Oceanic Methane Hydrates: Fundamentals, Technological Innovations, and Sustainability

By Lin Chen and Sukru Merey

Methane hydrates are still a complicated target for today’s oil and gas offshore engineers, particularly the lack of reliable real field test data or obtaining the most recent technology available on the feasibility and challenges surrounding the extraction of methane hydrates. Oceanic Methane Hydrates delivers the solid foundation as well as today’s advances and challenges that remain. Starting with the fundamental knowledge on gas hydrates, the authors define the origin, estimations, and known exploration and production methods. Historical and current oil and gas fields and roadmaps containing methane hydrates around the world are also covered to help lay the foundation for the early career engineer. Lab experiments and advancements in numerical reservoir simulations transition the engineer from research to practice with real field-core sampling techniques covered, points on how to choose producible methane hydrate reservoirs, and the importance of emerging technologies. Actual comparable onshore tests from around the world are included to help the engineer gain clarity on field expectations.Rounding out the reference are emerging technologies in all facets of the business including well completion and monitoring, economics aspects to consider, and environmental challenges, particularly methods to reduce the costs of methane hydrate exploration and production techniques. Rounding out a look at future trends, Oceanic Methane Hydrates covers both the basics and advances needed for today’s engineers to gain the required knowledge needed to tackle this challenging and exciting future energy source.

• Understand real data and practice examples covering the newest developments of methane hydrate, from chemical, reservoir modelling and production testing
• Gain worldwide coverage and analysis of the most recent extraction production tests
• Cover the full range of emerging technologies and environmental sustainability including current regulations and policy outlook

• Language: English
• Publisher: Elsevier Science
• Release date: Jan 10, 2021
• ISBN: 9780128185667

Lin Chen

Dr. Lin Chen is now a full Professor in the Institute of Engineering Thermophysics, Chinese Academy of Sciences, and a joint professor in the University of Chinese Academy of Sciences, China. His current research topics include unconventional energy resources (methane hydrate), supercritical fluids, multiscale heat/mass transfer, and advanced measurement techniques. In recent years, he has authored more than 120 well-cited international journal papers, conference papers/presentations/keynotes. He was the winner of AUTSE Young Scholar Award in 2018. He is the Associate Editor of ASME JNERS and board for The J. of Supercritical Fluids (Elsevier). He has published several books/chapters, including the most famous one on energy conversion (“Advanced Applications of Supercritical Fluids in Energy Systems”, IGI Global, 2017, 680 pages).

Book preview

Oceanic Methane Hydrates

Fundamentals, Technological Innovations, and Sustainability

Lin Chen

Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China

University of Chinese Academy of Sciences, Beijing, China

Sukru Merey

Department of Petroleum and Natural Gas Engineering, Batman University, Batman, Turkey

Table of Contents

Cover image

Title page

Copyright

Foreword by Dr. Maruyama

Foreword by Dr. Coffin

Preface

Acknowledgment

Chapter 1. Fundamentals of methane hydrate

1.1. Origin of gas hydrates

1.2. Existence of gas hydrates

1.3. Methane hydrate reservoirs

1.4. Methane hydrate exploration and estimation

1.5. Methane hydrate production methods

Chapter 2. Research and development in major countries: general view

2.1. From oil/gas fields to methane hydrate fields

2.2. On-land explorations and offshore explorations

2.3. Recent gas extraction trials and implications

2.4. Historical developments of field techniques

Chapter 3. Microscale concepts and dissociation dynamics

3.1. Microscopic structure of gas hydrate in sediment

3.2. Interfacial dynamics and microscale experiments

3.3. Pore network modeling

3.4. Sand movement and phase equilibrium process in microscale

3.5. Summary

Chapter 4. Core-scale in-lab experiments and numerical estimation

4.1. Pore-filling characteristics and chemistry of hydrate-bearing sediment

4.2. Permeability measurements and comparisons

4.3. Relative permeability estimation

4.4. Hydrate dissociation experiments in core-scale

4.5. Numerical modeling methods in core-scale

4.6. Summary and future concerns

Chapter 5. Numerical methods in multiscale system analysis

5.1. Importance and history of numerical simulators

5.2. Laboratory-scale (core-scale) simulations

5.3. Reservoir-scale simulations

5.4. Molecular dynamics simulation

5.5. Summary

Chapter 6. Real-field core sampling and analysis

6.1. Fundamentals of geomechanics in hydrate-bearing layers

6.2. Core sampling techniques for hydrate-bearing layers

6.3. Geomechanical analysis of core samples

6.4. Core sample geochemical analysis

6.5. Core sample visualization analysis

Chapter 7. Reservoir-scale considerations and methods

7.1. Key points to choose producible methane hydrate reservoirs

7.2. Importance of well logs to identify methane hydrate reservoirs

7.3. Real geological considerations

Chapter 8. Real onshore tests in Russia, Canada, and USA

8.1. Messoyakha permafrost field test

8.2. Mallik permafrost field test

8.3. The tests in the North Slope of Alaska

8.4. Summary

Chapter 9. Real offshore tests in Japan (2013, 2017) and China (2017)

9.1. Offshore production tests in Japan (2013, 2017)

9.2. Offshore production tests in China (2017)

9.3. Summary and implications for long-term production

Chapter 10. Geological and geochemical characterization of gas hydrate reservoirs in the Indian Sea

10.1. Introduction

10.2. Characteristics of gas hydrate-bearing sediments from Indian Margin

10.3. Geochemical footprints of gas hydrate reservoirs in Indian Margins

10.4. Summary

Chapter 11. Activities in the mid-East, Europe, and other regions

11.1. Activities in the Gulf of Mexico

11.2. Activities in Indian Sea

11.3. Activities in Ulleung Basin

11.4. Activities in the Black Sea

11.5. Activities in the Mediterranean Sea

11.6. Activities in other regions

Chapter 12. Comparisons of field activities in different worldwide sites

12.1. Geological settings

12.2. Technological routes

12.3. Outcomes and strategies

Chapter 13. Emerging technologies in methane hydrate projects

13.1. Industry-level developments

13.2. Exploration technologies

13.3. Drilling technologies

13.4. Coring technologies

13.5. Well completion technologies

13.6. Production technologies

Chapter 14. Sensing and monitoring technologies in real offshore tests

14.1. Introduction

14.2. Monitoring well system

14.3. Production well system

14.4. Environmental well system

14.5. Summary

Chapter 15. Operation and well monitoring and recording technologies

15.1. Deployment of monitoring methods at wellsite

15.2. Long-term autonomous monitoring technologies

15.3. Short-term real-time production monitoring technologies

15.4. Emerging monitoring technologies

15.5. Summary

Chapter 16. Economic aspect and environmental issues

16.1. Economic aspect: gas price comparison

16.2. Methods to reduce the cost of methane gas extraction

16.3. Environmental issues and regulations

16.4. Summary

Chapter 17. Policy assessment and outlook for future

17.1. General view from policy trend

17.2. Trends and development for regulations on methane hydrate exploration

17.3. Summary

Index

Copyright

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Foreword by Dr. Maruyama

I am very glad to know that Dr. Lin Chen is publishing this book on offshore methane hydrate. We met for the first time in Beijing around 14  years ago when I visited Peking University. At that time, he helped as an assistant in translating two JSME (Japan Society of Mechanical Engineering) text books of Thermodynamics and Heat Transfer Engineering, for which I was in charge from Japan side. After that, he visited my lab in Tohoku University twice in 2012 and 2013 and then collaborated with me as a Research Fellow, JSPS Fellow, and finally an Assistant Professor in Tohoku University, Japan. The keywords of thermodynamics and heat transfer engineering also apply to the methane hydrate research discussed in this book.

My past research life in Tohoku University was mainly focused on Fluid and Thermal Sciences. Methane hydrate research in my lab was also operated from a viewpoint of heat balance within reservoir layers, which has not been often touched as the world's major research groups of methane hydrate come from petroleum field or geological field. Therefore, the endothermic process of hydrate dissociation in commercial scale will become one key factor for the production efficiency. Especially for offshore methane hydrate exploration, the role of hot/cold water convective flow and the conductive heat transfer from the porous bearing layer will be very critical: quick drop of dissociation rate is identified with the drops of reservoir temperature. Based on this understanding, I initiated the methane hydrate research under the Core Research for Evolutional Science and Technology (CREST) of Japan Science and Technology Agency (JST): Breakthrough on multi-scale interfacial transport phenomena in oceanic methane hydrate reservoir and application to large-scale methane production. We tried to bring the study of interfacial dynamics and production strategy together through the scaling up of prediction models.

Dr. Lin Chen collaborated with my team as the most powerful core researcher. He worked in the direction of thermodynamic considerations for methane hydrate extraction. We worked together for several years and published papers and patents in this field. And I am very glad that the research results of the CREST project have also been introduced in this book. I think the book will also be a compilation of the CREST project.

As discussed in this book, to contribute to the enhancement of large-scale methane production, the mechanism of producing the methane gas from the oceanic methane hydrate reservoir involves multiscale processes. The microscale interfacial phenomena among solid, liquid, and gas phase in methane hydrate reservoir have been observed and evaluated by high-speed interferometry in my lab, while in this book, this method is introduced together with conventional measurement techniques to reveal the pore-to-core-scale happenings during dissociation process of methane hydrate. In my opinion, such coverage of fundamental developments in this book would be very useful for the understanding of researchers from a thermodynamic viewpoint.

And from this book, classic worldwide trials and most recent production in Japan and China have been introduced with details. The Japan test was executed in 2013, when we just started the design of low carbon emission extraction system with thermal stimulation. Knowing that the bottleneck of production rate partially comes from insufficient thermal management and low mobility of phases in methane hydrate reservoir, we designed the strategic production process of warming up and depressurization with Dr. Chen, which resulted in international patent later. In this book, a series of emerging techniques for well logging, monitoring, and real reservoir lifetime operation has also been included. I would be happy to see many new results and technologies be applied in real trials in the near future. And I believe the comparison and analysis of those very recent tests would be one useful source for professionals in methane hydrate field.

Sincerely I would like to recommend this book. I am sure this book will be one useful reference for researchers, engineers, and also graduate students who have an interest in offshore methane hydrate and energy topics. The discussions in policy trend are also unique among many books on this topic, which could also serve as a reference book for policymakers.

Shigenao Maruyama, Dr.

President

National Institute of Technology, Hachinohe College, Hachinohe, Japan

Professor Emeritus, Tohoku University, Sendai, Japan

Foreword by Dr. Coffin

For the last 50  years, gas hydrate studies have integrated geophysics, geology, geochemistry, and geobiology to determine gas in hydrate source(s), volumes, and stability. Teams formed to address these topics include basic research scientists interested in coastal sediment and water column carbon cycles and geobiology community diversities, industrial teams conducting drill site potentials, or government agencies planning near- and long-term national energy investments. For any of these focuses, work is successfully conducted with a thorough integration of the broad topics.

For all occasions, vitality within a team requires a patient attention to communicate diverse motivations in common open terminology. With integration of broad expertise to investigate gas hydrates, we have gained substantially more thorough and extensive knowledge in all our related fields. For example, a combination of seismic blanking data, transitioning to shallow blanking in TOPAS data showing elevated shallow sediment anaerobic oxidation of methane and spatial variations in the microbial community diversity will provide data for drill site assessment, shallow sediment carbon modeling, and new understanding of microbial community diversity. Thorough interpretation of these data expands the capability for future studies in new locations around the world. Keep this overview in mind as you read through "Oceanic Methane Hydrates: Fundamentals, Technological Innovations, and Sustainability" where authors Drs. Lin Chen and Sukru Merey present an outstanding global review of all the aspects that are required for a thorough understanding of gas hydrates.

This book is organized from large-scale seismic data down to microscale geomicrobiology and presents an excellent review of studies around the world. This will be a key reference for gas hydrate research and development for many years to come.

Richard B. Coffin, Dr., Professor

Department Chair Physical and Environmental Sciences,

Texas A&M University—Corpus Christi, Corpus Christi, TX, United States

Preface

In 2013 and 2017, Japan and China conducted two rounds of real offshore oceanic methane hydrate production tests, which attracted new attention for methane hydrate as a possible supplementation to the current energy and fuel market. Knowing its large amount and wide existence around the world coast regions, many countries have set new national plans for exploration and technological development in recent decades. Dr. Sukru and I from energy field got to know methane hydrate more than 20  years ago from school text book introduction. However, it was only in the very recent years that the drilling and extraction reports of methane hydrate field came to the news board. Dr. Sukru Merey and I started with the research of methane hydrate in our PhD period, while we focused on different aspects: Dr. Sukru Merey focused on drilling and exploration technologies and I focused on dissociation thermo-hydrodynamics and system operation analysis. Then we tried to work together and shared information about offshore developments in East Asia and Mid-East, and after seeing the success of 2017 tests in Japan and China, we found it a suitable time to propose a book that covers those most recent milestones in methane hydrate field.

It is indeed very difficult to choose from the many aspects of methane hydrate field to be included in a timely reference book. In our opinion, as discussed, the most urgent need in this field is to update information and generalize the happenings in most recent years, especially for the success of offshore production tests of Japan and China. From this viewpoint, three big advancements can be seen in recent years. The first one is in-lab research developments and technological innovations that help the understanding of molecular-scale and pore-scale behaviors of hydrate formation, dissociation, and evolution. The second one is the advancement in multiscale dynamics modeling methods, which helped the estimation of resources and engineering operation. The third one is the real production tests that happened in Nankai Trough (Japan) and Shenhu (China), which are based on previous onshore tests in Messoyakha (Russia), McKenzie Delta (Canada), and North Slope Alaska (US) and have become milestones in the history of methane hydrate exploration. The production rates from those fields are found increased from several hundred standard cubic meters to tens of thousands of cubic meters per day. Different production methods such as thermal stimulation, CO2/CH4 replacement, and depressurization have been executed and compared. However, professionals still hold that the hydrate fueled age is still several steps far away. Then people get to ask, why it is still far from commercial supply of gas from methane hydrate? To answer this question, to explain the current status of art in real methane hydrate exploration and production worldwide, and to provide information on technological, environmental, and economical aspects of offshore methane hydrate on earth, we set out to organize the current book. We believe that the most recent analysis and policy trend discussions will be useful for those who are working in this field like us as researchers and also for those who want to know more for engineering operation or policy making.

Compared with conventional offshore gas/oil reservoirs, the most important feature of offshore methane hydrate fields is the bearing layer geological conditions. Due to the unique origin (thermal source or bio-source) and existence conditions (high pressure and low temperature), oceanic methane hydrate can be found at layered structure in different types (bulk, turbidate layer, porous, etc.) or rested on the surface of seabed, which is not as deep as that of convectional gas/oil reservoir. For this reason, the oceanic methane hydrate fields are generally unconsolidated layers, which is more flexible than conventional offshore oil/gas reservoirs, and the multiphase coexistence nature during the extraction process adds to the production difficulty. In Part I of this book, such information about multiscale nature and dissociation dynamics in molecular scale, pore scale, core scale, and reservoir scales are introduced. Those discussions are from a very basic viewpoint of interaction between phases, and the predicting model developments are discussed in this section, in a hope that the fundamental laws for such complicated formation/dissociation processes could be clearly analyzed and understood.

After the big earthquake and nuclear accident in Japan (2011), around 15% of energy supply from nuclear sector is cut off. Such happenings in the energy sector expedited the development of offshore hydrate R&D in Japan. For other countries, similar trends are seen: major governmental players are seeking for diversity of energy sources. Though it is usually thought to be far away for the commercial use of gas from hydrate, the success of real extraction in Japan (2013, 2017) and China (2017, 2020) became hot news in this field. For the research and engineering sectors, summary and informative analysis of those tests are urgently needed for next step development. However, existing references of offshore methane hydrate are distributed in the vast ocean of literature. Major books in this field are found more focused on the very theoretical aspects or more like a government report for public information and are far from scientific/engineering research level. This book is designed to cover from the basics of gas hydrates, its experimental tests, most recent developments in real fields, and how it is interpreted in scientific language. Recent success in real tests of Japan and China remarks a new age that is in need of such summary. In Part II of this book, the introduction and discussion of real onshore and offshore production trials is made, including both early onshore activities and the offshore tests in Japan and China in the past decade.

In the spring of 2020, though the global world is combating with the COVID-19, the news from Shenhu (China) came and stated that the second tests have been successfully operated by horizontal well system. The production rate was maintained at a level higher than 2  ×  10⁴ m³/day, which is the highest in world record. Such news aroused worldwide discussion about next step toward technological robust age of methane hydrate R&D. Indeed, governmental policymakers, scientific researchers, engineers, and university students need the most recent information and new technological information/predictions in methane hydrate fields for future plans. For example, the Japan governmental program MH 21 ended its third phase in 2018 (the program started from 2000) and started a new round of project from 2019. China also started new round of intense exploration and production tests, targeting at commercial-scale development. In the mid-east region, United States, India, and many other countries are also designing roadmaps for next decade. Thus, in Part III of this book, the technological breakthroughs, major innovation trends, and economical and environmental developments are analyzed into detail.

Through those discussion and arrangements, we hope this book could be a new handbook on methane hydrate fundamental developments, in-lab innovations, advancements in numerical modeling, and real field test results and analysis. The basics of oceanic methane hydrate are updated in this book, while the microscale to macroscale developments of methane hydrate technologies are covered in detail. In addition to the advancements in lab technology and real field test applications, world policy trends considering environmental, ecological, and economical aspects have been discussed. Users of this book can get the most recent information in this field and also an overall prediction of future trends, technological innovations, and challenges for next decade.

Organization of the book

This book has gathered altogether seventeen chapters that cover from the very fundamentals of oceanic methane hydrate to lab-scale coring and analysis and to reservoir-scale production techniques and policy sectors. Those chapters are organized into three major parts. The contents of the book chapters cover first the basics of oceanic methane hydrate and the multiscale models that are in use for the analysis of dissociation process and multiphase flow physics, which is also scaled up toward reservoir-scale predictions (as Part I); then historic field practices and activities from the very beginning of onshore production to very recent oceanic production trials in Japan and China are discussed in detail, which brings a summary of most recent real field understanding of offshore production of methane hydrate (as Part II); after that, technological aspect of oceanic methane hydrate exploration, drilling, production and environmental monitoring, economical and policy-related contents are covered (as Part III).

Part I covers the fundamentals and multiscale models of oceanic methane hydrate studies. Five chapters (Chapter 1–5) are included in this part. In those chapters, fundamentals of offshore methane hydrate with its existence, exploration, and basic production methods are introduced. The differences between gas/oil fields to methane hydrate fields and their developments in major countries are introduced. This part is then focused on the molecular-scale, core-scale (in-lab scale), and reservoir-scale modeling and numerical simulation methods. The detailed dissociation methods, its physical models, and results are scaled up to provide information for reservoir-scale predictions.

Chapter 1 is Fundamentals of Methane Hydrate. This chapter describes the origins, existence, and structures of methane hydrate on earth. With its wide distribution in permafrost regions and in the deep ocean layers, methane hydrate is attracting worldwide attention as one promising energy resources. The different existence conditions in the deep oceanic layers affect the classification of different types of methane hydrate. And under those different existence conditions, exploration of core samples and production methods varies. In general, depressurization method is considered the most promising kind but systematic studies are still in need to realize those many production technologies into commercial stage, which then could really benefit the human beings.

Chapter 2 is Research and Development in Major Countries: general view. This chapter is a basic introduction to the most recent progress in methane hydrate exploration and real field development. Activities in major drilling and production sites in Canada (Mackenzie Delta), Japan (Nankai Trough), and China (Shenhu in the South China Sea) are introduced with their locations, production behaviors, problems, and current stages. Though the production methods (depressurization, thermal stimulation, CO2 replacement) diverge in safety and efficiency, potential has been confirmed for future large-scale utilization. With major active regions/states with ongoing projects, a detailed picture of worldwide hydrates explorations is summarized in this chapter. Those most recent developments show new possibilities in methane hydrate utilization in the coming decades with emerging technologies in this field.

Chapter 3 is Micro-Scale Concepts and Dissociation Dynamics. This chapter is focused on the microscopic structure of gas hydrate and relevant studies. The microstructure of natural gas hydrate is of importance for the physical and transport properties. The microstructure of gas hydrate dispersed in sediment is still not fully understood. There are a few occasions for core analysis with hydrate samples retrieved from sea floor or subpermafrost with partial decomposition. The assess to microstructural information on the submicron scale may give better understanding to material properties as function of the saturation in order to support geophysical exploration methods. Studies on pole scale can help to reveal mechanisms of gas hydrate formation and dissociation and guide efforts to experimental observations. The dissociation of gas hydrate is of central interest for in situ gas extraction processes. In-lab experiments such as interferometer measurements of interfacial transport are also introduced in this chapter. Microstructural details are crucial for evolution of mechanical stability upon extraction, in particular for the vicinity of the production well.

Chapter 4 is Core-Scale in-lab Experiments and Numerical Estimation. The most challenging problem for stable methane hydrate production from sea beds or under permafrost regions lies in the complex flow and transportation process, which usually occurs inside the unconsolidated porous layers. It is difficulty to visualize hydrates behavior inside porous media. In this chapter, topics on laboratory-scale explorations of the basic dissociation behaviors of methane hydrate are introduced. A series of experimental systems are introduced to show the formation and storage of methane hydrate under different conditions. It is found that the dissociation on a core scale is more heat transfer controlled. The basic core-scale features of methane hydrate in core scale and the understandings of methane hydrate behaviors are summarized from geological, chemical, and thermodynamic characteristics during the dissociation process in this chapter.

Chapter 5 is Numerical Methods in Multi-Scale Methane Hydrate Systems. The role of numerical modeling is critically important as it is practically the only tool that allows the assessment of the long-term gas production potential of methane hydrate reservoirs in the current stage. The ability to numerically simulate the behavior of methane hydrate under natural and laboratory conditions has improved notably in recent years. These simulation studies examine methane hydrate behavior at multiscale levels: molecular-scale, pore-scale, core-scale, and reservoir-scale. Pore-scale analysis and simulation has been introduced in Chapter 3. In this chapter, recent advances in hydrate numerical simulator are focused, including lab-scale (core-scale) simulation and reservoir-scale simulation. Molecular dynamics simulation will also be included with its capability and method introduction. Robust numerical simulator requires the description of the dominant physical processes (heat transfer, fluids flow, and hydrate phase behavior) involved in the formation and dissociation process. Furthermore, gas production enhancement methods related to exploiting oceanic methane hydrate will be discussed with the simulation results.

Part II deals with the field practices and activities in oceanic methane hydrate reservoirs. Seven chapters (Chapter 6–12) are included in this part. Chapters in this part are selected to discuss the real operation and production behaviors of onshore/offshore tests in recent years. The exploration, drilling, and coring technologies are also discussed. Considerations of those basic production trials onshore and offshore conditions are introduced first in this part and then the detailed review and analysis of the historic tests in Russia, Canada, and United States and the most important offshore tests of Japan and China are introduced and compared. Activities of other major players of offshore methane hydrate in the world are also introduced, which together with the lessons from those trials are also summarized in this part.

Chapter 6 is Real Field Core-Sampling and Analysis. Gas hydrates are sensitive to pressure, temperature and chemical condition changes. Although it is possible to collect gas hydrate reservoir data with logging while drilling techniques at in situ conditions, gas hydrate core samples are essential for better reservoir and core analysis. These samples should reflect original conditions. In this chapter, the coring technology for gas hydrates is discussed. Different types of gas hydrate coring techniques (i.e., pressure core sampler, pressure core barrel, pressure-temperature corer, hybrid pressure core sampler, high pressure-temperature corer, HYACE rotary corer, Fugro pressure corer, and Fugro rotary pressure corer) and their field applications are analyzed in detail. As the core samples representing in situ reservoir conditions are collected, their laboratory analyses are made. In this section of the book, the geomechanical, geochemical, and geological analyses of gas hydrate samples are given. In geomechanical analysis, the experimental setup investigating the strength of gas hydrate core samples in situ conditions is explained. In the geochemical and geological analysis of gas hydrate core samples, the applications and importance of source gas analysis, pore water analysis, grain size analysis, lithology analysis, and gas hydrate structure analysis are summarized. The determinations of gas hydrate reservoir properties (i.e., porosity, gas hydrate saturation, and permeability) from these core analyses are discussed by using real field data.

Chapter 7 is Reservoir-Scale Considerations and Methods. The number of gas hydrate exploration projects has increased abruptly since 1995. Gas hydrate explorations include seismic, drilling, well logging, and coring operations. According to the analysis of these data sets, mostly methane hydrate–bearing sands with higher gas hydrate saturation are considered for gas hydrate production tests. Higher gas hydrate saturation, porosity, and permeability of methane hydrate–bearing sands make these reservoirs more feasible compared to others. In this chapter, it is aimed to propose the key points to choose technically recoverable methane hydrate reservoirs. Then, gas hydrate production test might be conducted in these selected reservoirs. Mainly, all stages need to be accomplished until gas hydrate production trials are discussed together with real field examples. Well logging data based on logging while drilling is crucial to characterize gas hydrate reservoirs. In this section, the importance of this characterization and the main equations are explained. Due to the heterogeneity of field data, it is important to compare the gas hydrate reservoir analysis made by using different techniques (P wave velocity, resistivity log data, chloride content by using core data, volumetric calculation by using core data, image analysis of cores). All of these techniques are explained in this chapter.

Chapter 8 is Real Onshore Tests in Russia, Canada and USA. In this chapter, early trials of real methane hydrate exploration and production tests (mainly onshore tests) are introduced. Basic information on the engineering aspect of the production and the difficulties in operations and efficiency analysis has been made in this chapter. The Messoyakha field is the first commercial application of hydrate development and shows the potential of this vast resource, which was operated since 1970s. From the same time, the presence of hydrates was confirmed with an exploration well drilled at the Prudhoe Bay field in 1972. Canada also started the operations in early time in Mallik Hydrate Research Well in Mackenzie Delta, permafrost area, led by the GSC and Japan JNOC. The North Slope of Alaska is one of the most promising gas hydrate region in the United States. The Iġnik Sikumi Gas Hydrate Exchange Field Experiment was conducted by ConocoPhillips in partnership with the US Department of Energy, the Japan Oil, Gas and Metals National Corporation, and the US Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope during 2011 and 2012. Those different trials show the challenges in onshore characteristics of methane hydrate field and accumulated valuable data for further offshore developments.

Chapter 9 is Real Offshore Tests in Japan (2013, 2017) and China (2017). This chapter is focused on the most recent offshore methane hydrate production tests in Japan and China. In 2017, the new series of methane hydrate tests in China (Shenhu area, South China Sea) and Japan (Nankai Trough) led to new round of hot discussion of robust production technology. The basic location, production, and results analysis are included in this chapter for a basic performance introduction of those two tests. The outcomes and future trends are also discussed in this chapter. The discussion is partially based on the real production data and also verified by recent numerical developments. Based on the open production data, the detailed production process, characteristics, and future prospects are reconstructed and numerically discussed, so as to provide a general view of the production behaviors and potential prediction for future designs.

Chapter 10 is Geological and Geochemical Characterization of Gas Hydrate Reservoirs in the Indian Sea. In this chapter, the activities and findings on geological and geochemical aspects of gas hydrate reservoirs under the Indian National Gas Hydrates Program (Expedition 01; conducted in 2006) are introduced. The information of gas hydrate accumulations in the Krishna-Godavari Basin of Indian Sea is summarized. A suite of geochemical properties focusing on the chemical analysis of pore waters and exsolved gases gives an accurate and precise account of the gas hydrate saturation, while simultaneously providing a good picture of the overall geological processes and anomalies shaping a natural gas hydrate deposit and its surrounding environment. With the pore fluid geochemistry properties in view, a critical evaluation of the geochemical data from Indian Offshore Margins is also performed. Through careful examination of the data in the light of sediment porosity profile and existing geophysical data, this chapter establishes the importance and utility of geochemical suite of parameters in understanding the often complex and dominant phenomena governing the natural environment of gas hydrate deposits.

Chapter 11 is Activities in the Mid-East, Europe and Other Regions. Gas hydrate exploration activities targeting gas hydrate reservoirs as energy resources started after 1995. Between 2002 and 2020, many countries (Canada, USA, Japan, and China) have conducted gas hydrate production trials. In addition to these countries, there are also other countries in the Mid-East, Europe, and other regions (i.e., India, Korea, Taiwan, Turkey) conducting gas hydrate explorations. In this part of the book, the gas hydrate activities completed and planned in these countries are explained in detail. Most of the gas hydrate projects are supported by governments instead of private companies because these projects are in the category of research and development. Thus, the investments of these projects are not likely to bring profits in near future. According to the analysis made in this chapter, it is seen that most of the countries urging to produce natural gas from gas hydrate reservoirs need additional energy resources as soon as possible. In this chapter of the book, seismic, well log, drilling, and coring results in Gulf of Mexico, India, Korea, Taiwan, and Turkey are analyzed in detail. Moreover, there are also other countries not having gas hydrate potential but these countries (i.e., Germany) are interested in developing gas hydrate drilling, coring, and other related technologies.

Chapter 12 is Comparisons of Field Activities in Different Worldwide Sites. Gas hydrate reservoir characteristics vary significantly in both permafrost and marine environments. The origin of gas hydrates, salinity, porous structure, lithology, gas hydrate morphology, and other properties differs a lot. Thus, it is important to compare the gas hydrate reservoirs in different regions of the world. In this chapter of the book, it is aimed to compare gas hydrate reservoirs in Messoyakha field, Mallik field, Nankai Trough, Ignik Sikumi, and Shenhu area in terms of field activities and field results. The contribution of gas hydrates on gas production was understood later than the discovery of Messoyakha field as conventional gas reservoir initially. The experiences in gas hydrate production tests in Mallik field, Canada, were useful to activate the similar projects in Alaska, India, and Japan. Moreover, the gas hydrate production trials in Nankai Trough, Japan, and Shenhu, China, are also discussed. Briefly, this chapter compares and summarizes different gas hydrate field activities and reservoir properties in the world.

Part III is the Emerging Technologies and Environmental Sustainability analysis. Five chapters (Chapter 13–17) are included in this part. In those chapters, engineering aspects such as emerging technologies that are in use or will be in use for future offshore methane hydrate exploration, drilling, and production trials are introduced. Those innovations in technological aspects also include the detailed well monitoring and environmental monitoring, which are introduced into detail with the examples of recent tests in Japan and China. Environmental and economical discussion/estimation of offshore methane hydrate reservoir and its impact on ecological systems is very critical for the large-scale production in the future, which contents are also included in the policy trend analysis in this part.

Chapter 13 is Emerging Technologies in Methane Hydrate Projects. In this chapter of the book, the gas hydrate studies related to gas hydrate reservoirs are discussed. It is obvious that field scale gas hydrate studies have increased abruptly since 2000s. Logging while drilling tools has been developed to use in riserless gas hydrate drilling operations. Although gas hydrate drilling and coring operations were conducted by big drilling ships, it is likely that smaller ships and/or subsea robotic systems will be used more often in near future. In conventional coring, standard core barrels are used without any pressure and temperature preservation. On the other hand, gas hydrate exploration studies have promoted the development in pressurized coring and core handling technology. In order to monitor temperature and pressure changes during drilling, cementing, and production, sensor technology (i.e., DTS, RTD cables) has also improved. This chapter also analyzes the improvement in sand screen technology and gravel packing technology according to the sand production problems observed in gas hydrate production wells. Those technologies should cause less temperature reduction and less geomechanical risks in gas hydrate reservoirs.

Chapter 14 is Sensing and Monitoring Technologies in Real Offshore Tests. Abstract: This chapter introduces the main sensing and monitoring technologies in recent real offshore methane hydrate extraction test projects in China and Japan. In those tests, the monitoring process during drill, well completion, production, and recovery process is of key importance for production safety and status recording. Major technologies and operation process for those tests are introduced and outlined for the reference of real operation of methane hydrate production.

Chapter 15 is Operation and Well Monitoring and Recording Technologies. Methane hydrate wells currently have not been drilled and produced on a commercial scale. The wells that have been constructed thus far in the industry have been regarded as a well test to better understand the characteristics and behavior of methane hydrate production. These wells can be broadly split into three types or categories namely Production Well, Monitoring Well, and Environment Assessment Well. In this chapter, the basics and operation examples of monitoring system are introduced.

Chapter 16 is Economic Aspect and Environmental Issues. In this chapter, the natural gas industry and price variations are firstly summarized, which show the trends of the gas price in recent years. The competition between gas hydrate and conventional natural gas will be put forward in the future (before the large-scale use of methane hydrate). Case analysis and input/output comparison of the gas price from the methane hydrate are introduced in this chapter, which is based on the resources estimation and production technological analysis. Environmental issues in the production process of natural gas from methane hydrate reservoir are also very critical issues to be considered as one input cost of the future use of methane hydrate. Methods to reduce the cost of production and to increase environmental safety have also been included in this chapter.

Chapter 17 is Policy Assessment and Outlook for Future. In this chapter the worldwide project development and policy trend of major players in offshore methane hydrate explorations are discussed. The policy of each country is mainly dependent on the international market price, the energy structure, the socioeconomical status, and the international agreement/regulations. Such policy trends have been analyzed and compared in this chapter, which show different attitudes from low self-sufficiency rate countries (the policy tends to be optimistic) and high self-sufficiency groups (neutral for technological development). It is found that in Japan and China, the governmental policy has renewed in 2019 and will faster the new round of production trials, while the United States, Canada, and other players just continue the drilling tests in permafrost regions.

Target of the book

This book is focused on gathering and organizing the most recent developments in oceanic methane hydrate studies: the fundamentals, the technological developments, and sustainability considerations. There are several books published in methane/gas hydrate topics, such as the very classic one Clathrate Hydrate of Natural Gases (third edition in 2007) of Dendy Sloan and Carolyn A. Koh, which is more fundamental for material and chemical aspects of hydrate research. And there are also limited books in recent years for engineering aspect, such as the excellent book Exploration and Production of Oceanic Natural Gas Hydrate: Critical Factors for Commercialization (first edition in 2016) of Michael D. Max and Arthur H. Johnson, which is oriented for production engineers. There is not a book that could bridge the gap between fundamentals and the engineering aspect yet. Especially in very recent year (since 2017), first success of real offshore production tests is seen in Japan and China, which means new milestones for the exploration of offshore methane hydrate in the history of human beings. Fundamental breakthroughs as well as engineering aspects and the new technologies used