SYNTHESIS AND

CHARACTERIZATION OF

GAS HYDRATE

Hailong Lu

Steacie Institute for Molecular Sciences

National Research Council Canada

A

Because gas hydrate is only stable at relatively high

pressure and low temperature and it will dissociate

into gas and water once it is located outside of its

stable regime, most of its properties can be studied

only by experiments.

A

• To synthesize gas hydrate to obtain hydrate sample

for studying its chemical or physical properties

• To synthesize gas hydrate for studying its

thermodynamic, or kinetic, or physical properties

• To synthesize gas hydrate for studying the formation

or dissociation mechanism of gas hydrate in sediments

• etc

Synthesis of gas hydrate

AStarting materials Method Purpose

Gas, solution Gas + solution → gas

hydrate

hydrate stability, nucleation,

reaction kinetics, gas

composition fractionation,

…

Gas, ice Gas + ice → gas hydrate hydrate sample, structure,

further studies of chemical

and physical properties, …

Gas, solution-saturated

porous media

Gas + porous media →

gas hydrate

Hydrate stability, reaction

kinetics, physical properties,

…

Gas + sediments → gas

hydrate

Hydrate stability, reaction

kinetics, hydrate saturation,

…

ATo synthesize gas hydrate for obtaining gas hydrate sample

A

A

A

2600 2800 3000 3200

10000

12000

14000

16000

18000

20000

22000

24000

26000

Raman shift (cm-1)

MH1

HS stretching CH stretching

OH stretching

Figure The Raman spectrum of synthesized H2S-CH4 hydrate

ATo synthesize gas hydrate for studying its chemical properties

A

Studies of gas hydrate inhibitor for natural gas transportation through pipeline

Planar growth of THF hydrate in the presence of 0.25 mM WfAFP (Zeng et al., 2003)

A

0.5 1 1.5 2 2.5 3 3.5 43.2

3.4

3.6

3.8

4

4.2

T (oC)

Solution

temperature

Gas temperature

Gas releasing

Pressure increased due

to hydrate dissociation

Equilibrium

point (E)

Gas-Solution-Hydrate

phase line

A

B

Pressure-search method for hydrate equilibrium

condition

A

Gas-solution-hydrate

three phase line

P

T

Start of hydrate

formation

Start of

T ramp Start of hydrate

dissociation

Equilibrium point

Temperature-search method for determining

hydrate equilibrium condition

Lu and

Matsumoto

(2001)

Lu and

Matsumoto

(2005)

A

A

Lu and Matsumoto (2002)

ATo synthesize gas hydrate for studying the formation

mechanism of gas hydrate in sediments

A

Synthesize gas hydrate in sediments

Synthesize gas hydrate in natural sediments from Nankai

Trough, offshore Japan

A

The sediment column prepared was set into a pressure cell

for hydrate synthesis

A

75

80

85

90

95

100

105

110

115

0 50 100 150 200 250 300 350

P (

ba

r)

Time (hours)

Figure 9. The pressure change during the process of methane reaction with Nankai

Trough sediments at 3 C.

A

Relationship between

the saturation level of

methane hydrate and

particle size in silica

sands with various

particle sizes

A

A

A

0

20

40

60

80

100

0 5 10 15

Radial distance from disc edge (mm)

#44

#42#32

Figure 10. The radial distribution of water conversion rate in the tested sediment core.

A

Figure 24 MRI cell allowing in situ observation of the reactions in two sample

holders simultaneously.

Not to scale

sample

holder

Pressure cell

Slice 1

Slice 2

Slice 3

Slice 4

Slice 5

A

0

2 104

4 104

6 104

8 104

1 105

0 100 200 300 400 500 600

Inte

nsi

ty

Time (min)

Figure 27 Methane hydrate formation in powdered silica sands of 180 - 212 um and

125 - 180 um.

125 - 180 um

180 - 212 um

A

• Structure determination

• Gas composition determination

• Stability study

• Chemical and physical property study

• Determination of the saturation of gas

hydrate in sediments

• etc

Characterization of gas hydrate

A

Structure determination

Powder X-ray diffraction

Single-crystal X-ray diffraction

A

A

Hydrate sample to be ground with a mortar at LN2

temperature

A

Hydrate to be charged in a sample holder that is

mounted on a cold stage

A

A

5 10 15 20 25 30 35 40 45 50

0

500

1000

1500

2000

2500

3000

2 .84-2 .94 m bsf

4 3 2

5 2 0

Ic e

4 3 0

3 3 2

4 2 1Ice

3 3 0

4 1 1

4 1 0

4 0 0

3 2 1

3 2 0

2 2 2

Ice

Ice

Ic e

2 1 12 1 0

2 0 0

1 1 0

Inte

ns

ity

(A

.U.)

2 T h e ta (d e g ree )

XRD pattern of sI gas hydrate from Cascadia,

offshore Vancouver Island

A

0

100

200

300

400

500

600

10 20 30 40 50

Inte

ns

ity

(A

.U.)

2theta (degree)

II(1

11

) H

(00

1)

II(3

11

)H

(20

0) II

(40

0)

H(2

01

)

Ice

Ice

Ice

Ice

Ice

II(4

22

) H

(30

0)

II(3

33

)H

(10

3)

H(2

12

)II

(44

0)

H(2

20

)

II(5

31

)

II(6

20

)

II(6

22

) H

(22

2)

H(2

13

)

II(7

11

)

II(7

31

) H

(22

3)

II(2

20

)

II(2

22

)

II(4

44

)

XRD pattern of a complex sII & sH gas hydrate from

Barkley Canyon, Cascadia, offshore Vancouver Island

A

Table 2. X-ray Powder Data for sII and sH gas hydrates recovered from Barkley Canyon,

offshore Vancouver Island

Structure type hkl D(obs) D(calc) Res(d)

111 9.85729 9.95462 -0.09733

220 6.07354 6.09593 -0.02239

311 5.17622 5.19863 -0.02240

222 4.95215 4.97731 -0.02516

400 4.30239 4.31048 -0.00808

422 3.50004 3.51949 -0.01944

333 3.30190 3.31821 -0.01630

440 3.03881 3.04797 -0.00915

531 2.90192 2.91441 -0.01249

620 2.71886 2.72618 -0.00733

622 2.61504 2.59931 0.01573

444 2.50599 2.48865 0.01733

711 2.40201 2.41435 -0.01234

sII

a = 1.724 ± 0.002 nm

731 2.26099 2.24470 0.01629

001 9.85748 10.06147 -0.20399

200 5.29615 5.27786 0.01828

201 4.66743 4.67385 -0.00642

300 3.50002 3.51858 -0.01855

103 3.19003 3.19636 -0.00634

212 3.12585 3.12597 -0.00012

220 3.03883 3.04718 -0.00835

222 2.61507 2.60634 0.00873

sH

a = 1.219 ± 0.009 nm

c = 1.006 ± 0.009 nm

223 2.26097 2.25531 0.00566

A

Single X-ray diffractometer

A

A B

A: Single crystal of sII gas hydrate（Barkley Canyon)

B: Single crystal of sI gas hydrate（Northern Cascadia)

sII gas hydrate （A)

Fd-3m, a=17.141(1) Å

(composition:

2CH4·0.78C2H6·0.22C3H8

·17H2O)

Udachin et al. (2007)

ARaman study of gas hydrate

A

A

A

A

A

2 104

4 104

6 104

8 104

1 105

1.2 105

1.4 105

1.6 105

2800 3000 3200 3400 3600

Raman Shift

O-H stretching for H2O

C-H stretching for CH4

PC 10

Raman spectra of methane hydrate from the Sea of Japan

A

2600 2800 3000 3200

3048

2902

2914

3078

Raman shift (cm-1)

3208

U1328E 2X-2

2500 2550 2600 2650

2569

2593

2604

Raman spectra of mixed CH-HS hydrate from Cascadia, offshore Vancouver Island

A

Hester et al. (2007)

A

2700 2800 2900 3000 3100 3200

Inte

ns

ity

Raman shift (cm-1

)

2913

2901

2868

28762884

2938

2947 2975

2901 cm-1 is for methane in the large cage of sII, and 2913 cm-1 is for methane in the small cages of sII and sH hydrates;

2884 and 2947 cm-1 are for ethane in the large cage of sII; 2868 and 2884 cm-1 for propane in large cage of sII; 2876 and

2938 cm-1 for butane in large cage of sII.

2700 2800 2900 3000 3100 3200

Inte

ns

ity

Raman shift (cm-1

)

2913

2901

2868

28762884

2938

2947 2975

2901 cm-1 is for methane in the large cage of sII, and 2913 cm-1 is for methane in the small cages of sII and sH hydrates;

2884 and 2947 cm-1 are for ethane in the large cage of sII; 2868 and 2884 cm-1 for propane in large cage of sII; 2876 and

2938 cm-1 for butane in large cage of sII.

2913

2901

2868

28762884

2938

2947 2975

2901 cm-1 is for methane in the large cage of sII, and 2913 cm-1 is for methane in the small cages of sII and sH hydrates;

2884 and 2947 cm-1 are for ethane in the large cage of sII; 2868 and 2884 cm-1 for propane in large cage of sII; 2876 and

2938 cm-1 for butane in large cage of sII.

A

Hester et al. 2006

The hydration number of gas hydrates from the Sea of Japan, as

estimated from methane peak intensities of Raman

Method

Sample # Occupancy Rate Hydration

numberLarge cage Small cage

Raman PC10-1 0.96826 0.78423 6.23

PC10-2 0.96833 0.78290 6.24

PC11-1 0.96853 0.77867 6.24

PC11-2 0.96830 0.78331 6.24

PC20-1 0.96842 0.78108 6.24

PC20-2 0.96993 0.74612 6.29

ANMR study of gas hydrate

A

NMR zirconia rotor and cap

A

-14-1 2-10-8-6-4-2024681012141618

(ppm )

13C HP DE C M AS 2200 Hz IO DP

1

2

3

4

13C NMR spectra of methane hydrate from Cascadia, offshore Vancouver Island

(ppm)

-35-25-15-551525354555

-4

.4

-8

.2-

4.9

6.1

14

.8 13.7

16.7

17.5

23

.62

5.8

26.5

27.0

27

.327.7

22.7

33

.03

5.2

35.8

(ppm)

24.525.025.526.026.527.027.528.028.529.029.530.0

26.527.3

26.5

27

.7

25.7

(ppm)

24.525.025.526.026.527.027.528.028.529.029.530.0

26.527.3

26.5

27

.7

(ppm)

24.525.025.526.026.527.027.528.028.529.029.530.0

26.527.3

26.5

27

.7

25.7

-4

.9

(ppm)

-9.0-8.5-8.0-7.5-7.0-6.5-6.0-5.5-5.0-4.5-4.0-3.5-3.0

-8.2

13C NMR spectra of complex gas hydrate from Cascadia, offshore

Vancouver Island

( p p m )

- 1 8- 1 4- 1 0- 6- 2261 01 41 8

CH4

C2H6

13C NMR Spectrum of CH4+C2H6 hydrate(mixture of structure I & II)

DSC study of gas hydrate

U1328B 2H1-9

-100 -80 -60 -40 -20 0 20

T (oC)

CH4 hydrate

U1328B 2H1X-5 #2

U1328B 2H1X-5 #3

U1328B 2H1X-5 #1

U1328E 2X-2 80-90 cm

H2S hydrate

-80 °C

DSC pattern of

hydrate samples

from Cascadia

Characterization of natural gas hydrates

In-pore hydrate

Hydrate stored in liquid nitrogen

Massive hydrate

Observation

PXRD

SCXRD

Raman

13

C NMRAmount

Chemical &

Isotope

composition

(GC, MS)

Gas, waterP-T stability

determined in

small volume

pressure cell

Conventional

High pressure

Coupled with MS

DSC

Structure

Composition

Guest distribution

Gas/water ratio (massive)

Saturation (in-pore)

Components

Origin

Stability

regime

Dissociation T

Coexisting phase

Decomposition behavior

of complex hydrates

Concentration

Dissociation

Visible gas hydrate

Massive gas hydrate occurring

at seafloor, Barkley Canyon,

Cascadia (Chapman et al.,

2004)

Massive gas hydrate

occurring in sediments at

a seepage site, Joetsu

Basin, Japan Sea

Nodular gas hydrate

occurring in

sediments at a cold

vent field, Cascadia

Vein-like gas

hydrate in silty clay,

K-G Basin, offshore

India

Thin film-like gas

hydrate occurring at

the bedding plane in

silty clay, K-G Basin,

offshore India

Invisible gas hydrate – In-pore gas hydrate

Gas hydrate in volcanic

ash, offshore Andaman

Island

Gas hydrate in silty clay,

K-G Basin, offshore

India

Gas hydrate in sand,

Mallik, Mackenzie

Delta, N.W.T., Canada

Gas hydrate in sand,

Nankai Trough, offshore

Japan

Gas hydrate in clay silt,

South China Sea

A pressure cell with little dead-volume for hydrate

stability measurement

P

T

A

BC

D

E

F

G H

A: Start point

B, C, D, E, F, G: Equilibrium points

H: End point

Simple-dissociation method to study the

stability condition of gas hydrate

0

10

20

30

40

50

60

240 250 260 270 280

P (

bar)

T (K)

CH4-hydrate-water (Sloan, 1998)

this research

0

10

20

30

40

50

60

70

250 260 270 280 290 300 310

P (

bar)

T (K)

1

2

3

45

6

1. CH4 (sI)

2. CH4-methylcyclopentane (sH)

3. natural gas hydrates (sII-sH)

4. 95.2% CH4-propane (sII)

5. CH4-6% isobutane (sII)

6. CH4-cyclopentane (sII)

A B

Hydrate stability of A: sI methane hydrate, and B: sII and sH hydrate

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10 12 14 16 18 20

Inte

ns

ity

Retention time

me

tha

ne

eth

an

e

pro

pan

eis

ob

uta

ne

bu

tan

e

iso

pe

nta

ne

n-p

en

tan

e

me

thy

lcy

clo

he

xan

e

2-m

eth

ylp

en

tan

e

me

thy

lcy

clo

pe

nta

ne

cy

clo

he

xa

ne

3-m

eth

ylp

en

tan

e

n-h

ex

an

e

be

nze

ne

Supplementary Figure 1 The GC spectra of the gas sample recovered from the dissociated gas hydrates from Barkley

Canyon, offshore Vancouver Island.

*: The peak intesities from propane on are enhanced by 10 times than the original.

Void

AA

B

C

A’

B’

Subsampling of gas

hydrate-containing

sediment column (Mt.

Elbert, Alaskan North

Slope)

HYPV4

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35

Sat

ura

tio

n le

vel (

% p

ore

sp

ace)

Distance from core surface (mm)

HYLN7

0

20

40

60

80

100

0 5 10 15 20 25 30

Sat

ura

tio

n le

vel (

% p

ore

sp

ace)

Distance from core surface (mm)

The saturation level of gas hydrate in the sediment

cores recovered from Mt. Elbert, Alaskan North Slope

HYLN7

HYPV4

10 20 30 40 50

2 Theta (degree)

feld

spar

002

012

112

022

Ice

Ice

Ice

Ice Ic

e

Ice

Qu

artz

023

123

004

014

114

124

233

Iro

n o

xid

e

Illit

e

035

135 00

6

feld

spar

feld

spar

Iro

n o

xid

e

HYLN7

HYPV4

2880 2900 2920 2940

Raman shift (cm-1)

2902

2914

-280

-240

-200

-160

0 10 20 30 40

HYLN7

-50

-45

-40

0 10 20 30 40

HYLN7

δ13C

c1

(‰)

δD

C1

(‰)

Distance from core surface (mm)

Figure The distributions of δ13C and δD in HYLN7 and HYPV4

-50

-45

-40

0 10 20 30 40

HYPV4

Sample

Pressurizing gas

-280

-240

-200

-160

0 10 20 30 40

HYPV4

Sample

Pressurizing gas

0

20

40

60

80

100

0 10 20 30 40

HYPV4

Distance from core surface (mm)

Con

trib

uti

on

of

seco

nd

ary

hyd

rate

(%

)

Figure The contribution of secondary formation of methane

hydrate to hydrate saturation in HYPV4

Thanks!