Centennial Talk Hydrates

Bureau of Economic Geology

Bureau of Economic Geology Centennial Lecture ProgramBureau of Economic Geology Centennial Lecture Program

DEEP-WATER HYDRATES:

ENERGY POTENTIAL

AND

TECHNICAL CHALLENGES

DEEP-WATER HYDRATES:

ENERGY POTENTIAL

AND

TECHNICAL CHALLENGES

Dr. Bob A. HardageDr. Bob A. Hardage


• First organized research unit of

The University of Texas at Austin

• State Geological Survey of Texas

• One of three units of the

Jackson School of Geosciences

• Staff—140, which includes

80 researchers

• First organized research unit of

The University of Texas at Austin

• State Geological Survey of Texas

• One of three units of the

Jackson School of Geosciences

• Staff—140, which includes

80 researchers

Bureau of Economic GeologyBureau of Economic Geology


• Fossil energy

• Environment

• Outreach

• Advising state and federal government

• Maintaining collections for research:– Cores: 3 repositories, 1,500 miles of core

– Electric logs: 1,000,000 logs in archive

• Fossil energy

• Environment

• Outreach

• Advising state and federal government

• Maintaining collections for research:– Cores: 3 repositories, 1,500 miles of core

– Electric logs: 1,000,000 logs in archive

Full-Time Research MissionFull-Time Research Mission


Bureau Facilities in Austin, TexasBureau Facilities in Austin, Texas


What is hydrate?What is hydrate?


DefinitionsDefinitions

Clathratus: Latin word meaning “enclosed by bars.”

Clathrate: Any compound formed by the inclusion of one

kind of molecule within cavities in the crystal lattice of

another kind of molecule. (No chemical bonds constrain

the trapped molecule.)

Hydrate: A subgroup of clathrates involving gas molecules

trapped inside structured water molecules.

Clathratus: Latin word meaning “enclosed by bars.”

Clathrate: Any compound formed by the inclusion of one

kind of molecule within cavities in the crystal lattice of

another kind of molecule. (No chemical bonds constrain

the trapped molecule.)

Hydrate: A subgroup of clathrates involving gas molecules

trapped inside structured water molecules.


Clathrate Hydrate of Natural GasesStructure I

Clathrate Hydrate of Natural GasesStructure I

Watermolecule

(46)

Methanemolecule

(8)

Modified from Bjørn Kvamme, University of Bergen, Norway

Watermolecule

(46)

Methanemolecule

(8)


The Energy PotentialThe Energy Potential


Size ComparisonsSize Comparisons

One “very fine”mineral grain

One “very fine”mineral grain

One unit volumeof hydrate

One unit volumeof hydrate

Diameter ~ 60μmDiameter ~ 60μm Diameter ~ 6nmDiameter ~ 6nm

1012 unit volumesrequired to fill

the grain

1012 unit volumesrequired to fill

the grain

QAd6959F


Size Comparison of Hydrate Unit Volumeand Typical Pores

Size Comparison of Hydrate Unit Volumeand Typical Pores

QAd6609

Micrograph courtesy Robert G. Loucks, BEG

0.1 mm

Structure I Unit VolumeStructure I Unit VolumeFrio Sandstone

( = 30%)

Frio Sandstone

( = 30%)Pore diameter

~6x10-5m

~1013 unitvolumes ofhydrate inone pore

space

3x10-9m


Hydrates as an Energy SourceHydrates as an Energy Source

QAd6959

Energy densityof LNG

Energy densityof LNG

Energy densityof hydrate

Energy densityof hydrate == 0.420.42


QAd5851

Exposed Structure II Gas HydrateBlock GC 185

Exposed Structure II Gas HydrateBlock GC 185

Orange colorcaused by oilOrange colorcaused by oil

From Sasson and MacDonald (1997)


QAd5901

Deep-Water Oil Seeps and HydrateGulf of Mexico

Deep-Water Oil Seeps and HydrateGulf of Mexico

Oil

Hydrates


The Carrot Dangledby the GovernmentThe Carrot Dangledby the Government


Energy Policy Act of 2005Energy Policy Act of 2005

Sec. 353. Gas Hydrate Production Incentive(b) Suspension of Royalties

(3) Amount of Relief

...The maximum suspension volume shall be30 billion cubic feet of natural gas perlease. Such relief shall be in addition toany other royalty relief under any otherprovision....

Sec. 353. Gas Hydrate Production Incentive(b) Suspension of Royalties

(3) Amount of Relief

...The maximum suspension volume shall be30 billion cubic feet of natural gas perlease. Such relief shall be in addition toany other royalty relief under any otherprovision....


Technical Challenge:

How do you finddeep-water hydrate?


How do you finddeep-water hydrate?


Deep water

Hydrate stability zone

Free-gas zone

Gas/water contact

BSR(Bottom-simulating reflector)

Sea floor

BrightreflectivityExpulsion

crater

Characteristics ofDeep-Water Hydrate Systems


QAd6937D


BSR Event: Gulf of Mexico, Line ABSR Event: Gulf of Mexico, Line A

Line Bintersection

1.5

2.0

Tim

e (s

)

QAd5890(a)


BSR Event: Gulf of Mexico, Line ABSR Event: Gulf of Mexico, Line A

Line Bintersection

1.5

2.0

Tim

e (s

)

QAd5890


Deep water

Hydrate stability zone

Free-gas zone

Gas/water contact

BSR(Bottom-simulating reflector)

Sea floor

BrightreflectivityExpulsion

crater



QAd6937D


Profile 549

A. Carbonate-cemented shells

B. Layered clam shells

Study Site 2: Genesis Field AreaBlock GC 205

Study Site 2: Genesis Field AreaBlock GC 205

QAd6510



How do you evaluatethe resource?


How do you evaluatethe resource?


The Expensive Option:

Drill a well.

The Expensive Option:

Drill a well.


GR (API)

30 80 1.1 0.7 1.61.9 1.5 1.9

Bulk-density Velocity Resistivityg/cm3 km/sec ohm-m

Hydrate

~0.2-m400

600

500

300

200

Dep

th b

elo

w s

eafl

oo

r (m

)

Paull and others (1996)

Hydrate Log Data: Blake Ridge (ODP 995)Hydrate Log Data: Blake Ridge (ODP 995)

QAd5173


A More Attractive Option:

Develop a remote, large-areaevaluation technology

(seismic imaging?).

A More Attractive Option:

Develop a remote, large-areaevaluation technology

(seismic imaging?).


VSP OBC/OBSVibrator

Well

Air gun

Deep water

Similar geometry

Seafloor

Sea level

Multicomponentsensor

Multicomponentsensor

Sourcestation

Sourcestation

VSP AND DEEP-WATER OBC/OBS DATA ACQUISITION:SIMILAR ELEVATION DIFFERENCES BETWEEN

SOURCES AND RECEIVERS

VSP AND DEEP-WATER OBC/OBS DATA ACQUISITION:SIMILAR ELEVATION DIFFERENCES BETWEEN

SOURCES AND RECEIVERS

QAd4647


4-C OBC COMMON-RECEIVER GATHER, CDP 13949,LINE 549, BLOCK 204 (50-m SHOT SPACING)

4-C OBC COMMON-RECEIVER GATHER, CDP 13949,LINE 549, BLOCK 204 (50-m SHOT SPACING)

QAd4171


COMMON-RECEIVER GATHERS IN REDUCED-TIME FORMATWITH SPHERICAL DIVERGENCE CORRECTION

COMMON-RECEIVER GATHERS IN REDUCED-TIME FORMATWITH SPHERICAL DIVERGENCE CORRECTION

QAd4172


BASIC RESPONSES OF OBC SENSORSBASIC RESPONSES OF OBC SENSORS

QAd4170


SEPARATING DOWNGOING AND UPGOING WAVEFIELDSSEPARATING DOWNGOING AND UPGOING WAVEFIELDS

QAd4175


Hydrophone/15 (P) Vertical geophone (Z)

2.0

1.5

1.0

0.5

-2000 0 2000

Tim

e (s

)

Tim

e (s

)

2.0

1.5

1.0

0.5

-2000 0 2000

Source offset (m) Source offset (m)

GAS HYDRATE OBC VSP EXAMPLE 1GAS HYDRATE OBC VSP EXAMPLE 1

QAd4612x


Down wave Up wave

2.0

1.5

1.0

0.5

-2000 0 2000

Tim

e (s

)

Tim

e (s

)

2.0

1.5

1.0

0.5

-2000 0 2000


SEPARATION OF DOWN AND UP WAVEFIELDS:COMMON-RECEIVER GATHER, WATER DEPTH = 871 M



P + Z / cos() P - Z / cos()

QAd4613x


Seafloor

0.5

0.3

0.1

0

-2000 0

Tim

e (s

)

Source offset (m)

0.4

0.2

2000

P-P REFLECTIVITY: SEAFLOOR DATUMP-P REFLECTIVITY: SEAFLOOR DATUM

(1) Reflectivity (f) =Up wave (f)

Down wave (f)

+(2) Damping

+(3) Inverse Fourier transform

+(4) Time derivative

QAd4614x


HORIZON-ORIENTED STATIC CORRECTIONS: IDEAL FORANGLE-DEPENDENT REFLECTIVITY AND VELOCITY ANALYSIS

HORIZON-ORIENTED STATIC CORRECTIONS: IDEAL FORANGLE-DEPENDENT REFLECTIVITY AND VELOCITY ANALYSIS

Pre-NMO

3.5

2.5

1.0

0

-2000 0 2000

Tim

e b

elo

w s

eafl

oo

r (s

)

Source offset (m)

0.5

1.5

2.0

3.0

ddt

(PP) Static corrected

-2000 0 2000Source offset (m)

0.24

0.20

0.16

0.08

Tim

e b

elo

w s

eafl

oo

r (s

)

0.12

QAd4620x

Target event


COMPARISON OF DYNAMIC CORRECTIONS AND HORIZON-ORIENTED STATIC CORRECTIONS, WATER DEPTH = 871 MCOMPARISON OF DYNAMIC CORRECTIONS AND HORIZON-ORIENTED STATIC CORRECTIONS, WATER DEPTH = 871 M

QAd4619x

Static corrections Dynamic corrections

0.24

0.20

0.16

0.08

-2000 0 2000

Tim

e b

elo

w s

eafl

oo

r (s

)

-2000 0 2000


0.12

0.24

0.20

0.16

0.08

Tim

e b

elo

w s

eafl

oo

r (s

)

0.12


NMO-CORRECTED COMMON-RECEIVER GATHER WITHDEPTH-POINT-OFFSET OVERLAY, WATER DEPTH 871 MNMO-CORRECTED COMMON-RECEIVER GATHER WITHDEPTH-POINT-OFFSET OVERLAY, WATER DEPTH 871 M

QAd4618x

0.35

0.25

0.15

0.10

-2000 0

Tim

e b

elo

w s

eafl

oo

r (s

)

0.30

0.20

20001000-1000

0.05

0

Source offset (m)

Depthpointoffset

10 m

85 m

160 m


CONSTRUCTING P-P IMAGE WITH VSP MINI-IMAGESCONSTRUCTING P-P IMAGE WITH VSP MINI-IMAGES


BASIC RESPONSES OF OBC SENSORSBASIC RESPONSES OF OBC SENSORS

QAd4170


ISOLATING THE P-SV MODEISOLATING THE P-SV MODE

HL = Hemipelagic layer

QAd4177


QAd4179

Before After

EMPHASIZING P-SV EVENTS, LINE 549, BLOCK GC204EMPHASIZING P-SV EVENTS, LINE 549, BLOCK GC204


QAd4181

ESTIMATION OF P-SV REFLECTIVITYESTIMATION OF P-SV REFLECTIVITY


QAd4771

PS DATA, PS DATA, DYNAMIC TIME CORRECTIONSDYNAMIC TIME CORRECTIONS

PS DATA, PS DATA, DYNAMIC TIME CORRECTIONSDYNAMIC TIME CORRECTIONS


CONSTRUCTING P-SV IMAGE WITH VSP MINI-IMAGESCONSTRUCTING P-SV IMAGE WITH VSP MINI-IMAGESCONSTRUCTING P-SV IMAGE WITH VSP MINI-IMAGESCONSTRUCTING P-SV IMAGE WITH VSP MINI-IMAGES

QAd5877


Comparison of PP ImagesComparison of PP Images

QAd4760

Receiver number50 100 150

PP image (5-m spacing)

350

0

50

100

150

200

250

300

Receiver number50 100 150

Production PP (12.5-m CDP)

350

0

50

100

150

200

250

300

Seafloor

Expulsionchimney

Expulsionchimney

4 km4 km

Red

uce

d t

ime

(ms)

PP

tim

e (m

s)


Raw data

Flattened to seafloor

1000 m

Expulsionchimney

South North

0 1000

Chirp trace number4000 50002000 3000 6000

60

10

0

30

50

40

20

Chirp Sonar Data, Line 549Chirp Sonar Data, Line 549

Tim

e (m

s)

QAd4234(a)


Comparison of P-SV Image withAUV P-P Image

Comparison of P-SV Image withAUV P-P Image

PS

tim

e (m

s)

Vp

/Vs

= 3

4

PP

tim

e

(m

s)

Receiver number

Chirp-sonar (25-m spacing)

0

5

10

Receiver number

New PS processing

350

0

50

100

150

200

250

300

400

450

20

2520 100 16040 60 80 120 140 20 100 16040 60 80 120 140

15

Vp/Vs-50 -50

58

Seafloor

34

27

Unconformity

R014

4 km4 km

surface

QAd4767


GR (API)

30 80 1.1 0.7 1.61.9 1.5 1.9

Bulk-density Velocity Resistivityg/cm3 km/sec ohm-m

Hydrate

~0.2-m400

600

500

300

200

Dep

th b

elo

w s

eafl

oo

r (m

)

Paull and others (1996)

Hydrate Log Data: Blake Ridge (ODP 995)Hydrate Log Data: Blake Ridge (ODP 995)

QAd5173


ACCURACY OF INTERVAL VP (< 1%?)ACCURACY OF INTERVAL VP (< 1%?)



You have to know the morphology if velocity is

used to estimatehydrate concentration


Hydrate/Sediment Grain-to-Grain Morphology Models

Model C:Layered, Solid Phase

Model D:Layered, Disseminated Phase

Model A:Disseminated, Load-bearing

Model B:Disseminated, Non-Load-Bearing

Sediment

Hydrate

QAd4571


Model-Based Vp, Host Sediment = Sand, Porosity = 0.37

0 0.1 0.2 0.3 0.41500

2000

2500

3000

3500

4000

Vp

[m

/s]

Model C:Layered, Solid Phase

0 0.1 0.2 0.3 0.41500

2000

2500

3000

3500

4000

Vp

[m

/s]

Cgh = volume fraction of gas hydrate

Model D:Layered, Disseminated Phase

0 0.1 0.2 0.3 0.41500

2000

2500

3000

3500

4000V

p [

m/s

]

Model A:Disseminated, Load-bearing

0 0.1 0.2 0.3 0.41500

2000

2500

3000

3500

4000

Vp

[m

/s]

Model B:Disseminated, Non-Load-Bearing

Fast

Slow

Fast

Slow

cgh cgh

QAd4572


Hydrate Cores: Offshore Korea7

8 c

m

6 cm Load-bearing Veins

QAd6545


The BiggestTechnical Challenge:

How do you producethe hydrate?


Stability Domains: Hydrate, Ice, Methane

A B

100

200

500

1000

2000

10

50

100

200

Hydrate +water + gas

A B

Hydrate/gasphase boundary

Gas+water

Hydrate+ice+gas

Gas+ice Ice/water phase boundary

10-10 0 20 30 40Temperature (°C)

Dep

th (

m)

Pre

ssu

re (

atm

)

QAd4240

A = D ir ec t io n p h as e b o u n d ary sh ifts if Na C l o r N 2 is a d d edB = D ir ec tio n p h ase b o u n d a ry sh ifts if C O 2 , H 2S , C 2H 6 , o r C 3H 8 is ad d ed

Modified from Kvenvolden (1998)


So, how do we summarizethe technical challenges?


“Reports that say that something hasn’thappened are always interesting to me,because as we know, there are known knowns; there are things we know we know.We also know there are known unknowns; that is to say we know there are things we know we don’t know. But there are also unknown unknowns — the ones we don’t know we don’t know.”

Donald RumsfeldDepartment of Defense News BriefingFebruary 12, 2002


ACKNOWLEDGEMENTACKNOWLEDGEMENT

● U.S. Department of EnergyContract DE-FC26-05NT42667

● Minerals Management ServiceContract 1435-01-05-CT-39388

● U.S. Department of EnergyContract DE-FC26-05NT42667

● Minerals Management ServiceContract 1435-01-05-CT-39388

Hydrate research funded by:Hydrate research funded by:

Technology

Centennial Talk Hydrates