Testing Geothermal-Well Cements:

Standard Practice

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

July 1 979

Interim Report

|i Issued July 1 980

i

11^

Prepared forof Geothermal Energy

apartment of Energy

ington, DC 20461

TIOIIAL BUa*AU

09 BTANDAW>«

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$EP » 9 1980

NBSIR 80-2099-2

TESTING GEOTHERMAL-WELL CEMENTS:

STANDARD PRACTICE

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

July 1979

Interim Report

Issued July 1980

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
11I
I . Scope

The National Bureau of Standards is under contract with the U.S.

Department of Energy to verify certain properties of cementing materials

which are submitted as candidates for use in the finishing operations of

geothermal wells. Specimens will be set-cured in molds under water for

two days at elevated temperature and pressure. Subsequently, specimens

will be exposed demolded to light and heavy simulated geothermal fluids

for periods of one week or one month. Following each of these treatments,

the following properties will be measured at room temperature and pressure

compressive strength, splitting tensile strength, shear-bond strength of

the cement-steel interface, and cement permeability to water. Upon the

basis of this survey of properties at room temperature, a priority of

cementing materials will be established for further testing of select

physical properties while the specimens are at elevated temperature and

pressure.

II. Candidate Cementing Materials

A. Participants

Several laboratories, some of whom are under contract with the U.S.

Department of Energy, have been developing cementing materials for

geothermal wells. Any investigator who has a candidate cementing

material to submit to this property testing program will be deemed a

participant.
B. Placement Ability

1. Participants will provide written certification that the

slurry of each cementing material that they submit has passed the API

thickening time requirement for a class J cement in a 3050 m (10,000

ft.) well depth (Table 2.2 of reference 1). This requirement specifies

that the slurry must have a consistency less than 30 Be during the

initial 30 minutes of the stirring period and a consistency less than

100 Be up to 3 hours of the stirring period.

2. The thickening time of a slurry will be measured according to

the API thickening time test (section 7 of reference 2) . The pressure

and temperature control will follow the casing cement schedule 6g (p. 34

of reference 2) which, has been extended to provide that the slurry be

heated from 27 to 150 ®C in 36 min (average rate of 3.4 ®C/min) . [Note:

the task group may wish to consider a less severe pressure condition,

such as the 36 MPa (5300 psi) used by Dowell (p. 105 of reference 3),

rather than the 51.7 MPa (7500 psi) given in schedule 6g]

.

3. Participants may have these tests performed by Dowell under the

conditions described in reference 4 (see attached).

C . Mixing Proportions

1. Participants will give the mass ratio of the cementing components

which are to be mixed, for example: 1.00 cement, 0.40 filler, 0.025

additive, and 0.60 water.

2. They will give the slurry density, which may, for example, be

determined by the method in Appendix B of reference 2.

3. They may provide the details of any special slurry mix instructions

which differ from those described in section IV A below.

2
D. Description

1. Participants will identify each cementing component by a

convenient name, for example: API class H cement. Lone Star, Dallas,

Texas. (A manufacturer’s name is given to identify the material and

does not imply that this material is the best available)

.

2. Unless a cementing material is proprietary, its chemical

composition and preparation should be indicated for future reference and

identification, for example: 1.00 cement (0.23 Si02» 0.65 CaO, 0.04

Fe202, 0.05 AI

2 O2

, 0.02 SO^, and 0.01 MgO by mass fraction), clinkered

at 1500 °C, and pulverized (200 mesh); 0.40 silica flour (200 mesh);

etc.

E. Shipment

1. Participants should submit before January 1, 1980 cementing

materials which meet the above criteria of placement ability. Send the

cementing materials, excluding water, to the attention of Ralph Krause,

A355 Materials, National Bureau of Standards via , either of the following:

Commercial Carrier: Route 270 and Quince Orchard Road

Gaithersburg, Maryland 20760

or U.S. Mail: Washington, D. C. 20234

2. Preferably, the respective cementing components should be

packaged separately; and sufficient quantities should be provided to

prepare at least eight liters of slurry.

3. Alternatively, if some participants prefer to premix the dry

cementing components themselves or if these components might tend to

segregate in shipping, they should provide at least eight packages of

cementing material each, of which will form one liter of slurry.

3
III. Apparatus

A. Balances

1. The prescribed quantities of cementing components will be

weighed upon a pan balance which has a one kg capacity and an accuracy

within j^.l g.

2. The quantities of salts which are used to prepare the simulated

geotheraal fluids will be weighed upon a balance which has a 200 g

capacity and an accuracy within +0.1 mg.

B. Mixing Device

1. The components of a given cementing material will usually be

blended in a Waring Blender which has a two liter container and a twospeed propeller-type mixer of stainless steel, capable of rotating 4000

rpm or 10,000 rpm.

2. Also available is a Hobart N-50 mixer which has a 5 L stainless

steel bowl with a flat beater as described in ASTM Method C305 for

Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic

Consistency.

C. Molds

1. Specimens for the compressive and splitting tensile strength

tests will be set-cured in P3rrex tubes (20 mm OD, 1.2 mm wall thickness,

and 150 mm length) . Each tube will be thinly coated with silicone

grease and capped with a Teflon plug, which has a one mm hole to equalize

the pressure and to accommodate any thermal expansion of the slurry.

[Note: This specimen diameter is deemed appropriate due to the prospect

of having to handle many specimens. A constraint is the 5 cm ID of the

pressure vessels that are available for the geothermal exposures.]

4
2. Specimens for the shear-bond strength and permeability tests

will be set-cured in molds of modified, one- inch-pipe nipples of stainless

steel. Commercially available nipples (22 mm ID, 35 mm wrench pad, and

57 mm length) will be sawed in half perpendicular to their longitudinal

axes. The inside diameter of the resulting pieces will then be tapered

in a conical fashion such that the opening at the pipe threaded end is

about five per cent larger than the opening at the wrench pad end.

Removeable cover plates (3 mm thick) are machined to fit the ends of

these molds, so that the molds may be stacked within a pressure vessel.

A one mm groove is machined across the bottomside of the upper cover

plates to accommodate any thermal expansion of the slurry. Teflon

sheets (0.05 mm thick) will separate the specimen and the cover plates.

Some of the cover plates will have recesses to center smooth steel rods

(10 mm OD and 28 mm length) inside those molds which will be used for

the shear-bond strength tests.

3. A stainless steel rod (3 mm OD and 200 mm length) will be used

to puddle slurries in their molds.

D . Diamond Saw

A motorized diamond blade (150 mm OD, 0.5 mm width, 1725 rpm) will

be used to saw the molded rods of set cement into specimens. Two

miniature vises which are attached to a platform will secure a rod on

each side of a cut. The platform will move automatically at a constant

rate (0.5 mm/s) to feed the rod perpendicular to the blade, rotating in

a fixed position through a bath of water.

E. Calipers

The lengths and diameters of specimens will be measured with calipers

to an inaccuracy within +0*02 mm.

5
F. High Pressure Systems

1. A 4 L stirred autoclave of 316 stainless steel, which can be

operated up to a maximum pressure of 21 MPa (3000 psi) , will be used to

set-cure cementing materials in molds which are submerged in distilled

water

.

2. A series of four pressure vessels of Hastelloy C 276 (50 mm

ID, 250 mm internal length, two top ports, and one bottom port) will be

used to expose unprotected specimens of set cements in simulated geothermal

fluids at pressures up to a maximiim operating pressure of 60 MPa (8,700

psi) . The wetted parts of all high pressure valves and fittings are

also made of Hastelloy C276, except for the pressure lines which are

made of Monel tubing.

3. A source of compressed nitrogen or argon will be available to

provide pressures up to 40 MPa (5,800 psi) to all five pressure vessels.

4. A liquid metering pump with a Hastelloy C 4 pump head and a

tantalum diaphragm will deliver the simulated geothermal fluids with a

nominal flow up to 800 ml/hr to any of the four Hastelloy pressure

vessels. Being driven by an air motor, the pump can maintain a constant

output pressure up to a maximum of 69 MPa (10,000 psi) by adjustment of

the pressure of the air supply.

5. Bourdon gauges with Monel coils and sockets will be used to

indicate continuously the pressure within each vessel to an accuracy

within j4D.2 MPa (30 psi). A reference gauge will serve to calibrate

periodically the operating gauges. Another bourdon gauge will be used

to measure the partial pressure of CO

2 over the simulated geothermal

fluid reservoir to accuracy within _jjD.7 kPa (0.1 psi).

6
6. A pressure generator of 316 and 17-4PH stainless steels is

being considered to compress water in order to develop a pressure

difference across a permeability specimen. This generator is a manually

operated piston screw pump which can be operated up to 69 MPa (10,000

psi)

7. Whenever all liquid conditions are used in the Hastelloy

pressure vessels at elevated pressure and temperature, relief valves are

being considered to dump overflow fluids in the event of an inadvertent

over-pressurization. [Note: The use of these valves would possibly

avoid abortion of an on-going exposure; nevertheless, safety rupture

discs will also be installed on these vessels]

G. High Temperature Systems

1. Nichrome wire-wound, tube furnaces are available to surround

each of the five pressure vessels, the Hastelloy vessels having furnaces

of the split- tube type. These furnaces will be used to heat the vessels

and their contents to elevated temperatures at a rate of about 3 °C/min.

The maximum operating temperature is 340 °C for the stirred autoclave

and 400 °C for the Hastelloy pressure vessels.

2. A temperature controller with an adjustable proportional band,

reset, and rate controls will be used to operate each furnace automatically

from room temperature to the operating temperature for that furnace, and

to maintain the final temperature within +2 °C.

3. Chromel-alumel thermocouples will be used to indicate the

temperature of the contents inside of each pressure vessel and the

temperature at selected spots along the exterior surface of the pressure

vessels. A digital voltmeter which is calibrated in degrees Celsius

will be used to read the respective thermocouples to +1 °C

7
4. The stirred autoclave is equipped internally with a watercooling coil; the four Hastelloy vessels have externally applied watercooling coils.

5. A constant temperature bath of stirred water will be used to

hold specimens of set cements at 25 +1 °C preceding their property tests

at room temperature.

H. Fluid Handling Systems

1. Two reservoirs of stainless steel (four liter capacity each)

will store at room temperature the two simulated geothermal fluids of

different compositions, equilibrated respectively under appropriate

pressures of carbon dioxide. Manipulation of stainless steel valves

will direct either fluid to the high pressure metering pump.

2. A pH meter will be used to monitor the acidity of the fluids

in the reservoirs. Both a glass measuring electrode and a reference

electrode will be mounted in a stainless steel chamber to allow pH

measurement to be made at pressures up to one MPa (150 psi)

.

I. Load Testing Machine

A recently calibrated Tinius Olsen Electromatic Universal Testing

Machine (5400 kg load capacity) will be used to apply compressive

loading at a constant displacement rate of 0.5 mm/min. A sphericallyseated compression tool (79 mm diameter) is suspended from the crosshead

of the machine to compensate for possible non-parallel bearing surfaces

of a specimen being tested. The maximum load necessary to cause failure

of a specimen is indicated by a gauge.

J. Permeameter

1. A holder will be provided to receive the modified nipple mold

that contains the specimen to be tested.

8
2. A pair of capacitance-sensing, pressure transducers of 17-4PH

stainless steel will be used to measure [to a precision within 3 kPa

(0.4 psi)] the pressure difference that is applied to opposite sides of

a specimen which is under an ambient pressure up to 60 MPa (8,700 psi).

3. A recording potentiometer will be used to measure the net

output of these pressure transducers (14 kPa/mV) . The exponential decay

of this output is related to the permeability of the specimen being

tested (See Section VI A).

K. Pressure Transmitter

It is planned tentatively to use a stainless steel bellows to

transmit an applied pressure to one end of a steel rod so that the

shear-bond strength of the steel-cement interface can be measured at

elevated temperature and pressure.

IV. Preparation of Specimens

A. Slurry Mixing

The API recommended practice (section 3 of reference 2) will generally

be followed unless otherwise directed by the supplier. In brief, a

weighed quantity of distilled water which is required to prepare one

liter of slurry will be placed in the mixing container, the mixer turned

on the slow speed, and the weighed quantities of dry components added in

less than 15 s. Next, the cover will be placed on the container, and

stirring will be continued at the high speed for 40 s.

B . Mo Id ing

1. Prior to mixing a slurry of a given cementing material, silicone

grease will be thinly applied to the inside surfaces of ten Pyrex tube

molds. Also, seven modified nipple molds of stainless steel and five

9
smooth steel rods will be washed with trichloroethylene and dried.

These molds will provide all the specimens that are needed for the

series of property tests which will be conducted at room temperature and

pressure on a given cementing material.

2. The slurry of a cementing material which is prepared according

to section IV A will be poured into these molds and puddled as needed to

remove air bubbles. Five of the modified nipple molds will enclose the

smooth steel rods. The excess slurry in the modified nipple molds will

be struck off even. The molds will be appropriately covered as indicated

in section III C, submerged upright in distilled water at 25 '’C, and

sealed in the stirred autoclave.

C. Set-Curing

1. The set-cure will commence at the application of pressure and

temperature. First, the autoclave will be partially pressurized with

nitrogen or argon; then it will be automatically heated from room temperature

to 200 °C in about 75 min. , the temperature rate being fairly constant

at 3 °C/min during the first 60 min. The contents of the autoclave will

be maintained at 200 °C for the remainder of the cure. The quantity of

distilled water and the initial pressure of nitrogen are chosen such

that the volume ratio of the final gas phase to vessel capacity is about

ten percent and the final pressure will be near, but eventually adjusted

to 20 MPa (2900 psi) when the operating temperature is attained.

2. When the set-curing has progressed 48 h, the heating will be

terminated and water-cooling through an internal coil of the autoclave

will begin to reduce the temperature at a fairly constant rate, ultimately

to 60 °C in 45 min; then the pressure in the autoclave will be gradually

released.

10
D. Finishing Operations

1. At the conclusion of a set-cure the Pyrex molds of set cement

will be removed from the stirred autoclave, and the Pyrex tubes will be

broken away by diamond scribing the tubes and gentle tapping.

2. Each of the ten rods of set cement will be sawed perpendicular

to its longitudinal axis into three specimens which are twice as long as

their diameter. These pieces will be identified as the top, middle, and

bottom of a given rod.

3. The seven modified nipple molds of set cement will be removed

from the stirred autoclave, and their cover plates and Teflon sheets

detached. If the surfaces of the set cement are glazed they will be

scraped lightly with a wire brush under a stream of water to remove such

glaze.

4. The finished specimens resulting from a set-cure will be

submerged in water in a constant temperature bath at 25 °C for storing

until some specimens are property tested and the remainder are exposed

to simulated geothermal fluids. A weekly schedule which includes specimen

preparation is indicated in Table I.

V . Exposures in Simulated Geothermal Fluids

A. Fluid Compositions

Two aqueous solutions of different concentrations of certain salts

and carbon dioxide will be used to represent light and heavy geothermal

fluids, respectively. Appropriate quantities of NaCl, KCl, CaCl^, and

NaHCO^ will be weighed and dissolved in distilled water to provide the

compositions which are shown in Table II. When the solutions A and B

are placed in their respective reservoirs, carbon dioxide gas at given

partial pressure will be bubbled through the solutions at 25 °C until

11
they are equilibrated to give a pH. near 4.5. Tkereafter, this partial

pressure of CO2 will be maintained in the respective reservoirs, also in

the Hastelloy pressure vessels while they are at 25 °C. [Note: The

compositions of solutions A and B were arbitrarily selected. As reference

5 indicates, geothermal fluids from various locations differ considerably

in composition; moreover, the analyses at a given site show varying

results. The composition of solution A corresponds to the average of

the principal components in 14 analyses of the East Mesa 6-1 wellhead

fluid which was collected in the spring of 1977 (reference 6). The

analyses of the Salton Sea fluids which are reported in reference 5

served as guidelines in the selection of the composition of solution B.

The exposure temperatures given in Table 2 are consistent with the

corresponding Na/K mass ratios, which are used to indicate bottom hole

temperatures (reference 9). The exposure pressure of solutions A and B

corresponds to a well depth of about 2200 m.]

B. Temperature and Pressure Conditioning

1. The four Hastelloy pressure vessels will be divided evenly to

contain the two solutions A and B and will be operated at the temperatures

and pressures which are specified in Table II for these respective

solutions

2. In regard to the exposures of specimens which will be property

tested at 25 °C, the Hastelloy pressure vessels will be pressurized and

heated in a manner similar to that which is described in section IV C

for the stirred autoclave. The quantities of exposure solutions which

are added to the vessels containing the specimens at room temperature

are chosen such that the volume ratio of final gas phase to vessel

capacity is about ten percent when the operating temperature is attained.

Also, nitrogen or argon will be added to the contents of these vessels

12
at room temperature such that the final pressure will be near, but

eventually adjusted to the value given in Table II. Once a week the

vessels will be appropriately cooled and dismantled. Table I gives a

weekly schedule for these operations.

C. Scheduling of Set Cements

1. Specimens of a given set cement will commence being exposed

unprotected in the two solutions A and B about 27 and 51 h, respectively,

after the conclusion of their set-cure.

2. Eight rods of three sawed specimens each, which are designated

for the compressive and tensile strength tests, will be divided evenly

and deposited at the appropriate times in two Hastelloy pressure vessels,

holding solutions A and B, respectively. Teflon sheets or stainless

steel shins (0.05 mm thickness) will be used to separate the sawed ends

of these specimens to keep them from sticking together while they are

stacked in the vessels during the exposures. Half of these specimens

will be exposed one week and the other half, exposed four weeks. Table

III shows a schedule of depositing and withdrawing this type of specimen

for several set cements in a particular solution.

3. Likewise, the four specimens which are designated for the

shear-bond strength test and the two specimens which are designated for

the permeability test will be divided evenly and deposited in the other

two Hastelloy pressure vessels, holding solutions A and B, respectively.

Half of the shear-bond specimens will be exposed one week and the other

half, exposed four weeks; the same permeability specimens will be used

throughout. Table IV shows a schedule of depositing and withdrawing

these types of specimens for several set cements in a particular solution.

13
VI. Property Tests

A. Permeability of Set Cement

1. The measurement technique to be employed for determining

permeability is a pulsed technique, similar to that described in reference

10 , except that the range of conditions has been extended so that measurements

can be made both at room temperature and atmospheric pressure and at

elevated pressure and temperature, using the Hastelloy pressure vessels.

2. A mold with its set-cured specimen is sealed in a test holder,

using Teflon tape. The holder is filled with the fluid that was used in

the set-cure or in the particular exposure that this test follows. When

the ambient temperature and pressure are established on both sides of

the specimen, a vent valve on the holder is opened momentarily to allow

fluid from the fluid reservoir to be pumped through the holder until any

air in the holder is displaced.

3. A differential pressure of 2.0 MPa (.290 psi) is applied across

the specimen of set cement to establish the fluid flow through the

cement. The fluid in the holder is then isolated from its reservoir,

and the decline of the pressure difference is recorded as a function of

time

.

4. The fluid permeability (k) of the set cement is calculated

from the observed logarithmic slope

d In (P^-P

2 )/dt = -k A( 1 /V^+1 /V

2 )/u 6L

where

P^ = pressure of fluid in holder,

P

2 = ambient pressure downstream,

t = time,

A = cross-sectional area of specimen.

14
L = length of specimen,

y = fluid viscosity,

6 = fluid compressibility,

= volume of fluid in holder, and

= ambient volume downstream.

[Note: When measurements are made at room temperature and pressure, V

remains constant and I/V

2

is assumed zero.]

B. Shear-Bond Strength of Cement-Steel Interface

1. This test will be conducted at room temperature and pressure

and also at elevated temperature and pressure, using the Hastelloy

pressure vessels.

2. A mold containing a cement specimen with a centrally embedded

steel rod is supported in a test holder, and a load is applied to the

end of the steel rod which is in the larger opening of the mold. The

maximum force required to displace the steel rod is recorded and used to

calculate the shear-bond strength.

3. The shear-bond strength (o^) is calculated from

o = F/ttDL

s where

F = maximum force required to displace the steel rod,

D = diameter of steel rod, and

L = length of the cement-steel rod interface.

[Note: The shear-bond strength determined at room temperature can be

reduced from its actual value when the thermal expansion of the setcured cement is less than that of the steel; on the other hand the moldcement interface might fracture first during a test, despite its larger

diameter, if the relative thermal expansion difference is reversed.]

15
C. Compressive Strength of Set Cement

1. The testing procedure will generally be in accordance with

ASTM Standard Method C-39 (reference 11) except that the specimen

dimensions are smaller than those customarily used. The bearing block

faces and the test specimens are wiped clean, and the specimen is centered

directly under the spherically seated upper bearing block that is able

to rotate freely. The universal testing machine will apply a compression

load at a constant displacement rate of 0.5 mm/min until the maximum

force necessary to cause failure of the specimen is recorded.

2. The compressive strength (o^) is calculated from

a = 4F/ttD^

c where F = maximum force applied to the face of the cement specimen ^ and

D = diameter of the cement specimen.

D. Splitting Tensile Strength of Set Cement

1. The testing procedure will generally be in accordance with ASTM

Standard Method C496 (reference 12) except that the specimen dimensions

are smaller than those customarily used. Unused strips of cardboard

(0.5 mm thick) are used as cushions between the specimen and the load

bearing surfaces to distribute the load smoothly. Using marked diametral

lines, the specimen is centered on its side between the bearing blocks.

The testing machine is used to apply diametral compression loading at a

constant displacement rate of 0.5 mm/min until the maximum force required

to cause failure of the specimen is indicated.

2. The tensile strength (a^) is calculated from

= 2F/uDL

where F = maximum force applied along length of the cement specimen,

D = diameter of the cement specimen, and

L = length of the cement specimen.

16
E. Tests at Room Temperature and Atmospheric Pressure

1. The property tests listed above will be conducted on moist

specimens after the set-cure and after one and four week exposures to

I,

|i

i| the simulated geothermal fluids. Specimens will be stored in the 25 °C

!

! constant temperature bath prior to their testing. As Table I indicates,

i

I the tests will commence approximately four hours after the set-cure has

I been terminated and approximately 2 1/2 h after the exposures in solutions

A and B.

j 2. The two permeability specimens for a given set cement will be

used in the tests which follow a set-cure; and then these same specimens

j will be used again after their respective exposures in solutions A and

B.

3. Only one shear-bond strength specimen will be tested following

each set cure or exposure condition.

4. Three specimens sawed from a rod of a given set cement will be

used each time that either a compressive strength test or a tensile

strength test is conducted. Tables III and TV indicate the order of

weeks when the specimens of the various set cements are removed from

their exposures in either of the two simulated geothermal fluids. We

plan to duplicate this series of tests at a later time.

F. Tests at Elevated Temperatures and Pressures

When the first series of tests at room temperature and atmospheric

pressure are concluded, permeability and shear-bond strength test will

be conducted at elevated pressure and temperature. Priority for selection

of cements for these in situ tests will be based on the ranking of

materials from the tests at room temperature and atmospheric pressure.

Alternate in situ property tests are also being considered (for example,

shear-bond strength to rock, tensile-bond strength to steel and to rock,

and biaxial flexural strength), but we do not presently plan to conduct

these tests on all of the candidate cementing materials.
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Table I. Weekly schediile of specimen preparation, exposures, and room

temperature property testing.

Day Time Operation

Monday 8:30 am Prepare slurry and fill molds.

10:30 am Assemble stirred autoclave

11:00 am Commence set-curing . 1:00 pm Prepare simulated geothermal fluids .

Tuesday 8:30 am Calculate resxilts of previous week and

prepare report.

Wednesday 11:00 am Terminate set-curing. , 12:00 noon Dismantle stirred autoclave.

12:30 pm Remove molds from specimens

1:30 pm Saw specimens.

3:00 pm Conduct permeability tests on set-cured

specimens

4:30 pm Conduct load tests on set-cured specimens.

Thursday 8:30 am Terminate exposure of specimens in first

fluid

10:00 am Dismantle two pressure vessels holding first

fluid

11:00 am Conduct permeability tests on exposed specimens

1:30 pm Assemble two pressure vessels holding first

fluid

2:00 pm Commence resumption of exposure of specimens

in first fluid.

4:00 pm Conduct load tests on exposed specimens.

Friday 8:30 am Repeat Thursday schedule for specimens in

second fluid.
Table II. Temperature, pressure, and composition of solutions to

be used for exposure of set-cements.

Units Solution A Solution B

T' '‘C 190 320

P(total) MPa (psi) 20 (2900) 20 (2900)

PCCO^), 25^C MPa (psi) 0.2 (.30)^ 0.2 (30)^

pH, 25^C 4.5 4,5

NaCl mol/kg 0.31 2.3

KCl mol/kg 0.019 0.36

CaCl^ mol/kg 0.020 0.66

NaHCO^ mol/kg 0.0015 0.0035

Density, 25 g/ml 1.01 1.16

Total dissolved solids mass per cent 2 20

The solutions A and B simulate light and heavy geotheirmal fluids, which

are representative of the East Mesa 6-1 and Salton Sea areas, respectively

(reference 6 and 5)

.

These values are estimates based on data for ideal solutions from reference 7 and corrected by data for the salting out effect from reference 8.
Table III. Schedule of exposing compressive and tensile specimens of

set cements in a simulated geothermal fluid at an elevated

temperature and pressure.

Week Cement Deposited

Specimens

Withdrawn Balance

0

1

2

3

4

5

6

7

8

a

b

c

d

e

f

9

12a

12b

12c

12d

12e

12f

12

6a 18

6b 24

6c 18

6a 24

6b . 6d 24

6c, 6e 24

6f 18

6d 12

6e 6

10 6f 0
Table IV. Schedule of exposing shear-bond (s) and permeability (p)

specimens of set cements in a simulated geothermal fluid at an

elevated temperature and pressure.

1 Specimens

Week Cement Deposited Withdrawn Re-deposited . Balai

0 a 2s , P

a’ a

3

1 b Pb ^a’ Pa Pa 5

2 c Pc ®b’ Pb Pc 7

3 3 , p Pc 6

4 d Pd s , p

a* ^a. 7

5 e 2s , p e’ *^e ®d’ Pb’ Pd Pd 7

6 f 2s £J P£ ®c’ ®e’ Pc’ Pe Pe 7

7 Sf, Pf Pf 6

8

^d’ Pd 4

9

®e’ Pe 2

10 Sf’ 0
References

1. API Specification for Oil-Well Cements and Cement Additives, API

Spec lOA, 19th edition, American Petroleum Institute, Dallas, Texas,

April 1977.

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

Additives, API RP lOB, 20th edition, American Petroleum Institute,

Dallas, Texas, April 1977.

3. L. H. Eilers, E. B. Nelson, L. K. Moran, L. B. Sapngle, and

B. E. Simpson, "Development of Geothermal Well Completion Systems",

pp 91-106, Cementing of Geothermal Wells, Progress Report No. 8,

BNL 50850, Brookhaven National Laboratory, Upton, NY, January-March

1978.

4. B. E. Simpson, Dowell Division of Dow Chemical USA, Tulsa, Oklahoma,

74102, Letters to L. E. Kukacka, Brookhaven National Laboratory,

Upton, NY, February 17, 1978 and March 13, 1978.

5. S. R. Cosner and J. A. Apps, A Compilation of Data on Fluids from

Geothermal Resources in the United States, Report LBL-5936, Lawrence

Berkeley Laboratory, University of California, Berkeley, CA. , May 1978.

6. James C. Watson, Battle Pacific Northwest Laboratories, Richland,

Washington, private communication to Ralph Krause, National Bureau of

Standards, Washington, D. C., April 19, 1979.

7. D. D. Wagman, ^ Selected Values of Chemical Thermodynamic

Properties, Technical Notes 270-3 (Jan. 1968) and 270-6 (Nov. 1971),

National Bureau of Standards, Washington, D. C.

8. A. J. Ellis and R. M. Golding, The Solubility of Carbon Dioxide in Water

and in Sodium Chloride Solutions, Amer. J. Sci. 261 , 47 (1963).

9. A. H. Truesdell, Summary of Section III, Geochemical Techniques in

Exploration, Proceedings UNIS Development and Use of Geothermal Resources,

San Francisco, 1975.

10. S. K. Sanyal, R. M. Pirnie III, and G. 0. Chen, "A Novel Liquid

Permeameter for Measuring Very Low Permeability", Soc. Pet. Eng. J.,

206-210, June 1972.

11. "Standard Test Method for Compressive Strength of Cylindrical Concrete

Specimens," ANSI/ASTM C39-72, Annual Book of ASTM Standards, Part 14,

American Society for Testing and Materials, Philadelphia, PA., 1977,

pp. 25-28.

"Standard Test Method for Splitting Tensile Strength of Cylindrical

Concrete Specimens", ASTM C496-71, Annual Book of ASTM Standards,

Part 14, American Society for Testing and Materials, Philadelphia, PA.,

1977, pp 313-318.

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NBS-114A (REV. 9-78)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-2099-2

2>Gov!L AccMsion4. TITLE AND SUBTITLE

TESTING GEOTHERMAL-WELL CEMENTS

Standard Practice

5. Publication Date July 1980

PerfomUng. Organization Code

7. AUTHOR(S)

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

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10. Proiect/Task/Work Unit No.

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

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS City, Sr-M. ZIP)

Dr. Robert R. Reeber

Division of Geothermal Energy

U.S. Department of Energy

Washington, D.C. 20461

13. Type of Report & Period Covered

July 1979, Interim

14.. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

I

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

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

literature survey, mention it here,) The National Bureau of Standards is under contract with the U.S. Department of Energy

to verify certain properties of cementing materials which are submitted as candidates

for use in the finishing operations of geothermal wells. Specimens will be set-cured

in molds under water for two days at elevated tanperature and pressure. Subsequently,

specimens will be exposed demolded to light and heavy simulated geothermal fluids for

periods of one week or one month. Following each of these treatments, the following

properties will be measured at room temperature and pressure: compressive strength,

splitting tensile strength, shear-bond strength of the cement-steel interface, and

cement permeability to water. Upon the basis of this survey of properties at room temperature, a priority of cementing materials will be established for further testing

of select physical properties while the specimens are at elevated tanperature and

pressure.

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)

Compressive strength; exposure to geothermal fluids; geothermal -wel 1 cements;

permeability to water; shear-bond strength to steel; splitting tensile strength

18. AVAILABILITY

^Unlimited

I I For Official Distribution. Do Not Release to NTIS

I I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-Q03-

)(X)(Order From National Technical Information Service (NTIS), Springfield,

VA, 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

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22. Price

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