 6 3.5 + 0.5

E 18 (g,m) 14(dry) 5 175 + 3

18 (g,m) 27 (dry) 5 172 + 2 5 28.2 + 1 .8

176 4(dry) 5 178 + 2 5 19.7 + 2.6

592 (n) 22 (dry

)

5 220 + 11 5 17.2 + 0.9

950 16(wet) 4 175 + 5 4 20.0 + 1 .0

F 63 (f) 0.3(wet) 5 22.1 + 1.5 5 2.27+ 0.31

199 0.1 (wet) 5 25.1 + 6.3 5 2.95+ 0.30

G 63 (f) 0.3(wet) 5 35.8 + 1.8 5 3.16+ 0.51

199 0. 1 (wet) 5 31 .2 + 2.5 5 3.57+ 0.88

(a) See Table 1. Numerals denote a particular shipment.

Line-spaces separate the various batches prepared.

(b) The mix was altered to have 0.40 bwc water.

(c) The mix was further altered to have 0.025 bwc lignin, 0.025 bwc borax,

and 0.45 bwc water.

(d) The mix was altered to have 0.19 bwc water.

(e) The mix was altered to have 0.205 bwc water.

(f) Material was held in Pyrex molds using Silicone grease as release agent.

(g) Material was held in Pyrex molds using Kraxo release agent.

(h) Material was held in Pyrex molds using Teflon release agent.

(i) Material was held in Teflon-lined brass molds.

(j) Saturated steam was used in the autoclave instead of liquid water.

(k) The material was set cured elsewhere [3] in brass molds in saturated

steam at 1 20°C.

(m) This portion of cure was conducted in room air at 55 and 110°C.

(n) Specimens were subjected to an abrupt depressurization and subsequent

drying-out the last 1 or 2 days of the exposure.

- 9 -
Table 3. Shear-bond strength (j ) of the interface between a steel rod and

the A1(0H)

3

cement (a) after successive thermal cycles between 25

and 200°C f saturated steam and nitrogen at 6 to 13 MPa).

No. of Accumulated time, (hr.)

Cycles at 200°C a

$

/MPa

1 47 >3.6

2 114 >4.6

3 154 >4.1

4 202 >4.0

(a) Cementing material D from the third shipment was mixed with 0.205 bwc water
Table 4. Mineral phases as determined by x-ray diffraction analysis and

compressive strengths { a

) of the A1 (OH)^ cement (a) after select

exposures to water at 195°C and 21 MPa.

Exposure time

(h)

Interim

(da) a

c/MPa

Mineral

phases

i

65 (b) 0.18(wet) 1 .3 + 0.2 a" Si0

2

NaAlSi

2

0

6

-H

2

0

814 (c) 1 6 (wet) 9.8 + 1.3 a-Si

0

2

NaAlSi

2

0

6 -H

2

0

Na

3

A1

3

Sl 5°16' 6H

2

0

70 (d) 32(dry) 9.8 + 2.3 a-Si0

2

NaAlSi

2

0

6

-H

2

0

Na

3

A1

3

S1 5°16-

6H2°

NaAlSi04-n H

2

0

(a) Cementing-material D.

(b) Cement from third shipment was mixed with 0.205 bwc water and cured in

Telfon-1 ined

brass mold under saturated steam.

(c) Cement from first shipment was mixed with 0.18 bwc water, cured 456 h in a Pyrex mold, and exposed to liquid water for the remaining time.

(d) Cement from second shipment was mixed with 0.19 bwc water

a Pyrex mold under liquid water.

- 11 -

and cured in
References

1. R. F. Krause, Jr. and E. R. Fuller, Jr., Quarterly Report, National Bureau

Standards, in "Cementing of Geothermal Wells," Progress Report No. 10,

July-September, 1978, L. E. Kukacka, Project Leader, Brookhaven National

Laboratory, Upton, New York.

2. "API Recommended Practice for Testing Oil-Well Cements and Cement

Additives", API RP 10B, Twentieth Edition, April 1977, American Petroleum

Institute, Production Department, Dallas, Texas.

3. D. K. Curtice, Southwest Research Institute, San Antonio, Texas, private

communications to E. R. Fuller, Jr., National Bureau of Standards,

Washington, D. C., August 7, 1978.

4. G. L. Kalousek, Colorado School of Mines, Golden, Colorado, private

communication to E. R. Fuller, Jr. and R. F. Krause, Jr., National Bureau

of Standards, Washington, D. C., October 2, 1978.

5. R. S. Kalyoncu, Battelle Columbus Laboratories, Columbus, Ohio, private

communication to E. R. Fuller, Jr., National Bureau of Standards, Washington,

D. C., November 20, 1978.

6. D. K. Smith, Halliburton Services, Duncan, OK, private communication to

E. R. Fuller, Jr., National Bureau of Standards, Washington, D.C., June 29, 1

7. D. K. Smith, "Cementing", Table 14.2, p. 133, Society of Petroleum

Engineers of AIME, New York, 1976.

8. L. K. Moran, Dowell Division of Dow Chemical USA, Tulsa, OK, private

communication to E. R. Fuller, Jr., National Bureau of Standards, Washington,

D. C., August 18, 1978.

9. N. Carciello, Brookhaven National Laboratory, Upton NY, private communication

to R. F. Krause, Jr., National Bureau of Standards, Washington, D.C.,

August 23, 1978.

12
NBS-114A (REV. 9-78)

U.S. OEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSI.R 80-2099-1

2. Gov't Accession No* 3.

> pi''- MM __

4. TITLE AND SUBTITLE

TESTING GEOTHERMAL-WELL CEMENTS

Strength Measurements Following Hydrothermal Exposures

5. Publication Date

July 1980

M pm

s r

7. AUTHOR(S) 8. Performing Organ. Report No. Ralph F. Krause, Jr. and Edwin R. Fuller, Jr.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Sfrear, city, state, ZIP)

11. Contract/Grant No. FA77-A-01 -6010

13. Type of Report & Period Covered Dr. Robert R. Reeber

Division of Geothermal Energy

U.S. Department of Energy

Washington, D.C.

2QA61

15. SUPPLEMENTARY NOTES

April 1979 * Interim

I | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200-word or leas factual summary of moat significant information. If document includes a significant bibliography or

literature survey, mention it here.) Laboratory data were obtained for the compressive and tensile strength of some

candidate cements for geothermal wells after they were exposed to water at a tanperature of 195°C and a pressure of 17 to 21 MPa for various periods. Some of these

canents were being considered for use in the remedial cementing of a hot-dry-rock well

at Los Alamos Scientific Laboratory. The shear-bond strength to steel of the prime

candidate for this remedial canenting was also examined. The methods used are

preliminary to a standard property verification program, now being developed at the

National Bureau of Standards.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Cement; compressive strength; geothermal well; hydrothermal exposure; splittingtensile strength.

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