BYL001 Drakelow 2A Cored Samples Report

BYL001 Drakelow 2A Cored Samples Report / 13 juillet 2005

LAB TESTS ON DRAKELOW 2A CORED SAMPLES

BYL / R / J / 0002

Nombre de pages : 221 Révision : 0 Etat : RFA Date de diffusion :

N. GATELIER N. GATELIER R. SCHIRTZINGER

Emis (nom, visa) Vérifié (nom, visa) Approuvé (nom, date, visa)

Lab tests on Drakelow 2A cored samples

BYL001.doc / 13 juillet 2005

CONTENTS

1. INTRODUCTION ................................................................................................................. 3

2. PHYSICAL PROPERTIES ................................................................................................... 6

3. SHORT-TERM TESTS ON SALT SAMPLES ..................................................................... 7

3.1. Uniaxial tests on salt samples .............................................................................................. 7

3.2. Triaxial tests on salt samples ............................................................................................... 9

4. CREEP TESTS (LONG-TERM) ON SALT SAMPLES ..................................................... 16

5. SHORT-TERM TESTS ON MARL SAMPLES .................................................................. 18

5.1. Uniaxial test ........................................................................................................................ 18

5.2. Triaxial tests ....................................................................................................................... 18

MAIN PURPOSE OF THE REVISION AND TYPE OF MODIFICATIONS

Original issue.



1. INTRODUCTION

The description of the samples prepared in the laboratory is summarized in the

following tables.

The quality of the tested samples is checked by measuring their physical properties

(density and sound velocity). A summary of these measurements is presented in the

paragraph 2 of this intermediate report.

The main results of the tests performed on the salt samples are presented in the

paragraph 3 and 4 for respectively the short-term and long-term tests.

The short-term tests (typical duration 1 day for uniaxial and triaxial tests) give the

elastic and damage salt properties whereas the long-term tests (multi-step creep tests

with an overall duration of about 80 days) are performed to derive the creep

(viscoplastic) properties of the salt samples.

Finally, the results obtained from the short-term tests performed on the marl samples

are presented in paragraph 5. Elastic properties and failure criterion for the marl

formation are derived from the tests on the marl samples.

The data obtained from these geomechanical laboratory tests will be used as entry

data for the geomechanical assessment and modeling of the HGSL caverns at

DRAKELOW.



Description of the salt samples prepared in the laboratory

Facies Preparation of the samples

Salt-F1

Boxes 51

& 130

Sample

reference

Depth interval (m) Test

S46-2

S46-1

S18-3

S18-4

S18-1

S18-2

S46-1B

S18-5

S18-6

S18-7

682.72

682.51

573.02

573.19

572.66

572.86

682.57

Not available

Not available

Not available

682.90

682.51

573.15

573.33

572.79

572.99

682.62

Not available

Not available

Not available

Uniaxial compressive test

Triaxial test 2 MPa

Triaxial test 5 MPa

Triaxial test 8 MPa

Multi-stage creep test 5 MPa


Brazilian test

Triaxial test 2 MPa

Triaxial test 4 MPa

Triaxial test 6 MPa

Salt-F2

Boxes

61, 85 & 97

Sample

reference


S34-1

S34-2

S34-3

S34-4

S34-5

S30-1

S30-1B

S22-1

S22-2

S22-3

635.73

634.94

635.11

635.31

635.60

617.84

618.03

Not available

Not available

Not available

634.87

635.07

635.24

635.44

635.73

618.01

618.08

Not available

Not available

Not available

Triaxial test 2 MPa

Triaxial test 5 MPa

Triaxial test 8 MPa




Brazilian test

Triaxial test 2 MPa

Triaxial test 4 MPa

Triaxial test 6 MPa

Salt-F3

Boxes

108 & 19

Sample

reference

Depth interval (ft) Test

S38-1

S38-1B

S7-1

S7-2

S7-1B

651.94

652.10

527.61

527.91

528.08

652.07

652.15

527.74

528.08

528.13


Brazilian test



Brazilian test



Description of the marl samples prepared in the laboratory

Facies Preparation of the samples

Marl

Boxes

97, 19, 85

& 122

Sample

reference


M43-1

M43-2

M43-1B

M42-1

M24-1

M23-1B

M23-2B

M14-1

M14-2

M14-3

M14-1B

672.30

672.42

672.54

667.37

594.19

592.67

592.77

554.47

554.58

554.69

554.80

672.42

672.54

672.59

667.49

594.31

592.72

592.82

554.58

554.69

554.80

554.85

Triaxial test 2 MPa

Triaxial test 4 MPa

Brazilian test


Triaxial test 2 MPa

Brazilian test

Brazilian test

Triaxial test 2 MPa

Triaxial test 4 MPa

Triaxial test 6 MPa

Brazilian test



2. PHYSICAL PROPERTIES

The main physical properties of the salt samples are summarised in table 1 to table 4

below with some data derived from similar sites for comparison.

Byley Waha Michigan Salado

number of tests 14 30 15 33

density max 2276 2176 2175 2166

density min 2053 2106 2129 2088

density mean 2177 2147 2157 2128

Table 1. Salt density (unit : kg/m3)



Vp max 4432 4490 4611 4299

Vp min 3807 3308 3308 3018

Vp mean 4222 4137 4228 3664

uncommon value 1429 -- 1171 2636

Table 2. Sound velocity measured on salt samples (unit : m/s)



Rtb max 1.56 1.71 1.87 1.9

Rtb min 0.91 0.99 0.7 1

Rtb mean 1.24 1.31 1.39 1.4

Table 3. Brazilian tensile strength of salt samples (unit : MPa)

The uncommonly low sound velocity value shown in table 2 for the Drakelow 2A

sample has been measured on sample S7-1 which has been used for a creep test.

This sample has been damaged during the coring operation before testing. The creep

test result obtained with this sample can not be considered as representative of the

overall salt formation.

Rtb density Vp

number of tests 4 10 10

max 5.02 2547 3940

min 1.45 2494 2229

mean 2.97 2514 2978

uncommon -- -- 1848

Table 4. Main physical properties of the marl samples (unit : same as salt)



The sound velocity measured on the marl samples in the lab is lower than the sound

velocity measured in the field (borehole log measurement gives sound velocity in

between 3600 and 4200 m/s for the marl layers). This can be explained with the

following:

- cores are not fresh (it is preferable to perform the tests as soon as possible after

the coring operation to avoid samples weathering during storage),

- the coring operation (both in the field and in the lab) can induce damaged of the

samples,

- the sound velocity measured in the lab is performed without any confinement

whereas confinement exists under in situ condition.

3. SHORT-TERM TESTS ON SALT SAMPLES

3.1. Uniaxial tests on salt samples

For each test performed the longitudinal (axial) strain variation is presented as a

function of the axial stress:

S46-2 - UNIAXIAL TEST

0

5

10

15

20

25

30

35

40

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

LONGITUDINAL STRAIN

STRESS in M

Pa

Local Global

Figure 1 : Facies F1




0

5

10

15

20

25

30

35

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

LONGITUDINAL STRAIN

STRESS in M

Pa

Local Global



0

2

4

6

8

10

12

14

16

18

20

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

LONGITUDINAL STRAIN

STRESS in M

Pa

Local Global






UCS max 33.5 23.8 24.1 25.5

UCS min 19.7 18.9 19.5 15.3

UCS mean 28.3 21.2 21.2 19.2

Table 5. Uniaxial compressive strength of salt samples (unit : MPa)

3.2. Triaxial tests on salt samples

For each test performed the longitudinal (axial) strain variation is presented as a

function of the axial stress:

TRIAXIAL TEST - S46-1confining pressure 2 MPa

0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa

Figure 4 : Facies F1 – 2 MPa

Local GlobalLocal Global



S18-3 - TRIAXIAL TEST

confining pressure 5 MPa

0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa


S18-4 - TRIAXIAL TESTconfining pressure 8 MPa

0

5

10

15

20

25

30

35

40

45

50

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa






S34-1 - TRIAXIAL TEST


0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa

Figure 7 : Facies F2 – 2MPa


0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa

Figure 8 : Facies F2 – 5MPa






0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial Strain

Axial Stress in M

Pa



0

5

10

15

20

25

30

35

40

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa







0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa



0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa







0

5

10

15

20

25

30

35

40

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa



0

5

10

15

20

25

30

35

40

45

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa






S22-3confining pressure 6 MPa

0

5

10

15

20

25

30

35

40

45

50

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Axial strain

Axial stress in M

Pa


0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10

Confining pressure (MPa)

Axia

l str

ess a

t dilation (M

Pa)

Byley-F1

Byley-F2

Dilation criterion :

cohesion = 5.9 MPa

friction angle = 23.8°

Figure 16 : Dilation – damage criterion for salt samples




From the above values, it appears that both the elastic and damage properties of the

Drakelow 2A salt cores are within the typical range of values to be expected for a

bedded salt formation.

4. CREEP TESTS (LONG-TERM) ON SALT SAMPLES

The last temperature step (T=50°C) at constant deviatoric stress (12 MPa) is still under

way.

Figure 17 : Creep tests at increasing deviatoric stress (constant temperature) and

increasing temperature (constant deviatoric stress)



Figure 18 : Creep test on facies F3 (interrupted due to unconventional behaviour)

Preliminary creep parameters for the viscoplastic Lemaitre rheological law are given in

the table 6 below. Creep ability of the Byley formation is rated in the low to medium

range.

Facies α β K

MPa

Q/R

°K

αvol

/°K

F1 0.166 2.410 0.365 2217 40E-6

F2 0.107 2.112 0.291 2984 30E-6

F3 0.178 2.468 0.338 1887 40E-6

Table 6 - Creep parameters and thermal volumetric expansion coefficient (time unit is days)



5. SHORT-TERM TESTS ON MARL SAMPLES

5.1. Uniaxial test

M42-2


y = 13078x - 7.0195

y = 11313x - 15.843

y = 6561.2x - 9.1091

y = 7682.9x - 23.305

0

5

10

15

20

25

30

35

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01

LONGITUDINAL STRAIN

STRESS in M

Pa

Local Global

Figure 19. Uniaxial test on marl sample

Uniaxial compressive strength is equal to 31 MPa .

5.2. Triaxial tests

M43-1 - TRIAXIAL TESTS


y = 7365x - 8.3562

y = 8561.6x - 38.769

y = 7468.1x - 92.329

y = 9073.7x - 162.72

0

10

20

30

40

50

60

0 0.005 0.01 0.015 0.02 0.025

Global axial strain

Axial stress in M

Pa

Figure 20 : MARL M43-1 – 2 MPa



M24-1 - TRIAXIAL TEST


y = 6549.1x - 5.936

y = 7835.7x - 21.54

y = 7552.2x - 33.786

y = 3343.2x - 27.942

0

5

10

15

20

25

30

35

40

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014

Global axial strain

Axial stress in M

Pa




y = 6001.1x - 5.8275

y = 6258.9x - 16.469

y = 7686.3x - 39.545

y = 6731.7x - 62.361

0

5

10

15

20

25

30

35

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014

Global axial strain

Axial stress in M

Pa






y = 8669.9x - 7.9691

y = 8965.1x - 23.431

y = 10461x - 54.121

y = 5891.5x - 109.64

0

10

20

30

40

50

60

0 0.005 0.01 0.015 0.02 0.025

Global axial strain

Axial stress in M

Pa




y = 7681.2x - 8.3543

y = 9286x - 27.342

y = 10143x - 51.987

y = 4895.1x - 94.225

0

5

10

15

20

25

30

35

40

45

50

0 0.005 0.01 0.015 0.02 0.025

Global axial strain

Axial stress in M

Pa






y = 8472x - 2.5042

y = 9774.7x - 20.343

y = 9819.9x - 38.74

0

10

20

30

40

50

60

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016

Global axial strain

Axial stress in M

Pa


0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7

confining pressure (MPa)

Axia

l str

ess (M

Pa)

Failure criterion for marl :

cohesion = 7.0 Mpa

friction angle = 40°

Residual Failure criterion for marl :

cohesion = 3.5 Mpa

friction angle = 30.6°

Figure 26 : Failure criterion and residual criterion for marl samples

The results obtained for the marl samples (elastic and failure properties) are consistent

with data available in the literature.

BYL001 Drakelow 2A Cored Samples Report

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