Fiery Ice 2010 - GNS Science

7th International Workshop on Methane Hydrate Research and Development (Fiery Ice 2010) Te Papa, Wellington, New Zealand, 10-12 May 2010 (Workshop Report)

I. Pecher V. Stagpoole S. Henrys

GNS Science Miscellaneous Series 36 May 2011

BIBLIOGRAPHIC REFERENCE

Pecher, I.; Stagpoole, V.; Henrys, S. 2011. 7th International Workshop on Methane Hydrate Research and Development (Fiery Ice 2010) Te Papa, Wellington, New Zealand, 10-12 May 2010 (Workshop Report), GNS Science Miscellaneous Series 36. 29 p + Abstracts.

I. Pecher, GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand V. Stagpoole, GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand S. Henrys, GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand

© Institute of Geological and Nuclear Sciences Limited, 2011 ISSN 1177-2441 ISBN 978-0-478-19831-7

GNS Science Miscellaneous Series 36 i

CONTENTS

SPONSORS OF FIERY ICE 2010 .......................................................................................... II

LOCAL ORGANISING INSTITUTIONS ................................................................................. II

SUMMARY ............................................................................................................................ III

1.0 LIST OF PARTICIPANTS ........................................................................................... 1

2.0 SCIENTIFIC PROGRAM ............................................................................................ 3

3.0 POSTERS ................................................................................................................... 7

4.0 FIELDTRIP: EAST COAST RESERVOIRS AND TECTONICS .................................. 9

5.0 SUMMARIES OF BREAKOUT SESSIONS ................................................................ 9

5.1 Breakout Session 1: Pre-drilling characterization ........................................................... 9 5.2 Breakout Session 2: Exploration drilling and post-drilling characterization ..................11

5.2.1 New tools, logging vs. wireline, coil tube drilling ............................................ 11 5.2.2 Dynamic gas hydrate system ......................................................................... 11 5.2.3 Heterogeneity of gas hydrates ....................................................................... 11 5.2.4 Integration of available datasets..................................................................... 12

5.3 Breakout Session 3: Production tests and modelling ...................................................13 5.3.1 Testing ............................................................................................................ 13 5.3.2 Modelling ........................................................................................................ 13

5.4 Breakout Session 4: Gas hydrate petroleum system ...................................................15 5.5 Breakout Session 5: Laboratory studies (Jeffrey Priest, Dendy Sloan) ........................19 5.6 Breakout Session 6: Near-seafloor gas hydrates, vent sites, environmental

(biological) impact of hydrate production, and geohazards from gas hydrates ............21 5.7 Breakout Session 7: High-latitude Gas Hydrates .........................................................22 5.8 Breakout Session 8: Gas hydrate formation – laboratory, field, modelling...................23

6.0 POST-CONFERENCE WORKSHOP – GAS HYDRATE STUDIES OFFSHORE NEW ZEALAND: CHARTING THE (HOPEFULLY) NOT-SO-DISTANT FUTURE ... 24

7.0 FIERY ICE 2010 COMMITTEES ............................................................................... 25

7.1 Fiery Ice Steering Committee .......................................................................................25 7.2 Scientific and Organizing Committee............................................................................25 7.3 Conference Manager ....................................................................................................25 7.4 Handbook ......................................................................................................................25

APPENDICES

Appendix 1: Presentations ................................................................................................................26 Appendix 2: Abstracts .......................................................................................................................29

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SPONSORS OF FIERY ICE 2010

Support by the Office of Naval Research Global was provided by GRANT NUMBER: N62909-10-1-1038

LOCAL ORGANISING INSTITUTIONS

We are grateful to Positively Wellington Tourism for providing bags, maps, and other general information for conference participants.

GNS Science Miscellaneous Series 36 iii

SUMMARY

The workshop took place from 10-12 May 2010, preceded by a field trip on 9 May 2010 and followed by a post-conference workshop on New Zealand gas hydrates at GNS Science on 13 May 2010. 61 registrants took part from 15 countries. The key theme of the workshop was “Characterization of Gas Hydrate Reservoirs”. The conference consisted of one oral stream, a single poster session and eight breakout sessions for discussions.

A common thread running through the conference was that economic viability of gas production from hydrates is now being viewed as a realistic possibility within the next decade. Exploration techniques very similar to those for conventional oil and gas exploration have recently been developed and ground-truthed. A Petroleum System approach to understand gas hydrate occurrences is also in development; again very similar to approaches used for conventional hydrocarbon studies. There was also an almost surprising agreement on several previously hotly debated topics.

A distinctive highlight of the workshop was a speech given by Hon. Gerry Brownlee, Minister for Economic Development and Minister for Energy. This speech emphasized that the New Zealand government is seriously analysing its options for development of its gas hydrate resource.

The following breakout sessions provided an excellent overview on current developments of gas hydrates research (with session chairs and one selected key highlight):

1. Pre-drilling characterization of gas hydrate reservoir (Dan McDonnell, Tatsuo Saeki, Nathan Bangs)

• A workflow for gas hydrate exploration has been developed.

2. Exploration drilling and post-drilling characterization (Gary Humphrey, Pawan Dewangan)

• Focus on long-term monitoring and resolution.

3. Production tests and modelling (George Moridis, Takao Inamori)

• Long-term production test still missing.

4. Gas hydrate petroleum system (Kelly Rose, Kalachand Sain)

• System is being developed very similar to conventional petroleum systems

5. Laboratory studies (Jeffrey Priest, E. Dendy Sloan)

• Advocating benchmark tests between several laboratories with results to be presented at ICGH in Edinburgh, July 2011.

6. Near-seafloor gas hydrates, vent sites, environmental (biological) impact of hydrate production, and geohazards from gas hydrates (Reem Feij-Ayoub, Jens Greinert, Charlie Paull)

• Little is known compared to other gas-hydrate-related topics.

7. High-latitude gas hydrates (Umberta Tinivella, Jens Greinert, Richard Coffin)

• The most vulnerable system with respect to climate change.

8. Gas hydrate formation – laboratory, field, modelling (George Moridis)

iv GNS Science Miscellaneous Series 36

• Gas hydrate dissociation is understood, but formation still a big question.

A general theme throughout the conference was a focus on reservoir quality: high saturations of gas hydrate are not sufficient for economic viability of gas production – gas hydrates must also be stored in a reservoir rock with high permeability.

The workshop was concluded by a plenary discussion, chaired by Richard Coffin.

A post-conference workshop at GNS Science with a focus on New Zealand gas hydrates was attended by 27 participants of the Fiery Ice meeting. It was agreed that while the Hikurangi Margin represented a promising gas hydrate province, exploration now needed to focus on finding locations with high-quality (sand) reservoirs.

GNS Science Miscellaneous Series 36 1

1.0 LIST OF PARTICIPANTS Last Name First Name Organization Email Address Aboel-Naga Hossam The University of

Auckland New Zealand [email protected]

Bangs Nathan University of Texas USA [email protected]

Barnes Philip National Institute of Water & Atmospheric Research

New Zealand [email protected]

Castellazzi Claire NIWA New Zealand [email protected]

Chong Kevin NZ Centre for Advanced Engineering


Coffin Richard Naval Research Laboratory

USA [email protected]

Cook Richard Crown Minerals, MED New Zealand [email protected]

Cooper Joanna University of Otago New Zealand [email protected]

Crabtree Peter MED New Zealand [email protected]

Dewangan Pawan National Institute of Oceanography

India [email protected]

Diaz-Naveas Juan P.Universidad Catolica de Valparaiso

Chile [email protected]

Eaton Simon Shell Todd Oil Services New Zealand [email protected]

Edwards Nigel University of Toronto Canada [email protected]

Faure Kevin GNS Science New Zealand [email protected]

Fohrmann Miko GNS Science New Zealand [email protected]

Freij-Ayoub Reem CSIRO Australia [email protected]

Golding Thomas Victoria University New Zealand [email protected]

Gorman Andrew University of Otago New Zealand [email protected]

Greinert Jens NIOZ Netherlands

Hamdan Leila U.S. Naval Research Laboratory


Henrys Stuart Geological and Nuclear Sciences Ltd


Hooper George CAENZ New Zealand [email protected]

Humphrey Gary Fugro GeoConsulting, Inc. USA [email protected]

Inamori Takao JGI Japan [email protected]

Jaeger Rob Shell NZ New Zealand

Kastner Miriam Scripps Institution of Oceanography


Kinoshita Christo-pher USA [email protected]

Klaucke Ingo Leibniz Institute of Marine Sciences

Germany [email protected]

Kvamme Bjorn University of Bergen Norway [email protected]

Lee Joo Yong Korea Institute of Geosciences and Mineral Resources

Korea [email protected]

Liu Char-Shine National Taiwan University

Taiwan [email protected]

Maruyama Hiroaki Japan Oil, Gas and Metals National Corporation – Sydney

Australia [email protected]

Masutani Stephen University of Hawaii USA [email protected]

Matsushima Jun The University of Tokyo Japan [email protected]

McConnell Dan AOA Geophysics USA [email protected]

Mir Reza A. University of Toronto Canada [email protected]

Moridis George Lawrence Berkeley National Laboratory


mailto:[email protected]































mailto:Jun%[email protected]%1Etokyo.ac.jp




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Last Name First Name Organization Email Address Nagao Jiro National Institute of

Advanced Industrial Science and Technology (AIST)

Japan [email protected]

Nakatsuka Yoshihiro Japan Oil, Gas and Metals National Corporation


Patil Shirish University of Alaska Fairbanks


Paull Charles Monterey Bay Aquarium Research Institute


Pecher Ingo GNS Science New Zealand [email protected]

Plummer Rebecca SAIC/Naval Research Lab USA [email protected]

Priest Jeffrey University of Southhampton

UK [email protected]

Rose Kelly U.S. Department of Energy


Saeki Tatsuo Japan Oil, gas and Metals National corporation


Sain Kala-chand National Geophysical Research Institute

India

Schwalenberg Katrin Federal Institute for Geosciences and Natural Resources

Germany [email protected]

Sloan Dendy Colorado School of Mines USA [email protected]

Srinivasan Roopa Victoria University New Zealand [email protected]

Stagpoole Vaughan GNS Science New Zealand [email protected]

Swidinsky Andrei University of Toronto Canada [email protected]

Teniere Paul Solid Energy New Zealand Ltd.


Teske Andreas University of North Carolina at Chapel Hill


Tinivella Umberta Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS

Italy [email protected]

Uchida Tsutomu Hokkaido Univ. Japan [email protected]

Willoughby Ele University of Toronto Canada [email protected]

Wright Ian National Oceanography Centre, Southampton

UK [email protected]

Wu Daidai Guangzhou Institute of Energy Conversion, CAS

China [email protected]

Wu Nengyou Guangzhou Institute of Energy Conversion, CAS

China [email protected]

Yang Tsanyao Frank National Taiwan University

Taiwan [email protected]

























2.0 SCIENTIFIC PROGRAM

SUN 9 MAY 8:30 AM – 6:00 PM: Field trip

7:00 PM – 8:30 PM: Icebreaker & Registration

Start Lead author Institution Title (brackets: working titles) MON 10 MAY

8:00 Registration opens

8:30 I Pecher GNS Science, Lower Hutt, New Zealand

Welcome

8:45 B Kvamme U. Bergen, Norway Report from the 6th Fiery Ice workshop, Bergen, 2008

Key Aspects of Gas Hydrates Research 9:15 T Saeki JOGMEC, Chiba,

Japan Exploration Activities of Methane Hydrate Resources in the Eastern Nankai Trough

9:45 COFFEE

10:15 C Paull MBARI, Monterey, USA (Gas hydrates and geohazards)

10:45 M Kastner Scripps, La Jolla, USA

Links Between the Global Gas Hydrates Reservoir and Climate Change

Character-ization of Gas Hydrates Reservoirs 11:15 D McConnell AOA Geophysics,

Houston, USA

Can resource quality gas hydrate sands be identified with conventional seismic data? Findings from recent Chevron-US Dept of Energy JIP drilling

11:30 S Noguchi (presented by T Saeki)

JOGMEC, Chiba, Japan

3-D internal architecture of methane hydrate bearing turbidite channels in the eastern Nankai Trough, Japan

11:45 N Bangs U Texas Austin, USA

Rapid, Episodic Gas Migration into the South Hydrate Ridge Gas Hydrate Field Inferred from 4D Seismic Imaging

12:00 LUNCH

1:00 G Humphrey Fugro, Houston, USA

Coring, Pressure Coring and Core Analysis for Gas Hydrate Studies

1:15 G Humphrey Fugro, Houston, USA

Borehole Logging Application for Gas Hydrate Investigations

1:30 U Tinivella INOGS, Trieste, Italy

Geophysical Data and GIS: An Approach to Characterise the Gas Hydrate Reservoir (South Shetland Margin)

1:45 K Schwalen-berg BGR Hanover, Germany

Gas Hydrate Assessment Using Marine Electromagnetic Methods: Case Studies and Model Studies

Gas Hydrate Production 2:00 G Moridis Lawrence Berkeley

National Lab., USA Gas Production from Hydrate Accumulations in Geologic Media

2:15 T Inamori JOGMEC, Chiba, Japan

The Monitoring of the Gas hydrate Production Test in the Mackenzie Delta

2:30 B Kvamme U. Bergen, Norway (CO2-CH4 replacement)

2:45 POSTERS Posters and Coffee

4:15 Chairs Introduction to Breakout Sessions I


Breakout Sessions I

4:30 BREAKOUT

Breakout Sessions I 1. Pre-drilling characterization of gas hydrate reservoirs 2. Exploration drilling & post-drilling reservoir characterization 3. Production tests and modelling

6:00 END Conclusion of Monday Sessions

Public Talk, Rutherford House 7:30 C Paull MBARI, Monterey,

USA Gas Hydrate Research: Past, Present, and Future

TUE 11 MAY

8:15 Rapporteurs Start of Day and Resumes from Breakout Sessions I

Deep Biosphere 9:00 A Teske U North Carolina, Chapel Hill, USA The Marine Deep Subsurface Biosphere

Methane Cycling

9:15 R Coffin NRL, Washington, DC, USA

A Geochemical Overview of Shallow Sediment Methane Source and Cycling on the Alaskan Shelf of the Beaufort Sea

Shallow Gas Hydrates

9:30 J Greinert NIOZ, Texel, Netherlands

Gas Hydrate and Cold Seep Research Along the Hikurangi Margin, New Zealand: Results from 2006 and 2007

09:45 COFFEE Laboratory Studies 10:15 J Priest U Southampton, UK Hydrate Morphology and its Influence on

Sediment Properties

10:30 M Batzle (presented by ED Sloan)

Colorado School of Mines, Golden, USA

Geomechanical & Production Studies to Assess the Risks of Gas Production from Methane Hydrates in Nature

Wellbore Stability 10:45 R Freij-Ayoub CSIRO, CESRE, Perth, Australia

Numerical Modelling of Casing Integrity in Hydrate-Bearing Sediments

Gas Hydrate Programs

11:00 K Rose

US Department of Energy, Morgantown, WV, USA

Understanding the Energy and Environmental Implications of Gas Hydrates and the Potential Impact of Major Field Studies

11:30 T Uchida Hokkaido University, Sapporo, Japan

Gas Hydrate Program (Japan)

11:45 I Pecher GNS Science, Lower Hutt, New Zealand

Current State of Gas Hydrate Exploration in New Zealand

12:00 LUNCH

1:00 Hon G Brownlee New Zealand Government, Wellington

(Keynote speech, Minister of Economic Development, Minister of Energy and Resources)

2:00 E Willoughby U Toronto, Canada Gas Hydrates in Canada

2:15 I Wright NOC Southampton, UK

Overview of Marine Hydrate Research at National Oceanography Centre, Southampton

2:30 S Chand NGU Trondheim, Norway

Gas Hydrates on the Norway-Barents Sea-Svalbard Margin (GANS) - New Results on Gas Hydrate System and Fluid Flow

2:45 POSTERS Posters and Coffee

4:15 Chairs Introduction to Breakout Sessions II


Breakout Sessions II

4:30 BREAKOUT

Breakout Sessions II 4. Gas hydrate petroleum system 5. Laboratory studies 6. Near-seafloor gas hydrates, environmental impact of hydrate

production, and geohazards from gas hydrates (note: may be split into two)

6:00 END Conclusion of Tuesday Sessions

Dinner 7:00 Conference Dinner at Copthorne Oriental Bay

WED 12 MAY

8:15 Rapporteurs Start of Day and Resumes from Breakout Sessions II

(Contd., Gas Hydrate Programs) 9:00 N Wu

Guangzhou Institute of Energy Conversion, China

Gas Hydrates Research in Northern South China Sea

9:30 TF Yang National Taiwan University

Introduction to the Gas Hydrate Master Project of Energy National Science and Technology Program of Taiwan

10:00 COFFEE

10:30 P Dewangan National Institute of Oceanography, Goa, India

(Gas hydrates research at NIO)

10:50 K Sain

National Geophysical Research Institute, Hyderabad, India

Current State of India’s Gas-Hydrates Activities and NGRI’s Initiatives

11:10 J Diaz P. Universidad Catolica de Valparaiso, Chile

Advances in Hydrates Exploration at the Chilean Margin

11:40 J. Lee

Korea Institute of Geosciences and Mineral Resources, Daejeon

The Review of Gas Hydrate research in Korea

12:00 LUNCH

1:00 Chairs Introduction to Ad-hoc Breakout Sessions and Mini-workshops

Ad-hoc Breakout Sessions & Mini-Worshops

1:15 BREAKOUT Ad-hoc Breakout Sessions and Mini-workshops

2:45 COFFEE

3:15 Rapporteurs Resumes from Ad-hoc Breakout Sessions Mini-workshops

Plenary Discussion

4:00 PLENARY

Plenary Discussion: Characterization of Gas Hydrate Reservoirs Next Workshop Final Remarks

6:00 END Conclusion of Workshop


THU 13 MAY Post-conference Workshop, Gas Hydrate Studies Offshore New Zealand

Post-conference Workshop at GNS Science, 1 Fairway Drive, Lower Hutt: Gas Hydrate Studies Offshore New Zealand: Charting the (Hopefully) Not-so-distant Future Fiery Ice participants most welcome Objectives: The gas hydrates workshop has three overarching objectives: 1. Exploration for gas hydrates as an energy source: To determine options for energy-related gas

hydrates exploration with a focus on identifying sites for exploration drilling on the Hikurangi Margin within an (optimistic) timeframe of five years.

2. Basic science related to gas hydrates: To discuss possible collaboration on fundamental science questions related to gas hydrates in New Zealand

3. IODP drilling: To compile fundamental science questions broadly related to gas hydrates that may become part of an IODP proposal for the Hikurangi Margin


3.0 POSTERS

Lead author Presenter (if different) Institution Title

Barnes P - NIWA, Wellington, New Zealand

Tectonic and Geological Framework for Gas Hydrates and Cold Seeps on the Hikurangi Subduction Margin, New Zealand

Chen Q - Qingdao Institute of Marine Geology, China

High Pressure Differential Scanning Calorimetry Measurement of Hydrates Phase Equilibrium in Pore Water of Shenhu area, South China Sea

Davy B Pecher IA GNS Science, Lower Hutt, New Zealand

Giant Pockmarks on the Chatham Rise, New Zealand - Evidence for Massive Release of Gas from Hydrates During Glacial-Interglacial Cycles?

Golding T - Victoria University of Wellington, New Zealand

PEGASUS Survey 2009/2010: Am 80 km-long BSR and Associated Seismic Features From Line 02P2029

Fohrmann, M - GNS Science, Lower Hutt, New Zealand

Analysing Gas-Hydrate-Bearing Channel Systems Using an AVO Seismic Inversion Technique on the Southern Hikurangi Margin, New Zealand

Haeckel M Klauke I IfM-GEOMAR, Kiel, Germany The German collaborative project SUGAR

Hamdan LJ - NRL, Washington, DC, USA DIversity and Biogeochemical Structuring of Bacterial Communities in Methane Charged Sediments from the Porangahau Ridge, New Zealand

Hu GW Ye Y Qingdao Institute of Marine Geology, China

Acoustic Properties of Gas Hydrate-Bearing Unconsolidated Sediments and Elastic Velocity Models Validation

Inamori T - JOGMEC, Chiba, Japan Rock Physics Model of Methane Hydrate Bearing Sediments in the Nankai Trough and the Mackenzie Delta

Joshi RK Dewangan P National Institute of Oceanography, Goa, India

Geoscientific Investigations of Marine Sediments in the Vicinity of Gas Hydrates: Offshore Krishna Godavari (KG) Basin, India.

Klaucke I - IfM-Geomar, Kiel, Germany The Variability of Gas Seeps Along the Hikurangi Margin offshore New Zealand

Lee, JY - Korea Institute of Geosciences and Mineral Resources, Daejeon, Korea

Thermal stimulation production experiment using natural GH-bearing marine sediments from the Ulleung Basin – Preliminary Results

Liu CL Ye Y Qingdao Institute of Marine Geology, China

Characteristics of Marine Gas Hydrate Recovered from Shenhu Area in South China Sea

Liu CS - National Taiwan University Recent Advances on Seismic Investigation of the Gas Hydrate Field Offshore Southwestern Taiwan

Lorenson T Rose K USGS Menlo Park, USA Methane Concentrations in Sediment And Bottom-Water Of The Alaskan Beaufort Sea

Lorenson T Rose K USGS Menlo Park, USA Gas geochemistry of the Mount Elbert Gas Hydrate Test Well, Milne Pt. Alaska: Implications for Gas Hydrate Exploration in the Arctic

Matsushima J - University of Tokyo, Japan Experimental Approach to Characterize Seismic Attenuation in Methane Hydrate-Bearing Sediments

Mir RA - University of Toronto, Canada Controlled Source EM and 3D modeling of resistive targets

Nagakubo S Nakatsuka Y JOGMEC, Chiba, Japan Overview of the Research Program on Environmental Impact Assessment for the Marine Production Test in Offshore Japan

Navalpakam R - Victoria University of Wellington, New Zealand

AVO Analysis of Bottom Simulating Reflectors (BSRs) in the Central Hikurangi Margin

Ogebule OY Pecher IA Heriot-Watt University, Edinburgh, UK

Possible Evidence for Gas Hydrates in the Northland – Northern Taranaki Basin, New Zealand

Pecher IA - GNS Science, Lower Hutt, New Zealand

The Gas Hydrates Petroleum System on the Hikurangi Margin, New Zealand - Current State of Knowledge

Roach L - University of Toronto, Canada Long-term Seafloor Compliance Monitoring of the Bullseye Vent Gas Hydrate System


Lead author Presenter (if different) Institution Title

Schicks J Klaucke I Helmholtz Centre Potsdam, Germany

Methane Recovery From and Carbon Dioxide Sequestration in Natural Gas Hydrates: Development and Test of Innovative Methods

Shiga T Uchida T Hokkaido University, Sapporo, Japan Sintering Process Observations on Clathrate Hydrates

Swidinsky A - University of Toronto, Canada Joint Inversion of Navigation and Gas Hydrate Resistivity Structure Using a Fixed Transmitter and a Moving, Linear Receiver Array: A Model Study

Swidinsky A - University of Toronto, Canada Transient Electromagnetic Imaging of Thin Resistive Targets: Applications for Gas Hydrate Assessment

Toulmin S Pecher IA Heriot-Watt University, Edinburgh, UK

Gas Hydrate Formation on the Porangahau Ridge Offshore New Zealand – Evidence from Seismic, Heatflow, and Electromagnetic Data

Willoughby, E - University of Toronto, Canada Long-Term Seafloor Observatory Monitoring of Marine Gas Hydrates with NEPTUNE, Canada

Wu DD - Guangzhou Institute of Energy Conversion, China

Early Diagenesis Records and Geochemical Characteristics of Gas Hydrate in the South China Sea


4.0 FIELDTRIP: EAST COAST RESERVOIRS AND TECTONICS

The workshop was preceded by a fieldtrip to the East Coast on Sunday, 9 May 2010. The offshore East Coast region is New Zealand’s most prospective gas hydrates province. The field trip offered a transect through the uplifted subduction margin and included Miocene and younger deep-water sedimentary rocks that are similar to offshore strata that host gas hydrates. The tour started in Wellington, travelled northeast through the Wairarapa fore-arc to the coastal township of Castlepoint before returning to Wellington in the afternoon.

During the tour the tectonic development of the region was discussed in relation to petroleum systems and reservoir facies development. At Castlepoint deepwater reservoir facies-turbidites and mass-flow deposits were examined that are likely to have hosted gas hydrates in the past. The East Coast also has a working thermogenic petroleum system.

Highlights of the return trip were stops at thermogenic source rock outcrops and a winery visit. The tour also stopped at the Wellington Fault crush zone in the Hutt Valley.

5.0 SUMMARIES OF BREAKOUT SESSIONS

5.1 BREAKOUT SESSION 1: PRE-DRILLING CHARACTERIZATION (Summary by Nathan Bangs)

Session chairs: Dan McConnell, Tatsuo Saeki, Nathan Bangs 22 participants

In discussions of the pre-drilling characterization it quickly became evident that pre-drilling characterization of gas hydrate reservoirs cannot be achieved by any single tool, but instead it requires a combined suite of collocated experiments. Collocated studies reveal hydrate characteristics by their combined attributes, which can vary from location to location depending on the sedimentary environment, hydrate form, concentrations, and distribution. Furthermore, many of these data sets need to be acquired at a resolution that approaches or exceeds typical experiments and at the upper limits of equipment and facilities. Consequently every tool’s effectiveness varies between hydrate reservoirs, which makes acquiring multiple data sets crucial.

A logical approach to predrilling characterization is to acquire multiple data sets in a prioritized sequence. From discussions in our group, the consensus for a logical sequence is one that provides data in a sensible order for assessing the hydrate reservoir, and one that considers the practical aspects of conducting at-sea operations. The data acquisition we developed is as follows:


Cruise # 1

1. Multibeam and sidescan (critical for assessing seafloor vent systems, carbonates that are part of chemosynthetic communities, etc.)

2. CTD profiles

3. Conventional 2D seismics (5 – 80 Hz range and with long offsets)

4. Ocean Bottom Seismometers

Cruise # 2

5. Controlled Source Electrical/Magnetic surveys (acquired at slow speeds ~ 1kt)

6. Piston cores for fluid chemistry,

7. Heat flow probe studies

Cruise # 3

8. 3D seismic survey

Cruise # 4

9. High-resolution Ocean Bottom Seismometers+2D seismics

Cruise # 5

10. Specialized tools (sniffers, water column reflectivity, …..) where possible/practical

Cruise # 6

11. Ocean Bottom Cable surveys

Cruise # 7

12. Drilling

Because no single tool is completely effective at hydrate assessment and results vary with each particular reservoir, the degree to which hydrates need to be characterized before drilling is not definitive. In essence, drilling provides an additional data set that can constrain and calibrate predrilling data sets, and further refine models for further drilling. Predrilling characterization and drilling are not sequential phases but should be considered as overlapping phases of characterizing hydrate reservoirs.


5.2 BREAKOUT SESSION 2: EXPLORATION DRILLING AND POST-DRILLING CHARACTERIZATION (Summary by Gary Humphrey & Ingo Pecher)

Session chairs: Gary Humphrey, Pawan Dewangan

The session focused on borehole tools, the fact that gas hydrate systems are dynamic, the heterogeneity of gas hydrate deposits, and the need for data integration.

5.2.1 New tools, logging vs. wireline, coil tube drilling

Discussion

• Problems with existing tools such as caving in LWD, Core recovery, In situ Testing (temp & pressure), in situ pore water sampling

Recommendation

• Gas hydrate systems are poorly know therefore, multi tool approach should be used to get reliable information

5.2.2 Dynamic gas hydrate system

Discussion

• Gas hydrate systems are known to change rapidly with time

• We need to monitor the changes using permanent sensors (Pressure & Temperature)

• List of available sensors

Recommendation

• Continuous monitoring of temperature & pore pressure in the borehole

• Instrumented gas hydrate region

• Production test – before, during and after the test

• Need to develop the technology - temperature is OK, need work on pressure

5.2.3 Heterogeneity of gas hydrates

Discussion

• Gas hydrate are linked with deep-sea sands

• Large variation in both lateral and vertical directions

Recommendation

• Need for volume experiment (out of the borehole)

• Need for high resolution seismic tools such as DTAGS (Deep-Towed Array Geophysical System), 3D high-resolution seismic)

• Shear wave measurements using permanent sensors


5.2.4 Integration of available datasets

Discussion

• Exploration of gas hydrates has generated a wealth of information around the world

• Need for integration of different datasets for better reservoir characterization

Recommendation

• Sharing the data for gas hydrate community under the framework of UN and Google


5.3 BREAKOUT SESSION 3: PRODUCTION TESTS AND MODELLING (Summary by George Moridis)

Session Chairs: George Moridis, Takao Inamori

What is the state of the art in session topic?

5.3.1 Testing

• Very few tests, but the need is critical

• Mallik, Canada, 2002 is the golden standard in terms of design, NOT duration (partial validation of codes)

• Nankai Trough, Japan, 2004: 36 test wells (drilling, well testing, logging, LWD, wireline, etc.)

• Mallik 2007-2008 important, but results have not been released yet

• Mt. Elbert, Alaska, MDT test (2009): Determination of properties, analysis of behavior unique to hydrates, (partial) validation of codes

• Long term field test needed, planned for 2011 (18-24 months): L-pad, Mt. Elbert, Alaska - Critically important for code validation and analysis of long-term behavior

• 2012 Offshore field test, Nankai Trough: Maximum one test

5.3.2 Modelling

• Production:

– MH21 code

– TOUGH+HYDRATE code (Lawrence-Berkeley National Laboratory)

– STOMP-HYDRATE code

– CMG STARZ code

– Comparable results of models above quadruple point

– Partial model validation: Using lab tests, but the short-term duration and small size of the system does not allow full validation

• Production+Geomechanics:

– TOUGH+HYDRATE+FLAC3D (coupled codes), COTHMA (Masui) code

– Partial model validation: Using lab tests, but the short-term duration and small size of the system does not allow full validation

• Production+Geomechanics+Geophysics (?), Monitoring production

– TOUGH+HYDRATE+FLAC3D+IIT3D

What are current and future challenges?

• Validation of field tests – credibility issues

• Seismic data analysis and interpretation/accurate predictions of saturation through geophysical surveys.

• Reservoir characterization, heterogeneity description and scale/effects on behaviour.


• Testing in low-permeability systems (finer media, high gas-hydrate saturation, or both), feasibility of production under these conditions.

• Design and interpretation of uncooperative lab test results/usefulness in model validation.

• Development of constitutive relationships that accurately describe the geomechanical behaviour and stability of hydrate-bearing media.

• Behaviour of inclined wells (horizontal and vertical have been studied).

How do we address these challenges?

• No insurmountable technical challenges to production from hydrates (modelling, engineering, well installation and operation)

• There are some knowledge gaps (simulation, laboratory studies, material properties and parameters, etc.), but these are being addressed already.

How can we collaborate on this?

• Extensive collaboration on a global scale are in progress

• Good communication for conscious replication of effort

• Better coordination at the research management levels

• Importance of policy as a driver for research

See also references:

Moridis, G.J., T.S. Collett, M. Pooladi-Darvish, S. Hancock, C. Santamarina, R. Boswell, T. Kneafsey, J. Rutqvist, M. Kowalsky, M.T. Reagan, E.D. Sloan, A.K. Sum and C. Koh, Challenges, Uncertainties and Issues Facing Gas Production From Hydrate Deposits in Geologic Systems, Invited Paper SPE 131792, 2010 Unconventional Gas Conference, February 23-25, Keystone, Colorado.

Moridis, G.J., T.S. Collett, R. Boswell, M. Kurihara, M.T. Reagan, C. Koh and E.D. Sloan, Toward Production From Gas Hydrates: Current Status, Assessment of Resources, and Simulation-Based Evaluation of Technology and Potential, SPE Reservoir Evaluation & Engineering, 12(5): 745-771, 2009 (October 2009 issue, SPE-114163-PA. doi: 10.2118/114163-PA).


5.4 BREAKOUT SESSION 4: GAS HYDRATE PETROLEUM SYSTEM (Summary by Kelly Rose)

Session Chairs: Kelly Rose, Kalachand Sain 16 participants

Adapting the Conventional “Petroleum” System Approach to Natural Gas Hydrate Systems – Climate, Slope Stability & Resource Studies

Recent research and field studies have demonstrated that there are predictable controls on natural gas hydrate occurrences worldwide in marine and permafrost environments. As a result, researchers are finding that they can use elements of the conventional petroleum system approach to characterize and predict the nature of natural gas hydrate systems in the subsurface. Perhaps the best example to date of this approach is the U.S. Geological Survey’s use of a modified petroleum system approach to define “technically recoverable” natural gas hydrate (NGH) resources across the North Slope of Alaska [Collett et al., 2009]. However, other researchers have begun to apply this approach to climate, slope stability, and resource characterization studies across the globe.

Elements of the classic petroleum system approach that play a role in the evaluation of NGH systems include geologic and hydrologic components and processes necessary to generate and store hydrocarbons such as, a natural gas source, migration pathway, reservoir rock, trap and seal, and timing. In NGH-bearing systems an additional, unique component, gas hydrate stability conditions (pressure, temperature, and other factors), is also key to evaluating these occurrences.

During the 2010 Fiery Ice Workshop, one breakout session was dedicated to the discussing elements of the petroleum system approach and how they relate to the characterization and evaluation of subsurface NGH occurrences. A summary of the group’s findings for each element is provided below.

Source: The source of natural gas in a conventional petroleum system usually refers to a “mature source rock,” which is rich in organic matter, where hydrocarbons are generated and then migrate into a “reservoir” facies. Generally, gas from this type of source is generated as a result of thermogenic processes. This source-type applies to NGH systems, however, NGH systems can also be proximally and/or self-sourced. These self-sourced systems can be relatively “immature” and are frequently related to methane that is produced biogenically. Many examples of self-sourced, biogenic NGH occurrences have been observed in the field. NGH systems that contain gas from thermogenic sources overlie, and are associated with deeper, conventional petroleum accumulations. However, many biogenically sourced NGH accumulations in the marine environment have been found in regions where no pre-existing conventional petroleum accumulations exist. The nature of these biogenically-sourced occurrences means that NGH accumulations occur in many regions worldwide that previously were thought to be barren of natural gas resources.

Some key items that may require further consideration relative to NGH systems and sources include:

• In gas hydrate systems much of the gas is likely to be self-sourced from proximal sediments


• So the methanogens and microbial processes in these occurrences may need better constraints? What are the rates, types of bugs, extremophiles?

• “Immature” or “modern” biogenic and terrigenous organic matter is often associated with biogenic, shallow/younger hydrates; (e.g. Chilean margin, Andamans, upwelling of planktonic forms)

• In active margins is there any chance that methane from mantle sources is significant?

• There is a need to constrain and better understand the maturation timing and processes that control NGH source-gases, particularly for younger systems.

• The types of organic matter and methanogenesis impact source, but how much does this impact the source of gas for NGH systems?

• Need efficient and cost-effective methods for distinguishing gases from thermogenic sources consumed and converted to biogenic gases.

• Thermogenic-sourced reservoirs are more likely to contain mixed gases (for gas hydrate formation) which would depress the base of gas hydrate stability

• Microbial processes, can have a significant impact on the genesis but also consumption of gas concentrations in these reservoirs

Migration: Fluids and gas must have a means for migrating into the hydrate stability zone where, if they accumulate in sufficient quantities, hydrate may form. Many of the processes controlling fluid and gas flow in hydrate systems are similar to those that control conventional petroleum occurrences and include, diffusive flux, advective flux, migration along faults and fractures, and flow through permeable strata such as sand or ash layers. Often fluid and gas flow is influenced by stratigraphic and/or structural features in a given system.

Other factors that may be key and influence the migration of both gas and water in NGH systems include:

• Is gas migrating as free gas or in solution?

• Hydrate-lined conduits may serve as “express ways” for gas to migrate further up and into the stability zone

• Overpressuring, often associated with base of gas hydrate stability but could also occur within the GHSZ, where free gas accumulates beneath NGH cemented strata. The reduced permeability leads to overpressure conditions.

• Tectonic stresses can result in differential stresses; dilation fractures; earthquake controlled flux?

• In some systems fluid flux may be episodic

• Salt tectonic, mud diapir driven fluid and sediment injection and withdrawal pathways

• Fluid expulsion features may also serve as conduits for gas and water flux into or even through the GHSZ.

• Which part of the hydrate system are you targeting? (near base of stability; intra-stability; near surface; intra-permafrost)

Reservoir: Conventionally the term “reservoir” is used to refer to a porous and permeable geologic “container” where high concentrations of hydrocarbons accumulate. This “container” is usually associated with a lithology, such as a conglomerate, sand or ash bed,


but may also be structurally controlled such as a fault or facture system. Conventional reservoirs host NGH accumulations and are the primary target for NGH resource-studies. However, NGH has been observed much more frequently as disseminated accumulations in low to moderate concentrations in fine grained, low permeability lithologies (clays and silts) [Boswell and Collett, 2006]. For climate and stability studies, these “reservoirs” represent a far larger volume of NGH globally.

Many key questions about how the form and nature of a NGH “reservoir” impacts the saturation and stability of NGH accumulations remain unresolved. Some of these questions which were raised during the workshop include:

• What is the impact of mineralogy, sorting, grain size, grain shape, and degree of cementation of the reservoir facies on NGH accumulations? Some experimental studies are beginning to tackle these questions but many remain unresolved.

• To date no NGH accumulations have been found in carbonate reservoirs (lithologic-carbonates as opposed to authigenic carbonates which frequently precipitate in NGH systems). But the potential for such occurrences exists and may present unique characteristics.

• Lithified vs. unlithified systems

– Degree of consolidation can be quite variable in tectonically active regions, or arctic shallow marine, differences in lithology, burial history (will affect seismic/geophysical signatures)

– In disseminated systems may hydrate inhibit compaction, help maintain primary porosity?

• Mounds, shallow massive accumulations are enticing targets for all manner of NGH studies (resource, climate, stability) because of their high saturations, but how pervasive are they? What is their longevity?

• How dynamic are NGH reservoirs over time (crosses into the “timing” element of these systems analyses)

Trap & Seal: Traditionally, the term trap refers to geologic constraints, such as changes in lithology or structural elements that lead to the accumulation of hydrocarbons in the reservoir. Often, traps are “sealed” by low-permeability strata such as shales or clays. These elements are both applicable to NGH systems, in addition, the precipitation of NGH itself can lead to reduced permeability, and thus act as a self-seal. However, similar to the “reservoir” element described above, many questions were raised with regards to the traps and seals in NGH systems:

• What is the role of gas diffusion processes?

• Do we need a trap or seal? Are gas hydrates a self limiting system?

• Would a leaky system be better?

– Perfect seal means very low diffusion out of the system

– Leaky system provides constant gas source from lower to higher in system

• Hydrate seal at the base of gas hydrate stability often leads to a pool of free gas beneath. Can impact source and seal integrity over time in NGH systems.

• Authigenic carbonate and microbial mat caps can lead to discrete, laterally discontinuous seals


• Oil films may also serve as a trap/seal in certain NGH systems.

• What is the impact and frequency of episodic tectonic events on seal integrity in NGH systems?

Timing: The remaining key element from a conventional petroleum systems approach is the timing of different actions in the system such as, hydrocarbon migration into the reservoir, development of the trap, seal and structural elements of the system, age and maturation of the system. In addition, with NGH systems this element acquires some unique complexities. Because of the diversity of NGH accumulations observed in the natural environment, the impact of timing on NGH systems will vary. Some of these questions related to the timing of NGH formation, longevity, and stability includes:

• Charge, how much time does it take to fully saturate a particular NGH system?

• Does the age of the hydrate system matter? How old is the oldest NGH?

• What exactly happens, and how quickly does degradation of NGH occur if the methane source is turned off?

• Can you “date” the age of hydrate occurrences (carbonates, chemo critters)

• Role of sea level fluctuations and mean temperature variations?

• Role of changes in ocean currents?

Distinctive considerations: In addition to the traditional elements from a conventional petroleum system’s approach, there are aspects to consider that are particular to NGH systems. Probably the most distinctive of these is the need for proper stability conditions, pressure, temperature, and other elements which dictate whether NGH will form such as pore fluid chemistry. In some areas with geologic and/or hydrologic complexities, the NGH stability zone is impacted by salt and hyper-saline fluids, mud diapirism, and tectonic features, all of which have the potential to change stability conditions on a variety of scales within the overall NGH stability zone itself.

Boswell, R., and T. Collett (2006), The gas hydrate resource pyramid, Fire in the Ice, Fall 2006, 5-7.

Collett, T., A. Johnson, C. Knapp, and R. Boswell (2009), Gas hydrates: A review, in Natural Gas Hydrates: Energy Resource Potential and Associated Geologic Hazards, edited by T. Collet, et al., pp. 146-219, AAPG Memoir.


5.5 BREAKOUT SESSION 5: LABORATORY STUDIES (JEFFREY PRIEST, DENDY SLOAN) (Summary by Dendy Sloan)

Session chairs: Jeffrey Priest, Dendy Sloan 8 participants

Objective: Establishing International Standards for Hydrates by Inter-laboratory Sample Comparisons

Issues Raised

• What should be the common parameters between labs? Wave velocity? Strength?

• Characterisation of samples?

• Differences in formation methods?

• What type of geomaterial should be used? Ottawa, Leighton Buzzard, Toyoura sand – In Japan MH21 consortium has done work on standard tests between different universities and has common methodology between labs

General consensus is that having some ‘Standard test’ is worthwhile to validate individual laboratory results! Measurement of basic parameters (Vp and Vs) will allow different lab tests to be validated

Inter-laboratory results will compare five tests:

1. Dry F110 Ottawa Sand with two porosities: Porosity 1 will be 36% and porosity 2 will be 40% (±1%). The effective vertical and horizontal stresses will be: 3 MPa and 1.35 MPa, respectively, at a temperature of 5 °C, with an initial pore space water saturation of 0%.

2. Water-saturated F110 Ottawa Sand: Porosity 1 will be 36% and porosity 2 will be 40% (±1%). The effective vertical and horizontal stresses will be: 3 MPa and 1.35 MPa, respectively, at a temperature of 5 °C, with an initial pore space water saturation of 100%.

3. Partially Water-saturated F110 Ottawa Sand: Porosity 1 will be 36% and porosity 2 will be 40% (±1%). The effective vertical and horizontal stresses will be: 3 MPa and 1.35 MPa, respectively, at a temperature of 5 °C, with an initial pore space water saturation of 20%.

4. Frozen Partially Water-saturated F110 Ottawa Sand: Porosity 1 will be 36% and porosity 2 will be 40% (±1%). The effective vertical and horizontal stresses will be: 3 MPa and 1.35 MPa, respectively, at a temperature of -5 °C, with an initial pore space water saturation of 20%.

5. Partially Hydrate-saturated F110 Ottawa Sand: Porosity 1 will be 36% and porosity 2 will be 40% (±1%). The effective vertical and horizontal stresses will be: 3 MPa and 1.35 MPa, respectively, at a temperature of 5 °C, with an initial pore space water saturation of 20%. Each laboratory will specify their method of introducing gas, and will attempt to provide imagery.

The results from the above Tests 1-5 will be presented at the Seventh International Conference on Gas Hydrates in Edinburgh, U.K., July 17-21, 2011. Future tests will be on end members, where results (Vs, Vp) are compared with natural hydrate samples/well-logs,


etc., such as (a) cementing/strengthening (of sediment) hydrates, (b) pore-filling/load-bearing hydrates, (c) with hydrates as part of fluids, (d) hydrate layers/nodules/veins, (e) hydrate layers formed from auto-layering of broader grain size distribution of F110 Ottawa sand, (f) checking morphology using micro-CT X-ray imaging, cryo-SEM.


5.6 BREAKOUT SESSION 6: NEAR-SEAFLOOR GAS HYDRATES, VENT SITES, ENVIRONMENTAL (BIOLOGICAL) IMPACT OF HYDRATE PRODUCTION, AND GEOHAZARDS FROM GAS HYDRATES (Summary by Rick Coffin)

Session chairs: Reem Freij-Ayoub, Jens Greinert, Rick Coffin, Charlie Paull 10 participants

This session focused the environmental impact of deep sediment gas hydrate mining on the shallow sediment and deep ocean water column. Discussions were focused on three primary topics; 1) Needs for long term monitoring of environmental impact; 2) Understanding and predicting geohazards between different ecosystems; and 3) Methods that need to be applied and developed for monitoring during production. There was agreement during the discussions that monitoring would require integration of biology, geochemistry and geology for a thorough assessment of ecosystem impact. In addition, the monitoring protocol required to set the spatial and temporal plan needs consideration of the sediment and water column properties that influenced biological and chemical cycles.

There was strong consensus that there is a need for long term monitoring of the well during production. For initial ecosystem assessment and monitoring of environmental impact, there was a general consensus that the study area needs to be in a range of three times the platform with a thorough vertical sediment sampling at 10-20 cm intervals through core depths that were deep enough to assess changes in the deep sediment methane flux. Date from cores would include sediment and porewater geochemical profiles to assess methane cycling, microbial cycling rates and community diversity, and higher trophic level biology. Monitoring time scales for the sediment coring would depend on the initial rates for methane diffusion or advection and biological diversity at the sediment-water column interface. In situ monitoring platforms that include acoustics, methane sensors, and pH, oxygen, and salinity probes needs to be coupled with the sediment coring for a thorough long term assessment. A concern brought up during the discussion was implementation of a monitoring program that would be capable of observation of environmental impact relative to the natural ecosystem changes. To develop a thorough assessment of environmental impact monitoring of a non drill site with similar characteristics is needed. With the comparison of these sites observations could be made for changes in microbial and higher trophic level community diversity, as well as faster or slower rates in community production and general carbon cycling.

Geochemical and physical data obtained for the environmental impact assessment would contribute to the evaluation of geohazards before and during the mining. These data are necessary to assess slope stability controlled by hydrated sediment and the potential influence on platform stability, pipeline and cable breaking, and monitoring “creep” in and out of the gas hydrate stability zone. The environmental and geohazard assessment needs to include monitoring the shallow sediment and deep water column biological and geochemical monitoring as well as assessment of the well and sediment physical properties; e.g., well bore dimensions and sand water production. The data acquired to assess geohazards needs to be outlined for coastal and permafrost systems.


5.7 BREAKOUT SESSION 7: HIGH-LATITUDE GAS HYDRATES (Summary by Rick Coffin)

Session chairs: Jens Greinert, Umberta Tinivella, Rick Coffin 12 participants

Through this session Arctic and Antarctic climate change was discussed with a primary focus on the Arctic and identification of regions with methane hydrates that are subject reduced stability during climate change. However, it was stated that there is a need to select key regions in the Antarctic and start monitoring programs that would provide comparisons between the two oceans. While permafrost hydrates do not exist in the Antarctic there is interest in studying the coastal deep sediment hydrates.

For the Arctic, there is a need to determine the potential methane flux into the atmosphere as well as the water column and how it varies between regions like the Beaufort and Chukchi Seas, relative to the East Siberia, Laptev and Kara Seas off Russia and the Norwegian-Greenland Sea, off Norway. In the conversation it was clear that the permafrost and the identification of subglacial hydrates is a key focus for prediction of climate change impact on the Earth. However, there is also a need to predict the hydrate stability in the coastal sediment and the potential effect of warming on the methane flux to the water column and atmosphere. This discussion included the need to understand the relative contribution of tundra and coastal permafrost hydrates to the atmospheric methane flux. Key questions that came from the discussions included: 1) What is the abundance of hydrates in tundra and coastal gas fields? 2) What is the permafrost methane production rate and how much will production elevate during warming? 3) What is the net carbon balance between dissolved and particulate organic and inorganic carbon that is supported by methane cycling? 4) Will elevated methane contribute to coastal water column hypoxia? and 5) What are the key parameters needed for monitoring in testing sediment, water column and atmospheric flux models to predict the future methane endpoint and intermediate cycles.

While the discussion was primarily focused on the contribution of methane to climate change, there was also interest in the regional distribution of methane hydrates in terms of potential energy. Oil and gas exploration by Shell, BP, and ConocoPhillips in different regions of the Arctic Ocean has started to include seismic surveys for potential hydrate deposits. There is a need for further seismic expeditions and preliminary geochemical evaluation of the potential permafrost and deep sediment hydrate deposits. Another issues stated regarding the hydrate dissociation focused on US Navy concerns for changes shallow sediment and water column that will change strategic optic and acoustic signatures.

The focus on energy exploration and climate change requires a thorough review of the hydrate deposits in the tundra and coastal waters. There is a need for installation of long term monitoring systems for comparisons between regions. The monitoring and field calibration of the monitoring stations will provide data to predict the relative contribution of different seas in the Arctic to climate change and the time scale for significant changes. The data gathered requires thorough application and integration of seismic, geologic, geochemical and biological parameters. There needs to be consideration of new field and technology application and development to assess the hydrate loading and stability.


5.8 BREAKOUT SESSION 8: GAS HYDRATE FORMATION – LABORATORY, FIELD, MODELLING (Summary by George Moridis)

Session Chair: George Moridis 9 participants

Field

• Mathematical modelling: While dissociation seems to be modelled properly, formation modelling is only qualitatively OK. Quantitative models can only reproduce simple systems involving hydrate formation. The reason is that long-term hydrate formation in the oceans may occur at geologic time, and the scale is such that other processes (sedimentation, subduction, climate change, etc.) that are not accounted in the models become important. However, for dissociation, the consensus is that the existing codes are up to the task.

• Formation: Nucleation, bio-geo-thermo-hydraulic uncertainties;

• Different formation scenarios – slow and fast

• Formation in the deep sea – slow, we do know some rates (advective, diffusive); Hydrate formation through supersaturation of ocean water in CH4

→ More in-situ testing is needed

• Issued related to gas hydrate formation in sediments: Is it the first formation on geologic timescales, is it re-formation of gas hydrate after dissociation?

• Need to understand the formation of gas that forms hydrate (e.g., biogenic vs. thermogenic). There is a link between gas hydrate formation and the fluid-migration system

• Fast formation takes place at vent sites at the seafloor (simple tests can lead to uniqueness of system). However, how can we help characterise this process?

• Carbonates – how much carbon is sequestered?

Laboratory

• We do not know what we form, how does it relate to reality? The issue is that we have yet to recover an undisturbed hydrate sample, so we are not sure if artificial (man-made) hydrates adequately represent hydrates in nature.

• Do minor features matter?

• Are gas hydrates cementing or pore filling (both can be formed, either at the same time or at different times)?

• Formation dependent on where you force the hydrate to grow

→ Reference techniques for hydrate formation are required


6.0 POST-CONFERENCE WORKSHOP – GAS HYDRATE STUDIES OFFSHORE NEW ZEALAND: CHARTING THE (HOPEFULLY) NOT-SO-DISTANT FUTURE (Summary by Ingo Pecher)

13 May 2010 at GNS Science Session chair: Ingo Pecher 27 participants

This workshop provided a forum for a discussion by international experts on New Zealand’s gas hydrates. The workshop focussed almost entirely on gas hydrates as a possible future energy source, which is the key motivation for gas hydrate studies in New Zealand. The discussion was guided by results from the Fiery Ice breakout sessions, in particular the exploration template for drill-site selection compiled during Breakout Session 1 (“Pre-drilling characterization of gas hydrate reservoirs”). Highlights included:

• There was general agreement that with current technology, the most promising sites for gas hydrate production are sand reservoirs close to the base of gas hydrate stability (BGHS). Identifying such reservoirs should be a key focus of future research. But:

• There was also a discussion on whether it is our (mostly scientists’) role to define commercially interesting targets since we don’t know yet what will be commercially viable in several years.

• 3D seismic data are essential for identifying possible target sites for exploration drilling, not only for structural and lithological interpretation of reservoirs (e.g., sand channels) but also for gas hydrate quantification.

• Controlled-source electromagnetics, which is a promising technique for gas hydrate quantification, needs to target the zone around the BGHS (~700 mbsf), much deeper than for previous studies (~100-200 mbsf).

• Seep sites are not necessarily of interest for identifying commercially interesting gas hydrate deposits.

• Shallow gas hydrates are currently not of interest for gas production but they represent a geo- and platform/drilling hazard.

• Dredging of outcrops e.g., on channel walls, may provide access for studying potential reservoir rocks without drilling.

In general, the workshop participants seemed to be optimistic that the Hikurangi Margin is likely to contain concentrated gas hydrate deposits in high-quality reservoirs that may be economically promising in the future.


7.0 FIERY ICE 2010 COMMITTEES

7.1 FIERY ICE STEERING COMMITTEE • Richard B. Coffin, Naval Research Laboratory, Washington, DC, USA

• Bjørn Kvamme, U. Bergen, Norway

• Stephen M. Masutani, Univ. Hawaii, Honolulu, USA

• Hideo Narita, National Institute of Advanced Science and Technology (AIST) Sapporo, Japan

• Tsutomo Uchida, Hokkaido Univ., Japan

7.2 SCIENTIFIC AND ORGANIZING COMMITTEE • Ingo Pecher, GNS Science, Lower Hutt, New Zealand (conference convenor)

• Janet Simes, Absolutely Organised, Wellington, New Zealand (conference manager)

• Mac Beggs, New Zealand Oil & Gas Ltd., Wellington, New Zealand

• Richard Cook, Ministry for Economic Development, Wellington, New Zealand

• Kevin Chong, New Zealand Centre for Advanced Engineering, Christchurch, New Zealand

• Andrew Gorman, Univ. Otago, Dunedin, New Zealand

• Reem Freij-Ayoub, CSIRO Petroleum Resources, Perth, Australia

• Jens Greinert, Nederlands Instituut voor Onderzoek der Zee (NIOZ), Texel, Netherlands

• Stuart Henrys, GNS Science, Lower Hutt, New Zealand

• Geoffroy Lamarche, National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand

• Vaughan Stagpoole, GNS Science, Lower Hutt, New Zealand

• Umberta Tinivella, L' Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy

• John Townend, Victoria University of Wellington, New Zealand

7.3 CONFERENCE MANAGER • Janet Simes, Absolutely Organised Ltd.

7.4 HANDBOOK • Vaughan Stagpoole

• Janet Simes

• Kitty Higbee


APPENDIX 1: PRESENTATIONS First Author (presented by) Affiliation Presentation Title

Nathan Bangs University of Texas at Austin, USA

Rapid, episodic gas migration into the South Hydrate Ridge gas hydrate field inferred from 4D seismic imaging

Phil Barnes NIWA, Wellington, New Zealand

Tectonic and geological framework for gas hydrates and cold seeps on the Hikurangi Subduction Margin, New Zealand

Mike Batzle (Dendy Sloan)

Colorado School of Mines, Golden, USA

Geomechanical & Production Studies to Assess the Risks of Gas Production from Methane Hydrates in Nature

Shyam Chand Geological Survey of Norway, Tromsø

Gas hydrates on the Norway – Barents Sea – Svalbard Margin (GANS) – New results on gas hydrate system and fluid flow

Chen Qiang Qingdao Institute of Marine Geology, China

High pressure differential scanning calorimetry measurement of hydrates phase equilibrium in pore water of Shenhu area, South China Sea

Rick Coffin NRL, Washington, DC, USA A geochemical overview of shallow sediment methane source and cycling on the Alaskan Shelf of the Beaufort Sea

Bryan Davy (Ingo Pecher)

GNS Science, Lower Hutt, New Zealand

Giant pockmarks on the Chatham Rise, New Zealand – Evidence for massive release of gas from hydrates during glacial-interglacial cycles?

Juan Diaz-Naveas P.Universidad Catolica de Valpraiso, Chile

Advances in hydrates exploration at the Chilean margin

Miko Fohrmann GNS Science, Lower Hutt, New Zealand

Analysing sand-dominated channel systems for potential gas-hydrate-reservoirs using an AVO seismic inversion technique on the Southern Hikurangi Margin, New Zealand

Reem Freij-Ayoub CESRE, Perth, Australia Numerical modelling of casing integrity in hydrate bearing sediments

Tom Golding Victoria University Wellington and GNS Science, Lower Hutt, New Zealand

Pegasus Survey 2009/2010: An 80 km-long BSR and associated seismic features from line 02P2029

Jens Grienert Royal NIOZ, Texel, Netherlands

Gas hydrate and cold seep research along the Hikurangi Margin, New Zealand: Results from 2006 and 2007

Matthias Haeckel (Ingo Klaucke)

IfM-GEOMAR, Keil The German collaborative project SUGAR

Leila Hamdan NRL, Washington, DC, USA Diversity and biogeochemical structuring of bacterial communities in metane charge sediments from the Porangahau Ridge, New Zealand

Hu Gaowei Qingdao Institute of Marine Geology, China

Acoustic properties of gas hydrate-bearing unconsolidated sediments and elastic velocity models validation

Gary Humphreys Fugro GeoConsulting, Inc., Houston, USA

Coring, pressure coring and core analysis for gas hydrate studies

Takao Inamori JOGMEC, Chiba, Japan Rock physics model of methane hydrate bearing seidments in the Nankai Trough and the Mackenzie Delta

Rajesk Kumar Joshi JOGMEC, Chiba, Japan Geoscientific investigations of marine sediments in the vicinity of gas hydrates: offshore Krishna Godavari (KG) basin, India

Miriam Kastner Scripps, La Jolla Links between the global gas hydrate reservoir and Climate Change

Ingo Klaucke IfM-GEOMAR, Kiel, Germany

The variability of gas seeps along the Hikurangi Margin offshore New Zealand

Bjørn Kvamme University of Bergen, Norway

Report from the 6t Fiery Ice workshop, Bergen, 2008 (no abstract)

CO2-CH4 Replacement (no abstract)

Joo Yong Lee Korea Institute of Geosciences and Mineral Resources, Daejeon, Korea

Review of gas hydrate research in Korea

Thermal stimulation production experiment using natural GH-bearing marine sediments from the Ulleung Basin – Preliminary Results

Liu Changling (Ye Yuguang)

Qingdao Institute of Marine Geology, China

Characteristics of marine gas hydrate recovered from the Shenu area of the South China Sea

Char-Shine Liu National Taiwan University Recent advances in seismic investigation of the gas hydrate field offshore south-western Taiwan


First Author (presented by) Affiliation Presentation Title

Tom Lorensen USGS Methane concentrations ins sediment and bottom-water of the Alaskan Beaufort Sea

Gas geochemistry of the Mount Elbert gas hydrate test well, Milne Pt. Alaska: Implications for gas hydrate exploration in the Arctic

Jun Matsushima University of Tokyo, Japan Experimental approach to characterising seismic attenuation in methane hydrate-bearing sdiments

Dan McConnell AOA Geophysics, USA Can resource quality gas hydrate sands be identified with conventional seismic data? Findings from recent Chevron-US Dept of Energy JIP drilling (no abstract)

Reza Mir University of Toronto, Canada

Controlled Source EM and 3D modelling of resistive targets

George Moridis Lawrence Berkeley National Lab, USA

Modelling Studies of Gas Production From Hydrate Deposits and of the Corresponding Geomechanical System Response

Sadao Nagkubo (Yoshihiro Nakatsuka)

JOGMEC, Chiba, Japan Overview of the Research Program on Enviromental Impact Assessment for the Marine Production Test in Offshore Japan

Roopa Srinivasan Victoria University Wellington, New Zealand

AVO Analysis of Bottom Simulating Reflectors (BSRs) in the Central Hikurangi Margin (no abstract)

Ning Fu Long China University of Geosciences, Wuhan, Hubei

A concept of utilizing solar energy to exploit gas hydrates buried in oceanic sediments

Charlie Paull Monterey Bay Aquarium Research Institute (MBARI), USA

PUBLIC LECTURE: Gas Hydrate Research: Past, Present, and Future

Satoshi Noguschi (Tatsuo Saeki)

Japan Oil, Gas and Metals National Corporation

3-D internal architecture of methans hydrate bearing turbidite channels in the eastern Nankai Trough, Japan

Oluwakemi Y. Ogebule (Ingo Pecher)

Heriot-Watt University, Edinburgh, UK

Possible evidence for gas hydrates in the Northaland – Northern Taranaki Basin. New Zealand.

Ingo Pecher GNS Science, Lower Hutt, New Zealand

The gas hydrate petroleum system on the Hikurangi Margin, New Zealand – Current state of knowledge

Current state of gas hydrate exploration in New Zealand

Jeffrey Priest University of Southampton, UK

Hydrate morphology and its influence on sediment properties

Lisa Roach Dept. of Physics, University of Toronto

Long-term seafloor compliance monitoring of the Bullseye Vent gas hydrate system

Kelly Rose US Department of Energy, USA

Understanding the Energy and Environmental Implications of Gas Hydrates and the Potential Impact of Major Field Studies

Tatsuo Saeki JOGMEC, Chiba, Japan Exploration Activities of Methane Hydrate resources in the eastern Nankai Trough

Kalachand Sain National Geophysical Research Institute, Hyderabad, India

Current state of India’s gas-hydrate activities and NGRO’s initiatives

Judith Schicks (Ingo Klauke)

Helmholtz Centre Potsdam, Germany

Methane recovery from and carbon dioxide sequestration in natural gas hydrates: Development and test of innovative methods

Katrin Schwalenberg DTH Hanover, Germany Gas hydrate assessment using marine electromagnetic methods: Case studies and model studies

Toshigi Shiga (Tsutomu Uchida)

Hokaido University, Japan Sintering process observations on clathrate hydrates

Andrei Swidinsky University of Toronto, Canada

Joint inverstion of navigation and gas hydrate resistivity structure using a fixed transmitter and a moving, linear receiver array: A model study

Andreas Teske University of North Carolina Chapel Hill, USA

The Marine Deep Subsurface Biosphere

Umberta Tinivella INOGS, Triest, Italy Geophysical data and GIS: An approach to characterise the gas hydrate reservoir (South Shetland Margin)

Suzannah Toulmin (Ingo Pecher)

Heriot-Watt University, Edinburgh, UK

Gas hydrate formation on the Porangahau Ridge offshore New Zealand – Evidence from seismic, heatflow and electromagnetic data

Tsutomu Uchida Hokaido University Gas Hydrate Program (Japan)

Ele Willoughby Dept. of Physics, University of Toronto, Canada

Long-term seafloor observatory monitoring of marine gas hydrates with NEPTUNE Canada

Gas Hydrates in Canada (no abstract)


First Author (presented by) Affiliation Presentation Title

Ian Wright National Oceanography Centre Southampton, UK

Overview of Marine Hydrate Research at National Oceanography Centre, Southampton

Wu Daidai Guangzhou Institute of Energy Conversion, China

Early diagenesis records and geochemical characteristics of gas hydrate in the South China Sea

Wu Negyou Guangzhou Institute of Energy Conversion, China

Gas hydrate research in the northern South China Sea

Yang Tsanyao Frank National Taiwan University Introduction to the gas hydrate master project of energy national science and technology program of Taiwan


APPENDIX 2: ABSTRACTS

RAPID, EPISODIC GAS MIGRATION INTO THE SOUTH HYDRATE RIDGE GAS HYDRATE FIELD INFERRED FROM 4D SEISMIC IMAGING

Nathan L. B. Bangs1, Mathew J. Hornbach1, and Christian Berndt2

1University of Texas at Austin, USA 2University of Kiel, Germany

In July 2008 we acquired a high-resolution 3D seismic reflection survey on board the R/V Thompson across South Hydrate Ridge in the vicinity of the 2002 IODP Leg 204 drill sites. We used two GI airguns as a source and recorded the data on the 10 streamer P-Cable system. The 30-m-long, single-channel streamers had 12.5 m separation; with this system we acquired a high-resolution binned volume with 12.5 x 12.5 m spacing that imaged a 6 x 3 km2 swath oriented NS across the summit of South Hydrate Ridge.

These data overlap with an older 3D volume acquired in 2000 using a similar source and a 600 m 48-channel streamer. We compared reflections between the two data sets to infer changes within the past eight years. The BSR, which we do not expect to change over such short time, indicates a remarkable similarity between the two data sets. BSR amplitudes patterns coincide and high amplitude BSR reflections as small as 25-50 m across appear collocated in both data volumes. Though the BSR shows little change in 8 years, Horizon A, identified from drilling as a 4 m-thick sandy turbidite layer that is gas charged and is the main feeder for gas to the hydrate field at the summit, shows significant reflection amplitude changes between 2000 and 2008. High amplitude areas of Horizon A have moved up-dip ~100 m in an area 500 m SE of Site 1248. The largest change, however, is at the summit beneath Site 1250, where Horizon A shows a significant increase in amplitude since 2000. From this 4D comparison we infer that the gas is migrating very quickly along Horizon A, where it is currently accumulating and perhaps building pressure beneath the summit vents of south Hydrate Ridge. Coincidentally vigorous gas venting at the seafloor ceased between 2007 and 2008 implying the vent between Horizon A and the seafloor has become plugged and is causing gas to accumulate along Horizon A beneath the summit. Gas flow to the seafloor will presumable resume once a new conduit is established. If our estimated rate of free gas migration is typical, the gas in the current gas-charged areas of Horizon A will likely migrate 1.2 km along Horizon A to the summit and vent episodically to the seafloor within several centuries.

TECTONIC AND GEOLOGICAL FRAMEWORK FOR GAS HYDRATES AND COLD SEEPS ON THE HIKURANGI SUBDUCTION MARGIN,

NEW ZEALAND

Philip M. Barnes1; Geoffroy Lamarche1; Joerg Bialas2; Stuart Henrys3; Ingo Pecher4; Gesa L.

Netzeband2; Jens Greinert5; Joshu J. Mountjoy1,6; Katherine Pedley6; Gareth Crutchley7

1National Institute of Water & Atmospheric Research, Wellington, New Zealand. 2Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel, Germany.

3 GNS Science, Lower Hutt, New Zealand. 4Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh, Scotland. 5Renard Centre

of Marine Geology, University of Gent, Belgium. 6Department of Geological Sciences, University of Canterbury, New Zealand.

7Department of Geology, University of Otago, New Zealand.

Gas hydrates, bottom simulating seismic reflectors (BSRs), and fluid/methane vent sites are widespread on the Hikurangi subduction margin of New Zealand. We use seismic reflection and multibeam bathymetric data to characterize their tectonic and geological framework. The tectonic structure and geomorphology of the margin varies along strike primarily in response to changes in subducting crustal structure, convergence rate and obliquity, and sediment supply. The imbricated frontal wedge of the central margin is characteristic of wide (ca. 150 km), poorly drained and over pressured, low taper (~4°) accretionary thrust systems associated with a relatively smooth subducting plate, a thick trench-fill sedimentary sequence, weak basal décollement, and moderate convergence rate. This region differs from the northern, Hawkes Bay to East Cape, sector of the margin where subducting seamounts, faster convergence rate, and reduced trench sediment supply have resulted in a dramatically reduced and steeper active frontal wedge, complex deformation and uplift of frontal ridges above subducting asperities, and a tectonic regime dominated by non-accretion and tectonic erosion. Five areas with multiple fluid/methane seep sites, referred to informally as Wairarapa, Uruti Ridge, Omakere Ridge, Rock Garden, and Builders Pencil, typically lie in about 700-1200 m water depth on the crests of thrust faulted ridges along the mid-slope. There is a clear relationship between the seep sites and major thrust faults, which are conduits for fluid and gas migration sourced from the deeper, inner parts of the thrust wedge, and probably from subducting sediments. Beneath the seafloor seeps on ridge crests, in the hanging wall section of thrust faults, there is typically a conspicuous break in the BSR, and commonly a seismically-resolvable fault-fracture network through which fluids and gas percolate. All of these seep sites lie near the outer edge of a deforming Cretaceous and Paleogene inner foundation, at the rear of the accreted trench fill turbidites. One seep site lies in close proximity to a major strike slip fault. Another occurs directly above a subducting seamount. We consider that the Cretaceous and Paleogene inner foundation is, on the whole, relatively impermeable and focuses fluid migration preferentially to its outer edge via major low angle thrust faults and the décollement. The findings presented in this poster are reported in Barnes et al., 2009. Marine Geology doi:10.1016/j.margeo.2009.03.012.

GEOMECHANICAL AND PRODUCTION STUDIES TO ASSESS THE RISKS OF GAS PRODUCTION FROM METHANE HYDRATES IN

NATURE

M. Batzle, C. Koh, N. Lu, M. Prasad, D. Sloan, A. Sum, D. Wu, Y.-S. Wu, X. Yin

Colorado School of Mines, Golden, Colorado 80401, USA

The work will combine the skill sets of researchers in Chemistry, Geophysics, Mechanical Engineering, Petroleum Engineering, and Chemical Engineering to assess risks to hydrated gas production, using both experiments and modeling. A subset of the planned work will be presented for the following topics:

1. Geophysical and Rock Property Measurements, including CT scanning 2. Sample Preparation and Characterization – International Round Robin

Testing/Standards 3. Micro-structural Modeling of Hydrate in Sediment 4. Predicting Mechanical Stability of Sediments with Hydrates 5. Micromechanical Force Experiments for Hydrate Self-adhesion and Wall Adhesion 6. Production Experiments and Simulations using LBNL’s TOUGH model to assess

Depressurization, Thermal Stimulation, and CO2/CH4 Exchange 7. Slim-Tube Measurements of Hydrate Flow Properties

GAS HYDRATES ON THE NORWAY - BARENTS SEA - SVALBARD

MARGIN (GANS) – NEW RESULTS ON GAS HYDRATE SYSTEM AND FLUID FLOW.

S. Chand1, H. Haflidason2, J. Mienert3 and the GANS working group4

1,4 Geological Survey of Norway (NGU), Postbox 6315, Sluppen, 7491, Trondheim, Norway, Email: [email protected]; Phone: +47 7390 4283; 2,4 University of Bergen (UiB), Bergen Norway; 3,4 Univeristy of Tromsø (UiT), Tromsø, Norway; 4Norwegian Geotechnical Institue

(NGI), Oslo Norway; 4SINTEF Petroleum Research, Trondheim, Norway Gas hydrates are gaining more and more importance not only due to their economic value as a resource but also due to their asscoiation to margin stability and climate change. The worldwide volume of methane stored in gas hydrates is many times higher compared to the total amount of conventional hydrocarbon resources. Also, the occurrence of methane hydrate and associated free-gas in polar regions, especially, is important to be quantified since potential natural methane-leakage to the atmosphere may have a higher impact on the more delicately balanced climate at high latitudes. Due to this importance, the Norwegian margin was under intense gas hydrate studies since the beginning of last decade from various European and National programs which paved the way for assessment of gas hydrate systems to a certain level. The GANS project aimed to further develop the already existing knowledge and focus on quantifying gas accumulations in the form of hydrates in sediments, assess their dynamics and impacts on the seabed, and their response on sediments and biota along the Norway - Barents Sea - Svalbard (NBS) margin. This is materialised by studying the geophysical characterisation of gas hydrates, the geological and geochemical setting of gas hydrate reservoirs and seeps, gas hydrate dissociation and its effects on geomechanical properties and theoretical and experimental evaluation of gas hydrate dynamics. The three study areas differ in their structural and geological setting as well as their depositional history, occurrences of various seep structures and glacial tectonics. The interdesciplenary study aims to bring out the complementary skills and knowledge related to the development of the whole system. The presentation gives an overview on the distribution of gas hydrates and shallow gas reservoirs along the study areas. We also present various results from the project showing how the gas hydrate system is linked to the underlying geology and the development of the margin.


HIGH PRESSURE DIFFERENTIAL SCANNING CALORIMETRY

MEASUREMENT OF HYDRATES PHASE EQUILIBRIUM IN

PORE WATER OF SHENHU AREA, SOUTH CHINA SEA Chen Qiang, Ye Yuguang, Liu Changling

Qingdao Institute of Marine Geology, Qingdao, Shandong China, 266071 In this paper, we focused on the determination of phase equilibrium conditions of hydrates formed in the pore water from core sediment in Shenhu area, South China Sea. A relatively new technique was applied to this research, which is high pressure differential scanning calorimetry (HP DSC) method. During the study, we first carried out some preliminary experiments to verify the feasibility of the HP DSC method, including nitrogen hydrates and methane hydrates phase equilibrium measurements in water-hydrates- gas (W-H-G) system. Fig. 1 gave the results of the HP DSC measured value compared with reference value. It turns out that they fit each other very well. The pore water used in this study is collected by a suction filter from the sample core in Shenhu area, South China Sea. The sampling Voyage is HY4-2006-1, the latitude and longitude is E 115°35.57572' N 20°02.70441', and the sampling depth is 1170m. Fig. 2 listed the phase equilibrium points of hydrates in pore water as well as some reference values. Usually, the salinity of seawater is around 3.5%, so based on the phase equilibrium diagram, it can be seen that the hydrates stability is influenced by salinity, higher salt contents make the hydrates dissociation easier. The hydrates in pore water from Shehu area equilibrium temperature is about 2 K below in H2O at pressure from 10 to 30 MPa.

Fig. 1 Nitrogen hydrates and methane hydrates phase equilibrium data in (W-H-G) system

Fig. 2 Phase equilibrium points of hydrates in pore water, H2O and 14% NaCl solution

A GEOCHEMICAL OVERVIEW OF SHALLOW SEDIMENT METHANE SOURCE AND CYCLING ON THE ALASKAN SHELF OF THE BEAUFORT SEA

Richard Coffin, Leila Hamdan, Joseph Smith, Rebecca Plummer, Marine Biogeochemistry Section, Naval Research Laboratory, Washington, DC, USA

During September 2009 the Naval Research Laboratory lead an international collaboration for scientists in the MITAS (Methane In The Arctic Shelf/Slope) expedition, onboard the USCGC Polar Sea, in the Beaufort Sea region of the Alaskan North Slope. The goals of the expedition were to investigate the source(s), cycling, and flux of methane in surface sediments and the water column and to evaluate the relative contributions of shallow gas, nearshore permafrost methane, and offshore sediment methane hydrates to the overall methane flux from the sediments to the water column. This presentation will focus on geochemical data derived from analyses of sediment porewaters collected to show spatial variations in vertical methane fluxes and cycling in the shallow sediments of the Beaufort Sea Shelf and Slope. Initial results show large variations in the vertical methane fluxes between the 3 different regions with biogenic methane the source through the study region (Figure 1). With different levels of methane flux there are changes in stable carbon isotope ratios of the organic and inorganic carbon pools that show spatial variation in the methane contribution to shallow sediment carbon cycling. Preliminary results from the sites surveyed indicated a more rapid vertical methane flux over the shelf hydrates than the nearshore permafrost.

Figure 1. MITAS 1 locations for water column and sediment sampling in the Beaufort Sea on the Alaskan Shelf.

GIANT POCKMARKS ON THE CHATHAM RISE, NEW ZEALAND – EVIDENCE FOR MASSIVE RELEASE OF GAS FROM HYDRATES

DURING GLACIAL-INTERGLACIAL CYCLES?

Bryan Davy1, Ingo A. Pecher1, Ray Wood1, Lionel Carter2 & Karsten Gohl3 1GNS Science, Lower Hutt, New Zealand

2Victoria University Wellington, Antarctic Research Centre, Wellington, New Zealand 3Alfred Wegener Institute for Polar Sciences, Geosciences, Bremerhaven, Germany

DRAFT Recently collected multi-beam swath bathymetry and sub-bottom profiler data from the southwest margin of the Chatham Rise east of New Zealand show bottom features typical of gas release and sub-bottom features typical of gas hydrates that cover at least 20,000 km2. The gas escape features occur both at the sea-floor and on disconformities beneath the sea-floor that are interpreted to have formed at sea-level low stands. Among these are gas escape features up to 11 km in diameter whose formation during a glacial period may have resulted in a sudden release of large volumes of methane into the atmosphere. Here we present perhaps the most direct evidence to date for large-scale expulsion of methane from “melting” gas hydrates during glacial cycles.

ADVANCES IN HYDRATES EXPLORATION AT THE CHILEAN MARGIN

Juan Diaz-Naveas1

1Escuela de Ciencias del Mar, P. Universidad Catolica de Valparaiso, Av. Altamirano 1480, Valparaiso, CHILE [email protected]

Chile has been active in gas hydrate research since 2001 under the umbrella of two projects financed by the Chilean program FONDEF, which focuses on innovation based on very applied or technological projects. The majority of the Chilean hydrate investigation has been concentrated on hydrate exploration. The investigations were carried out with the enthusiastic cooperation of numerous institutions: University of Toronto (Canada), University of Aarhus (Denmark), German Federal Geological Survey (BGR), University of Bremen (Germany), University of Kiel (Germany), University of Tokyo (Japan), University of Bergen (Norway), NRL-DC and NRL-Stennis (USA) and University of Concepción (Chile) and Northern Catholic University (Chile). During the first FONDEF project (2001 – 2005) a compilation of available data from the Chilean continental margin was accomplished. Later, three research cruises took place in 2002, 2003 and 2004. The data acquired was multibeam bathymetry, multichannel reflection seismics (seismic line-spacing: 25km), heat flow measurements, controlled source electromagnetics, deep-towed reflection seismics, gravimetry, magnetometry, benthic sampling and porewater geochemistry. Two important results obtained were a first high-resolution bathymetric map and the geographical and depth distribution of BSR’s beneath the continental slope between 32º and 40ºS. During the second FONDEF project (2006 - 2009) the research focused on a smaller target area located between 34º and 37ºS, because those BSRs were closer to the coast and shallower beneath the seabed. Those conditions should be more advantageous from an economical point of view for hydrate exploitation, although deeper BSRs could be more convenient from a geomechanical point of view. The exploration methods applied during this second project were multibeam bathymetry, multichannel seismics (seismic line-spacing: 5km), water-column dissolved methane content and benthic sampling. The high resolution map was improved by filling large areas with no data. As a result there is a much better overview on the geology and geomechanics of this region. A byproduct of this bathymetry is the discovery of a new fault that could be a right-lateral strike-slip one. The fault appears to extend from 34º to 37ºS, contained incidentally inside the rupture zone of the 27th February 2010 Mw=8.8 Chilean earthquake. This is a fact that must be taken into account, because the most promising hydrate-bearing region in Chile was affected by this great earthquake. Seismic data enable to distinguish several patterns of BSRs: some of them are very clear, others are more evident because of the change in the reflectivity pattern; some are very isolated, but many are related to bright spots and to fluid venting. The latter is supported by the evidence of conduits and seabed pockmarks. In general, the underlying geology is very heterogenous, showing mild deformation in some cases, and strong deformation in others, and these in turn combined with complex depositional patterns, such as across margin submarine canyons shifts. In addition there are some exotic behaviours. For instance some BSRs don’t deepen in a subparallel way when the seabed deepens. The shallower BSR location respect to the expected one could indicate a transient behaviour after a too fast seabed (tectonic?) subsidence. Another aspect discovered in 2006 on seismic lines is the venting of plumes from the seabed. In situ measurements of dissolved methane from those plumes showed concentrations of up to ~440nmolL-1. During benthic sampling many species were recovered, and at least 6 new species were described for the first time. During the first months of 2013 the new state-of-the-art Chilean research vessel “AGS61 Cabo de Hornos” should enter operations. Among others it will be equipped with seismic compressors and several multibeam sonars, both for the seabed and for subbottom profiling.


ANALYSING SAND-DOMINATED CHANNEL SYSTEMS FOR POTENTIAL GAS-HYDRATE-RESERVOIRS USING AN AVO

SEISMIC INVERSION TECHNIQUE ON THE SOUTHERN HIKURANGI MARGIN, NEW ZEALAND

Miko Fohrmann and Ingo A Pecher

GNS Science, PO Box 30-369, Lower Hutt, New Zealand The Hikurangi Margin, a subduction-zone margin east of New Zealand’s North Island, contains gas hydrates in a very variable geologic environment. Significant gas hydrate saturations have been inferred in particular from controlled-source electromagnetic data collected in 2007. However, little is known so far about the quality of the host rock for gas hydrates. High permeability is likely to be a key requirement for any future production. Sands are typically the most permeable reservoir rocks. We have therefore started searching for potential gas-hydrate bearing sands, in particular, in channel systems. Extensive canyons are present in the southern part of the margin. We have identified high-amplitude reflections in 2-D seismic data that cross bottom simulating reflections with a polarity reversal. These reflections may be located in paleo-channel systems. We suggest these reflections may be caused by high-permeability layers, probably sand-dominated, containing a significant gas column beneath the gas hydrate stability zone and gas hydrates within it. We are currently applying high-resolution velocity analyses on a 2D seismic dataset followed by AVO inversion to confirm our interpretation and will present first results form these analyses.

NUMERICAL MODELLING OF CASING INTEGRITY IN HYDRATE BEARING SEDIMENTS

Reem Freij-Ayoub

CESRE, Perth, WA 6102, Australia

Casing and formation integrity for a well drilled in hydrate bearing sediments is investigated using numerical modeling. An axisymmetric numerical model that investigates the stability of the casing and formation during heating the casing is investigated using FLAC3D.

The model simulates a vertical wellbore drilled in cemented sandy sediments. The middle layer of sediments is cemented with an appreciable amount of gas hydrate entrapped in the pore space. The other two layers are cemented with a stable non hydrate material. The casing is heated by circulating a hotter fluid that can be a drilling fluid. It is found that the casing maximum von Mises stresses occur at the top of the casing. Heating the casing causes the von Mises stresses of the casing to increase along the casing profile but not at the top of the casing. The design of a string of casing is based on the minimum safety factor which corresponds to the maximum von Mises stress value calculated at the top of the casing. There has been no appreciable difference noted in the von Mises stress response of the casing whether or not the sediments contained hydrates. Additional compressive hoop stresses are generated in the casing as heating continues and the pore pressure increases in the formation due to fluid expansion and hydrate dissociation. These stresses are larger when the casing is placed through a hydrate bearing layer. Nevertheless the absolute maximum thrust in the casing drops upon heating the casing and the wellbore. This maximum thrust occurs at the top of the casing for all the cases studied and is detected close to the base of the hydrates layer in case of its presence after 4 days of heating. No risk of hydrostatic buckling is found

Figure. The axisymmetric model represents a vertical wellbore.

PEGASUS SURVEY 2009/2010: AN 80 KM-LONG BSR AND ASSOCIATED SEISMIC FEATURES FROM LINE 02P2029

Thomas Golding1, Ingo Pecher2, and Stuart Henrys2

1SGEES, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand 2GNS Science, P.O. Box 30368, Lower Hutt, New Zealand

The PEGASUS seismic survey has recently been shot by Crown Minerals (Ministry of Economic Development, New Zealand). The marine 2D seismic data were collected using a 12 km-long streamer along an array of lines over the PEGASUS basin (Fig. 1). Here we show a preview of the data. We present an 80 km-long segment from line 02, which includes a prominent BSR that is continuous over the entire 80 km. We highlight several seismic features associated with the BSR. These features may be indicative of highly concentrated zones of gas hydrates.

Figure 1. The Pegasus basin and PEGASUS seismic survey lines collected by Crown Minerals in 2009/2010. The data we present here are from a segment of line 02, highlighted in thick orange.

GAS HYDRATE AND COLD SEEP RESEARCH ALONG THE HIKURANGI MARGIN, NEW ZEALAND: RESULTS FROM 2006 AND 2007

J. Greinert1, K. Faure2, L. Naudts3, M. De Batist3, J. Bialas4, P. Linke4, I. Pecher2, A. Rowden5 1 Royal NIOZ, PO.Box 59, 1790 AB, Texel, Nethlands

2 GNS Science, PO Box 31-312, 6009, Lower Hutt, New Zealand 3 Renard Centre of Marine Geology, Gent University, Ghent, Belgium

4 IFM-GEOMAR, Wischhofstr. 1-3, 24148, Kiel, Germany 5 NIWA, Private Bag 14901, 6021, Wellington, New Zealand

Prior to 2006, the knowledge about cold seeps around New Zealand was based mainly on accidental recovery of seep fauna or methane-derived carbonates by fishermen and the detection of flares in fish-finding sonars. Lewis and Marshall (1996; NZJGG) compiled these findings, providing the first details on 13 seep sites. Four of those are located at the Hikurangi Margin along the east coast of New Zealand’s North Island. Three international cruises in 2006 and 2007 enhanced our knowledge considerably about methane seepage along the Hikurangi Margin, an area which has widely distributed and in places very strong BSR. Two cruises on the RV TANGAROA (led by GNS Science and NIWA, NZ) in 2006 focused on extensive reconnaissance work (multibeam mapping, seismic surveys, flare imaging, visual observations) as well as fauna sampling, geochemical pore water analyses and CTD casts including water sampling for methane analyses. Several new seep sites were discovered during these cruises.

Echosounder and sidescan surveys unmistakably revealed active seep sites by detecting bubbles in the water column and carbonate precipitation at the seafloor forming massive chemoherm complexes. These complexes are associated with typical seep fauna like tube worms, bivalve mollusk species (Calyptogena, Bathymodiolus),and bacterial mats. At the fringe of these chemoherms dark sediment patches were observed which exhibit a novel seep habitat dominated by dense beds of two new species of heterotrophic ampharetid polychaetes. Bubble release was visually observed at several sites and recorded in the backscatter of various acoustic devices. At one site (680m water depth) very strong, pulsing outbursts could be observed repeatedly with methane fluxes of 20 to 25 l/min (60 to 74 mol/min). Intense CTD sampling and onboard methane analyses revealed that at least three of the areas are actively venting methane with an upper boundary at about 500 m, due to a density barrier. ADCP data indicate tide-dependent changes in current speed and direction. Delta 13C values of dissolved methane range from -71 to -19 ‰, reflecting bacterial oxidation of methane in the water column, with a removal rate of 38 nM/day (or 11 to 19\%/day). Equilibrator surveys, analyzing the sea surface and atmospheric methane concentrations show no significant oversaturation and fluxes for the entire studied area of the Hikurangi Margin.

Pore-water measurements, including in situ measurements during lander deployments, were aimed at evaluating flux rates of dissolved geochemical species and free gas. These measurements revealed that the dark sediment patches represent a remarkable seep habitat because of its very high methane fluxes and total oxygen consumption rates. Detailed seismic and controlled-source electromagnetic surveys allowed quantification of gas hydrates and regional estimates of fluid-flow focusing and the impact on the gas hydrate stability and BSR occurrence. Furthermore, the geophysical data imaged fluid pathways under seeps and indicated that more seep sites could be found at the seafloor. In 2006 and 2007, 23 new seep sites have been identified and visually observed, which resulted in a total of 31 seeps sites for the Hikurangi Margin. With more cruises proposed, this number is likely to increase.

THE GERMAN COLLABORATIVE PROJECT SUGAR Utilization of a natural treasure – Developing innovative techniques for the exploration and production of natural gas from hydrate-bearing sediments

M. Haeckel, K. Wallmann, J. Bialas, I. Klaucke IFM-GEOMAR, Wischhofstr. 1-3, D-24148 Kiel, Germany

Gas hydrates occur in nature at all active and passive continental margins as well as in permafrost regions, and vast amounts of natural gas are bound in those deposits. Geologists estimate that twice as much carbon is bound in gas hydrates than in any other fossil fuel reservoir, such as gas, oil and coal. Hence, natural gas hydrates represent a huge potential energy resource that, in addition, could be utilized in a CO2-neutral and therefore environmentally friendly manner.

However, the utilization of this natural treasure is not as easy as the conventional production of oil or natural gas and calls for new and innovative techniques. In the framework of the large-scale collaborative research project SUGAR (Submarine Deposits of Gas Hydrates – Exploration, Production and Transportation), we aim to produce gas from methane hydrates and to sequester carbon dioxide from power plants and other industrial sources as CO2 hydrates in the same host sediments. Thus, the SUGAR project addresses two of the most pressing and challenging topics of our time: development of alternative energy strategies and greenhouse gas mitigation techniques.

The SUGAR project is funded by two federal German ministries and the German industry for an initial period of three years. In the framework of this project new technologies starting from gas hydrate exploration techniques over drilling technologies and innovative gas production methods to CO2 storage in gas hydrates and gas transportation technologies will be developed and tested. Beside the performance of experiments, numerical simulation studies will generate data regarding the methane production and CO2 sequestration in the natural environment. Reservoir modelling with respect to gas hydrate formation and development of migration pathways complete the project. This contribution will give detailed information about the planned project parts and first results with focus on the production methods.

DIVERSITY AND BIOGEOCHEMICAL STRUCTURING OF BACTERIAL COMMUNITIES IN METHANE CHARGED SEDIMENTS FROM THE

PORANGAHAU RIDGE, NEW ZEALAND

Leila J. Hamdan1, Patrick M. Gillevet2, Masoumeh Sikaroodi2 and Richard B. Coffin1

1Marine Biogeochemistry Section, U.S. Naval Research Laboratory, Washington, DC 22375, USA 2 George Mason University, Department of Environmental Science and Policy, Manassas, VA

20110, USA

Bacterial diversity in sediments from the Porangahau Ridge was studied using multi-tag pyrosequencing (MTPS). The goal of the study was to describe changes in community structure along a 7 km transect in conjunction with changing biogeochemical regimes. Low diversity was found in sediments located in a syncline east of the ridge where low sediment deposition was observed. At this location, communities were dominated by Betaprotebacteria. Low diversity was also observed in sediments collected over a methane seep near the flank of the ridge. In these samples, Chloroflexi/GNS and Deltaproteobacteria sequences were abundant. Sediments collected east of the ridge towards land, which were gas-charged and organic rich had the highest diversity. In organic rich surface sediments, enrichment of Alphaproteobacteria sequences was observed. Within sediment horizons where geochemical evidence suggest the occurrence of anaerobic oxidation of methane (AOM) at the sulfate-methane transition zone (SMTZ), an overall reduction in diversity was observed concomitant with enrichment of sequences related to the sulfate-reducing Desulfosarcina/Desulfococcus. Given that community structure is influenced by supply of terrestrial, pelagic and in situ substrates, MTPS data were explored in relation to geochemical data (e.g., sulfate, chloride, nitrogen, phosphorous, methane, bulk inorganic and organic carbon pools) using the Bio-Env procedure. Statistical differences in the influence of organic carbon, methane and nutrients on community structure were observed in each location. However, at the SMTZ regardless of location on the transect methane was the principal structuring factor on community composition.

ACOUSTIC PROPERTIES OF GAS HYDRATE-BEARING UNCONSOLIDATED SEDIMENTS AND ELASTIC VELOCITY MODELS

VALIDATION

Gao W. Hu1,2, Yu G. Ye1, Jian Zhang1, Changling Liu1 1Qingdao Institute of Marine Geology, Qingdao 266071, China

2China University of Geosciences, Wuhan 430074, China

Methane hydrate was formed and subsequently dissociated in unconsolidated sands (particle size, 0.09 - 0.125 mm). In the whole process, bender elements technique and Time Domain Reflectometry (TDR) were simultaneously used to measure the acoustic properties and hydrate saturations of the host sediments, respectively. The result shows that Vp and Vs increase rapidly vs. hydrate saturations, although they increase relatively slowly in the range of saturation 25% - 60%. It indicates that gas hydrate may first cement grain particles of the unconsolidated sediments. When hydrate saturation is higher, gas hydrate may contact with the sediment frame, or continue cementing sediment particles.

The experimental data were then compared with the velocities predicted by various velocity models (Figure). The results indicate that Vp and Vs predicted by the Weighted Equation (WE) model are consistent with the measured data when hydrate saturation is less than 90%, while Vp and Vs predicted by the BGTL (Biot-Gassmann Theory modified by Lee) model are close to the measured data when hydrate saturation is higher than 20%. The velocities predicted by the Effective Medium Theory (EMT) and the Kuster-Toksöz (K-T) equation are partly consistent with the measured data. The above results suggest that the WE model can best fits both Vp and Vs of the hydrate-bearing unconsolidated sediments in our experiments (with parameters W=2 and n=0.1).

Figure. Comparison of velocities (Vp, Vs) predicted by velocity-models with measured data in our experiments.

CORING, PRESSURE CORING AND CORE ANALYSIS FOR GAS HYDRATE STUDIES

Gary D. Humphrey

Fugro GeoConsulting, Inc., Houston, TX 77081, USA

Fugro has a long track record of experience in methane hydrate work:

• Current studies - Production Well - Planning Study and Conductor Installation Study. • Coring and Logging expeditions for US GOM (DOE JIP), Shell Malaysia, India (NGHP-I),

China-GMGS, Korea UBGH-1, as well as science expeditions on ODP Leg 204 and IODP Leg 311.

• Many office studies for international oil companies to model the effects of methane hydrate dissociation as a result of normal oil and gas production.

• Upcoming second expedition in the East Sea for KNOC – UBGH-II. This talk will focus on our experience with pressurized and non-pressurized coring and core analysis as they relate to methane hydrate investigations.

BOREHOLE LOGGING APPLICATION FOR GAS HYDRATE INVESTIGATIONS

Gary D. Humphrey

Fugro GeoConsulting, Inc., Houston, TX 77081, USA

Fugro Alluvial Offshore Ltd has been the main supplier for offshore borehole geophysical logging to the Fugro Group since 1999. It uses slimline wireline logging tools to measure high-resolution geophysical data in the shallow section (4,000 m TD). Its first major involvement in offshore logging was in 1999 when results from borehole logging were used to help Statoil delineate relic slip surfaces associated with their deepwater development at Ormen Lange. Since then, it has been involved in projects throughout the world where borehole logging can assist in the evaluation of engineering parameters, geohazard assessment and resource evaluation. In 2007, FAOL were involved in projects associated with the evaluation of gas hydrates as both a geohazard and a potential energy resource. During site investigations performed offshore China, geophysical logs were recorded in pilot holes drilled for shallow gas assessment. The information from these logs was then processed in real time to define the sampling strategy for the subsequent collection of hydrate and geotechnical cores. Similarly, for investigations offshore Korea, wireline logging was combined with data from logging while drilling (LWD) to help characterize the hydrate zones. Similar work is planned offshore Korea latter this year. The talk will focus on how results from borehole geophysical logs can be used to quickly and easily characterize hydrate zones, despite the very variable nature of the resource. Although work is still required to better quantify the in situ nature of gas hydrates, the importance of borehole geophysics in this role is well established and as will be demonstrated in the talk.

(a) (b) (c) (d) (a)

ROCK PHYSICS MODEL OF METHANE HYDRATE BEARING SEDIMENTS IN THE NANKAI TROUGH AND THE MACKENZIE DELTA

Takao Inamori1 and Tatsuo Saeki2

1JGI, Inc., Tokyo, Japan, 112-0012 2TRC, JOGMEC, Chiba, Japan, 261-0025

It is well known the methane hydrate exists both below the sea floor in water depths over 500 m or in polar regions under the frozen ground of the Earth. We have made cross-plots of the methane hydrate and Vp, Vs, or Vp/Vs from the well log data in the eastern Nankai Trough in Japan and the Mackenzie Delta in Canada. We found that as the methane hydrate saturation (Smh) increases, Vp and Vs increase, and Vp/Vs decreases from these plots. We discuss the rock physics model of methane hydrate bearing sediments and calculate Vp, Vs, and Vp/Vs, as the function of Smh, based on four imaginary rock physics models of methane hydrate bearing sediments proposed by Helgerud (2001). From the comparison between real sonic log data and the calculated results from four models, we infer that the rock physics model of methane hydrate bearing sediments is the matrix-supporting model at both the eastern Nankai Trough and the Mackenzie Delta. However, there are still some errors and differences in Vp, Vs and Vp/Vs between the modelled and real data. For example, we have estimated the effect of Vp, Vs, and Vp/Vs due to the change of clay content in the matrix-supporting model. As the clay content decreases, Vp and Vs increase, and Vp/Vs decreases. The clay content from core data corresponds with the calculated Vp, Vs, and Vp/Vs as a function of the Smh and the clay content in the matrix supporting model. In the eastern Nankai Trough, it was inferred that clay content estimated from the logging or core data of wells was approximately 50 to 60%. Our cross-plots show that the Vp, Vs and Vp/Vs values correspond to values of 50 to 60% clay content on matrix-support model. In the Mackenzie Delta in Canada, it was inferred that clay content from the logging and core data of wells was approximately 10%. Our cross-plots show that the Vp, Vs and Vp/Vs values correspond to values of 10% clay content on matrix-support model. In case of the estimation of Smh from Vp, Vs, and Vp/Vs, we need to consider the geology, especially sand/clay ratio of the methane hydrate bearing sediments. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21).

Figure. (a) The logs of Vp, Vs, and Smh log in the Nankai Trough. (b) Cross-plot between Smh, Vp and Vs for the Nankai Trough. (c) The logs of Vp, Vs, and Smh in the Mackenzie Delta. (d) Cross-plot between Smh, Vp and Vs for the Mackenzie Delta.

THE MONITORING OF THE GAS HYDRATE PRODUCTION TEST IN THE MACKENZIE DELTA

Takao Inamori1, Koji Yamamoto2, Tatsuo Saeki2, and Gilles Bellefleur3

1JGI, Inc., Tokyo, Japan, 112-0012 2TRC, JOGMEC, Chiba, Japan, 261-0025 3GSC, Ottawa, Ontario, Canada, K1A 0E9

The Research Consortium for Methane Hydrate Resources in Japan (hereafter MH21) and Natural Resources Canada (hereafter NRCan) in Canada jointly conducted the onshore gas hydrate production test in the Mackenzie Delta, Northwest Territories, Canada in the early April of 2007. Our production test aimed at the production of gas hydrate by depressurizing in the gas hydrate-bearing layer. During the twelve and half hours of the pump operation, at least 830 Sm3 of gas was produced from gas hydrate-bearing formation. Sonic data were acquired at the open-hole after drilling, the cased-hole before the production test, and the cased-hole after the production test by the Sonic Scanner which developed by Schlumberger. This sonic tool is able to acquire the data in the cased hole. The Sonic Scanner data were almost good and detect the P-slowness and S-slowness in all cases except the perforation test interval. S-wave velocity decreased to compare the difference between the before the production test and after from 1092 to 1104 m, because the gas hydrate dissociated at this interval. And P-wave was not detected at the same interval. It will be concluded the decrease of P-wave velocity caused by small amount of the methane free-gas by the dissociation of gas hydrate. The P-wave could not occur because of the drop of P-wave velocity at this zone with lower velocity than sonic wave velocity of water. It will be concluded the gas hydrate-bearing type is matrix-support from the relationships between P-wave velocity, S-wave velocity, P and S wave velocity ratio and the gas hydrate saturation in the Mackenzie delta. Using the relationship between S-wave velocity and gas hydrate saturation, it would be inferred the gas hydrate saturation decreased from over 60% to below 30% around the borehole. This study has been conducted as a part of the research undertaken by the Research Consortium for Methane Hydrate Resources in Japan (MH21).

GEOSCIENTIFIC INVESTIGATIONS OF MARINE SEDIMENTS IN THE VICINITY OF GAS HYDRATES:

OFFSHORE KRISHNA GODAVARI (KG) BASIN, INDIA. R.K. Joshi, A. Mazumdar, P. Dewangan, M. V. Ramana and T. Ramprasad

National Institute of Oceanography, Dona Paula, Goa, 403 004, India Correspondence – [email protected] (+918322450492)

The JOIDES expedition on the Indian continental margins (April-August 2006) under the aegis of National Gas hydrate program (NGHP) has confirmed the existence of not only one of the richest marine gas hydrate deposit in offshore KG basin, but also the thickest and deepest gas hydrate occurrence in offshore Andaman islands. The total reserve in the offshore KG basin is estimated at ~1894 TCM; if exploited, and is a better alternative for the conventional hydrocarbons but, the exploitation needs detailed geoscientific investigations of the basin for understanding all the biogeochemical processes responsible for the formation and occurrence of gas hydrate deposits. The National Institute of Oceanography (NIO) has planned and collected large number of shallow cores (~30 m long) from Krishna Godavari and Mahanadi offshore basins onboard ORV Marion Dufresne in the gas hydrate prone area during 2007. This paper presents some of the interesting results of the analysis carried out on one of the cores close to proximity of the known drilling location, where massive gas hydrate recovered. The grain size analysis suggest that, the study area is mainly comprises of clay (45-73%) having smectite as a dominant mineral, while the coarse fraction is less (0.03-9%) and only available as patches. The important constituents of coarse fraction are microfossils; mainly foraminifera both planktic and benthic, the other important findings are the presence of authigenic carbonates, few of them are provided with the impression of a bacteria Beggiatoa sp. that usually form mats near the cold seep environment, various types of pyrite, the occurrence of cold seep communities dominated by a bivalve Calyptgena sp., and gastropods. The presence of either gas hydrate or methane has brought up major changes in the framework of the basin and it is distinctly reflected in the coarse fraction distribution downcore.

Interpretation of down core reveal that the KG offshore basin possess all ideal geological conditions such as high organic carbon content (1-2%), high rate of sedimentation, low geothermal gradient, thick sedimentary column (~8 km), complex network of fracture pattern etc that are conducive for the formation and occurrence of hydrate deposits.

Key words: Gas hydrates, offshore KG basin, grain size, cold seep communities, authigenic carbonate, foraminifera.

LINKS BEETWEEN THE GLOBAL GAS HYDRATES RESERVOIR AND CLIMATE CHANGE

Miriam Kastner Scripps Institution of Oceanography, La Jolla, CA 92093, USA

Only in 1974 was methane recognized as an important contributor to anthropogenic forcing, and the significance of the global C reservoir that is sequestered in gas hydrates was realized just in the eighties. Methane is a powerful greenhouse gas, ~26 times more powerful than CO2. Estimates of the methane C in oceanic gas hydrates range from ~10,000 to 500 gigatons (1015 g), hence, the gas hydrates reservoir is so large that it has a possibility to impact climate.

Because gas hydrate stability depends on pressure and temperature (and environmental chemistry), an increase in seafloor temperature, that will shift the stability field, could have important climatic consequences, by causing accelerated dissociation of gas hydrates. Thus, the mode of occurrence of the oceanic gas hydrates, the deep versus the shallow (near and/or at the seafloor) deposits, is an important factor in determining their potential survival when seafloor temperatures will rise. The most vulnerable gas hydrate deposits are the large Arctic permafrost and slope deposits. The nature of decomposition, gradual or catastrophic, and the interplay between methane fluxes from decomposing methane hydrates and biogenic methane oxidation, strongly influence how much methane will impact the environment, the ocean chemistry and/or the atmospheric methane concentrations. In the atmosphere, methane is a transient having a rather short, approximately a decade residence time.

Methane hydrates have already begun to dissociate at the sea-floor at high latitudes, it is dissociating today, as for example, described by Westbrook et al. (2009). How widespread is it and how much methane, if any, is release into the atmosphere, are, however, unknowns.

Key problems that need to be addressed in order to be able to fully integrate modeling of he impact of temperature on dissociation, the methane transport processes, and biochemical oxidation reaction rates, are the inventories of the most vulnerable methane hydrates, and the understanding of the dynamics of gas hydrate dissociation in response to increasing temperatures. Recent model calculations on the response of rising temperatures on the stability of the three main modes of gas hydrate occurrences, and the potential thrusts on climate change, will be discussed.

THE VARIABILITY OF GAS SEEPS ALONG THE HIKURANGI MARGIN OFFSHORE NEW ZEALAND

Ingo Klaucke, Jörg Bialas, Gesa Netzeband, Wilhelm Weinrebe

Leibniz Institute of Marine Scienes, IfM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel, Germany Geoacoustic and seismic data of several locations along the Hikurangi margin offshore New Zealand indicate both spatial and temporal strong variability of cold seeps. On Opouawe Bank eleven different seep locations, displaying a range of seep activity were identified in the study area which consists of an elongated, northward-widening ridge that is part of the accretionary Hikurangi Margin and well separated from direct terrigenous input by margin channels surrounding the ridge. The geoacoustic signature of individual cold-seep sites ranged from smooth areas with slightly elevated backscatter intensity resulting from high gas content or the presence of near-surface gas hydrates, to rough areas with widespread patches of carbonates at the seafloor. Five cold seeps also show indications for active gas emissions in the form of acoustic plumes in the water column. Repeated sidescan sonar imagery of the plumes indicates they are highly variable in intensity and direction in the water column, probably reflecting control of gas emission by tides and currents. Although gas emission appears strongly focused in the Wairarapa area, the actual extents of the cold seep structures are much wider in the subsurface as is shown by sediment echosounder profiles, where large gas fronts were observed. Seismic data from the same area, however, show indications in form of gas blanking for many more seep locations. Although the blanking zones seem to reach the seafloor in the seismic data, a seafloor expression is not always observed suggesting that these cold seeps no longer reach the seafloor and implying that seep activity was much more widespread in the past. Geochemical data and the volumes of authigenic carbonates at the seafloor seem to corroborate the idea that cold seep activity was more widespread and more intense in the past.

Figure 1: Sidescan sonar mosaic of Opouawe Bank offshore Wairarapa, North Island, New Zealand showing eleven modern cold seeps.

THE REVIEW OF GAS HYDRATE RESEARCH IN KOREA

Joo Yong Lee, Byung Jae Ryu, and Sung-Rock Lee Korea Institute of Geosciences and Mineral Resources, Daejeon, Korea

Natural gas hydrates research in Korea is mainly focused on gas hydrate as a new energy resource. The Korean government launched its Gas Hydrate Development program in 2005, and studies from various research areas have been performed ever since. The research includes locating potential gas hydrate reservoirs, quantifying hydrate content, characterizing physical properties of reservoirs, developing production technology, and designing production systems. During phase 1 (2005-2007), detailed 2D and 3D seismic surveys were conducted that identified specific target areas for detailed exploration, focusing on BSRs, seismic chimney structures, acoustic blanking zones, enhanced reflections, and gas seepage areas. The first deep drilling expedition, UBGH01 was undertaken in 2007 and produced well logging data and deep drilling core analyses data for the detailed characterization of gas hydrate reservoirs from 5 LWD sites, 3 coring sites, and 1 wire line logging site in East Sea, Korea. Initiated by the recovery of actual hydrates in Korea during phase 1, the development of production technology and selection of optimal test production sites became the main objectives for phase 2. The next expedition, UBGH02, is scheduled for 2010 to quantify hydrate reserves and to establish a test production area for the next phase.

THERMAL STIMULATION PRODUCTION EXPERIMENT USING NATURAL GH-BEARING MARINE SEDIMENTS

FROM THE ULLEUNG BASIN – PRELIMINARY RESULTS

Joo Yong Lee, Jaehyung Lee, and Jeawoong Jung Korea Institute of Geosciences and Mineral Resources, Daejeon, Korea

An experimental device (GHOBS I – Gas Hydrate Ocean Bottom Simulator I) that can simulate the deep ocean-bottom environment has been designed to perform experimental studies of hydrate-bearing sediments. The purpose of GHOBS I is primarily focused on the physical characterization of GH-bearing sediments and the behavior of GH-bearing sediments during GH production under different stress conditions, hydrate saturations, and sediment types and structures. Detailed information on the device is described in Lee et al. 2009. Natural gas hydrate-bearing sediments recovered from Ulleung Basin, East Sea in 2007 and stored in liquid nitrogen have been used for a lab-scale test production study. The water depths at the coring sites range from 1800 to 2100 m and the tested cores have been obtained from 96 and 138 mbsf. The thermal stimulation method has been applied for lab-scale production tests. Thermal stimulation induces the vertical deformation due to diminishing hydrate particles and pore volume expansion by thermal expansion of pore fluid and gas expansion in pores. X-ray CT scanned images showed the significant disturbance of pore distribution. Preliminary results on the evolution of geophysical properties also support the change in pore structures and pore volume during production. These preliminary results introduce the behavior of GH-bearing muddy sediments during thermal stimulation production. Reference Lee, J.Y., Lee, J.H., and Lee, M.H. (2009) Depressurization of Natural GH-bearing Sediments using New instrumented Pressure Chamber with Vertical Effective Stress – Preliminary Results, 2009 AGU Fall meeting, 14-18 December, San Francisco, USA.

CHARACTERISTICS OF MARINE GAS HYDRATE RECOVERED FROM THE SHENHU AREA OF THE SOUTH CHINA SEA

Liu Changling1, Ye Yuguang1, Meng Qingguo1, Liu Jian2 and Yang Shengxiong2

1Qingdao Institute of Marine Geology, CGS, Qingdao 266071, China 2Guangzhou Marine Geological Survey, CGS, Guangzhou 510760, China

A gas hydrate drilling project in South China Sea was organized and carried out by China

Geological Survey in 2007. This was the first time for China to obtain marine gas hydrate samples from the Shenhu Area of the South China Sea. The field observations and results showed that gas hydrates disseminated in the marine sediment, either could be pore-filling, grain-cementing, or a combination of both. The gas hydrate layer is just above the BGHSZ, with a depth of 17.5-33.5. In this paper, a micro-laser Raman spectrometer was used to investigate these hydrates samples in detail. The clathrate structure and guest molecules were discussed. The results show that the gas hydrate samples are typical structure I (sI) (see Figure 1), and the guest is mainly methane molecules, which account for more than 99.2%. The cage occupancy of methane is larger than 99% for large cage, and 86% for small cage. The hydration number is calculated to 5.99 based on Raman intensities.

Keywords: Gas hydrate; Laser Raman Spectroscopy; Shenhu Area; South China Sea

Figure 1. Raman spectrum of gas hydrate recovered from Shenhu Area,

South China Sea

RECENT ADVANCES ON SEISMIC INVESTIGATION OF THE GAS HYDRATE FIELD OFFSHORE SOUTHWESTERN TAIWAN

Char-Shine Liu1, Shi-Wei Liao1, Shu-Lin Tu1, Ho-Han Hsu1, Chi-Chin Tsai1, Philippe Schnurle1*,

Song-Chuen Chen2, Yunshuen Wang2, and San-Hisung Chung2 1Institute of Oceanography, National Taiwan University, Taipei, Taiwan

2Central Geological Survey, MOEA, Taipei, Taiwan * Now at Department of Marine Geosciences, IFREMER, Brest, France

Marine seismic reflection data collected from offshore southwestern Taiwan show that

prominent seismic bottom simulating reflectors (BSRs) are presented that indicate the existence of gas hydrate in the seafloor sediment with free gas zone underneath (Liu et al., 2006). As the Taiwan gas hydrate program shifted from regional survey to specific sites in 2008, we have focused our attention on two types of seismic studies which could provide critical information in establishing the gas hydrate system in a selected gas hydrate concentrated zone. The first is to construct detailed gas hydrate reservoir characteristics using 3D seismic technique, and the second is to estimate the gas hydrate concentration in the sediment from high resolution velocity information.

A pseudo-3D data set was collected in 2008 using a 2D seismic data acquisition system with a line-spacing down to 100 m. We have built a 3D volume using 3D seismic data processing techniques. This 3D seismic data volume consists of 1431x92 bins with a bin size of 12.5 m by 100 m. The BSR surface can be clearly mapped with areas of high amplitudes easily observable. Paleo-channel fills which may provide sands for good gas hydrate reservoirs are identified from this 3D volume. However, due to the still large cross-line bin size (100 m), some of the fluid migration paths observed on in-line 2D seismic profiles were not clearly shown in 3D volume. We will combine both the 3D volume together with in-line 2D profiles to construct the structure framework and fluid migration model of the survey area.

Large offset seismic data enable us to derive accurate velocities for gas hydrate bearing strata and for the free gas bearing strata beneath BSRs. Pre-stack depth migration (PSDM) technique has been employed to analyze the large offset seismic data of EW9509 and MGL0905 cruises, and accurate velocity structures along several selected seismic sections were established together with the seismic depth sections. Using effective medium modeling and the velocity anomalies values derived from PSDM, we calculated the gas hydrate concentration based on the seismic velocity and gas hydrate concentration relationships of Helgerud (2001). In general, where high velocity anomalies have been observed, the estimated gas hydrate saturations in the strata are between 10 to 20%, and concentrations higher than 40% are also exist at a few places. So far, we are still in the early stage of quantitative analysis of BSR concentration, but experiences gained from these preliminary studies will help us to better constrain the gas hydrate properties in the area offshore southwestern Taiwan.

REFERENCES Liu, C.-S., P. Schnurle, Y. Wang, S.H. Chung, S.C. Chen and T.H. Hsiuan, 2006, Distribution and

characters of gas hydrate offshore southwestern Taiwan. Terr. Atmos. Oceanic Sci., 17, 615-644.

Helgerud, M. B., 2001, Wave speeds in gas hydrate and sediments containing gas hydrate: A laboratory and modeling study: Ph.D. thesis, Stanford University.

METHANE CONCENTRATIONS IN SEDIMENT AND BOTTOM-WATER OF THE ALASKAN BEAUFORT SEA

Thomas D. Lorenson1, Jens Greinert2, Edna Huetten3, Leila J. Hamdan4, Richard B. Coffin4, Kelly

A. Rose5, Warren Wood, and the MITAS scientific party6 1USGS, Menlo Park, CA USA, 2NIOZ, Texel, The Netherlands, 3RMAG, Gent, Belgium, 4NRL,

Washington DC, USA, 5NETL, Morgantown WV, USA, 6NRL, Stennis, MS USA A cruise to assess Methane In The Alaskan Shelf (MITAS) of the Beaufort Sea was conducted on the USCGC Polar Sea in September, 2009. Three transects consisting of water column and sediment measurements were taken across the Alaskan Beaufort Sea shelf and slope in water depths ranging from 20 to 2000 m. The transects were conducted off of Camden Bay (T1), Thetis Island (T2), and Cape Halkett (T3), Alaska. As part of this study, methane and other hydrocarbon gases were measured in sediment and from bottom waters to test the concept of methane leakage from ocean sediments into the water column and atmosphere due to warming of the Arctic Ocean sediments presently sequestering methane hydrates. Our measurements on the shelf were limited where previous observations had noted methane releases. Our results reveal that bottom water methane concentrations were elevated (up to 76 nM) in the shallow ~20 m water depths of T2 where previous measurements in the 1990’s found high methane concentrations. Coring sites on the continental slope targeted slump features with evidence of migrating gas along submarine landslides related to slope-hosted gas hydrate deposits. Methane concentrations well above background were also measured from the slope regions of T3 where elevated bottom water methane concentrations (71 nM) corresponded to sediments rich in methane (~2 mM) These results confirm that the Alaskan Beaufort Sea shelf and slope sediments are a source of methane to the Arctic Ocean.

GAS GEOCHEMISTRY OF THE MOUNT ELBERT GAS HYDRATE TEST WELL, MILNE PT. ALASKA: IMPLICATIONS FOR GAS HYDRATE

EXPLORATION IN THE ARCTIC

Thomas D. Lorenson1, Timothy S. Collett2, Robert B. Hunter3 1U.S. Geological Survey, 345 Middlefield Rd., MS-999, Menlo Park, CA 94025, USA, 2U.S. Geological

Survey, Denver Federal Center Box 25046, MS-939, Denver, CO 80225, USA, 3ASRC Energy Services, 3900 C St., Suite 702, Anchorage, AK 99503, USA

Gases were analyzed from well cuttings, core, gas hydrate, and formation tests at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, drilled within the Milne Point Unit, Alaska North Slope. The well penetrated a the upper units of the Eileen gas hydrate deposit, which overlies the more deeply buried Prudhoe Bay, Milne Point, West Sak, and Kuparuk River oil fields. Gas sources in the upper 200m are dominantly from microbial sources (C1 isotopic compositions ranging from -86.4 to -80.6‰). The C1 isotopic composition becomes progressively enriched from 200 m to the top of the gas hydrate bearing sands at 600 m. The tested gas hydrates occur in two primary intervals, units D and C, between 614.0 and 664.7 m, containing a total of 29.3 m of gas hydrate-bearing sands. The hydrocarbon gases in cuttings and core samples from 604 to 914 m are composed of methane with very little ethane. The isotopic composition of the methane carbon ranges from -50.1 to -43.9‰ with several outliers, generally decreasing with depth. Gas samples collected by the Modular formation Dynamics Testing (MDT) tool in the hydrate-bearing units were similarly composed mainly of methane, with up to 284 ppm ethane. The methane isotopic composition ranged from –48.2 to –48.0‰ in the C sand and from –48.4 to –46.6‰ in the D sand. Methane hydrogen isotopic composition ranged from –238 to –230‰, with slightly more depleted values in the deeper C sand. These results are consistent with the concept that the Eileen gas hydrates contain a mixture of deep-sourced, microbially-biodegraded thermogenic gas, with lesser amounts of thermogenic oil-associated gas, and coal gas. Thermal gases are likely sourced from existing oil and gas accumulations that have migrated up-dip and/or up-fault and formed gas hydrate in response to climate cooling with permafrost formation.

EXPERIMENTAL APPROACH TO CHARACTERIZE SEISMIC ATTENUATION IN METHANE HYDRATE-BEARING SEDIMENTS

Jun Matsushima, Makoto Suzuki, Yoshibumi Kato, and Shuichi Rokugawa

The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8656 Japan

Methane Hydrate (MH)-bearing marine sediments have long been seismically identified based on the presence of free gas below the methane hydrate stability zone and prominent bottom simulating reflectors (BSRs) that mark the impedance contrast between MH-bearing sediment and sediment that contains free gas or water. Most previous attempts to estimate MH bearing sediments from seismic data have used seismic velocities, because MH within the sediment pore space stiffens the sediment and causes an increase in seismic velocity. Although seismic velocity is potentially a useful indicator of MH concentration, seismic velocity is strongly controlled by the micro-scale MH distribution in pore spaces. Recent seismic surveys have shown that the presence of MH in sediments has significant influence on seismic attenuation. While the presence of MH increases the seismic velocity of the host sediment, seismic waveforms are attenuated by the presence of MH. The combined use of seismic velocity and attenuation provides greater insight into the MH-bearing sediments. Intuitively, one would expect that the stiffer material is characterized as higher velocity and lower attenuation. For a more detailed understanding of the rock physical mechanism responsible for these attenuation phenomena, laboratory measurements are required. Numerous researchers have focused on the physical interactions between pore fluids and solids. We used partially frozen brine as a solid-liquid coexistence system to investigate attenuation phenomena. Ultrasonic wave transmission measurements on this ice-brine coexisting system were conducted to examine the influence of unfrozen brine in the pore microstructure of ice on ultrasonic waves. We observed variations in the transmitted waves with a frequency content of 150–1000 kHz through a liquid system to a solid-liquid coexistence system by changing the temperature from 20 °C to –15 °C and quantitatively estimated the attenuation in a frequency range of 350–600 kHz. However, these attenuation results measured from experimental data are not entirely due to the intrinsic properties of the ice-brine coexisting system. These estimates include an attenuation component due to scattering effects. The level of scattering attenuation is related to the magnitude heterogeneity of acoustic impedance between ice and unfrozen brine. If the wavelength of a seismic wave is much longer than the scale length of heterogeneity in an ice-brine coexisting system, the system is considered a homogeneous material. Although scattering attenuation is important only at wavelengths comparable to the scale length of heterogeneity, smaller-scale heterogeneities influence the ultrasonic waveform with respect to the size of heterogeneities. To isolate the intrinsic attenuation from the total attenuation, herein the scattering attenuation is estimated based on synthetic data generated from information about the microstructure of an ice-brine coexisting system by conducting Magnetic Resonance Imaging (MRI) measurements. We obtained a series of two-dimensional apparent diffusion coefficient (ADC) maps of the ice-brine coexisting system using a diffusion-weighted magnetic resonance imaging (DW-MRI) technique at –5 °C, and found a strongly heterogeneous spatial distribution of unfrozen brine. From these maps, we constructed a synthetic seismic data set propagating through two-dimensional media, and generated synthetic data with a second-order finite difference scheme for the two-dimensional acoustic wave equation. We estimated ultrasonic scattering attenuation in such systems by the centroid frequency shift method and assuming that the quality factor (Q-value) is independent of frequency. Then we employed Biot’s poroelastic model to describe the propagation of ultrasonic waves through partially frozen media to determine a plausible mechanism for intrinsic attenuation in ice-brine coexisting systems. Although the scattering effect on attenuation does not fully fill the gap between the calculated attenuation from Biot’s model and the measured attenuation results from the experimental study, considering both the scattering effect and Biot’s poroelastic model can partly explain the attenuation mechanism in an ice-brine coexisting system.

CONTROLLED SOURCE EM AND 3D MODELING OF RESISTIVE TARGETS

Reza A. Mir, R. Nigel Edwards

University of the Toronto, Toronto, Ontario, Canada, M5S 1A7

Natural gas hydrates occur ubiquitously along active continental margins worldwide. Their formation in seafloor sediments displaces electrically conductive seawater and blocks interconnected pore spaces. As a result, the overall effect of hydrate presence in sediments is an increase in bulk electrical resistivity. Controlled source electromagnetic (CSEM) methods are capable of detecting resistive anomalies at shallow depths below the seafloor. CSEM involves generating a time-varying EM field at the seafloor, which in accordance with Faraday’s law, induces current systems in the seawater and the subjacent seafloor. The subsequent diffusion of the electromagnetic field as a function of time depends on the electrical conductivity structure of the seafloor. In particular, the diffusion speed of the EM disturbance will depend directly on conductivity over the range of values of interest found at the seafloor. Therefore, time-series measurements of the field at different stations for varied offsets from the CSEM source can be inverted for crustal conductivity and used to detect resistive anomalies. Not surprisingly, CSEM has become a valuable tool in detecting marine gas hydrates, a target that has proved challenging for conventional geophysical exploration techniques. As an example, several CSEM experiments have been used to map gas hydrates in the Cascadia margin, offshore west coast of Vancouver Island, Canada.

In order to design CSEM experiments that provide useful data for detection and evaluation of resistive anomalies, modeling studies are needed which demonstrate the information content of EM data and give possible insights in interpreting them. Here, results from a numerical modeling study for a multi-receiver marine CSEM system are presented. The earth models include a simple quarter-space contact, as well as a 3D resistive target in which the effect of heterogeneous hydrate distribution on EM data is investigated.

Figure: (Top) Model used has a contact separating a quarter-space from a quarter-space. Stars are the position of the contact with respect to the array. (Bottom) Apparent resistivity vs. profile calculated for the model using the arrival time of the EM disturbance at the receiver.

MODELING STUDIES OF GAS PRODUCTION FROM HYDRATE DEPOSITS AND OF THE CORRESPONDING

GEOMECHANICAL SYSTEM RESPONSE

George J. Moridis Earth Sciences Division, Lawrence Berkeley National Laboratory

Gas hydrates are solid crystalline compounds in which gas molecules are lodged within the lattices of ice crystals. The vast amounts of hydrocarbon gases that are trapped in hydrate deposits in the permafrost and in ocean sediments may constitute a promising energy source. We use the TOUGH+HYDRATE simulation code to investigate gas production from a wide range of hydrate deposits. Additionally, we investigate the geomechanical stability of oceanic hydrate-bearing sediments under production.

Class 1 hydrate deposits are characterized by a Hydrate-Bearing Layer (HBL) underlain by a two-phase zone involving mobile gas, and are obvious candidates for gas production. Class 2 hydrate deposits are characterized by a HBL that is underlain by a saturated zone of mobile water. Class 3 hydrate deposits are characterized by an isolated HBL that is not in contact with any hydrate-free zone of mobile fluids. The base of the HBL in Class 2 and 3 deposits may occur within or at the edge of the zone of thermodynamic hydrate stability. Class 4 deposits involve disperse, low-saturation accumulations, are typical of marine systems, and represent the majority of the global inventory of hydrates.

Class 2 hydrates are promising, as they appear to yield large rates of hydrate-originating gas over long periods. Under favorable conditions and an appropriate well design, Class 2 deposits can deliver sustainably high, long-term rates. Production from depressurization-based dissociation of Class 3 deposits based on a constant bottom-hole pressure appears to be a promising approach even in deposits characterized by high hydrate saturations. This approach allows the production of very large volumes of hydrate-originating gas at high rates for long times using conventional technology. Finally, Class 4 deposits do not appear to be promising targets for gas production under any combination of system properties, initial conditions and production parameters.

Production from hydrate deposits is characterized by (a) the need for confining boundaries, (b) a continuously declining water production and an improving RWGC over time (opposite to conventional gas reservoirs), and (c) the development of a free gas zone at the top of the hydrate layer (necessitating the existence of a gas cap for production). Depending on the type and properties of the sediments in the hydrate-bearing media, gas production from oceanic deposits may affect (possibly seriously) the wellbore stability and the geomechanical integrity of HBS under the conditions that are deemed desirable for production.

OVERVIEW OF THE RESEARCH PROGRAM ON ENVIRONMENTAL IMPACT ASSESSMENT FOR THE MARINE PRODUCTION TEST IN

OFFSHORE JAPAN

Sadao Nagakubo1, Yoshihiro Nakatsuka1, Nao Arata1, Hideo Kobayashi2, Koji Yamamoto1 1Japan Oil, Gas and Metals National Corporation (JOGMEC), Chiba, Japan, 2610025

2National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan, 3058569

The Research Consortium for Methane Hydrate Resources in Japan (MH21) was established to realize the Japanese Methane Hydrate R&D Program initiated in FY2001.This program has moved into Phase-2 (FY2009-2015), planning to conduct two marine production tests in around offshore Japan. Environmental Impact is one of the great concerns for these offshore production tests and for the commercial production of methane hydrate (MH) in the future. In the first phase of this program (FY2001-2008), Environmental Impact Assessment (EIA) group was organized, aiming to establish an environmentally friendly production system concerned with environmental preservation. Numerical models and monitoring sensors were developed concerning the possibilities of environmental risks such as methane leakage and seafloor deformation in this first phase. Also marine baseline surveys in Eastern Nankai Trough were conducted as one of the model field of this program. In the Phase-2 of this program, main target is to identify the environmental risks and to verify the significance of these identified environmental risks. Also investigation for avoidance plan or mitigation plan is considered. In this series of process, we will implement the EIA on the two offshore production tests to acquire the environmental data for commercial production. In this presentation, we highlight the overview related to identification and verification of the significance of environmental risks. For the identification of environmental risks, appropriate occurrence type of MH deposits, the production method, and the development system was clarified due to the result of Phase-1. By considering the following principles such as; (a) Compliance of Japanese domestic law, (b) Economical efficiency, (c) Consistency with the EIA procedure and production system, four risks has been extracted from the clarified result as specific environmental risks at this moment. Extracted risks are the following; (1) Methane leakage, (2) Seafloor deformation, (3) Submarine landslide, (4) Disposed water from the MH dissociation. Also from the results, we could estimate that environmental risks on commercial development of MH concentrated zone are not significant.

A CONCEPT OF UTILIZING SOLAR ENERGY TO EXPLOIT GAS HYDRATES BURIED IN OCEANIC SEDIMENTS

Fulong Ning1, Guosheng Jiang1, Ling Zhang1, Nengyou Wu2, Jin’an Guan2

1Faculty of Engineering, China University of Geosciences, Wuhan, Hubei 430074, China 2Guangzhou Institute of Energy Conversion, Chinese Acad. of Sci., Guangzhou 510640, China

Since gas hydrates were first found in extensive deposits in nature, many countries have eyed this new latent energy resource, which has attributes of high energy, large reserves, and cleanness. Such methods have been proposed in this field as thermal stimulation, depressurization, inhibitor injection, CO2 replacement, and mixing exploitation, the first three of which are typical. Because thermal stimulation has a relatively high rate of gas production, some special and novel ideas, such as fire flooding, burial of nuclear wastes, electromagnetic heating, microwaves and downhole combustion, are other innovative ways of dissociating hydrates, but none has been tried. So far only above-mentioned three typical methods have been tried only in permafrost areas and have not been used in the exploitation of marine gas hydrates because of challengeable operation conditions, giant cost and climate factor. Here, a conceptual method of using renewable energy, solar energy, for oceanic gas hydrate exploitation and its related devices was proposed. First, the solar energy is collected and transformed to electricity, and then to heat energy, which is transported to heat the oceanic gas hydrates formation beneath the seafloor, and dissociates the gas hydrate. So the natural gas is produced by collecting the released gas. The device includes solar cell system installed at the platform and the distributor with electric heater. The solar system is connected with electric heater via insulated cable, and provides power for the heater. Also, an instance for Shenhu Area is provided to illustrate the calculation of capacity of electric power and solar cell system under ideal conditions. Now the technological breakthrough in photovoltaics has been achieved to convert normally and continuously, even for an overcast sky, and solar-cell prices fell from $27 per watt of capacity in 1982 to near $4 per watt today. It is proved that the exploitation of oceanic gas hydrates by solar energy is technically and economically feasible in the special sea area and hydrates reservoirs, and may be a good assistance for depressurization exploitation of marine gas hydrates in future.

Figure Sketch of utilization of solar energy for exploiting gas hydrates 1. Solar cells 2. controller 3. free-maintenance colloidal accumulator 4. inverter 5. pressure gauge 6. insulating and pressure proof cables 7. central pipe 8. production casing 9. heater 10. sea floor 11. hydrates deposit 12. platform 13. gas production tree 14. cut-off valve 15. gas-liquid separator 16. water tank 17. purification plant 18. submarine pipe

GAS HYDRATE RESEARCH: PAST, PRESENT, AND FUTURE

Charlie Paull Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, CA, USA

Monday 10 May at 7.30 pm Lecture Theatre 2, Rutherford House, Pipitea Campus of Victoria University, Wellington.

This public lecture will give an overview of what gas hydrates are, how our collective knowledge of them has been obtained, and predictions of the future trends associated with gas hydrate research will be presented. This will include video images of gas hydrate behaviour on the seafloor collected using remotely operated vehicles (ROVs). Dr. Paull is a marine geologist who holds degrees from Harvard, University of Miami, and Scripps Institution of Oceanography. Presently, he is a Senior Scientist and Chair of Research and Development at the Monterey Bay Aquarium Research Institute (MBARI). Over Dr. Paull’s career he has pursued a broad diversity of research topics. These include identifying the first cold seep communities, being the chief proponent and co-chief scientist for the first ODP Leg dedicated to gas hydrate research, serving as chief scientist for the MBARI Monterey Ocean Observing System which has developed and installed cable-connected deep-water sea floor infrastructures, and leading various sea floor exploration efforts using ROV’s, autonomous underwater vehicles, and submersibles. These efforts are documented in over 175 peer-reviewed publications. He recently chaired the US National Research Council’s report “Realizing the Energy Potential of Methane Hydrate for the United States”.

3-D INTERNAL ARCHITECTURE OF METHANE HYDRATE BEARING TURBIDITE CHANNELS IN THE EASTERN NANKAI TROUGH, JAPAN

Satoshi Noguchi1*, Naoyuki Shimoda1, Osamu Takano1,2, Nobutaka Oikawa1,3,

Takao Inamori1,4, Tatsuo Saeki1, Tetsuya Fujii1 1Japan Oil, Gas and Metals National Corporation

2JAPEX Research Center, Japan Petroleum Exploration Co., Ltd. 3Japan Petroleum Exploration Co., Ltd.

4JGI, Inc.

The reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough, offshore Japan is discussed using a combination of 3-D seismic and well log data. The MH bearing turbidite channels consist of complex patterns of strong seismic reflectors, which exhibit a 3-D internal architecture of the channel complex extending in a northeast – southwest direction. According to a seismic sequence stratigraphic analysis, the channel complex can be roughly classified into three depositional sequences. Each depositional sequence results in a different depositional system, which primarily controls the reservoir architecture of the turbidite channels. In the southwestern part of the channel complex around ß2 well, the thickness of the turbidite channels is much greater than that of the northeastern part of the channel complex around ß1 well. However, the depositional sequence of the northeastern part represents a sand-dominated turbidite system ensuring that the reservoir potential is high despite the relatively smaller thickness of the turbidite channels. For constructing a geological frame model, we examined further details of reservoir characteristics of the geological frame of the channels around ß1 well. The bottom frame of several channels is oriented along north-to-south and north-northeast-to-south-southwest directions, which coincide with the distributary patterns of the higher amplitude values in amplitude map. The several magnitudes of these amplitude patterns within the turbidite channels reveal complex stacking patterns of several orders of the flow units. An anomalously high interval velocity between BSR (bottom simulating reflector) and the top of the MH bearing sediments is identified in the northeastern part of the channels. The turbidite sediments in the northeastern side of channels are derived from the north-northeast direction, which is different from the sediments supply systems of the rest of the channels. The different sediments supply system of northeastern side of channels is related to the abundance of coarse sediments, which may lead to the different reservoir architecture of the turbidite channels.

Keywords: methane hydrate, turbidite, channel, sequence stratigraphy, reservoir characterization

POSSIBLE EVIDENCE FOR GAS HYDRATES IN THE NORTHLAND-

NORTHERN TARANAKI BASIN, NEW ZEALAND

Oluwakemi Y. Ogebule1 and Ingo A. Pecher2,1 1Institute of Petroleum Engineering & ECOSSE, Heriot-Watt University, Edinburgh, Scotland (UK)

2GNS Science, Lower Hutt, New Zealand

We present indirect evidence from seismic data for gas hydrates in the deep-water Northland and northern Taranaki Basins, close to New Zealand’s primary petroleum province west of the North Island. We analyzed migrated seismic data from the study area for high-amplitude reflections with negative polarity compared to the seafloor reflection in the predicted regional gas hydrate stability zone. We interpret these events as gas pockets and infer that the gas is likely to be surrounded by gas hydrate. We also observe a reflection that mimics the shape of the base of gas hydrate stability and possibly is a bottom simulating reflection. If our findings are confirmed, we may have discovered a new gas hydrate province offshore New Zealand.

THE GAS HYDRATE PETROLEUM SYSTEM ON THE HIKURANGI MARGIN, NEW ZEALAND – CURRENT STATE OF KNOWLEDGE

Ingo A. Pecher1,2, Suzannah J. Toulmin2, Stuart A. Henrys1, Philip Barnes3, Katrin Schwalenberg4,

Jens Greinert5, Richard Coffin6 1GNS Science, Lower Hutt, New Zealand

2Heriot-Watt University, Edinburgh, Scotland (UK) 3NIWA, Wellington, New Zealand

4Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, Germany 5NIOZ, Texel, Netherlands

6Naval Research Laboratory, Washington, DC, USA Gas hydrates are increasingly being viewed as part of a “petroleum” system including gas sources, migration paths, emplacement mechanisms, reservoir rocks, and seals. Several research cruises across the Hikurangi Margin east of the North Island have been conducted in the past five years and a clearer picture of the margin’s gas hydrate system is emerging. The source of gas for hydrate formation in the study areas appears to be almost exclusively biogenic. We caution however, that our study areas are largely confined close to or beyond the seaward edge of source rocks for thermogenic gas. Closer to shore, thermogenic gas may contribute to hydrate formation. Bottom simulating reflections (BSRs) as proxies for gas hydrates are primarily present beneath thrust ridges and other features that focus fluid flow, whereas the slope basins almost entirely lack BSRs. We propose that fluid flow is instrumental for transporting biogenic gas produced in accreted turbidites upward. “Funnelling” of fluids along the base of low-permeability slope basins into thrust ridges subsequently concentrates gas flux into the hydrate stability zone providing sufficient gas to form BSRs and leading to the observed pattern of BSR distribution. It has also been suggested that fluids may provide nutrients for the deep biosphere, which would mean the productivity of the gas source may be linked to fluid flow. This would be an additional or alternative explanation for the inferred link between fluid flow and gas hydrate occurrence. The host rock for gas hydrates beneath many thrust ridges may consist of indurated, fractured mudstones as recovered by dredging on Rock Garden east of Hawke’s Bay where the core of a thrust ridge crops out. Further south however, we have recently discovered BSRs beneath submarine channels. Channel systems may provide high-quality, permeable reservoir rocks for gas hydrates. Gas hydrate deposits on the Hikurangi Margin, mostly inferred from a presence of BSRs, appear less evenly distributed than on many other convergent margins. Individual deposits however, may contain very high concentrations of hydrates. Controlled-source electromagnetic data suggest localized gas hydrate saturations well above 50% of pore space. We suggest that beyond identification of deposits of highly concentrated gas hydrate, we now need to focus on reservoir quality in order to evaluate the economic potential of gas hydrates on the Hikurangi Margin. Reservoir quality encompasses properties such as permeability and connectivity. Constraining these parameters is a common challenge for hydrocarbon exploration and thus, we can draw on established techniques.

CURRENT STATE OF GAS HYDRATE EXPLORATION IN NEW ZEALAND

Ingo A. Pecher1,2, TAN0607 Scientific Party, SO191 Scientific Party, and many others 1GNS Science, Lower Hutt, New Zealand

2Heriot-Watt University, Edinburgh, Scotland (UK) Gas hydrates research in New Zealand has picked up significantly in the last five years. In particular, three surveys dedicated to studying gas hydrates on the Hikurangi Margin were conducted since 2005, a seismic reflection profile across gas hydrate deposits on the southern Hikurangi Margin in 2005 (05CM-38), a two-week cruise on the R/V Tangaroa in 2006 (TAN0607), and a 2.5-month campaign by the R/V Sonne in 2007 (SO191). A six-week cruise on the R/V Sonne (NEMESYS) is already planned for 2011. In addition, data from surveys commissioned by Crown Minerals (Ministry of Economic Development) for regional petroleum exploration are proving to be extremely valuable for gas hydrates exploration. In this talk, we will present an overview on the current state of gas hydrates exploration on the Hikurangi Margin and elsewhere offshore New Zealand and on our future plans.

MORPHOLOGY OF GAS HYDRATE AND ITS INFLUENCE ON SOIL PROPERTOES

Jeffrey Priest1

1School of Civil Engineering and the Environment, University of Southampton, UK Methane gas hydrates are ice-like inclusions found within deep water sediments and permafrost and of interest as a potential future energy source, a possible driver for climate change or a trigger to underwater slope instability. This presentation discusses the influence of hydrate morphology on the physical characteristics of hydrate-bearing sediment formed under laboratory conditions. Results from detailed testing on gas hydrate bearing sediments using a specially designed dynamic test cell, where methane hydrate was formed using different formation techniques, have shown that hydrate formation conditions strongly influence the resultant stiffness of the hydrate bearing sediments. Results using different sediments show that the grain size and shape also influence the interaction between the hydrate and the sediment. These results suggest that hydrate interaction with the sediment is strongly dependent on morphology, and that natural hydrate may exhibit contrasting seismic signatures depending upon the geological environment in which it forms.

LONG-TERM SEAFLOOR COMPLIANCE MONITORING OF THE BULLSEYE VENT GAS HYDRATE SYSTEM

Lisa A. N. Roach, Eleanor C. Willoughby and R. Nigel Edwards

Department of Physics, University of Toronto, 60 St. George St., Toronto, ON, M5S 1A7, Canada

Gas hydrates contain immense stores of powerful greenhouse gases relevant in climate change science, they represent an important potential alternate source of energy and may possibly be impactful as a geo-hazard. These wide reaching and ranging influences make gas hydrate research pertinent. To date, very little is known about the temporal variations of gas hydrate deposits. For example, on the Cascadia margin-an active margin, near ODP Site 889, there are four very prominent blank zones. At the largest of these, the Bullseye Vent, where coring results have confirmed the presence of gas hydrates, there have been evidence which suggests that this deposit maybe changing over time. It is therefore crucial to the characterization of gas hydrate deposits to understand the nature of these changes.

NEPTUNE Canada, a seafloor observatory offshore British Columbia, Canada has provided the necessary infrastructure for the long-term monitoring of gas hydrate deposits. We have set up a Seafloor Compliance (SFC) experiment at ODP Site 889, specifically to investigate the temporal nature of shear properties of the Bullseye Vent. The experiment consists of a differential pressure gauge (DPG) and a gravimeter. The DPG measures the fluctuation of pressure generated by ocean gravity and infra-gravity waves, which though evanescent, nonetheless palpitate the seafloor. The gravimeter simultaneously measures the associated acceleration of the seafloor due to the deformation by the gravity waves. Apart from the DPG data from the SFC experiment, we have additional pressure data from a bottom pressure recorder (BPR) located ~300m away. From the BPR we can extract pressure information about tsunami waves which provide longer wavelength palpitation of the seafloor.

The displacement which results from the pressure wave is dependent on the elastic structure of the sediments and the source of the pressure signal (i.e. amplitude and wavelength). Since pressure signal from ocean waves decay exponentially with depth only waves of wavelength greater than the water depth are capable of generating significant pressure at the seafloor. SFC is, as a function of frequency, is the ratio of the acceleration to the pressure signal. Longer wavelength waves penetrate deeper into the sediments resulting in lower frequency compliance data relating to deeper structure and vice-versa.

We have been able to continuously, with few interruptions, measure the seafloor pressure and acceleration over a 4 month period. During this time, we have also recorded pressure signals from earthquakes and resulting tsunamis. Here, we present results about the character of the pressure signal in the northeast Pacific over this period as well as some preliminary results on the compliance of gas hydrate system under tsunamis.

UNDERSTANDING THE ENERGY AND ENVIRONMENTAL IMPLICATIONS OF GAS HYDRATES AND THE POTENTIAL IMPACT

OF MAJOR FIELD STUDIES Kelly Rose1

1U.S. Department of Energy, National Energy Technology Laboratory, Morgantown WV: [email protected]

Since 2000, the U.S. Department of Energy has collaborated with 6 other agencies of the federal government to study the varied mplications of gas hydrates in nature. This effort includes investigations of both arctic and marine gas hydrates with respect to gas hydrate’s role in the global carbon cycle and climate change, its contribution to a range of geohazards, and its potential as a future energy resource. For the past three decades, discussions relating to the contribution of natural gas hydrates to the global carbon cycle as well as the resource potential of gas hydrates has been framed by a series of global assessments of in situ gas hydrate occurrences. These assessments have generated a wide range of exceedingly large “resource” estimates (spanning several orders of magnitude around a rough mean of 700,000 trillion cubic feet of encased methane gas) that, even at their most modest, exceed the widely-accepted estimates of known conventional oil and gas resources. Proper understanding of gas hydrate resource potential, however, requires a clear communication of the nature of those estimates. Fortunately, new data are being returned from the field and understood in the context of laboratory and numerical simulation studies, is providing increased clarity on the distribution and nature of natural gas hydrate accumulations. Going forward, the vast estimates of gas hydrate global abundance will remain relevant to a host of scientific issues. Going forward, the U.S. gas hydrates program will continue to include a wide range of fundamental investigations, from the molecular to the reservoir scale, of the physical nature and behavior of gas hydrate and gas-hydrate-bearing sediments. In addition, the program will pursue large and complex programs in the field designed to assess the occurrence of gas hydrate and to collect in-situ data from hydrate accumulations. In recent years, these efforts have found success in both Alaska and in the Gulf of Mexico, where drilling programs have validated the geological-geophysical approach to gas hydrate exploration based on an integration of direct detection with analyses of key component of gas hydrate petroleum systems. The components include not only sufficient pressure and temperature regimes, but also gas sourcing, gas migration pathways, reservoir quality, and time. While both of these programs are strongly associated with constrianing the resource potential of these accumulations, the results will also have significant implications for global climate studies, in particular in relation to understanding hydrate stability in sub-permafrost regions of the Arctic. In Alaska, the program hopes to initiate, in 2011, a comprehensive and extended term production testing program in partnership with Alaska North Slope operators that will investigate the response of gas hydrate-bearnig sediments to various destabilizing forces. This intial stage of scientific testing will provide insight into the design of future production/environmental monitoring tests, as well as guide the further development of numerical models used to investigate the response of gas hydrate to natural phenomena, including ongoing climate change. In the Gulf of Mexico, the program, in partnership with an international industrial consortium led by Chevron, conducted “Leg II” drilling operations in early 2009 that confirmed gas hydrate occurrence in a wide variety of settings. Planning is now underway for a Leg III program in the Fall of 2010 that is designed to collect pressurized core samples of gas hydrate-bearing sediments to enable detailed study on the physical-chemical properties of gas hydrate-bearing sediment and the geological controls on gas hydrate occurrence.

EXPLORATION ACTIVITIES FOR METHANE HYDRATE RESOURCES IN THE EASTERN NANKAI TROUGH

Tatsuo Saeki, Tadaaki Shimada and Satoshi Noguchi

TRC, JOGMEC, Chiba, Japan, 261-0025

Aiming for commercialization of methane hydrate production, the “Research Consortium for Methane Hydrate Resources in Japan” (MH21) has carried out geological and geophysical surveys in the eastern Nankai Trough since 2001 as a national Japanese project under the support of METI (the Ministry of Economy, Trade and Industry). Data and knowledge provided through 2D/3D reflection seismic surveys and the multi-well drilling campaign (METI 2D seismic survey “Tokai-oki to Kumano-nada” [2001-2002], METI 3D seismic survey “Tokai-oki to Kumano-nada” [2002], and METI Exploratory Test Wells Tokai-oki to Kumano-nada” [2004]) have revealed that concentrated zones of methane hydrate, of which reservoirs are turbidite sand bodies, exist locally in methane hydrate distribution areas suggested by Bottom Simulating Reflections (BSRs). In other words, methane hydrate concentrated zones are groups of relatively higher saturated methane hydrate bearing bodies distributed continuously over a large region, and they are distributed partially in methane hydrate bearing zones, therefore, in the view of resource explorations, methane hydrate concentrated zones can be more attractive than other methane hydrate bearing zones. It is expected that methane hydrate concentrated zones can be targets for future offshore production. The interpretation workflow for the delineation of methane hydrate concentrated zones using reflection seismic data consists of identifications regarding the following four indicators: (1) BSRs, (2) turbidite sequences (above BSRs), (3) strong seismic reflections and (4) relatively high interval velocities. The first and second indicators can be utilized to delineate candidates of methane hydrate concentrated zones because they suggest methane hydrate occurrences and possible good reservoirs. Moreover, the third and forth indicators may mean seismic characters relating to methane hydrates saturations and existences of methane hydrate saturated layers. Methane hydrate concentrated zones proven by multi-wells drilling satisfied the above four indicators. More than 10 methane hydrate concentrated zones were delineated successfully in the eastern Nankai Trough by utilizing the above workflow and their amounts of methane gas in place were estimated through a probabilistic approach. The current research phase has shifted to interpretation and analysis work of detailed internal structures and quantitative geophysical properties of methane hydrate concentrated zones in order to plan future offshore production tests.

CURRENT STATE OF INDIA’S GAS-HYDRATES ACTIVITIES AND NGRI’S INITIATIVES

Kalachand Sain1, Maheswar Ojha and Nittala Satyavani

Gas-hydrate Group, National Geophysical Research Institute, Uppal Road,

Hyderabad – 500007, India (Council of Scientific & Industrial Research) E-mail: [email protected]

Phone: +91 040 27178319 Fax: +91 040 23434651

The bathymetry, seafloor temperature, sedimentary thickness, rate of sedimentation and total organic carbon content indicate good prospects of gas-hydrates in shallow sediments along the margins of India. By reprocessing and analyzing available marine seismic data, we have identified the BSRs in both the Bay of Bengal and the Arabian Sea. The coring and drilling by the Indian National Gas Hydrate Program, mostly confined to the eastern Indian offshore, have validated the ground truth in the Krishna-Godavari (KG), Mahanadi (Mn) and Andaman offshore basins. Based on seismic traveltime tomography; waveform inversion; amplitude versus offset (AVO) modeling; AVO attributes; seismic attributes and rock physics modeling, we have developed several approaches for the detection, delineation and quantification of gas-hydrates. These techniques have been employed to the existing seismic data for the investigation of gas-hydrates in different offshore basins in India. It has become essential now to identify new prospective zones; to demarcate the extension of hydrate- and underlying gas-bearing sediments; and to evaluate the resource potential. For this and to fill the data gap, we have recently acquired multi-channel seismic data along 3250 line km in both the KG and Mn blocks. The preliminary analysis of seismic data exhibits wide-spread occurrences of BSRs at about 250-300 ms below the seafloor in both blocks. The BSRS observed in slope regions are distinct compared to those observed in the plain regions. The OBS data are yet to be acquired in two most promising areas in both blocks within 10 X 10 sq. km with a view delineate the lateral/areal extension of gas-hydrate- and free-gas laden sediments and assess their resource potential. Keywords: Indian margins, seismic techniques, gas-hydrates, detection, assessment

METHANE RECOVERY FROM AND CARBON DIOXIDE SEQUESTRATION IN NATURAL GAS HYDRATES: DEVELOPMENT AND

TEST OF INNOVATIVE METHODS

Judith Maria Schicks1, Bernd Steinhauer1, Erik Spangenberg1, Ronny Giese1, Joerg Erzinger1 Klaus Wallmann2, Matthias Haeckel2, Ingo Klaucke2 and SUGAR Partners

1Helmholtz Centre Potsdam – German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany

2IFM-Geomar, Wischhofstraße 1-3, 24148 Kiel, Germany

Natural gas hydrates occur at all active and passive continental margins, in permafrost regions and deep lakes. Due to the huge amount of carbon bonded in these worldwide occurrences, the production of methane from natural gas hydrate formations seems to be a promising new source for large quantities of energy. But natural gas hydrates remain stable as long as they are in mechanical, thermal and chemical equilibrium state with their environment. Thus, for the production of gas from hydrate bearing sediments, at least one of these equilibrium states must be disturbed by depressurization, thermal stimulation or addition of chemicals such as methanol or CO2. In the framework of the German national gas hydrate research project SUGAR, all three reaction routes – alone or in combination – are tested considering new aspects. In this context thermal stimulation using in situ combustion is tested in a pilot plant scale. Different reaction routes such as the total and the partial catalytic oxidation of methane are tested in a heat exchange reactor, which is placed in a large-scale reservoir simulator (LARS) with a volume of 425 L. The latter was realized to synthesize hydrates in sediments under conditions similar to nature and to test the efficiency of the reactor with respect to hydrate dissociation and gas production rates Thermocouples and methane sensors placed in the reservoir simulator collect data regarding the expansion of the heat front and the methane release, respectively. These data are used for numerical simulations for up scaling from laboratory to field conditions. However, thermal stimulation may be used alone or in combination with CO2 sequestration. Therefore, laboratory studies on methane recovery from bulk hydrate phases as well as hydrate bearing sediments by use of CO2 injection (gaseous, liquid, supercritical) are performed using several analytic tools such as Nuclear Magnetic Resonance, confocal Raman spectroscopy and X-ray diffraction. Preliminary results from the laboratory studies on the CO2-hydrocarbon swapping process in simple and mixed gas hydrates will be presented and discussed with respect to kinetic of the process as well as long term stability of the resulting CO2 containing hydrate phase in its environment. Also, the experimental set up of LARS and the reactor design will be presented.

GAS HYDRATE ASSESSMENT USING MARINE ELECTROMAGNETIC METHODS: CASE STUDIES AND MODEL STUDIES

Katrin Schwalenberg1, Grant Caldwell2, and Nigel Edwards3

1Federal Institute for Geosciences and Natural Resources, Hanover, Germany 2Geological and Nuclear Science, Lower Hutt, NZ

3University of Toronto, Canada

Marine CSEM (controlled source electromagnetics) has proven to be a useful exploration tool for gas hydrate assessment. Successful case studies can be reported from the Cascadia Margin, from the Hikurangi Margin, Hydrate Ridge and from the Gulf of Mexico. Hydro-acoustic and seismic surveys are useful to identify vent and seep structures which are often indicative for gas hydrate accumulations. Borehole logs and core samples provide in-situ data from the gas hydrate stability zone. However, there is still need for area-wide gas hydrate assessment. Electromagnetic methods are particularly sensitive to the presence of gas hydrate in the sub seafloor, because the electrical resistivity of the gas hydrate bearing layer is much higher than of the seawater saturated background sediments. There is a direct relation between the seafloor resistivity structure and the delay time of an electromagnetic disturbance propagating away from a horizontal electric dipole source on or near the seafloor which is measured at a receiving dipole at some offset. This can be used to map and assess sub seafloor gas hydrates. 1D inversion has been used so far to tackle the vertical resistivity structure resolving the depth extent of a gas hydrate layer. This is often sufficient to evaluate a prospective gas hydrate reservoir. To study more complex structure we can calculate 3D CSEM model responses and derive a 3D resistivity tensor from all components of the electric field vector. These images are instructive to study CSEM field propagation und reservoir resolution.

Figure. Electric field propagation of a seafloor horizontal electric dipole (HED). The presence of a resistive gas hydrate target clearly affects the current pattern.

SINTERING PROCESS OBSERVATIONS ON CLATHRATE HYDRATES

Toshiki Shiga, Masafumi Nagayama, Kazutoshi Gohara, and Tsutomu Uchida

Hokkaido University, N13 W8 Kita-ku Sapporo 060-8628, Japan Clathrate hydrates are recently paid attention as the novel storage and transportation materials of natural gases or hydrogen. Since these materials are treated as powder or particles, and the storage temperatures are set at moderate conditions (around 253 K) due to the economic reason, it is necessary to consider the sintering of hydrate particles for their easily handling. The sintering process is observed in snow and ice particles especially when they are stored at temperatures near the melting point. Clathrate hydrates have the framework similar to ice, so the sintering process may also occur for them even though they require not only water molecules but also guest molecules. However, no experimental investigations have been carried out until today. In the present study, we observed the sintering process of clathrate hydrates to clarify whether the sintering occurs or not, and if it occurs, how fast the sintering progresses.

We prepared the spherical tetrahydrofran (THF) hydrate to observe the sintering process under microscope. A droplet of the THF solution with the stoiciometric concentration was frozen in liquid nitrogen and annealed at 274-275 K to make a small spherical particle of THF hydrate (2-3 mm in diameter). Some THF hydrate particles were stored in the temperature controllable cell located on the stage of the microscope (Nikon FMZ-10) equipped with CCD camera (Olympus CS230B) and time-lupus S-VHS video recorder. The temperature of the sample cell was controlled at above 263 K within ±0.2 K.

The microscopic observations revealed that THF hydrate particles were sintered like ice particles (see Figure 1). We confirmed that the sintering part was not ice but THF hydrate by temperature increasing above ice melting point. The sintering rate was smaller than that of ice particles at the same temperature conditions. However, it became the same order when the atmosphere of the sample cell was saturated with THF vapor. This indicated that the sintering rate of THF hydrate was controlled by the molecular diffusion process through vapor phase.

(a) (b)

Figure 1: microscopic image of sintering (a) ice and (b) THF hydrate particles (stored at 260 K for 14 hours)

1mm 1mm

JOINT INVERSION OF NAVIGATION AND GAS HYDRATE RESISTIVITY STRUCTURE USING A FIXED TRANSMITTER AND A MOVING, LINEAR

RECIEVER ARRAY: A MODEL STUDY

Andrei Swidinsky and R. Nigel Edwards

University of Toronto, Ontario M5S 1A7, Canada

In marine settings, the controlled source electromagnetic (CSEM) method using an electric dipole-dipole configuration has shown great promise in assessing gas hydrate deposits both through one-dimensional modeling (Edwards, 1997) and through surveys performed at the Cascadia margin, offshore Vancouver Island (Schwalenberg et al. 2005). The technique is effective because the electrically insulating gas hydrate replaces the more conductive seawater in the sediment pore space. A typical survey consists of a horizontal electric dipole transmitter towed at or above the seafloor, with electric fields measured on the seabed by independently deployed nodal receivers or, in our configuration, by cable based receivers towed in-line with the source. The in-line configuration maximizes sensitivity to seafloor resistors while other setups provide useful supplementary information. An alternative to the fully towed survey could be to have a stationary dipole transmitter of known position and orientation located on the seafloor, connected to a drilling platform or to a seafloor nodal system such as the one currently in use by NEPTUNE Canada. A streamer of electromagnetic receivers may be towed around the nearby area, and the conductivity structure of the seafloor obtained from electric field measurements. Such a situation raises the question: If the ship track is known and the cable is assumed to be pulled straight, do we even need to know where the streamer is at all? A study of this nature is also relevant in the search for submarines and other man-made objects which act as electrical sources. In this case, the streamer location is well-known, but the location of the source and the earth conductivity structure is not. We investigate the sensitivity of this type of survey configuration to one-dimensional gas hydrate models using a linear eigenparameter analysis. We also examine the choice of starting models by inverting synthetic, noisy data using the downhill simplex method, better know as Amoeba. Results show that with enough frequencies and receivers, the earth model can be independently resolved from the streamer location, and that the inclusion of magnetic field data should further reduce any ambiguity. Synthetic inversions indicate that the location of the array must be known on the order of a few hundred meters to be used as suitable starting model. Such a level of accuracy should be possible using simple trigonometric arguments based on the amount of cable deployed and its tilt off the stern of the survey vessel. Edwards, R. N. [1997] On the resource evaluation of marine gas hydrate deposits using sea-floor transient electric dipole-dipole methods, Geophysics, 62(1), 63-74.

Schwalenberg, K., Willoughby, E.C., Mir, R., and Edwards, R.N. [2005] Marine gas hydrate signatures in Cascadia and their correlation with seismic blank zones, First Break, 23, 57-63.

TRANSIENT ELECTROMAGNETIC IMAGING OF THIN RESISTIVE TARGETS: APPLICATIONS FOR GAS HYDRATE ASSESSMENT

Andrei Swidinsky and R. Nigel Edwards

University of Toronto, Ontario M5S 1A7, Canada

Gas hydrates are a solid ice-like mixture of water and low molecular weight hydrocarbons. The most common hydrocarbon is methane. Hydrates are found in two regions: under the permafrost in polar areas, and to a far greater extent under the ocean, along continental slopes and margins. Over the years, interest in gas hydrates has dramatically increased due to their potential as a future energy resource, their possible role in climate change, and their presence as a geohazard. In marine settings, the transient controlled source electromagnetic (CSEM) method using an electric dipole-dipole configuration has shown great promise in assessing gas hydrate deposits. The technique is effective because the electrically insulating gas hydrate replaces the more conductive seawater in the sediment pore space.

Marine CSEM responses can be inverted to yield a geo-electrical structure of the subsurface, where regions of high resistivity in the otherwise conductive and typically homogenous host may be interpreted as gas hydrate. Although these deposits have been shown, through various studies, to be three-dimensional (3D) structures, current CSEM interpretation techniques are limited to one- dimensional inversion. As a result, there is a need for fast and efficient 3D imaging methods which can be used to find starting models for rigorous inversions and even to process the data in real-time. A possible solution may lie in the enormous imaging toolbox available to exploration seismologists. Migration is one particular seismic technique that has previously been adapted to image subsurface conductivity structure with electromagnetic data. (e.g., Zhdanov et. al. 1996, Tompkins, 2004, etc.) However, the methodologies that exist reformulate the basic machinery of migration to work with raw CSEM data, and although this approach appears successful, it does not make use of any pre-existing seismic software readily available. In contrast, we chose to take the reverse approach to the problem and to transform backscattered electromagnetic data from resistive targets such as gas hydrate into a form that is compatible with the original seismic migration method. It should be stressed that such a transformation is incapable of improving the inherent low resolution of the electromagnetic method, but allows access to the wealth of seismic processing tools.

As an aid in three-dimensional interpretation, we describe a numerically effective method of transforming marine CSEM data into a form suitable for seismic-style processing. Our approach uses Linear Programming to produce reflection wavelets that show strong similarities to those found on seismic sections. Current work is focused on applying the transform to real marine CSEM data obtained above resistive gas hydrate structures, in addition to CMP stacking and migration of transformed synthetic EM data from various hydrate models, such as the extremely simplified ones presented here.

Tompkins, M. J. [2004] Marine controlled-source electromagnetic imaging for hydrocarbon exploration: interpreting subsurface electrical properties, First Break, 22, 27-33.

Zhdanov, M. S., Traynin, P., and Booker, J. [1996] Underground imaging by frequency domain electromagnetic migration, Geophysics, 61, 666-682.

THE MARINE DEEP SUBSURFACE BIOSPHERE

Andreas P. Teske

University of North Carolina, Chapel Hill, NC, USA

Deep marine subsurface sediments represent a distinct microbial biosphere of novel bacteria, archaea and eukaryotes with deep phylogenetic roots and unexplored physiologies. In this talk, I will present a short overview on the current state of microbial exploration of the marine subsurface biosphere, and show how microbial community composition and activity relates to basic geochemical characteristics of marine sediments, such as availability of electron acceptors, organic carbon sources, and position of energy-rich geochemical interfaces at the surface and within subsurface sediments.

GEOPHYSICAL DATA AND GIS: AN APPROACH TO CHARACTERISE THE GAS HYDRATE RESERVOIR (SOUTH SHETLAND MARGIN)

Umberta Tinivella1, Flavio Accaino1, Michela Giustiniani1, and Maria F. Loreto1

1Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS, 34010 - Trieste, Italy

The presence of gas hydrate and free gas in the accretionary prism along the South Shetland margin (Antarctic Peninsula) was confirmed by low and high resolution geophysical data. This area can be considered as a useful site to study the seismic characteristics of sediments containing gas hydrate, and estimate gas hydrate and free gas amount. In order to reach this target, we extracted a detailed and reliable velocity field by using iteratively the pre-stack depth migration, analysing the flatness of the reflections in the Common Image Gathers and adopting a layer stripping approach. The final velocity field was translated in terms of gas hydrate and free gas amount. Two different gas distributions within sediments can be considered (patchy or uniform). All 2D final depth velocity models were interpolated to produce a 3D velocity and concentration models of the area. From the depth seismic sections, the BSR geometry along the margin was reconstructed. It is worth to mention that all geophysical dataset are included in a GIS project, in order to better correlate all information and obtain a consistent interpretation of the available data. The 3D depth velocity model was translated in terms of 3D gas hydrate concentration by using theoretical approaches. A regional gas hydrate concentration was estimated, while the free gas volume was only locally detected. The estimated total volume of hydrate in area of 600 km2 (where the interpolation is reliable), is 16 109 m3. Moreover, considering that 1 m3 of gas hydrate correspond to 140 m3 of free gas in standard conditions, the total free gas is about 2.3 1012 m3. The 3D models (velocity and concentration), integrated with 2D seismic interpretation, geothermal anomalies derived by BSR depth, and all information derived by the entire geophysical dataset, is very useful to detect areas with or without fluid anomaly within sediments related to presence/absence of the BSR.

Figure. Left: Map of velocity anomalies extracted just above the BSR. Right: Map of the gas hydrate amount extracted just above the BSR. White arrows indicate high gas hydrate amount in correspondance of the high velocity anomalies. Black lines: seismic lines. Ellipse: gas hydrate reservoir.

GAS HYDRATE FORMATION ON THE PORANGAHAU RIDGE

OFFSHORE NEW ZEALAND – EVIDENCE FROM SEISMIC, HEATFLOW, AND ELECTROMAGNETIC DATA

Suzannah J. Toulmin1, Katrin Schwalenberg2, Ingo A. Pecher3,1, Gareth J. Crutchley4,5, Andrew R.

Gorman4, and Warren T. Wood6

1Institute of Petroleum Engineering & ECOSSE, Heriot-Watt University, Edinburgh, Scotland (UK) 2Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, Germany

3GNS Science, Lower Hutt, New Zealand 4University of Otago, Dunedin, New Zealand

5Now with: IfM-Geomar, Kiel, Germany 6Naval Research Laboratory, Stennis Space Center, MS, USA

The gas hydrate stability zone beneath the Porangahau Ridge, a thrust ridge on the Hikurangi Margin’s accretionary prism, has been studied with seismic, heatflow, and controlled-source electromagnetic (CSEM) surveys between 2005 and 2007. We observe high-amplitude anomalies in seismic data above the regional level of bottom simulating reflections (BSRs) beneath this ridge. The amplitude anomalies originate at the BSR. Full-waveform inversion indicates these high-amplitude zones are caused by low-velocity layers most likely due to free gas. We suggest that the base of gas hydrate stability zone is upwarped locally to above the level of the high-amplitude zones because of advective heatflow from expulsion of warm fluids. Seafloor thermal data however, do not show any pronounced thermal anomaly. This apparent discrepancy is best explained by heatflow being transient. We speculate fluid expulsion is in the process of “shutting down” (based on additional seismic data, most likely from north to south) leading to cooling from the seafloor downward. The CSEM data reveal a zone that appears to have anomalously low resistivity in the vicinity of the seismic high amplitude reflections. While we cannot entirely rule out artifacts in the resistivity structure in particular from seafloor topography, we suggest the most likely explanation for low resistivity is high salinity of pore waters. The resistivity anomaly is too pronounced to be caused directly by a thermal anomaly. We suggest that salinity increases as a result of salt exclusion from gas hydrates during on-going hydrate formation following cooling of the seafloor. While gas hydrates increase resistivity in sediments, it is conceivable that during the early stages of hydrate formation, the increase of resistivity due to elevated salinity during hydrate formation offsets the decrease due to the presence of hydrates. Furthermore, it is possible that hydrate formation takes place deeper in the sediment section and highly saline fluids are being transported upwards into regions with low gas hydrate concentration resulting in a decrease of resistivity. Local thermal disturbances, albeit probably on a smaller scale than on the Porangahau Ridge, caused by fluid expulsion along faults may be common features on active margins. We speculate that “freezing” of gas in connection with the disappearance of such thermal disturbances may constitute an underrated mechanism for gas hydrate formation.

GAS HYDRATE PROGRAM (JAPAN)

Tsutomu Uchida

Hokkaido University, N13 W8 Kita-ku Sapporo 060-8628, Japan Several hydrate projects are currently underway in Japan. They can be classified into three categories: Resource and Environments, Utilization and Basic/Scientific Research. In the Resource and Environments category, three large projects are ongoing. MH21, which many institutions are belonging to, is the largest project in Japan. Other two projects are the Sea of Okhotsk expedition led by Prof. Shoji, Kitami Institute of Technology, and the marine gas-cycle observations, led by Prof. Matsumoto, University of Tokyo. In the Utilization category, some Japanese companies are interested in gas hydrates for their use in storage or as a transportation material for natural gas or hydrogen. Mitsui Engineering and Shipbuilding Co., Ltd. (MES) have constructed a hydrate pellet supply plant near an LNG storage facility, and investigated the NGH (natural gas hydrate) chain from the pellet formation to its consumption by the natural gas user. In comparison, studies of hydrogen storage in clathrate hydrates are still at the laboratory stage. A conceptual feasibility study of plant scale hydrogen storage with clathrate hydrates has been performed by IHI Corporation and Prof. Mori, Keio University. The third category is Basic and Scientific Research. These studies are usually done for pure scientific interests, but they are sometimes useful for those shown in the former two categories. In this presentation, two unique studies are introduced. Dr. Ohmura, Keio University, has studied the combustion characteristics of methane hydrates, in conjunction with MES. This would be the first experience of showing how methane hydrate burns. Also, it provides the first evidence that the combustion of methane hydrate is gentle and safe. Another study provides experimental results of the sintering process of hydrate particles. This can be utilized for evaluating hydrate storage conditions, but it belongs to the crystal growth problem.

LONG-TERM SEAFLOOR OBSERVATORY MONITORING OF MARINE GAS HYDRATES WITH NEPTUNE Canada

Eleanor C. Willoughby, Lisa A.N. Roach, Reza Mir and R. Nigel Edwards

Department of Physics, University of Toronto, 60 St. George St., Toronto, ON, M5S 1A7, Canada

Naturally-occurring gas hydrate deposits are common on continental slopes and margins, under roughly 400 m of water. Whenever water and methane are found under sufficient pressure and low enough temperature, a stable ice-like hydrate will form. Vast stores of methane, a potential resource yet also a power greenhouse gas, are trapped in these clathrates (or cages). Gas hydrates may have an impact on seafloor stability. Thus, concerted effort has been made to map and measure the extent of gas hydrate deposits, for reasons of resource assessment on the one hand, and hazard assessment on the other. In order to understand their role in the carbon cycle, the next step would be to study the nature of the evolution of these deposits in time – something difficult to do with sporadically repeated ship-borne geophysical surveys. The seafloor pressure and temperature conditions which control gas hydrate stability can vary, whether due to on-going sedimentation, tectonics, sea level change or local temperature variations. Further, repeated seismic surveys and observations of sporadic methane venting from the seafloor suggest that large gas hydrate deposits like the “Bullseye” cold vent offshore Vancouver Island, BC, Canada, may be evolving in time. It is clearly important to monitor these deposits to learn about their stability or evolution in time. Seafloor observatories, built or planned in a variety of marine environments, are seen as a means to shift the focus of marine science from exploration to real-time monitoring. By gathering long-term time series data a variety of scientific problems can be addressed. Offshore Vancouver Island, the NEPTUNE-Canada cable-linked ocean-floor observatory has two nodes dedicated to geophysical studies of gas hydrate systems: at the Bullseye Vent and in Barkley Canyon. Here, we introduce the on-going experiments which can help assess and monitor these gas hydrate deposits, and present early results from NEPTUNE Canada. Experiments designed to record the physical properties of the gas hydrate-rich sediments, or to monitor venting of free gas, as well as experiments intended for earthquake or tsunami monitoring can all provide insight pertinent to the evolution of the gas hydrate-free gas systems. Instrumentation at the Bullseye Vent includes a controlled-source electromagnetic (CSEM) array to monitor the sub-seafloor electrical resistivity and a seafloor compliance (SFC) installation to monitor the sub-seafloor elastic properties, in particular the shear modulus. These will soon be augmented by a sector-scanning sonar installation to monitor bubbles in the water column associated with methane venting. At the Barkley Canyon, there are seafloor crawlers equipped with sensors to measure methane, temperature, pressure, water currents, salinity, turbidity and a pan/tilt webcam. Both sites also include an ocean-bottom seismometer with differential pressure gauge and also a bottom-pressure recorder. These data can be mined to determine sub-seafloor physical properties related to the gas hydrate deposit or the nearby ‘background’ geology.

OVERVIEW OF MARINE HYDRATE RESEARCH AT NATIONAL OCEANOGRAPHY CENTRE, SOUTHAMPTON.

Wright, I.C.1, James, R.H.1, Minshull, T.1, Ellis, M.1, Connelly, D.1, Best, A.1, Westbrook, G.K.2,1, Pälike, H.1, Rohling, E.1, Griffiths, G. 1

1 National Oceanography Centre, Southampton, European Way, Southampton, SO14

3ZH, United Kingdom 2 School of Geography, Earth and Environmental Sciences, University of Birmingham,

Birmingham, B15 2TT, United Kingdom Marine hydrate research at NOCS continues to follow parallel threads of exploration geophysics to document geological processes of hydrate formation and ephemeral gas release, experimental rock physics of hydrate-saturated sediments, the biogeochemistry and fate of methane gas in seafloor sediments and ocean waters, and the development of long-term monitoring observatories for the Arctic. Various aspects of this research will be presented. Following discovery of plumes of methane bubbles that probably originate from the decomposition of hydrate on uppermost continental slope of western Svalbard (Westbrook et al. 2009), the ESONET-funded AOEM experiment will deploy a seafloor lander for two years commencing October 2010 at 400 m water-depth to monitor bottom-water temperatures and flows, sub-seafloor sediment temperatures, micro-seismicity and hydro-acoustics, and methane gas flux. A new UK Arctic research programme currently under development will commence in 2011, in which a central research theme will be quantifying processes leading to methane and CO2 release in the Arctic. Key aspects of the programme will be estimating large-scale inventories of terrestrial and continental shelf organic carbon and methane, and their vulnerability to climate change, and understanding the fate and impact of methane and CO2 release. The entire Arctic programme will seek high levels of international collaboration. In addition, long-range Autonomous Underwater Vehicles (AUVs) with appropriate sensors are proposed for year-round deployment at Svalbard, including sites of seafloor hydrate dissociation covered with winter sea-ice.

EARLY DIAGENESIS RECORDS AND GEOCHEMICAL CHARACTERISTICS OF GAS HYDRATE IN THE SOUTH CHINA SEA

Daidai WU1, 2, 3, Nengyou WU1, 2, and Ying YE3

1 Guangzhou Institute of Energy Conversion, CAS, Guangzhou 510640, China 2Guangzhou Center for Gas Hydrate Research, CAS, Guangzhou 510640, China 3Departmnetn of Earth Sciences, Zhejiang University, Hangzhou 310027, China

According to the known gas hydrate reserves, the South China Sea (SCS) has the most favourable of settings for offshore gas hydrate occurrences. Based on the geological background and conditions for gas hydrate formation, such as high sedimentation rate, thick sediments, distinctive geological structure in these area, it has indicated that Taixinan Basin, Pearl River Mouth Basin, Xisha Trough, Qiongdongnan Basin and Dongsha Area in the South China Sea are very probable for gas hydrate reserves. We have researched the early diagenesis and geochemical characteristics systematically of gas hydrates in the South China Sea by analyzing authigenic mineral compositions, chemical compositions in pore water, organic carbon content, sedimentation rate and methane concentrations in the headspace of sediments. The marine core sediments of site T1 in Qiongdongnan Basin, site T2 in Jianfengbei Basin, sites CG10, HD196A and HD319 in Taixinan Basin, and other sediments of sites TVG-1 and TVG-11 in Jiulong Methane Reef were collected. Finally, in the light of some indicators inferred from the above methods and some results collected from the former research, some prospective gas hydrates are identified in the northern slope of the South China Sea, especially in Taixinan and Qiongdongnan basins.

Complicated authigenic minerals, such as miscellaneous carbonates, sulphates and frambiodal pyrite, were identified by XRD and SEM in sediment samples from Qiongdongnan, Taixinan and Jianfengbei basins. These authigenic minerals consistently indicate gas hydrate proximity. The assemblage and fabric characters of carbonates are similar to that being found in cold-seep sediments, which is thought to be related to microorganisms fueled by dissolved methane (e.g., especially in Jiulong Carbonate Reef).

The cold-seep evidences have been found in TVG-1 and TVG-11 samples from the authigenic minerals assemblage and microstructure tectonics in Jiulong Methane Reef. Their high value of CH4/Ba2+ values are very similar to the cold-seeps in Gulf of Mexico and Black Sea. The microstructure in the sediments of Methane Reef shows that carbonate deposition is related with microorganisms. The sample TVG-1 was formed earlier than the TVG-11, because aragonite has been found in TVG-11, and aragonite had transformed into calcite in TVG-1.

Results of sediment pore water chemical composition analysis from Qiongdongnan Basin and Taixinan Basin, show that the concentrations of SO4

2- decrease sharply in pore water, and the depths of SMI (Sulfate-methane interface) are shallow. The concentrations of Ca2+, Mg2+, Sr2+ decrease clearly, and the ratios of Mg2+/Ca2+ and Sr2+/Ca2+ increase sharply as the depth increased. These geochemical characteristics are similar to chemical compositions abnormalities in pore water of the shallow sediments where the gas hydrate occurs in the world. Those results strongly indicate there should be gas hydrates or deep-water oil (gas) reservoirs underneath.

Abundant organic carbon content in Taixinan Basin sediments, special in the site HD196A, which is over 1% in most of its sediments. That indicates that there are enough gas resources to form gas hydrate. The deposition rate in the Taixinan Basin is fast, ranging from 16.7 to 20.8 cm/ka since the Late Pleistocene. Methane concentration in the headspace of sediments increases sharply in the bottom of core samples, which indicates that there is positively a hydrocarbon reservoirs underneath the sampling site. Therefore, Taixinan Basin, special the site HD196A, is a positive area for gas hydrate formation.

In summary, because of thick sediments, abundance organic matters, the gas resources for gas hydrate, temperature and pressure conditions, entrapped basin and so on, Jianfengbei Basin, Qiongdongnan Basin and Taixinan Basin in the South China Sea all have the most favourable conditions for gas hydrate to occur. Overall Taixinan Basin has the best chance for gas hydrate formation, and then Qiongdongnan Basin. Gas hydrate is a very complicated reservoir system, and there is much investigation and research on gas hydrate need to be carried out.

GAS HYDRATE RESEARCH IN NORTHERN SOUTH CHINA SEA Nengyou WU1,2,3 and Shengxiong YANG3

1Guangzhou Institute of Energy Conversion, CAS, Guangzhou 510640, China 2Guangzhou Center for Gas Hydrate Research, CAS, Guangzhou 510640, China

3Guangzhou Marine Geological Survey, CGS, Guangzhou 510750, China

A Chinese gas hydrate program Gas Hydrate Research in Northern South China Sea has been initiated since 2001. The objectives of program are to reveal the evidences for gas hydrate, including the geophysical, geological and geochemical indicators; to determine the distribution of gas hydrate; to evaluate the gas hydrate as the future new energy resources; to study the mechanism of gas hydrate formation.

Based on the geological, geophysical and geochemical investigations for gas hydrate in the

north slope of the South China Sea, including the joint SO-177 cruise by cooperation between Guangzhou Marine Geological Survey, China and Leibniz Institute of Marine Sciences (IFM-GEOMAR), Germany in 2004, the evidence for gas hydrate occurrence has preliminarily suggested great promise for gas hydrates in this region (Wu et al., 2003; Song et al., 2004; Suess et al., 2005; Chen et al., 2005; Wu et al., 2005; Jiang et al., 2005; Wu et al., 2006a, 2006b; Han et al., 2008; Yang et al., 2008; Jiang et al., 2008). Seismic data shows a well-developed BSR in profiles perpendicular to the SE-facing slope of the NE South China Sea. A certain degree of reprocessing and/or closer examination reveals the acoustic anomaly patterns. Studies of velocity structure of hydrated sediments are useful for better understanding the distribution of gas hydrates. The unambiguous images of bacterial mats, gas hydrate-derived carbonates and vent-clams were available by a self-contained deep-towed photographic system. A lot of carbonate and clam samples were recovered by TV-guided grab. A number of geochemical anomalies may be related to the formation and dissociation of gas hydrates, including the headspace gas in sediments, carbon isotopes of the methane, downward and spatial profiles of Cl-, SO4

2- and major cations (e.g., Ca, Mg, Ba, Sr, B, and NH4) contents, and 18O, D, 11B, and 87Sr/86Sr ratios of the pore waters.

In order to determine the nature and distribution of gas hydrate, a gas hydrate drilling

expedition GMGS-1 was initiated by Guangzhou Marine Geological Survey, China Geological Survey using M/V Bavenit along with specialized Fugro & Geotek equipment in Shenhu Area from 18 April –11 June of 2007. The services include the drilling, wire-line logging, in-situ temperature measurement and pore water sampling, pressurized and non-pressurized coring, and onboard analysis such as the IR Imaging, degassing and gas chromatography, MSCL/P logging, X-ray scanning, pore water geochemical analysis (Zhang et al., 2007; Wu et al. 2007). The geochemistry of sediments from large piston cores and drilling cores were measured and showed that the sulfate-methane interface (SMI) is from 10 to 27 mbsf in the research area. Methane was the dominant hydrocarbon gas in all gas analyses. The δ13CCH4 values of headspace gases from the gravity piston core sediments range from -74.3‰ to -46.2‰, and mostly less than -55‰. These data show that the gas source for gas hydrate formation is microbial. The gas hydrate drilling recovered high concentrations of hydrate (maximum 26-48%, with the gas composition of >99% methane) in a disseminated form in foraminifera-rich clay sediment. The hydrate-bearing sediments ranged from 10 meters to 25 meters in thickness and were concentrated in the lower part of the gas hydrate stability zone (GHSZ), just above the base of the gas hydrate stability zone (BGHSZ). It is likely that the methane that created this gas hydrate is from in-situ microbial methane production (Wu et al., 2007; Wu et al., 2008).

INTRODUCTION TO THE GAS HYDRATE MASTER PROJECT OF ENERGY NATIONAL SCIENCE AND TECHNOLOGY PROGRAM OF

TAIWAN

Tsanyao Frank Yang1, and research team of gas hydrate project of CGS of Taiwan2

1Department of Geosciences, National Taiwan University, Taipei 106, Taiwan 2PIs and project managers of gas hydrate Project of Central Geological Survey, Taiwan, Taipei 235,

Taiwan

Bottom Simulating Reflectors (BSRs), which have been considered as one of major indicators of the gas hydrate in sub-seafloor, have been detected and widely distributed in offshore SW Taiwan. The Central Geological Survey of Taiwan launched a 4-year multidisciplinary gas hydrate investigation program in 2004 to explore the potential of gas hydrate resources in the area. The results indicate that enormous amounts of gas hydrate should occur beneath the seafloor, although none of solid gas hydrate samples have been found. Therefore, a second stage of another 4-year program started in 2008 to extend the studies/investigation. In the ongoing projects, some specific areas will be studied in detail to assess the components of gas hydrate petroleum system and provide a better assessment of the energy resource potential of gas hydrate in the target area. In addition to the field investigations, phase equilibrium of gas hydrate via experiment, theoretical modeling, and molecular simulations has also been studied. The results can provide insights into gas hydrate production technology. Considering the high potential energy resources, the committee of the energy national science and technology program suggests initiating a master project to plan the strategy and timeline for the gas hydrate exploration, exploitation and production in Taiwan. The preliminary plan will be introduced in this presentation.

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