U. S. DEPARTMENT OF THE INTERIOR U. S. GEOLOGICAL SURVEY

High-Temperature Permeability Studies I. Permeability of Granite andNovaculite at 300° to 500°C

by

D. E. Moore, L.-Q. Liu, D. A. Lockner, R. Summers, and J. D. Byerlee 1

Open-File Report 95-28

This report is preliminary and has not been reviewed for conformity with U. S. Geological Survey editorial standards or with the North American Stratigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U. S. Government.

1 345 Middlefield Road, Menlo Park, CA 94025

Abstract

This report presents the data collected during initial investigations of the permeability

of rock and gouge materials at elevated temperatures, conducted to test the hypothesis that

impermeable mineral seals can form in fault zones in the intervals between earthquakes. The

work was focused on granite and granite gouge, but some early experiments used novaculite

and/or quartz gouge. The novaculite exhibited creep under the applied effective pressure at

elevated temperatures, reducing its suitability for the investigation of permeability change by

mineral sealing reactions. The permeability of intact granite decreased over time at

temperatures between 300°C and 500°C at a constant effective pressure, and the rate of change

increased overall with increasing temperature but with some reversals. The permeability

reductions in the granite were caused by solution transfer and metamorphic reactions. The flow

rate was initially high for a granite sample with a through-going fracture, but it eventually

dropped to the level of intact granite as the fracture surface became sealed with mineral

deposits. The rate of permeability decrease at a given temperature was higher for samples

containing granite gouge than for intact granite samples, because of the enhanced reactivity of

the very fine-grained materials in the gouge. Application of a differential stress to a gouge-

bearing sample led to an increase in permeability, however, because flow of the gouge caused

tensile cracks to form in the adjoining rock.

The higher temperature results are consistent with the rapid development of

impermeable barriers at the base of the seismogenic zone. The lower temperature data provide

less conclusive support for rapid sealing at shallower depths, because of conflicting rates at

300° and 350°C. This uncertainty precludes extrapolation of the rates to temperatures below

300°C. The results suggest, however, that the generation of fault gouge should enhance the

initial sealing rates at any depth. In addition, the relatively high permeability of fractures may

also be readily reduced by mineral deposition.

Introduction

The 21 experiments presented in this report represent the initiation of a long-term

investigation of permeability at elevated temperatures and pressures. The ultimate goal of the

research is to provide data on high-temperature permeability under static and stressed

conditions, for application to the analysis of fault-zone behavior. Recent studies of active and

exhumed faults have demonstrated the importance of fluids and fluid-rock interactions to fault-

zone processes at depth (Sibson, 1981; Knipe, 1992; Chester and others, 1993). Mineral

sealing processes, in particular, may have an important effect on fluid pressures in fault zones,

and some recent models of the earthquake cycle call for the development of mineral seals within

faults in the intervals between earthquakes (Byerlee, 1993; Chester and others, 1993). High-

temperature permeability investigations on rock and gouge materials will help determine

whether or not the implied rapid sealing rates of these models are reasonable.

The main purpose of this report is to provide a data repository for experiments that are

discussed elsewhere in the literature (Moore and others, 1994, and in preparation). The

results of some early reconnaissance experiments are also included, because they provide a

useful background for the direction of subsequent experiments. This report also documents the

evolution of the experimental design and the possible impact of design changes on the

permeability measurements.

Previous Studies

Most of the early investigations of permeability at elevated temperatures and pressures

were conducted to test the feasibility of hot dry rock geothermal energy systems (for example,

Balagna and Charles, 1975; Potter, 1978; Summers and others, 1978) and the disposal by

burial of high-level nuclear waste (for example, Morrow and others, 1981, 1984, 1985;

Moore and others, 1983, 1986). Many of these studies focused on granitic rock types, because

granitic bodies were to provide the source of heat for the hot dry rock systems and they were

also favored burial sites for nuclear waste in Canada and Europe.

Summers and others (1978) measured the permeability of Westerly granite at

temperatures of 100° to 400°C, in the presence of a large pore-pressure drop of 27.4 MPa.

The permeability rose immediately upon heating but then dropped dramatically over the first

one-half day. At 400°C, flow essentially ceased after a few days. The marked permeability

reductions were attributed to solution of minerals near the pore-pressure inlet and their

redeposition at the outlet, in response to the pressure gradient.

Morrow and others (1981) and Moore and others (1983) investigated the effect of fluid

flow down a temperature gradient on the permeability of Westerly and Barrre granite. These

experiments simulated the thermal regime around buried canisters of nuclear waste. Similar to

the results of Summers and others (1978), permeability decreased markedly over time, with

the most rapid decreases occurring in the first few days. The rate of initial decrease was

greater for the experiments with the highest maximum temperatures. A sample in which water

flowed along a throughgoing fracture had similar permeability decreases. The fracture surfaces

showed evidence of mineral dissolution on the high-temperature side and deposition on the low-

temperature side.

Morrow and others (1985) extended the measurements of permeability in a

temperature gradient to other crystalline rock types such as quartzite, anorthosite, and gabbro.

Morrow and others (1984) and Moore and others (1986) conducted similar experiments on

tuffaceous rocks from the Nevada Test Site, which is also under consideration for the

underground disposal of nuclear waste. The pore fluid for the crystalline rock experiments was

deionized water, whereas a groundwater collected at the Nevada Test Site was used for the tuff

experiments. The permeability of all the crystalline rock types decreased over time, and the

rate and amount of decrease were directly correlated with the percentage of quartz in the rock.

The quartzite sample became almost completely sealed in an experiment at 250°C maximum

temperature. On the other hand, the tuffs were very porous and vuggy, resulting in high

permeabilities that did not change with time.

Balagna and Charles (1975) and Potter (1978) conducted permeability studies on

granitic core samples obtained from the Los Alamos Scientific Laboratory experimental

geothermal borehole. Balagna and Charles described the anisotropy relative to permeability of a

foliated monzo-granite gneiss. Potter found that the permeability of two quartz monzonite core

samples first decreased and then increased with increasing temperature to 200°C. The

permeability minimum of the 9522'-sample was near 140°C whereas the minimum for the

8580'-sample occurred at about 130°C. Potter proposed that the permeability minima reflect

the temperatures at which the pore/crack systems in the samples last equilibrated. Potter also

tested Westerly granite, whose behavior differed in that permeability decreased only slightly

with increasing temperature to about 100°C and then increased exponentially above 100°C.

According to Potter, the results for Westerly granite may reflect the unroofing of the pluton to

surface weathering conditions. The permeability of the quartz monzonite increased during long-

term flow experiments at 200°C, perhaps as a result of quartz dissolution that widened cracks.

Flow in these experiments was in one direction only, and the initial pore fluid was distilled,

deaerated water.

Aruna (1976) investigated the permeability of nearly pure quartz sandstone and

unconsolidated sands. Permeability measured using water decreased by a factor of two as

temperature was increased, but no permeability changes were found with other pore fluids.

Aruna therefore attributed the permeability decreases to reactions between quartz and water.

Scholz and others (in review) measured the permeability of granular mixtures of quartz and

labradorite at temperatures to 350°C, using deionized water. The aggregates compacted upon

heating, with accompanying rapid decreases in permeability; thereafter, permeability

decreased more slowly. Permeability change was an irregular function of temperature, with

more pronounced decreases occurring at 200°C than at 250°C. Scholz and others ascribed the

permeability reductions to compaction combined with some mineral precipitation in low-stress

regions such as the throats of pores.

The objective of our current research is to obtain permeability data under nearly

uniform pressure-temperature conditions, avoiding the large temperature and/or fluid-

pressure gradients of many previous studies that would generate strong driving forces for

mineral precipitation. Recent improvements in the experimental design, described in the next

section, allow us to run experiments of several weeks' duration, thereby providing a more solid

basis for extrapolation to the time scale of earthquake-recurrence intervals. With the triaxial

deformation apparatus used in these experiments we can apply a differential stress to the

sample, although thus far this capability has only been utilized in preliminary tests.

Nevertheless, plans for future studies include sliding experiments using fault gouge.

Procedures

Most of the experiments in this study were conducted on Westerly granite (Table 1), a

granodiorite consisting principally of plagioclase (-40%), quartz (-25%), K-feldspar

(-25%), and biotite (-5%) (Moore, 1993). Samples of Arkansas novaculite, which is a fine-

grained, porous metachert (Keller and others, 1977), were used in a few early experiments

(Table 1). Four experiments employed one of two gouge materials. The one gouge consisted of

Westerly granite, which was crushed and the fraction less than 90 (im in size ground in a ball

mill to produce a rock flour. The second gouge was a finely ground (5(im) quartz powder

obtained from U. S. Silica, Mill Creek, Oklahoma.

Most of the samples were intact cylinders of rock 21.9 mm long and 19.1 mm in

diameter. One granite sample consisted of a cylinder that was fractured in tension parallel to

the axis (Fig. 1), to simulate the fractured country rock adjacent to a fault zone. The gouge-

6

Tab

le

1.

Sum

mar

y of

E

xper

imen

ts

All

expe

rimen

ts w

ere

cond

ucte

d at

15

0 M

Pa

conf

inin

g pr

essu

re a

nd

100

MP

a flu

id

pres

sure

.

Exp

erim

ent

Num

ber

HTQ

P01

HT

QP

02

HT

QP

03

HTQ

P04

HT

QP

05

HT

QP

06

HT

QP

07

HT

QP

08

HT

QP

09

HT

QP

10

HTQ

P11

HT

QP

12

HTQ

P13

HT

QP

14

HT

QP

15

HT

QP

16

HT

QP

17

HT

QP

18

HT

QP

19

HT

QP

20

HTQ

P21

Ms

Num

ber*

Sam

ple

Con

figur

atio

n

- -

inta

ct n

ovac

ulite

- -

qtz

goug

e, n

ovac

ulite

end

pie

ces

- -

quar

tz g

ouge

, gra

nite

end

pie

ces

- -

gran

ite g

ouge

, gr

anite

end

pie

ces

500i-

500i-

400i-

400s

- -

450i-

300i-

35

0i-

300i-

400f

35

0i-

35

0i-

- -

45

0i-

- -

- -

- -

1 2 1

inta

ct

inta

ct

inta

ct

gran

ite

gran

ite

gran

ite

gran

ite g

ouge

, gr

anite

end

pie

ces

1 1 1 2

inta

ct

inta

ct

inta

ct

inta

ct

inta

ct

gran

ite

gran

ite

gran

ite

gran

ite

gran

ite

tens

ile f

ract

ure

in

gran

ite

3 2 2

inta

ct

inta

ct

inta

ct

inta

ct

inta

ct

inta

ct

inta

ct

gran

ite

gran

ite

gran

ite

gran

ite

gran

ite

gran

ite

gran

ite

Tem

p.

(°C

)

400

400

400

500

500

500

400

400

450

450

300

350

300

400

35

0

350

45

0

450

400

400

40

0

# D

ays

heat

ed

1.9

4.2

14.1 9.9

10.0 9.8

45.8

23

.7

0.3

19.5

19.5

13.6

17

.6

27.8

12

.9

19.1 0.1

20.0

9.9

5.9

31.9

k -

room

T

(m2

x 10

'21)

6856

10

81

7

14

4

82

102

609

193

876

30

9

1240

413

473

104

- -

63

103

489

466

34

8 99

71

k -

heat

ed

initi

al

12693

13920

38.

514.

326.

46

5.

13

7.

1230.

21

1.

364.

166.

171.

99

.

- -

21

3.

170.

326.

404.

23

4.

197.

139.4 4 8 4 6 9 6 5 1 5 6 1 0 4 0 1 6 6

(m2

x 10

-21)

fin

al

41

46

43

68

66 42 19

0

18

171

17

9

12

9 59 92

56 (31

12

2 91

27

3

121

13

6

13

6

38

.8 .0 .4 .4 .3 .8 .2 .9 .1 .0 .5 4)

.4 .5 .3 .4 .4 .8 .6S

ampl

e nu

mbe

rs u

sed

in M

oore

and

oth

ers

(199

4)

\ -IV , x/

\//- \

/ *- I /-- '/

\ \ I / .\ - I x

/\

/:X^'I / ^ I \ \?< r ' x/

''/-

. \ X \ __ \ V \ __ \

\ __ \ _ \ _

Intact Rock

Gouge

Intact Rock

Tensile Fracture Sandwich

Figure 1. Sample configurations used in some experiments. The remaining samples were cylinders of intact rock.

8

bearing samples had a sandwich form (Fig. 1), consisting of a layer of gouge held in place

between end pieces of intact rock. The three parts of the sandwich samples were initially the

same length, but the gouge layer shortened under compaction when the confining pressure was

applied.

The experimental assembly is shown schematically in Figure 2. The sample was placed

between titanium carbide end plugs and Lucalox (aluminum oxide) insulating pieces in a copper

jacket. Beginning with experiment HTQP06, a stainless steel screen was added to each end of the

rock sample, to ensure that water reached the entire cross-sectional area of the cylinder. The

jacketed sample was put inside a cylindrical furnace in a triaxial deformation apparatus. The

jacket has a double seal (Fig. 3) to isolate the sample from the confining pressure medium. The

space between the two O-ring seals is vented to air, such that a leak past one O-ring would be

discharged from the sample assembly. The double seals greatly reduce the possibility of a jacket

leak, thereby increasing the potential for long-term experiments.

All of the experiments in this group were conducted at a confining pressure of 150 MPa

and a pore pressure of 100 MPa; the pore fluid was deionized water. The confining pressure

corresponds to a depth of about 5 km in a fault zone. In recent earthquake models, fluid

pressure within a fault is considered to vary between hydrostatic values immediately after an

earthquake to nearly lithostatic levels in some seal-bounded compartments (for example,

Byerlee, 1993; Byerlee and Lockner, 1994). The selected fluid pressure for the experiments

is intermediate between the two end-member cases. The confining and pore pressures were held

constant by a computer-controlled servo-mechanism. The fluid pressure at each end of the

sample was maintained by a separate pump (Fig. 2). During an experiment, the pumps were set

to maintain the pore pressure on one side of the sample at a fixed value up to 2.0 MPa above the

pressure on the other side, to produce steady-state flow through the sample. The high- and

low-pore-pressure sides were reversed periodically during each experiment to measure

permeability in both directions; the flow rate stabilized within a few minutes of a given

S 3 ®

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Pore-pressure Inlet Vent

Viton O-Ring

Steel Ring

Viton O-Ring

Jacket Seals

Figure 3. Close-up view of double jacket seals for separation of the confining- and pore- pressure media. The steel ring, situated between the two O-ring seals, contains a vent to air. A leak past one O-ring would be discharged from the sample assembly along the vent.

11

reversal. During experiments HTQP01-HTQP05, a given flow measurement lasted a maximum

of 1 hour, and up to 5 measurements at different pore-pressure drops and flow directions were

made each day. In subsequent experiments, flow was reversed by means of a computer command

file at intervals of 2 x 104 , 4 x 104 , or 9 x 104 s, depending on the flow rate. The capacity of

the smaller pore-pressure pump is about 0.28 cm3 , and in most cases the entire fluid volume

moved through the sample before the direction of flow was reversed. As a result, periods of flow

alternated with periods without flow during all of the experiments. The same small volume of

fluid was continually pushed back and forth through the sample. In this way, although the

initial fluid is deionized water, it should rapidly become charged with ions upon heating, making

its composition more akin to natural groundwaters. The small amount of fluid utilized combined

with the two-way flow system should minimize the effects of leaching caused by the use of

deionized water (see, for example, Potter, 1978).

Confining pressure was applied first to the sample, followed by pore pressure. After the

pressures had equilibrated, one or more room-temperature measurements of permeability

were made. The sample was then heated to a temperature in the range 300° to 500°C. All the

temperatures tested are high for the fault depth represented by the confining pressure; they

were chosen to accelerate mineral reactions. Heating took place over a period of 15 to 30

minutes, depending on the amount of temperature increase. Temperature was monitored by a

thermocouple inserted along the upper pore-pressure inlet. For experiments HTQP01-

HTQP20, the thermocouple and the midpoint of the sample cylinder were positioned at the

temperature maximum of the furnace. Temperature decreased by 2% between the middle and

ends of the sample in these experiments; for example, during an experiment at 400°C the

middle of the cylinder would be at 400°C and the ends at 392°C. A new furnace with a smaller

temperature gradient was used in experiment HTQP21. With this furnace, the top of the sample

and the thermocouple were placed at the temperature maximum, and temperature decreased by

less than 2% across the entire length of the cylinder.

1 2

Permeability of the intact and sandwich samples was determined by measuring the fluid

flux at intervals over a constant pore-pressure gradient, according to Darcy's law:

(q/A) = (k/n) (APp/AI) (1)

where q is flow rate; A is the circular cross-sectional area of the cylinder; k is permeability

(units of m2); [i is the dynamic viscosity of water at the temperature and pressure of the

experiment; APp is the pore-pressure drop along the cylinder; and Al is the length of the

cylinder. Rearranging terms to solve for k gives:

k = |i (q/A) (AI/APp) (2)

The flow rate of water through the cylinder was determined by measuring the change with time

of fluid volume in the pore fluid reservoir, giving q25°C- The flow rate through a sample heated

to temperature T was then calculated by:

qT = q25°C (VT/V25°C) (3)

where v is the specific volume of water. Data for the specific volume of water at the

temperatures and pressures of the tests come from Table 1 of Burnham and others (1969);

dynamic viscosities were obtained from Table IX of Todheide (1972). The accuracy of the

calculated permeability values is estimated to be within ±5% over most of the range of

measurements. The error increases for k less than 1 x 10'21 m2 , which is at the lower

measuring limits of the experimental apparatus.

In the case of the fractured sample, flow was initially concentrated in the break rather

than distributed through the cylinder. Morrow and others (1981) demonstrated that the

13

parallel plate model analogy to Darcy's law (Gale, 1975) is appropriate for an irregular

fracture surface. Here, the cross-sectional area A = wd in equation (1), where w is the

fracture width (equal to the diameter of the cylinder) and d is the separation between the

fracture walls. Because d is not known, it is combined with k to produce a new parameter X

(Morrow and others, 1981):

A, = \i (q/w) (AI/APp) (4)

Both k and X relate flow in a crack to the pore-pressure gradient, but X has units of m3 instead

of m2 and is not strictly a crack permeability.

Permeability Measurements

The data collected during the 21 experiments of this study are presented in Table 2. A

time of 0 days is the time that the sample reached the selected temperature of the experiment.

The time listed for a given measurement is the midpoint of the measuring interval, which will

be longer for the lower-permeability samples. The columns of pore-pressure drop (APp ),

flow rate (q), and length are presented in the units that yield k in terms of m2 . The reported

values of APp are somewhat variable, because (1) the actual pore-pressure drop was generally

slightly lower than the set point, and (2) the zero position of APp tended to drift during an

experiment, due to drift of the transducer and preamplifier in response to room temperature

variations. For convenience, the set-point value is used in the text. Columns of length are

included for experiments in which sample length changed as a result of compaction (gouge-

bearing samples) or creep (novaculite samples). The one exception is gouge experiment

HTQP08, in which the final sample length was used for all calculations of k. This results in a

maximum error of 0.3% for the initial determinations of k. The last column presents k in units

14

Table 2. Permeability measurements made during experiments HTQP01

through HTQP21.

HTQP01File #

HTQP01-01HTQP01-02

HTQP01-03HTQP01-04

HTQP01-05HTQP01-06HTQP01-07

Time (days)-0.09-0.04-0.03

0.020.060.080.831.071.80

Temp. (°C)

25200200400400400400400400

Length (cm)

2.3802.3802.3802.3802.3802.3802.3752.3712.368

APp (bars)9.502.00

-2.703.124.29

-4.543.864.044.36

q x 10' 6

(cm 3/s)87.63

166.84-165.53

165.66166.18

-165.92166.32166.58167.24

k x 10' 18 (m2)

6.85612.693

9.3285.7694.2093.9714.6724.4634.146

k (nDa)6946

128619451584542654023473445224201

HTQP02File #

HTQP02-01HTQP02-02

HTQP02-03

HTQP02-04

HTQP02-05

HTQP02-06

HTQP02-07

HTQP02-08

Time (days)-0.02

0.020.040.060.070.090.110.130.140.290.300.980.991.271.283.063.083.994.014.224.23

Temp. (°C)

25400400400400400400400400400400400400400400400400400400400400

Length (cm)

2.38502.38502.38502.38502.38502.38502.38502.38502.38502.31382.31382.29942.29942.29682.29682.28672.28672.28422.28422.28352.2835

APp (bars)9.4500.938

-1.8101.080

-1 .9900.938

-2.3600.800

-2.4501.750

-1.1302.460

-2.4602.140

-2.1103.600

-3.5503.840

-4.1403.700

-4.000

q x 10' 6

(cm 3/s)137.24164.08

-164.47164.61

-165.79166.05

-164.87165.13

-166.58167.90

-168.29167.11

-166.05165.53

-168.95166.97

-168.82165.74

-166.45166.45

-168.68

k x 10' 18 (m2)

10.81719.0459.893

16.5949.071

19.2747.606

22.4737.403

10.13412.0787.1317.0858.1108.3954.8424.9644.5014.1924.3394.396

k (nDa)

10960192961002416813

9191195287706

227707501

10268160087225717982178506490650304560424747514454

15

HTQP03File #

HTQP03-01HTQP03-03

HTQP03-05

HTQP03-07

HTQP03-09

HTQP03-11

HTQP03-13

HTQP03-15

HTQP03-17

HTQP03-19

HTQP03-21

HTQP03-23

Time (days)-1 .03

0.090.130.170.210.261.111.151.191.221.283.143.183.223.263.304.134.174.214.264.305.145.185.235.275.316.126.176.216.256.297.137.178.118.158.198.238.27

11.1311.1811.2211.2611.3012.1012.1412.1812.2212.2613.11

Temp. (°C)

25400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

Length (cm)

2.48552.42932.42932.42932.42932.42932.42022.42022.42022.42022.42022.41782.41782.41782.41782.41782.41662.41662.41662.41662.41662.41542.41542.41542.41542.41542.41422.41422.41422.41422.41422.37802.37802.24852.24852.24852.24852.24852.23492.23492.23492.23492.23492.22802.22802.22802.22802.22802.2213

APp (bars)10.00

-20.00-10.00

0.0010.0019.64

-20.00-10.00

0.0010.0019.69

-20.00-10.00

0.0010.0019.67

-20.00-10.00

0.0010.0020.00

-20.00-10.00

0.0010.0020.00

-20.00-10.00

0.0010.0020.00

-20.00-10.00-20.00-10.00

0.0010.0020.0019.7510.000.00

-9.90-19.64

19.599.690.00

-9.88-19.67

19.61

q x 10' 6

(cm 3/s)1.86

-5.79-3.13

0.023.877.75

-7.49-3.99

0.294.227.54

-8.67-3.77

0.033.516.51

-6.15-2.79

0.522.334.39

-8.66-4.68

0.764.864.64

-6.20-2.66

0.163.014.39

-5.86-3.78-5.29-2.82-0.38

1.913.667.213.160.77

-6.46-15.55

10.885.410.14

-5.76-11.61

11.03

k x 10- 20 (m2)

14.413.213.47

4.294.384.144.41

4.664.234.784.16

3.873.653.393.08

2.572.424.775.16

5.362.563.422.93

3.322.423.184.102.712.89

1.961.883.723.22

6.668.085.655.68

5.936.005.70

k (nDa)146.032.535.2

43.544.441.944.7

47.242.948.442.1

39.237.034.431.2

26.024.548.352.3

54.325.934.729.7

33.624.532.241.527.529.3

19.919.037.732.6

67.581.957.257.5

60.160.957.8

16

File #

HTQP03-25

Time (days)13.15 13.19 13.23 13.27 14.08

Temp. (°C)

400 400 400 400 400

Length (cm)

2.2213 2.2213 2.2213 2.2213 2.2000

APp (bars)

9.74 0.00

-9.90 -19.66

20.00

q x 10' 6

(cm 3/s)5.20 0.40

-5.36 -11.93

13.30

k x 10-2° (m2)

5.41

5.49 6.15 6.68

k (nDa)54.8

55.6 62.3 67.7

HTQP04File #

HTQP04-01HTQP04-02

HTQP04-04

HTQP04-06

HTQP04-08

HTQP04-10

HTQP04-12

HTQP04-14

Time (days)-0.07

0.020.050.070.092.942.962.983.003.883.903.923.954.864.884.914.935.865.885.915.936.856.886.906.929.859.879.909.92

Temp. (°C)

25500500500500500500500500500500500500500500500500500500500500500500500500500500500500

Length (cm)

2.26652.29642.29642.29642.29642.28832.28832.28832.28832.28792.28792.28792.28792.28752.28752.28752.28752.28722.28722.28722.28722.28682.28682.28682.28682.28572.28572.28572.2857

APp (bars)19.99

-19.70-9.67

9.4419.4019.509.44

-9.78-19.70

19.509.44

-9.78-19.70

19.509.44

-10.00-19.70

19.509.55

-10.10-19.70

19.609.55

-10.10-19.70

19.609.78

-10.10-20.10

q x 10' 6

(cm 3/s)2.32

-94.87-45.6646.0597.3729.0814.08

-18.09-37.76

26.7113.29

-12.57-26.6222.5710.59

-1 1.25-22.37

15.927.83

-9.09-16.58

14.777.01

-5.56-13.55

8.754.01

-2.95-9.00

k x ID' 20 (m2)8.21

50.9849.9951.6453.1315.7315.7319.5120.2214.4514.8513.5614.2512.2111.8311.8611.97

8.618.648.458.877.947.745.807.254.704.303.084.72

k (nDa)83.2

516.5506.5523.2538.3159.4159.4197.7204.9146.4150.5137.4144.4123.7119.9120.2121.387.287.585.689.980.478.458.873.547.643.631.247.8

17

HTQP05File #

HTQP05-01HTQP05-03

HTQP05-05HTQP05-07

HTQP05-09

HTQP05-11

HTQP05-13

HTQP05-14

HTQP05-16

HTQP05-18

HTQP05-21

HTQP05-22

HTQP05-24

Time (days)-0.08

0.040.081.231.962.002.983.033.994.044.985.025.085.125.986.026.977.019.909.97

10.1310.1810.9511.00

Temp. (°C)

25500500500500500500500500500500500500500500500500500500500

25252525

APp (bars)19.9919.56

-19.6019.6019.50

-19.70-19.74

19.51-19.74

19.51-20.08

19.50-20.08

19.50-20.00

20.00-20.08

19.9619.50

-20.0819.50

-20.0819.50

-20.08

q x 10' 6

(cm 3 /s)3.00

62.37-64.47

38.3630.86

-32.43-26.25

27.89-22.76

23.82-0.70

7.83-3.45

6.910.400.40

-6.253.605.78

-1.769.34

-10.6611.65-9.28

q/AP x 10' 6

0.15013.18873.28931.95711.58261.64621.32981.42951.15301.22090.03490.40150.17180.35440.02000.02000.31130.18040.29640.08760.47900.53090.59740.4622

k x 10' 21 (m2)

102.4321.7331.9197.5159.7166.1134.2144.2116.3123.2

3.540.517.335.8

2.02.0

31.418.229.9

8.8326.7362.1407.5315.3

k (nDa)103.8325.9336.3200.1161.8168.3136.0146.1117.8124.8

3.541.017.536.3

2.02.0

31.818.430.3

8.9331.0366.9412.9319.5

HTQP06File #

HTQP06-01HTQP06-02

HTQP06-03

Time (days)0.000.050.280.510.740.971.201.441.671.902.132.362.592.82

Temp.

CO25

500500500500500500500500500500500500500

APp (bars)19.6019.12

-20.0119.60

-19.4719.60

-19.6319.79

-19.2519.67

-19.5419.73

-19.2120.20

q x 10' 6

(cm 3/s)17.588.2

-77.874.0

-71.971.5

-71 .472.3

-68.069.1

-67.767.6

-64.666.2

q/APp x 10' 6

0.89294.61303.88813.77553.69293.64803.63733.65343.53253.51303.46473.42633.36283.2772

k x 10' 21 (m 2 )

609.0465.4392.3380.9372.6368.1367.0368.6356.4354.5349.6345.7339.3330.7

k (nDa)617.0471.5397.5385.9377.5373.0371.8373.5361.1359.2354.2350.3343.8335.1

18

File #

HTQP06-04

HTQP06-05

HTQP06-06HTQP06-07HTQP06-08

Time (days)3.063.293.523.753.994.224.454.684.915.255.385.626.398.28

10.0910.3210.55

Temp. (°C)

500500500500500500500500500500500500500500

252525

APp (bars)

-19.2019.64

-19.7719.59

-19.6219.57

-19.6519.87

-18.8919.56

-19.6519.6419.95

-20.0019.56

-19.7419.62

q x 10' 6

(cm 3/s)-63.3

62.4-61.3

60.0-58.355.0

-54.956.4

-50.950.8

-46.840.0

0.3-0.013.9

-1 1 .87.6

q/APp x 10' 6

3.29693.17723.10073.06282.97152.81042.79392.83842.69452.59712.38172.03670.01350.00400.71060.59780.3874

k x 10-21 (m2)

332.6320.6312.9309.0299.8283.6281.9286.4271.9262.1240.3205.5

1.40.4

484.7407.7264.2

k (nDa)337.0324.8317.0313.1303.8287.3285.6290.2275.5265.6243.5208.2

1.40.4

491.1413.1267.7

HTQP07File #

HTQP07-01

HTQP07-02

HTQP07-03

HTQP07-04

Time (days)-0.52-0.29-0.10

0.080.320.560.781.011.241.471.711.942.172.402.632.863.093.333.563.794.034.264.49

Temp. (°C)

252525

400400400400400400400400400400400400400400400400400400400400

APp (bars)19.65

-19.9019.6119.90

-19.9318.96

-20.2220.09

-19.2619.50

-19.3819.18

-20.2219.73

-19.4518.78

-20.5119.13

-19.5919.59

-18.5218.94

-20.00

q x 10' 6

(cm 3 /s)7.80

-5.595.59

27.47-27.17

23.39-25.56

25.10-24.74

23.95-24.44

23.42-25.36

23.42-24.28

22.76-24.57

22.93-23.52

22.76-21.45

20.72-22.76

q/APp x 10- 6

0.39690.28090.28511.38041.36331.23361.26411.24941.28451.22821.26111.22111.25421.1871.24831.21191.19801.19861.20061.16181.15821.09401.1380

k x 10-2° (m2)

27.0719.1619.4513.7613.5912.3012.6012.4612.8112.2512.5712.1712.5011.8312.4512.0811.9411.9511.9711.5811.5510.9111.35

k (nDa)274.3194.1197.1139.4137.7124.6127.7126.2129.8124.1127.4123.3126.6119.9126.1122.4121.0121.1121.3117.3117.0110.5115.0

1 9

File #

HTQP07-05

HTQP07-06

HTQP07-07

HTQP07-08

HTQP07-09

HTQP07-10

HTQP07-11

HTQP07-12

HTQP07-13

Time (days)4.734.965.205.435.665.896.136.366.596.827.287.527.757.988.218.448.678.909.149.379.609.83

10.0610.2910.5210.7611.0011.2411.4711.7111.9412.1912.4212.6512.8813.1113.3413.5713.8114.0314.2614.4914.7214.9515.1815.4115.6415.8716.1016.3416.57

Temp.

File #

HTQP07-14HTQP07-15

HTQP07-16

HTQP07-17

HTQP07-18

HTQP07-19

HTQP07-20

HTQP07-21

HTQP07-22

Time (days)16.8017.0317.2617.4917.7217.9618.1918.4218.6518.8819.1119.3419.5819.8120.0420.2720.5020.7320.9621.2021.4321.6621.8922.1222.3522.5922.8223.0523.2823.5123.7423.9724.2024.4424.6724.9025.1325.3625.5925.8326.0626.2926.5226.7526.9827.2127.4527.6827.9128.1428.37

Temp. (°C)

400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

APp (bars)

-19.9219.62

-19.9519.57

-19.9419.57

-19.9319.57

-19.9219.57

-20.0019.57

-19.9519.61

-19.9719.61

-19.9719.61

-19.9719.61

-19.9719.61

-19.9719.59

-19.9719.59

-19.9719.60

-19.9719.60

-19.9719.60

-19.9719.61

-19.9719.61

-19.9719.61

-19.9719.61

-19.9719.64

-19.9719.59

-19.9719.59

-19.9719.61

-19.9719.62

-19.97

q x 10' 6

(cm 3/s)-11.12

10.95-11.05

10.60-10.50

10.04-10.10

10.30-10.00

10.00-9.61

9.47-9.7610.08-8.36

9.20-9.45

9.33-8.09

9.87-9.08

8.86-8.38

9.33-8.68

8.95-7.62

8.25-7.62

8.66-7.50

7.61-7.66

8.29-7.26

7.99-6.45

7.05-7.46

8.45-6.29

7.59-7.13

8.08-5.99

8.37-7.59

7.57-6.38

6.32-6.83

q/APp x 10' 6

0.55820.55810.55390.54160.52660.51300.50680.52630.50200.51100.48050.48390.48920.51400.41860.46910.47320.47580.40510.50330.45470.45180.41960.47630.43470.45690.38160.42090.38160.44180.37560.38830.38360.42270.36350.40740.32300.35950.37360.43090.31500.38650.35700.41250.29990.42730.38010.38600.31950.32210.3420

k x 10-2° (m2)

5.575.565.525.405.255.115.055.255.015.094.794.824.885.124.174.684.724.744.045.024.534.504.184.754.334.553.804.203.804.403.743.873.824.213.624.063.223.583.724.303.143.853.564.112.994.263.793.853.193.213.41

k (nDa)56.456.355.954.753.251.851.253.250.851.648.548.849.451.942.247.447.848.040.950.945.945.642.448.143.946.138.542.638.544.637.939.238.742.736.741.132.636.337.743.631.839.036.141.630.343.238.439.032.332.534.6

21

File #

HTQP07-23

HTQP07-24

HTQP07-25

HTQP07-26

Time (days)28.6028.8329.0729.8830.3430.8031.2631.7332.1932.6533.1233.5834.0434.5134.9735.4335.8936.6037.0637.5237.9938.4538.9139.3839.8440.3040.7641.2341.6942.1542.6243.0843.5444.0044.4744.9345.3945.80

Temp. (°C)

400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

APp (bars)19.59

-19.9720.33

-19.9719.65

-19.9719.66

-19.9719.63

-19.9719.64

-19.9719.65

-19.9719.62

-19.9721.67

-20.0019.93

-20.0019.93

-20.0020.31

-19.3620.41

-19.3621.25

-18.7021.25

-18.2021.80

-18.2021.80

-18.2021.80

-18.2021.80

-18.20

q x 10' 6 (cm 3/s)

6.97-6.32

7.17-6.71

6.97-6.09

6.57-5.61

6.63-5.61

6.63-5.29

6.24-5.47

6.26-5.07

6.05-4.89

4.66-4.69

4.62-4.54

5.69-4.80

5.10-4.49

4.97-4.41

4.55-3.61

4.57-3.38

4.52-3.75

4.54-3.53

4.39-3.34

q/APp x 10' 6

0.35580.31650.35270.33600.35470.30500.33420.28090.33770.28090.33760.26490.31760.27390.31910.25390.27920.24450.23380.23450.23180.22700.28020.24790.24990.23190.23390.23580.21410.19840.21060.18570.20730.20600.20830.19400.20140.1835

k x 10-2° (m2)3.553.163.523.353.543.043.332.803.372.803.372.643.172.733.182.532.782.442.332.342.312.262.792.472.492.312.332.352.131.982.101.852.072.052.071.932.011.83

k (nDa)36.032.035.733.935.930.833.728.434.128.434.126.732.127.732.225.628.224.723.623.723.422.928.325.025.223.423.623.821.620.121.318.721.020.821.019.620.418.5

22

HTQP08File #

HTQP08-01HTQP08-02

HTQP08-03

HTQP08-04

HTQP08-05

HTQP08-06

HTQP08-07

HTQP08-08

HTQP08-09

Time (days)-0.05

0.030.260.490.720.951.181.411.651.882.112.342.572.803.043.273.503.733.964.194.665.125.586.046.516.977.437.908.368.829.299.75

10.2210.6911.1511.6112.0712.5413.0013.4613.9414.4014.8615.3315.7916.2516.7217.1817.64

Temp. (°C)

25400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

APp (bars)19.6013.60

-19.1819.67

-18.9620.02

-18.9620.32

-18.4620.52

-18.5220.44

-18.5219.12

-20.2818.70

-20.4319.57

-19.2518.99

-19.9019.26

-20.1819.33

-20.1819.97

-20.1318.76

-20.4118.75

-20.5619.60

-20.2919.27

-19.8419.45

-19.1919.27

-18.8219.28

-18.7419.57

-19.7519.33

-19.8719.39

-19.2519.56

-19.35

q x 10' 6

(cm 3/s)25.92

172.90-170.00

152.90-140.00

138.42-127.76

132.63-113.82

123.68-107.50

115.21-100.00

99.74-105.66

94.47-102.11

94.47-92.63

89.34-89.47

82.37-83.03

78.03-77.11

71.58-72.50

64.61-69.08

60.20-65.1357.63

-60.4655.53

-57.1753.36

-52.8350.59

-48.0348.82

-46.0548.03

-48.5545.00

-46.2543.62

-42.1741.91

-40.59

q/APp x 10' 6

1.322412.71328.86347.77337.38406.91416.73846.52716.16586.02735.80455.63655.39965.21655.21015.05194.99804.82734.81194.70464.49604.27674.11454.03673.82113.63353.60163.44403.38463.21073.16782.94032.97982.88172.87432.74342.72542.62532.55212.53222.45732.45432.45822.32802.32762.24962.19062.14262.0977

k x 10' 19 (m2)8.758

12.3098.5827.5267.1496.6946.5246.3205.9705.8365.6205.4575.2285.0515.0444.8914.8394.6744.6594.5554.3534.1413.9843.9083.7003.5183.4873.3343.2773.1093.0672.8472.8852.7902.7832.6562.6392.5422.4712.4522.3792.3762.3802.2542.2532.1782.1212.0742.031

k (nDa)887.4

1247.1869.5762.5724.3678.2661.0640.3604.9591.3569.4552.9529.7511.8511.1495.6490.3473.6472.0461.5441.0419.6403.7396.0374.9356.4353.3337.8332.0315.0310.7288.5292.3282.7282.0269.1267.4257.6250.4248.4241.0240.7241.1228.4228.3220.7214.9210.1205.8

2 3

File #

HTQP08-10

HTQP08-11

HTQP08-12HTQP08-13

HTQP08-14

Time (days)18.1018.5719.0319.4919.9620.4220.8821.3421.8122.2722.7323.1923.66

Temp. (°C)

400400400400400400400400400400400400400

APp (bars)20.20

-19.31-19.15

19.69-19.03

19.56-18.99

20.24-18.98

20.31-18.91

20.18-18.70

q x 10' 6

(cm 3 /s)41.64

-40.43-39.01

39.8737.6637.50

-36.3237.20

-35.3337.58

-34.5736.05

-33.19

q/APp x 10' 6

2.06142.09372.03712.02491.97901.91721.91261.83791.86141.85031.82811.78731.7749

k x 10' 19 (m2)

1.9962.0271.9721.9611.9161.8561.8521.7791.8021.7911.7701.7301.718

k (nDa)202.2205.4199.8198.7194.1188.0187.6180.2182.6181.5179.3175.3174.1

HTQP09File #

HTQP09-02

HTQP09-03

Time (days)-0.66 -0.43 -0.19

0.06 0.31

Temp. (°C)

25 25 25

450 450

APp (bars)19.62

-19.97 19.69 19.36

-19.76

q x 10' 6

(cm 3 /s)9.00

-9.17 8.70

41.64 -36.00

q/APp x 10' 6

0.4587 0.4592 0.4417 2.1508 1.8219

k x 10' 19 (m2)

3.129 3.132 3.013 2.116 1.792

k (nDa)317.0 317.3 305.3 214.4 181.6

*Experiment terminated because furnace failed.

HTQP10File # Time

(days)HTQP10-01 -0.02

0.030.220.450.680.911.151.381.611.842.07

Temp.

25450450450450450450450450450450

APp (bars)20.2420.24

-18.4621.32

-17.7021.26

-17.6621.57

-17.2921.57

-17.86

q x 10' 6

(cm 3 /s)36.7875.00

-50.0054.34

-43.0952.17

-42.5751.71

-40.0049.93

-41.91

q/APp x 10' 6

1.81723.70552.70862.54882.43452.45392.41052.39732.31352.31482.3466

k x 10' 19

(rr.2)12.3953.6452.6642.5072.3952.4142.3712.3582.2762.2772.308

k (nDa)

1255.9369.3269.9254.0242.7244.6240.2238.9230.6230.7233.8

24

File #

HTQP10-02

HTQP10-03

HTQP10-04

HTQP10-06

HTQP10-07

HTQP10-08

HTQP10-09

HTQP10-10

HTQP10-12

HTQP10-13

Time (days)2.302.532.773.013.243.473.703.944.174.404.624.865.095.325.565.796.026.256.486.716.947.418.809.269.72

10.1910.6511.1111.5712.0512.5112.9713.4413.9014.3614.8315.2915.7516.2216.6817.1417.6018.0718.5319.0019.4619.79

Temp.

HTQP11File #

HTQP11-01

HTQP11-02

HTQP11-03

HTQP11-04

HTQP11-06

HTQP11-06 1

Time (days)-0.04

0.030.200.440.670.921.151.381.611.842.122.583.053.513.974.464.925.115.626.086.547.017.477.938.398.869.329.80

10.2610.7211.1811.6512.1112.5713.0413.5013.9714.4414.9015.3615.8316.2916.7517.2117.6818.1418.6019.0719.53

Temp. (°C)

25300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300

APp (bars)19.60

-19.4820.05

-19.0720.18

-19.0220.18

-18.7220.94

-18.3020.91

-18.4221.26

-17.8621.61

-17.6719.18

-19.7919.49

-19.8319.49

-19.7519.61

-20.3119.27

-19.7819.95

-19.4119.95

-19.3020.16

-19.9719.07

-20.6118.91

-20.4018.64

-20.6318.70

-20.9518.91

-20.2819.27

-20.3619.25

-20.1919.28

-20.6118.98

q x 10' 6

(cm 3/s)11.86

-30.5920.77

-18.4519.22

-16.5417.12

-15.5817.39

-14.7515.87

-13.7016.00

-12.4115.77

-12.0813.24

-14.8313.72

-14.0513.40

-13.5813.21

-13.6512.67

-13.4212.82

-12.1412.63

-12.1612.42

-11.8211.63

-12.1711.11

-11.8010.95

-11.8010.76

-12.0511.05

-11.5810.88

-11.4310.88

-11.4010.71

-11.5810.60

q/APp x 10' 6

0.60511.57031.03590.96750.95240.86960.84840.83230.83070.80600.75900.74380.75260.69480.72980.68360.69030.74940.70400.70850.68750.68760.67360.67210.65750.67850.64260.62550.63310.63010.61610.59190.6099

0.59050.58750.57840.58740.57200.57540.57520.58430.57100.56460.56140.56520.56460.55550.56190.5585

k x ID' 20 (m2)

41.2716.6110.9610.2410.08

9.208.988.818.798.538.037.877.967.357.727.237.307.937.457.507.277.277.137.116.967.186.806.626.706.676.526.266.456.256.226.126.226.056.096.096.186.045.975.945.985.975.885.945.91

k (nDa)418.1168.3111.0103.8102.193.291.089.389.186.481.479.780.774.578.273.374.080.375.576.073.773.772.272.070.572.768.967.167.967.666.163.465.463.363.062.063.061.361.761.762.661.260.560.260.660.559.660.259.9

26

File #

HTQP11-07

HTQP11-08

Time (days)20.06 20.52 20.99 21.45

Temp. (°C)

25 25 25 25

APp (bars)

-20.00 20.00

-19.70 20.33

q x 10- 6

(cm 3 /s)-3.07

2.89 -2.80

2.80

q/APp x 10' 6

0.1535 0.1445 0.1421 0.1377

k x 10- 20 (m2)

10.47 9.86 9.69 9.39

k (nDa)106.1 99.9 98.2 95.1

HTQP12File #

HTQP12-01

HTQP12-02

HTQP12-03

HTQP12-05

HTQP12-06

HTQP12-07

Time(days)0.020.050.360.590.831.061.291.521.751.982.212.452.682.933.203.393.663.864.154.334.620.030.170.400.630.881.121.351.581.812.042.282.512.973.433.90

Temp.(°C)

252525252525252525252525252525252525252525

350350350350350350350350350350350350350350350

APp(bars)

-19.4419.54

-18.5021.31

-17.7721.39

-17.5921.55

-17.5819.69

-19.1220.20

-19.3019.17

-19.9319.62

-19.6418.95

-20.2519.88

-19.64-19.60

19.19-20.04

20.08-19.20

19.20-20.01

19.80-19.51

19.60-19.62

19.62-19.62

19.64-19.45

q x 10' 6

(cm 3/s)-131.25108.55

-104.2882.89

-73.1677.30

-65.0777.04

-59.0876.64

-66.7871.25

-61.2143.03

-20.3954.01

-18.5834.55

-15.9735.56

-13.62-32.70

24.00-23.78

21.84-20.86

19.87-21.26

19.77-19.15

18.82-20.30

18.98-20.07

19.08-18.84

q/APpx 10' 6

6.75155.55535.63683.88974.11713.61383.69933.57493.36063.89233.49273.52723.17152.24471.02312.75280.94601.82320.78861.78870.69351.66841.25071.18661.08761.08651.03491.06250.99850.98150.96021.03470.96741.02290.97150.9686

k x ID' 20(m2)

460.52378.93384.48265.32280.82246.50252.33243.85229.23265.50238.24240.59216.33153.1169.78

187.7764.53

124.3653.79

122.0147.3017.1512.8612.2011.1811.1710.6410.9210.2610.099.87

10.649.94

10.529.999.96

k(nDa)

4666.03839.33895.62688.22845.32497.52556.52470.72322.62690.62413.82437.72191.91551.3707.0

1902.5653.8

1260.0545.0

1236.2479.2173.8130.3123.6113.3113.2107.8110.6104.0102.2100.0107.8100.7106.6101.2100.9

27

File #

HTQP12-08

HTQP12-09

HTQP12-10

HTQP12-11

HTQP12-12

HTQP12-13

Time (days)4.374.835.305.766.226.697.157.618.078.549.009.469.93

10.3910.8511.3111.7812.2412.7013.1713.63

Temp. (°C)

350350350350350350350350350350350350350350350350350350350350350

APp (bars)19.57

-19.2718.96

-19.6518.85

-19.1918.68

-19.4519.53

-19.8319.73

-19.9219.37

-19.9619.37

-19.5719.96

-19.6219.78

-19.9119.93

q x 10' 6

(cm 3 /s)18.63

-18.3617.94

-18.0017.54

-18.2917.13

-18.6517.57

-18.9117.24

-18.6517.83

-18.4917.84

-17.9918.41

-17.6818.35

-17.9017.84

q/APp x 10' 6

0.95200.95280.94620.91600.93050.95310.91700.95890.89960.95360.87380.93620.92050.92640.92100.91930.92230.90110.92770.89900.8951

k x 10- 20 (m2)

9.799.799.739.429.579.809.439.869.259.808.989.629.469.529.479.459.489.269.549.249.20

k (nDa)99.299.298.695.497.099.395.599.993.799.391.097.595.896.596.095.796.193.896.793.693.2

HTQP13File #

HTQP13-01

HTQP13-02

HTQP13-03

HTQP13-04

Time (days)-1.62-1 .36-0.82-0.60-0.27

0.080.340.570.801.031.271.501.741.972.202.432.662.893.19

Temp. (°C)

2525252525

300300300300300300300300300300300300300300

APp (bars)

-18.4021.60

-20.00-17.91

22.09-19.61

19.63-19.61

19.63-19.62

19.63-19.63

19.64-19.64

19.64-19.65

19.64-19.65

19.02

q x 10' 6

(cm 3 /s)-2.14

2.86-3.13-2.63

3.41-18.46

16.38-17.32

16.47-16.71

15.40-15.38

15.20-14.61

14.28-13.88

14.54-13.14

12.64

q/APp x 10' 6

0.11650.13220.15660.14710.15440.94140.83440.88320.83900.85170.78450.78350.77390.74390.72710.70640.74030.66870.6646

k x 10- 20 (m2)

7.959.02

10.6910.0310.539.968.839.348.889.018.308.298.197.877.697.477.837.077.03

k (nDa)80.591.4

108.3101.6106.7100.989.594.690.091.384.184.083.079.777.975.779.371.671.2

28

File #

HTQP13-05

HTQP13-06

HTQP13-07

HTQP13-08

HTQP13-09

HTQP13-10

HTQP13-11

HTQP13-12

HTQP13-13

HTQP13-14

Time (days)3.664.124.585.045.515.976.446.907.367.828.298.759.229.68

10.1410.6111.0711.5312.0012.4712.9313.3913.8514.3214.7915.2515.7216.1816.6417.1117.5718.44

Temp. (°C)

300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300300

25

APp (bars)

-20.0318.90

-20.0918.82

-21.0719.49

-20.9319.35

-20.7519.00

-20.6719.10

-20.4019.08

-20.9419.08

-21.0520.06

-19.3018.66

-19.3519.27

-19.5919.30

-20.1819.59

-20.3019.36

-19.9719.13

-20.2519.97

q x 10" 6

(cm 3 /s)-13.72

12.68-13.42

12.22-13.21

11.96-13.22

11.46-13.16

11.70-12.58

11.54-12.37

11.57-12.08

11.03-12.00

11.20-11.86

10.85-11.27

10.42-10.24

10.65-10.79

10.83-10.55

10.77-10.51

10.00-10.82

2.81

q/APp x 10' 6

0.68500.67090.66800.64930.62700.61360.63160.59220.63420.61580.60860.60420.60640.60640.57690.57810.57010.55830.61450.58150.58240.54070.52270.55180.53470.55280.51970.55630.52630.52270.53450.1407

k x 10-2° (m2)

7.257.107.076.876.636.496.686.276.716.526.446.396.426.426.106.126.035.916.506.156.165.725.535.845.665.585.505.895.575.535.659.60

k(nDa)73.571.971.669.667.265.867.763.568.066.165.364.765.065.061.862.061.159.965.962.362.458.056.059.257.359.355.759.756.456.057.297.3

HTQP14File #

HTQP14-01

HTQP14-02

Time (days)-0.90-0.82-0.59-0.36-0.13

0.020.090.18

Temp. (°C)

2525252525

400400400

APp (bars)-6.67

9.41-6.9510.12-8.18

0.82-1.08

1.18

q x 10' 6

(cm 3 /s)-169.6

170.7-170.5

172.3-169.5

171.6-171.6

173.3

q/APp x 10' 6

25.42718.14024.53217.02620.721

209.268158.889146.864

Jt x ID'22 (m3)

2594.81851.22503.51737.52114.63122.32370.62191.2

k x 10-20 (m2)

29

File #

HTQP14-04

HTQP14-05

HTQP14-06

HTQP14-07

HTQP14-08

HTQP14-09

HTQP14-10

HTQP14-11

HTQP14-12

HTQP14-13

HTQP14-14

HTQP14-15

HTQP14-16

Time (days)0.410.650.871.111.341.571.802.032.272.502.733.934.124.354.584.815.045.285.515.745.976.206.436.666.907.137.367.599.94

10.2210.6911.1311.5912.0612.5212.9813.4513.9114.3714.8415.3015.7616.2216.6917.2017.7918.1718.7519.2219.6820.00

Temp.

400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

APp (bars)-1.33

1.39-1.41

1.44-1.36

1.37-1.35

1.29-1.27

1.23-1.22

1.30-1.31

1.32-1.35

1.30-1.29

1.32-1.29

1.29-1.28

1.27-1.23

1.24-1.27

1.24-1.26

1.24-1.72

1.52-2.16

1.67-3.97

1.58-5.30

1.58-1.75

2.39-6.764.08

-11.666.95

-16.9214.49

-19.9819.86

-19.9919.90

-19.9319.93

-19.98

q x 10- 6

(cm 3/s)-171.8

174.5-174.1

177.0-173.0

176.6-174.7

175.8-172.3

175.7-170.8

177.2-175.8

175.5-174.8

172.8-175.7

178.4-175.0

171.3-171.7

171.8-173.4

174.4-173.0

173.2-171.6

174.0-171.4

170.7-174.6

173.3-175.1

170.7-175.8

171.4-174.0

174.2-175.3

171.5-173.3

175.8-177.7

175.0-7.95.2

-4.13.5

-5.93.4

-10.3

q/APp x 10' 6

129.173125.540123.475122.917127.206128.905129.407136.279135.669142.846140.000136.308134.198132.954129.482132.923136.202135.152135.659132.791134.141135.276140.976140.645136.220139.677136.190140.32399.651

112.30380.833

103.77244.106

108.03833.170

108.48199.42972.88725.93242.03414.86325.29510.50212.0770.3950.2620.2060.1770.2980.1710.515

Jt x 10-22

1927.31873.01842.21833.91897.91923.31930.82033.32024.22131.32088.82033.72002.21983.71931.91983.22032.12016.52024.01981.22001.42018.32103.42098.42032.42083.92032.02093.61486.81675.61206.01548.3

658.11611.9494.9

1618.51483.51087.53869.0

627.2221.8377.4156.7180.2

6.03.93.12.64.42.57.7

k x 10-20

3.942.612.051.762.971.705.13

30

File #

HTQP14-17

HTQP14-18HTQP14-19HTQP14-20HTQP14-21

Time (days)20.9021.5522.9823.6525.0725.7627.1527.3827.79

Temp. (°C)

400400400400400400400400400

APp (bars)20.00

-20.0020.00

-20.0019.97

-20.0019.91

-20.0020.00

q x 10' 6

(cm 3/s)3.1

-7.53.1

-7.84.0

-7.63.9

-8.34.3

q/APp x 10' 6

0.1550.3760.1560.3900.1980.3810.1980.4160.215

X x 10- 22 (m3)

2.35.62.35.83.05.73.06.23.2

k x 10-20 (m2)

1.543.741.563.891.983.801.974.142.14

HTQP15File #

HTQP15-04

HTQP15-05

HTQP15-06

HTQP15-07

HTQP15-08

HTQP15-09

Time (days)-0.64-0.41-0.18

0.040.180.420.660.891.121.351.591.822.052.282.512.742.973.213.443.673.904.134.364.594.825.065.295.525.755.986.21

Temp. (°C)

252525

350350350350350350350350350350350350350350350350350350350350350350350350350350350350

APp (bars)20.00

-20.0020.00

-19.6019.37

-19.8119.93

-19.4619.36

-19.5319.79

-19.4719.74

-19.5319.77

-19.4819.78

-19.4819.72

-19.4819.90

-19.6919.74

-19.6020.14

-19.9919.44

-19.6019.54

-19.7219.31

q x 10' 6 (cm 3/s)

1.80-2.00

1.73-40.63

29.49-26.36

25.01-23.75

23.56-23.57

23.49-23.18

23.19-23.17

23.21-23.17

23.21-23.17

23.21-23.17

23.26-23.20

22.93-23.33

23.44-23.95

22.71-23.17

23.48-23.47

22.41

q/APp x 10' 6

0.09000.10000.08652.07291.52241.33051.25471.21791.21691.20691.18711.19081.17481.18611.17411.18921.17351.18921.17701.19091.16901.17821.16161.19031.16391.19831.16801.18191.20161.19171.1606

k x 10- 20 (m2)6.146.826.00

21.3115.6513.6812.9012.5212.5112.4112.2012.2412.0812.1912.0712.2212.0612.2212.1012.2212.0212.1111.9412.2311.9612.3212.0112.1512.3512.2511.93

k (nDa)62.269.160.8

215.9158.6138.6130.7126.9126.7125.7123.6124.0122.4123.5122.3123.9122.2123.9122.6123.9121.8122.7121.0124.0121.2124.8121.7123.1125.2124.1120.9

31

File #

HTQP15-10

HTQP15-11

HTQP15-12

HTQP15-13

Time (days)6.446.686.917.147.147.377.607.838.068.308.538.768.999.229.459.699.92

10.1510.3810.6110.8411.0711.3111.5411.7712.0012.2312.4612.6912.6912.93

Temp.

File #

HTQP16-04

HTQP16-05

HTQP16-06

HTQP16-07HTQP16-08

HTQP16-09

HTQP16-10

HTQP16-11

HTQP16-12

HTQP16-13

HTQP16-14

HTQP16-15

Time (days)1.551.782.012.242.472.702.933.173.403.633.864.104.334.564.795.035.265.505.735.966.196.426.646.887.118.048.508.969.439.89

10.3510.8211.2811.7412.2012.6713.1313.5914.0614.5214.9815.4515.9116.3716.8317.3017.7618.2218.6919.09

Temp. (°C)

350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350350

APp (bars)

-19.4819.85

-19.4519.74

-19.4619.93

-19.3819.89

-19.3220.58

-18.8719.50

-19.6119.77

-19.4619.37

-19.9119.76

-19.1719.93

-19.6419.57

-18.6520.37

-20.1920.15

-20.4119.60

-19.5819.57

-19.6319.40

-19.9819.61

-19.8119.94

-20.0219.29

-19.7919.23

-19.8719.63

-19.6919.48

-20.0019.15

-20.0019.00

-19.9619.24

q x 10' 6 (cm 3/s)

-19.3619.20

-18.8718.71

-18.5518.83

-18.6018.81

-18.6418.71

-18.0018.18

-18.7118.51

-18.0018.15

-18.8418.22

-18.0017.76

-17.1016.87

-18.6718.45

-18.0017.50

-18.8417.64

-18.4518.02

-18.5118.91

-18.9418.61

-19.1418.09

-19.2018.09

-18.7417.73

-18.8416.80

-18.5517.79

-17.8917.76

-17.3118.13

-17.8817.12

q/APp x 10' 6

0.99410.96730.97030.94780.95300.94470.95960.94560.96500.90910.95390.93260.95410.93640.92500.93710.94630.92190.93900.89110.87090.86221.00110.90560.89150.86830.92310.90000.94210.92080.94310.97430.94790.94900.96590.90700.95810.93760.94700.92180.94820.85590.94190.91300.89450.92740.86570.95400.89560.8896

k x 10-2° (m2)

10.229.949.979.749.809.719.869.729.929.359.819.599.819.639.519.639.739.489.659.168.958.86

10.299.319.168.939.499.259.689.479.69

10.019.749.769.939.329.859.649.749.489.758.809.689.399.209.538.909.819.219.15

k (nDa)103.5100.7101.198.799.398.4

100.098.5

100.594.799.497.199.497.596.397.698.696.097.892.890.789.8

104.394.392.990.496.193.798.195.998.2

101.598.798.8

100.694.599.897.798.696.098.789.298.195.193.296.690.299.493.392.7

33

HTQP17*File #

HTQP17-01

HTQP17-02

Time (days)-0.83 -0.65 -0.41 -0.17

0.02 0.10

Temp.

File #

HTQP18-06

HTQP18-07

HTQP18-08

HTQP18-09

Time (days)6.807.037.267.497.727.958.198.428.658.889.119.349.81

10.2710.7311.2011.6712.1312.5913.0613.5213.9914.4514.9115.3815.8816.3016.7617.2417.7018.1618.6319.0919.5520.02

Temp. (°C)

450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450450

APp (bars)

-19.3719.47

-19.4919.48

-19.4919.49

-19.8619.28

-19.6619.61

-19.7419.45

-19.5119.35

-19.6619.21

-19.6619.36

-19.7719.13

-19.9119.29

-20.0019.36

-19.8219.53

-19.8619.36

-19.9519.42

-20.1719.19

-20.1619.36

-20.10

q x 10' 6

(cm 3 /s)-37.0235.98

-36.8935.94

-36.0134.86

-34.7334.21

-34.8033.94

-34.0632.84

-33.4232.47

-32.2130.85

-32.0030.54

-30.8629.48

-30.2428.51

-29.5528.24

-28.8727.42

-27.6526.67

-27.3125.56

-26.5724.89

-25.7224.24

-24.80

q/APp x 10' 6

1.91151.84781.89281.84521.84761.78871.74881.77421.76991.73101.72561.68861.71301.67811.63831.60601.62771.57731.56121.54081.51901.47781.47771.45891.45641.40421.39241.37761.36911.31601.31741.29701.27581.25211.2340

k x 10' 19 (m2)

1.8801.8181.8621.8151.8171.7601.7201.7451.7411.7031.6971.6611.6851.6511.6121.5801.6011.5521.5361.5161.4941.4541.4541.4351.4331.3811.3701.3551.3471.2951.2961.2761.2551.2321.214

k (nDa)190.5184.2188.6183.9184.1178.3174.3176.8176.4172.5172.0168.3170.7167.2163.3160.1162.2157.2155.6153.6151.4147.3147.3145.4145.2140.0138.8137.3136.5131.2131.3129.3127.2124.8123.0

HTQP19File #

HTQP19-01

HTQP19-02

Time (days)-0.66 -0.41 -0.18

0.02 0.14

Temp. (°C)

25 25 25

400 400

APp (bars)19.61

-19.92 19.64

-19.59 19.61

q x 10' 6

(cm 3/s)10.59 -9.75

9.84 -46.00 33.54

q/APp x 10' 6

0.5400 0.4895 0.5012 2.3481 1.7103

k x 10' 19 (m2)

3.683 3.339 3.419 2.341 1.705

k (nDa)373.2 338.3 346.4 237.2 172.8

35

File #

HTQP19-03

HTQP19-04

HTQP19-05

HTQP19-06

HTQP19-07

Time (days)0.370.610.841.081.311.541.772.012.242.472.702.933.163.393.633.864.094.324.554.785.025.255.485.715.946.176.406.646.877.107.337.567.798.028.268.498.728.959.189.419.649.88

Temp. (°C)

400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400

APp (bars)

-19.2719.74

-19.3119.62

-19.5419.78

-19.3919.65

-19.6119.78

-19.3919.99

-19.4919.63

-19.4919.92

-19.6319.62

-19.6719.64

-19.4519.61

-19.8519.66

-19.5319.45

-19.4819.49

-19.3319.44

-19.8019.59

-19.6519.44

-19.8119.73

-19.3919.60

-19.7819.66

-19.6019.76

q x 10' 6

(cm 3/s)-30.19

28.83-27.44

27.10-27.10

26.92-26.61

26.47-26.72

26.54-26.22

26.59-26.28

25.69-26.00

26.61-26.21

25.85-26.00

26.34-26.47

25.66-26.31

26.00-26.00

25.62-26.44

26.00-25.36

25.75-26.28

25.85-26.21

26.19-26.41

26.30-26.31

26.61-26.93

26.77-26.70

27.03

q/APp x 10' 6

1.56671.46071.42091.38111.38671.36101.37211.34731.36271.34181.35221.33001.34831.30861.33401.33561.33531.31761.32181.34131.36121.30831.32551.32251.33131.31741.35741.33341.31201.32481.32721.31961.33401.34741.33311.33291.35691.35741.36161.36161.36241.3680

k x 10' 19

HTQP20File #

HTQP20-01

HTQP20-02

HTQP20-03

HTQP20-04

HTQP20-05

Time (days)-0.52-0.22

0.060.300.540.771.001.241.471.701.942.172.402.632.863.093.323.563.794.024.264.494.724.965.185.405.635.86

Temp.

File #

HTQP21-04

HTQP21-05

HTQP21-06

HTQP21-07

HTQP21-08

HTQP21-09

HTQP21-10

HTQP21-11

HTQP21-12

HTQP21-13

HTQP21-14

HTQP21-15

HTQP21-16

HTQP21-17

Time (days)1.832.072.302.532.773.003.233.463.703.934.164.514.985.445.916.386.847.307.778.248.709.169.63

10.1010.5611.0211.4811.9512.4112.8713.3313.7914.2614.7315.2015.6616.1216.5817.0517.5117.9718.4418.9019.3719.8320.3020.7621.2321.6822.1522.60

Temp.

File #

HTQP21-18

HTQP21-18 1

Time (days)23.0723.5323.9924.4524.9225.3825.8426.3126.7727.2327.7028.1728.6429.1529.6530.1130.5831.0631.5031.90

Temp. (°C)

400400400400400400400400400400400400400400400400400400400400

APp (bars)19.52

-20.0919.65

-19.9719.58

-19.9919.61

-19.9719.04

-20.7220.27

-19.6820.86

-19.8419.81

-19.8419.61

-19.9619.62

-19.97

q x 10- 6

(cm 3/s)9.19

-9.559.33

-9.589.49

-9.429.61

-9.429.16

-9.458.77

-9.148.52

-8.788.78

-8.498.62

-7.738.56

-7.73

q/APp x 10' 6

0.46760.47560.47490.47970.48460.47140.48990.47190.48120.45610.43260.46420.40840.44260.44300.42810.43980.38740.43610.3872

k x 10- 20 (m2)

4.664.744.734.784.834.704.884.704.804.554.314.634.074.414.424.274.383.864.353.86

k (nDa)47.248.048.048.549.047.649.547.748.646.143.746.941.344.744.843.244.439.144.039.1

39

of nanodarcies (1 nda = 9.87 x 10'22 m 2), for easier comparison with much of the older

literature on permeability.

The original intent was to initiate investigations on a pure quartz system, because of its

mineralogical and chemical simplicity and because solution-transfer processes involving silica

are commonly invoked as a major cause of permeability change (for example, Morrow and

others, 1985; Udell and Lofy, 1989; Lowed and others, 1993). An ultra-fine quartz powder

was to be used in sliding experiments representing motion along a fault. Because quartzite,

which is strong, also has very low permeability (for example, Morrow and others, 1985),

novaculite was considered for use as the quartz-rich end pieces. The first three experiments

tested the novaculite and quartz powders, with or without an applied differential stress. The

results of these initial experiments are summarized below.

HTQP01. This experiment was conducted to evaluate the performance of novaculite at

elevated temperatures and under an axial load. The sample was held at room temperature at 100

MPa confining pressure and 20 MPa pore pressure for about 65 hours, to determine how the

novaculite would hold up under pressure. The pressures were then raised to 150 MPa confining

pressure and 100 MPa pore pressure. At room temperature, flow rate was measured at a

differential pore pressure of 1.0 MPa; upon heating, however, this pore-pressure difference

could not be attained. For the heated samples, therefore, the differential pore pressure at a

constant flow rate was measured.

The sample was heated first to 200°C and subsequently to 400°C; permeability was

measured immediately after each temperature increase (Fig. 4). A differential stress of 120

MPa was then applied to the sample (File numbers HTQP01-04 to HTQP01-07 in Table 2). At

that time, the novaculite began to creep (Table 2), although the shortening did not noticeably

affect permeability in this case. The sample suffered a permanent change in shape during the

experiment, the length decreasing by 0.051 mm and the diameter increasing by 0.025 mm.

40

10 -16

CM

§ 10 !5COo>

Q.

10'

'17

18

200°C

25°C

T I I

400°C Novaculite

200 ° C HTQP01

120 MPa differential stress

-0.5 0.5 1 Time, t (days)

1.5

Figure 4. Permeability of intact novaculite sample HTQP01 at 25°C, 200°C, and 400°C. All of the 400°C measurements except for the first were conducted with an imposed differential stress of 120 MPa.

41

HTQP02. This experiment tested the behavior of the quartz powder without an applied

differential stress (Fig. 5), to provide a baseline for comparison with intended later

experiments involving sliding on a sawcut or fracture surface. The gouge layer shortened by

about 15% as the confining pressure was applied. Upon heating, the sample began to creep

(Table 2, Fig. 6) at an initially rapid rate, but within a few hours it settled into a slower,

steady rate of creep. The final sample length was 1.96 mm less than the initial length. If the

shortening was concentrated in the gouge layer, its length was reduced by about one-fourth.

Based on the results of experiment HTQP01, however, the novaculite may also have shortened to

some extent.

The permeability of this gouge-bearing sample at 400°C was relatively high (Fig. 5)

and, at first, a strong function of the flow direction (Table 2). By the end of the experiment,

the permeability had decreased to 20-25% of the initial heated values, and the variation with

flow direction had decreased substantially. Much of the permeability decrease may be

attributable to compaction/creep at 400°C.

HTQP03. This second experiment using the fine-grained quartz gouge substituted

granite end pieces for the novaculite of the previous experiment. The change was made to better

test the ability of rock to become sealed in the presence of a reactive gouge. The high

permeability and tendency to creep of novaculite, which were identified in the earlier

experiments, were not conducive to monitor potentially modest permeability changes resulting

from mineral reactions. The stronger, lower-permeability granite was deemed to be a better

candidate for such investigations.

Because the sample was slow to saturate at room temperature, the confining pressure

was temporarily lowered to 110 MPa to force water through the sample more quickly.

Confining pressure was restored to 150 MPa prior to the measurement of room-temperature

permeability. Upon heating, the gouge layer began to compact, as in previous experiments

(Table 2, Fig. 7). It was considered that, as a result of the compaction, water would escape

42

k-16

CM

400°C quartz gouge novaculite end pieces

.QCOo

0>0.

m-18

-* -*'. HTQP02 * % !

-

i i i i

012345 Time, t (days)

Figure 5. Permeability at 400°C of sandwich sample HTQP02, consisting of a layer of fine- grained quartz gouge between 0.795 cm-long cylinders of novaculite.

?^ ^

+*c

EooCO

CLCO

Q

i

0.8

0.6

0 4V . ~

0.2

0

-0.2

i i i i

j -^~^~^ HTQP02 -: I ;'- -.1'

-*-

400°C quartz gougenovaculite end pieces

i i i i

0 1 2 3 4 £Time (days)

Figure 6. Change in sample length, measured as ram displacement, following heating of sample HTQP02. A positive ram displacement corresponds to sample shortening. (It is the relative change in displacement that is important in this and subsequent displacement plots, not the absolute values.)

43

.

from the gouge into the rock, leading to the possibility of a count erf low of water during a

permeability measurement. In order to identify and remove any effects of compaction upon flow

rate, permeability was measured at pore-pressure drops of 0 MPa, ±1.0 MPa, and ±2.0 MPa.

The permeability of granite/gouge sample HTQP03 at 400°C (Fig. 8) was more than 2

orders of magnitude below that of the novaculite/gouge sample HTQP02 (Fig. 5). Experiment

HTQP03 was run for one week at 400°C and 0 differential stress. The measurements of

permeability at different pore-pressure drops and flow directions on any given day covered a

wide range of values (Fig. 8a), and the average daily permeability also varied erratically with

time (Fig. 8b). After 7 days, a differential stress was applied, at a slow rate of increase, to a

set point of 355 MPa (Fig. 7b). The sample compacted considerably during the application of

the stress (Fig. 7a), and the initial measurement of k at 76.5 MPa differential stress was

somewhat lower than the unstressed measurements. However, the permeability measurements

taken at 355 MPa differential stress were larger than for the unstressed state (Fig. 8). Thin-

section examinations reveal the cause of this increase: HTQP03 bulges outwards at the site of the

gouge layer, whereas HTQP02, which was not stressed, has collapsed inwards (Fig. 9a). Sample

HTQP03 has a concentration of microcracks at the gouge-granite interfaces (Fig. 9b) that

probably formed as the gouge flowed outwards under the differential stress. The crack density,

measured as the number of crack intersections along lines perpendicular to the cylinder axis,

increases 3- to 4-fold from each end of the sample to the rock-gouge interface. The formation

of the tensile cracks led to the measured permeability increase.

Granite Experiments (HTQP04 - HTQP21).

Following the initial experiments on novaculite and quartz gouge, we switched to a

wholly granitic system, despite its more complex mineralogy. The group of investigations

reported here considers the effects of temperature and sample configuration on permeability,

without an applied differential stress. The high-temperature results for the granite samples

are presented in Moore and others (1994), and the effect of rock-water interactions on

45

a)>-19

1 U

^.CM

^

*£ sz(0oEG) Q.

-in- 20

I

--

HTQP03

§^ D DQ QB

B * °B qB " o B

B

iD

D D ".0 JPcr g

~

.D

D

-

400°C quartz gouge

/ ii -, * x granite (all data) **i

end piecesi

5 10 Time, t (days)

15

b) -19

Permeability, k (m2)

-a, _

D c

i 10 0

1

- HTQP03n°° -

D D

(averaged data)i

i

, n

335 MPa

76.5 MPaU^

________ >

increasing differential

stress

i

n B n

355 MPa dif. str. -

0 5 10 15 Time, t (days)

Figure 8. Permeability of sandwich sample HTQP03 - quartz gouge and granite end pieces - over time at 400°C. Permeability was measured each day at ±1.0 MPa and ±2.0 MPa differential pore pressure, a). Plot of all data collected, b). Plot of the average daily permeability. After 7 days, a differential stress was applied at a rate of increase of 0.005625 MPa/s, to a maximum load of 355 MPa.

46

a)

'."f-:: .V:-'^-"-.-.::V:?::'>-^;-i-:'.-.--.

HTQP02 HTQP03

b) Microcracks \Intact Rock

Gouge

Intact Rock

HTQP03

Figure 9. a). Contrasting changes in shape of gouge-bearing samples HTQP02 and HTQP03. Sample HTQP02 was not subjected to an axial toad, and the gouge caved in under the effective pressure. HTQP03 was subjected to a differential stress, at which time the gouge apparently began to flow outwards, b). Sketch of part of sample HTQP03, showing microcracks formed in the granite adjacent to the gouge layer, as a result of outward flow of the gouge under the applied axial load. The crack densities of the granite cylinders decrease with increasing distance from the gouge-rock boundary.

47

permeability will be discussed in a subsequent paper (Moore and others, in preparation). The

following sections include aspects of the experiments not dealt with in detail in those papers,

such as room-temperature permeability and the possible effects of the copper jackets on the

results.

Room-temperature k. The reported room-temperature permeability of intact Westerly

granite at 50 MPa effective pressure is in the range 2 x 10'21 m2 to 1 x 10" 19 m2 (Brace and

others, 1968; Morrow and others, 1986). However, the measured room-temperature

permeability values of many of the intact granite samples in this study were considerably

higher (Fig. 10). The first measurement of experiment HTQP12 was especially high (Table 2),

and k was subsequently lowered by repeatedly removing the pore pressure and raising confining

pressure. This response demonstrated that the non-annealed copper jackets used in

experiments HTQP01 to HTQP12 (Table 3) were too stiff to form a proper seal around the

sample, at least at room temperature. The pressure cycling of experiment HTQP12 improved

the seal by pressing the jacket more closely to the granite sample. To help alleviate this

problem, the copper jackets used in subsequent experiments were annealed (Table 3). The

samples housed in annealed jackets yielded more reasonable values of room-temperature k,

although most of these values are at the upper limit of reported room-temperature

permeabilities (Fig. 10). In addition, problems occurred with annealed jackets that were

subsequently plated with gold. Apparently, the plating process caused the copper to become

work hardened, thereby increasing jacket stiffness.

To further improve the jacket seal, the experimental start-up procedures were modified

for the final experiment, HTQP21, as follows: 1) apply confining pressure (dry); 2) anneal the

sample assembly at 650°C for 30 minutes; 3) return the sample to room temperature and

apply fluid pressure; 4) measure permeability at room temperature; and 5) heat the sample to

the run temperature. This procedure yielded the second-lowest measurement of room-

temperature k and also eliminated some problems encountered in duplicating the high-

48

O+**ECO

O)

OCO

CO O

1_ O CL

O Occ

i

... ,

....

i

.._

>

j L* I I annealed jacket }

/

*CO 0>c cCO

0-C--

* 0>.* -o.2.

>

<

r

k

f

:

o^ 05nrt--

C&T-

v0-

c-

.. v

A

!

. _,

. _ ._

. ... ._,

«

i

H

..-

> -

"

l~

I :

» B

«»^ -

-4

.««*.

....,

̂

i

«

>

i

''./. Tf i S. t\t f

' .f. 4 4 f. S \S f

f.f. 4 4 S. S \t t

'\f. 4 4 S. S :t t

>: s. i 4 s. s :s t t«-«S->S->S-««--S"S--^

M-»l"

Table 3. Characteristics of Copper Jackets

Experiment #__________Cu-Jacket Type_____

HTQP01

HTQP02

HTQP03

HTQP04

HTQP05

HTQP06

HTQP07

HTQP08

HTQP09

HTQP10

HTQP11

HTQP12

HTQP13

HTQP14

HTQP15

HTQP16

HTQP17

HTQP18

HTQP19

HTQP20

HTQP21

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

not annealed

annealed

annealed

annealed, w/wo qold plating*

annealed, w/wo gold plating*

annealed, gold-plated

annealed, gold-plated

annealed, gold-plated

annealed

annealed*** The experimental log does not indicate whether or not these two samples were gold plated. However, the room-temperature values of k obtained for the two samples are more consistent with the use of non- plated, annealed copper jackets (Fig. 8; Table 2). In addition, copper deposits occur in cracks on the sides of both samples, but no traces of gold were found.

** The jacket was annealed a second time, with the sample inside and under confining pressure.

50

temperature data. As a result, this modification will be followed in future experiments. That

the annealing did not cause obvious thermal cracking of the granite (see below) may be owing to

the lack of an applied fluid pressure.

High-temperature k. Permeability was expected to increase upon initial heating as a

result of thermal cracking (Heard and Page, 1982; Fredrich and Wong, 1986). For the

samples in annealed copper jackets, the measured permeability did increase with heating (Table

2), and the amount of increase was roughly proportional to temperature. The first high-

temperature k measurements of the other samples were generally lower than the room-

temperature values, however, because improved jacket sealing upon heating outweighed the

effects of thermal cracking. The initial measurements of k are relatively well correlated with

temperature (Fig. 11 a), irrespective of the jacket type used. The two experiments at 300°C

provide a direct comparison of the annealed (HTQP13) and non-annealed (HTQP11) jackets

(Fig. 12). After the first measurement, which is somewhat higher for the sample in the non-

annealed jacket, the results are essentially identical. Similarly, the spread of the data after 10

days at temperatures above 300°C (Fig. 11b) is generally less pronounced than for the initial

values. Together, these results indicate that the jacket does not affect the high-temperature

permeability measurements (possible exceptions are HTQP19 and HTQP20, described below).

High-temperature permeability decreased over time in all of the granite experiments.

The rate of decrease for most of the intact samples (Figs. 12-16) was rapid in the first day or

two following heating but subsequently dropped to a uniform rate that in most cases continued

until the end of the experiment. However, both of the intact-rock experiments at 500°C (Fig.

16) were characterized by a rapid decrease in k after 5 to 6 days. The final permeability

measurement of HTQP06 was roughly 3 orders of magnitude below the initial heated value, and

over the last 3 days of the experiment flow through the sample had in effect ceased. The other

500°C experiment, HTQP05, differed somewhat in that permeability partly recovered at a later

time. Changes over time in the lengths of samples HTQP05 and HTQP06 are plotted in Figure

51

a)

.Q CO 0)

i_ 0)0.

b)

COo>i_0)0.

10 -18

g 10'19 -

10 -20heated ermeability

250 300 350 400 450 500 550Temp (°C)

,-18

10' 19

io-202!

i............................j

r :::::::i:::zz

P

> *i.

f................ ...........|

srmeability

1>». ...... .... .«

^

after 10 d

I

. . . ..... ................................ .

ays

50 300 350 400 450 5CTemp (°C)

Figure 11. Permeability of intact granite plotted relative to temperature, a) Initial heated permeability values, b) Permeability after about 10 days, excluding the 500°C values. An exponential equation was fit to the data in a); the units of T and k correspond to the axes.

52

10-18

£ 10sCOo

-19

10 20

300°C Intact granite

HTQP11-

HTQP13

5 10 15 Time, t (days)

20

Figure 12. Permeability of 300°C intact granite samples. Experiment HTQP11 (circles) used non-annealed copper jackets and experiment HTQP13 (squares) used annealed copper jackets. Room-temperature permeability of the 2 samples differed, but the high-temperature plots are nearly coincident.

5 x 10'19

.0COok.o o.

10 19

5 x 10'20

350°C Intact granite

HTQP15

HTQP16

HTQP12

5 10 15 Time, t (days)

20

Figure 13. Changes in permeability of intact granite samples at 350°C. After the first 1-2 days, the rate of permeability decrease in all three experiments slowed considerably, to lower rates than observed at 300°C. (HtQP12 - squares; HTQP15 - diamonds; HTQP16 - circles).

53

,-18

400°C Intact granite

10 20 30 Time, t (days)

40 50

Figure 14. Permeability of 400°C intact granite samples. The flat trends of HTQP19 and HTQP20 may reflect problems with the seal between the copper jacket and the sample. (HTQP07 squares; HTQP19 - open circles; HTQP20 - diamonds; HTQP21 - filled circles).

10-18

.0 CO Q>

k. Q> Q.

10-19

450°C Intact granite

10 15 Time, t (days)

20 25

Figure 15. Permeability changes in intact granite at 450°C. The data from the 2 experiments are nearly coincident. (HTQP10 - squares; HTQP18 - circles).

54

k-181 U

1

S io-19

J«:

^ 10'20

r- CM CM CMi i0 Cr-" r1

iqeauuad

: 1 1 1 1 :

L^^^ HTQP06 = 3P°ooooooooooooooooooon :^-A-*--\JOQ

1 D ° e o '_ \ HTQP05 i

- ^ D E

D D

r T

: D :D

; 500°C Intact granite ° ;i i i i

2468 Time, t (days)

10

Figure 16. Permeability of intact granite at 500°C. After 5-6 days in both experiments, the rate of permeability reduction abruptly changed, decreasing by 2-3 orders of magnitude in less than one day. In HTQP06, flow essentially ceased over the last 3 days of the experiment. HTQP05 - squares; HTQP06 - circles).

55

17. The measured displacement during HTQP05 fluctuates irregularly over a small range,

whereas that of HTQP06 is unchanging except in association with two transient, 40-45° drops

in temperature (associated with adjustments to the experimental apparatus). In neither

experiment does the onset of rapid permeability decrease correlate with a change in

displacement.

Overall, the rate of uniform permeability reduction in the intact granite samples

increased with increasing temperature in the examined range, but with some reversals. For

example, the data from the two experiments at 300°C (Fig. 12) have steeper slopes than the

nearly flat trends of the three experiments at 350°C (Fig. 13). The repeated experiments at

400°C (Fig. 14) yielded conflicting rates, with HTQP19 and HTQP20 unable to duplicate the

permeability reductions of HTQP07. The results of HTQP19 and HTQP20 were considered to

reflect jacket-sealing problems, perhaps a crease or fold in the copper.