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Oceanic Methane Hydrates

Oceanic Methane Hydrates Book
Author : Lin Chen,Sukru Merey
Publisher : Gulf Professional Publishing
Release : 2021-01-10
ISBN : 012818566X
Language : En, Es, Fr & De

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Book Description :

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

Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change

Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change Book
Author : Anonim
Publisher : Unknown
Release : 2008
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating global climate, implicating global oceanic deposits of methane gas hydrate as the main culprit in instances of rapid climate change that have occurred in the past. However, the behavior of contemporary oceanic methane hydrate deposits subjected to rapid temperature changes, like those predicted under future climate change scenarios, is poorly understood. To determine the fate of the carbon stored in these hydrates, we performed simulations of oceanic gas hydrate accumulations subjected to temperature changes at the seafloor and assessed the potential for methane release into the ocean. Our modeling analysis considered the properties of benthic sediments, the saturation and distribution of the hydrates, the ocean depth, the initial seafloor temperature, and for the first time, estimated the effect of benthic biogeochemical activity. The results show that shallow deposits--such as those found in arctic regions or in the Gulf of Mexico--can undergo rapid dissociation and produce significant methane fluxes of 2 to 13 mol/yr/m2 over a period of decades, and release up to 1,100 mol of methane per m2 of seafloor in a century. These fluxes may exceed the ability of the seafloor environment (via anaerobic oxidation of methane) to consume the released methane or sequester the carbon. These results will provide a source term to regional or global climate models in order to assess the coupling of gas hydrate deposits to changes in the global climate.

Complete Guide to Methane Hydrate Energy

Complete Guide to Methane Hydrate Energy Book
Author : U. S. Department of Energy (DOE),National Energy Technology Laboratory (NETL),U. S. Government
Publisher : Unknown
Release : 2017-09-02
ISBN : 9781549655081
Language : En, Es, Fr & De

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Book Description :

In March 2013, Japanese researchers announced a breakthrough in the extraction of natural gas from methane hydrates. This marked the latest important development in the quest for energy from methane hydrate, known as the ice that burns. This book presents a comprehensive collection of up-to-date publications about this vital new resource, covering all aspects of the field, including the possible effects of hydrate gas production on climate change. Contents include: Energy Resource Potential of Methane Hydrate; Methane Hydrate Program Report to Congress - October 2012; Interagency Coordination on Methane Hydrates R&D: Demonstrating the Power of Working Together; Report of the Methane Hydrate Advisory Committee on Methane Hydrate Issues and Opportunities including Assessment of Uncertainty of the Impact of Methane Hydrate on Global Climate Change; Report to Congress - An Assessment of the Methane Hydrate Research Program and An Assessment of the 5-Year Research Plan of the Department of Energy Prepared by the Federal Methane Hydrate Advisory Committee - June 2007; An Interagency Roadmap for Methane Hydrate Research and Development; Methane Hydrates R&D Program. Methane hydrate is a cage-like lattice of ice inside of which are trapped molecules of methane, the chief constituent of natural gas. If methane hydrate is either warmed or depressurized, it will revert back to water and natural gas. When brought to the earth's surface, one cubic meter of gas hydrate releases 164 cubic meters of natural gas. Hydrate deposits may be several hundred meters thick and generally occur in two types of settings: under Arctic permafrost, and beneath the ocean floor. Methane that forms hydrate can be both biogenic, created by biological activity in sediments, and thermogenic, created by geological processes deeper within the earth. While global estimates vary considerably, the energy content of methane occurring in hydrate form is immense, possibly exceeding the combined energy content of all other known fossil fuels. The U.S. Department of Energy methane hydrate program aims to develop the tools and technologies to allow environmentally safe methane production from arctic and domestic offshore hydrates. The program includes R&D in: Production Feasibility: Methane hydrates occur in large quantities beneath the permafrost and offshore, on and below the seafloor. DOE R&D is focused on determining the potential and environmental implications of production of natural gas from hydrates. Research and Modeling: DOE is studying innovative ways to predict the location and concentration of subsurface methane hydrate before drilling. DOE is also conducting studies to understand the physical properties of gas hydrate-bearing strata and to model this understanding at reservoir scale to predict future behavior and production. Climate Change: DOE is studying the role of methane hydrate formation and dissociation in the global carbon cycle. Another aspect of this research is incorporating GH science into climate models to understand the relationship between global warming and methane hydrates.

Natural Gas Hydrate in Oceanic and Permafrost Environments

Natural Gas Hydrate in Oceanic and Permafrost Environments Book
Author : M.D. Max
Publisher : Springer Science & Business Media
Release : 2003-05-31
ISBN : 9781402013621
Language : En, Es, Fr & De

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Book Description :

This is the first book published on the emerging research field of naturally occurring gas hydrates (focusing on methane hydrate) that is not primarily a physical chemistry textbook. This book is designed as a broad introduction to the field of hydrate science, demonstrating the significance of the hydrate cycle to energy resource potential, seafloor stability, and global climate and climate change, along with other issues. The best known hydrate localities are described, as are research and laboratory methods and results. The book consists of chapters grouped in related themes that present up-to-date information on methane hydrate. Each of the contributing authors is expert in hydrate science and most have been carrying out research in hydrate for a considerable time. Audience: This book will be an important source of information for marine geologists, geophysicists, geochemists, and petroleum geologists and regulators. It is also intended as a graduate-level textbook.

Basin Scale Assessment of Gas Hydrate Dissociation in Response to Climate Change

Basin Scale Assessment of Gas Hydrate Dissociation in Response to Climate Change Book
Author : Anonim
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating climate. However, the behavior of contemporary oceanic methane hydrate deposits subjected to rapid temperature changes, like those now occurring in the arctic and those predicted under future climate change scenarios, has only recently been investigated. Field investigations have discovered substantial methane gas plumes exiting the seafloor along the Arctic Ocean margin, and the plumes appear at depths corresponding to the upper limit of a receding gas hydrate stability zone. It has been suggested that these plumes may be the first visible signs of the dissociation of shallow hydrate deposits due to ongoing climate change in the arctic. We simulate the release of methane from oceanic deposits, including the effects of fully-coupled heat transfer, fluid flow, hydrate dissociation, and other thermodynamic processes, for systems representative of segments of the Arctic Ocean margins. The modeling encompasses a range of shallow hydrate deposits from the landward limit of the hydrate stability zone down to water depths beyond the expected range of century-scale temperature changes. We impose temperature changes corresponding to predicted rates of climate change-related ocean warming and examine the possibility of hydrate dissociation and the release of methane. The assessment is performed at local-, regional-, and basin-scales. The simulation results are consistent with the hypothesis that dissociating shallow hydrates alone can result in significant methane fluxes at the seafloor. However, the methane release is likely to be confined to a narrow region of high dissociation susceptibility, defined by depth and temperature, and that any release will be continuous and controlled, rather than explosive. This modeling also establishes the first realistic bounds for methane release along the arctic continental shelf for potential hydrate dissociation scenarios, and ongoing work may help confirm whether climate change is already impacting the stability of the vast oceanic hydrate reservoir.

Detection and Production of Methane Hydrate

Detection and Production of Methane Hydrate Book
Author : Anonim
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand processes that control production potential of hydrates in marine settings, Mallik was included because of the extensive data collected in a producible hydrate accumulation. To date, such a location had not been studied in the oceanic environment. The project worked closely with ongoing projects (e.g. GOM JIP and offshore India) that are actively investigating potentially economic hydrate accumulations in marine settings. The overall approach was fivefold: (1) collect key data concerning hydrocarbon fluxes which is currently missing at all locations to be included in the study, (2) use this and existing data to build numerical models that can explain gas hydrate variance at all four locations, (3) simulate how natural gas could be produced from each location with different production strategies, (4) collect new sediment property data at these locations that are required for constraining fluxes, production simulations and assessing sediment stability, and (5) develop a method for remotely quantifying heterogeneities in gas hydrate and free gas distributions. While we generally restricted our efforts to the locations where key parameters can be measured or constrained, our ultimate aim was to make our efforts universally applicable to any hydrate accumulation.

Realizing the Energy Potential of Methane Hydrate for the United States

Realizing the Energy Potential of Methane Hydrate for the United States Book
Author : National Research Council,Division on Earth and Life Studies,Board on Earth Sciences and Resources,Committee on Earth Resources,Committee on Assessment of the Department of Energy's Methane Hydrate Research and Development Program: Evaluating Methane Hydrate as a Future Energy Resource
Publisher : National Academies Press
Release : 2009-06-30
ISBN : 9780309157636
Language : En, Es, Fr & De

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Book Description :

Natural gas, composed mostly of methane, is the cleanest of all the fossil fuels, emitting 25-50% less carbon dioxide than either oil or coal for each unit of energy produced. In recent years, natural gas supplied approximately 20-25% of all energy consumed in the United States. Methane hydrate is a potentially enormous and as yet untapped source of methane. The Department of Energy's Methane Hydrate Research and Development Program has been tasked since 2000 to implement and coordinate a national methane hydrate research effort to stimulate the development of knowledge and technology necessary for commercial production of methane from methane hydrate in a safe and environmentally responsible way. Realizing the Energy Potential of Methane Hydrate for the United States evaluates the program's research projects and management processes since its congressional re-authorization in 2005, and presents recommendations for its future research and development initiatives.

Natural Gas Hydrate

Natural Gas Hydrate Book
Author : M.D. Max
Publisher : Springer Science & Business Media
Release : 2012-12-06
ISBN : 9401143870
Language : En, Es, Fr & De

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Book Description :

1. THE BEGINNINGS OF HYDRATE RESEARCH Until very recently, our understanding of hydrate in the natural environment and its impact on seafloor stability, its importance as a sequester of methane, and its potential as an important mechanism in the Earth's climate change system, was masked by our lack of appreciation of the vastness of the hydrate resource. Only a few publications on naturally occurring hydrate existed prior to 1975. The first published reference to oceanic gas hydrate (Bryan and Markl, 1966) and the first publication in the scientific literature (Stoll, et a1., 1971) show how recently it has been since the topic of naturally occurring hydrate has been raised. Recently, however, the number of hydrate publications has increased substantially, reflecting increased research into hydrate topics and the initiation of funding to support the researchers. Awareness of the existence of naturally occurring gas hydrate now has spread beyond the few scientific enthusiasts who pursued knowledge about the elusive hydrate because of simple interest and lurking suspicions that hydrate would prove to be an important topic. The first national conference on gas hydrate in the U.S. was held as recently as April, 1991 at the U.S. National Center of the U.s. Geological Survey in Reston Virginia (Max et al., 1991). The meeting was co-hosted by the U.s. Geological Survey, the Naval Research Laboratory, and the U.S.

Contribution of Oceanic Gas Hydrate Dissociation to the Formation of Arctic Ocean Methane Plumes

Contribution of Oceanic Gas Hydrate Dissociation to the Formation of Arctic Ocean Methane Plumes Book
Author : Anonim
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of carbon into the atmosphere. Because methane is a powerful greenhouse gas, such a release could have dramatic climatic consequences. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope (150 m - 400 m) west of Svalbard suggests that this process may already have begun, but the source of the methane has not yet been determined. This study performs 2-D simulations of hydrate dissociation in conditions representative of the Arctic Ocean margin to assess whether such hydrates could contribute to the observed gas release. The results show that shallow, low-saturation hydrate deposits, if subjected to recently observed or future predicted temperature changes at the seafloor, can release quantities of methane at the magnitudes similar to what has been observed, and that the releases will be localized near the landward limit of the GHSZ. Both gradual and rapid warming is simulated, along with a parametric sensitivity analysis, and localized gas release is observed for most of the cases. These results resemble the recently published observations and strongly suggest that hydrate dissociation and methane release as a result of climate change may be a real phenomenon, that it could occur on decadal timescales, and that it already may be occurring.

Charting the Future of Methane Hydrate Research in the United States

Charting the Future of Methane Hydrate Research in the United States Book
Author : National Research Council,Division on Earth and Life Studies,Board on Earth Sciences and Resources,Ocean Studies Board,Committee to Review the Activities Authorized Under the Methane Hydrate Research and Development Act of 2000
Publisher : National Academies Press
Release : 2004-11-14
ISBN : 0309092922
Language : En, Es, Fr & De

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Book Description :

Methane hydrate is a natural form of clathrate - a chemical substance in which one molecule forms a lattice around a "guest" molecule with chemical bonding. In this clathrate, the guest molecule is methane and the lattice is formed by water to form an ice-like solid. Methane hydrate has become the focus of international attention because of the vast potential for human use worldwide. If methane can be produced from hydrate, a reasonable assumption given that there are no obvious technical or engineering roadblocks to commercial production, the nation's natural gas energy supply could be extended for many years to come. This report reviews the Department of Energy's (DOE) Methane Hydrate Research and Development Program, the project selection process, and projects funded to date. It makes recommendations on how the DOE program could be improved. Key recommendations include focusing DOE program emphasis and research in 7 priority areas; incorporating greater scientific oversight in the selection, initiation, monitoring, and assessment of major projects funded by the DOE; strengthening DOE's contribution to education and training through funding of fellowships, and providing project applicants with a set of instructions and guidelines outlining requirements for timely and full disclosure of project results and consequences of noncompliance.

Natural Capital and Exploitation of the Deep Ocean

Natural Capital and Exploitation of the Deep Ocean Book
Author : Maria Baker,Eva Ramirez-Llodra,Paul Tyler
Publisher : Oxford University Press
Release : 2020-08-28
ISBN : 0192578774
Language : En, Es, Fr & De

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Book Description :

The deep ocean is by far the planet's largest biome and holds a wealth of potential natural assets. Human exploitation of the deep ocean is rapidly increasing whilst becoming more visible to many through the popular media, particularly film and television. The scientific literature of deep-sea exploitation and its effects has also rapidly expanded as a direct function of this increased national and global interest in exploitation of deep-sea resources, both biological (e.g. fisheries, genetic resources) and non-biological (e.g. minerals, oil, gas, methane hydrate). At the same time there is a growing interest in deep-sea contamination (including plastics), with many such studies featured in high profile scientific journals and covered by global media outlets. However, there is currently no comprehensive integration of this information in any form and these topics are only superficially covered in classic textbooks on deep-sea biology. This concise and accessible work provides an understanding of the relationships between biodiversity and ecosystem functioning, both at the seafloor and in the water column, and how these might be affected as a result of human interaction, exploitation and, ultimately, environmental change. It follows a logical progression from geological and physical processes, ecology, biology, and biogeography, to exploitation, management, and conservation. Natural Capital and Exploitation of the Deep Ocean is aimed at marine biologists and ecologists, oceanographers, fisheries scientists and managers, fish biologists, environmental scientists, and conservation biologists. It will also be of relevance and use to a multi-disciplinary audience of fish and wildlife agencies, NGOs, and government departments involved in deep-sea conservation and management.

S 1418 the Methane Hydrate Research and Development Act of 1998

S  1418  the Methane Hydrate Research and Development Act of 1998 Book
Author : United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment
Publisher : Unknown
Release : 1999
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download S 1418 the Methane Hydrate Research and Development Act of 1998 book written by United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

H R 1753 and S 330 Methane Hydrate Research and Development Act of 1999

H R  1753 and S  330  Methane Hydrate Research and Development Act of 1999 Book
Author : United States,United States. Congress. House. Committee on Resources. Subcommittee on Energy and Mineral Resources
Publisher : Unknown
Release : 1999
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download H R 1753 and S 330 Methane Hydrate Research and Development Act of 1999 book written by United States,United States. Congress. House. Committee on Resources. Subcommittee on Energy and Mineral Resources, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Methane Gas Hydrate

Methane Gas Hydrate Book
Author : Ayhan Demirbas
Publisher : Springer Science & Business Media
Release : 2010-02-28
ISBN : 1848828721
Language : En, Es, Fr & De

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Book Description :

Gas hydrates represent one of the world’s largest untapped reservoirs of energy and, according to some estimates, have the potential to meet global energy needs for the next thousand years. "Methane Gas Hydrate" examines this potential by focusing on methane gas hydrate, which is increasingly considered a significant source of energy. "Methane Gas Hydrate" gives a general overview of natural gas, before delving into the subject of gas hydrates in more detail and methane gas hydrate in particular. As well as discussing methods of gas production, it also discusses the safety and environmental concerns associated with the presence of natural gas hydrates, ranging from their possible impact on the safety of conventional drilling operations to their influence on Earth’s climate. "Methane Gas Hydrate" is a useful reference on an increasingly popular energy source. It contains valuable information for chemical engineers and researchers, as well as for postgraduate students.

Oceanic Gas Hydrate Research and Activities Review

Oceanic Gas Hydrate Research and Activities Review Book
Author : U. S. Department U.S. Department of the Interior
Publisher : CreateSpace
Release : 2015-06-22
ISBN : 9781511916554
Language : En, Es, Fr & De

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Book Description :

Gas hydrates are ice-like crystalline structures of water that from "cages" that trap low molecular weight gas molecules, especially methane. Gas hydrates have recently attracted international attention from government and scientific communities. The document outlines the major issues surround gas hydrates, research initiatives that are underway around the world, and the potential information needs of and the old the Minerals Management Service may play in future activities.

Exploration and Production of Oceanic Natural Gas Hydrate

Exploration and Production of Oceanic Natural Gas Hydrate Book
Author : Michael D. Max,Arthur H. Johnson
Publisher : Springer
Release : 2018-10-24
ISBN : 3030004015
Language : En, Es, Fr & De

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Book Description :

This second edition provides extensive information on the attributes of the Natural Gas Hydrate (NGH) system, highlighting opportunities for the innovative use and modification of existing technologies, as well as new approaches and technologies that have the potential to dramatically lower the cost of NGH exploration and production. Above all, the book compares the physical, environmental, and commercial aspects of the NGH system with those of other gas resources. It subsequently argues and demonstrates that natural gas can provide the least expensive energy during the transition to, and possibly within, a renewable energy future, and that NGH poses the lowest environmental risk of all gas resources. Intended as a non-mathematical, descriptive text that should be understandable to non-specialists as well as to engineers concerned with the physical characteristics of NGH reservoirs and their production, the book is written for readers at the university graduate level. It offers a valuable reference guide for environmentalists and the energy community, and includes discussions that will be of great interest to energy industry professionals, legislators, administrators, regulators, and all those concerned with energy options and their respective advantages and disadvantages.

Encyclopedia of Ocean Sciences

Encyclopedia of Ocean Sciences Book
Author : Anonim
Publisher : Academic Press
Release : 2019-04-12
ISBN : 0128130822
Language : En, Es, Fr & De

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Book Description :

The oceans cover 70% of the Earth’s surface, and are critical components of Earth’s climate system. This new edition of Encyclopedia of Ocean Sciences summarizes the breadth of knowledge about them, providing revised, up to date entries as well coverage of new topics in the field. New and expanded sections include microbial ecology, high latitude systems and the cryosphere, climate and climate change, hydrothermal and cold seep systems. The structure of the work provides a modern presentation of the field, reflecting the input and different perspective of chemical, physical and biological oceanography, the specialized area of expertise of each of the three Editors-in-Chief. In this framework maximum attention has been devoted to making this an organic and unified reference. Represents a one-stop. organic information resource on the breadth of ocean science research Reflects the input and different perspective of chemical, physical and biological oceanography, the specialized area of expertise of each of the three Editors-in-Chief New and expanded sections include microbial ecology, high latitude systems and climate change Provides scientifically reliable information at a foundational level, making this work a resource for students as well as active researches

Exploration of Gas Hydrates

Exploration of Gas Hydrates Book
Author : Naresh Kumar Thakur,Sanjeev Rajput
Publisher : Springer Science & Business Media
Release : 2010-10-08
ISBN : 3642142346
Language : En, Es, Fr & De

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Book Description :

Gas hydrates are ice-like crystalline substances that form a rigid cage of water molecules and entrap hydrocarbon and non-hydrocarbon gas by hydrogen bonding. Natural gas hydrate is primarily composed of water and methane. These are solid, crystalline, ice-like substances found in permafrost areas and deepwater basins around the world. They naturally occur in the pore space of marine sediments, where appropriate high pressure and low temperature conditions exist in an adequate supply of gas (mainly methane). Gas hydrates are considered as a potential non conventional energy resource. Methane hydrates are also recognized as, an influence on offshore platform stability, a major factor in climate change contributing to global warming and a significant contribution to the ocean carbon cycle. The proposed book treats various geophysical techniques in order to quantify the gas hydrate reserves and their impact on environment. The primary goal of this book is to provide the state of art for gas hydrate exploration. The target audiences for this book are non-specialist from different branches of science, graduate students and researchers.

Numerical Investigations of the Fluid Flows at Deep Oceanic and Arctic Permafrost Associated Gas Hydrate Deposits

Numerical Investigations of the Fluid Flows at Deep Oceanic and Arctic Permafrost Associated Gas Hydrate Deposits Book
Author : Jennifer Mary Frederick
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Methane hydrate is an ice-like solid which sequesters large quantities of methane gas within its crystal structure. The source of methane is typically derived from organic matter broken down by thermogenic or biogenic activity. Methane hydrate (or more simply, hydrate) is found around the globe within marine sediments along most continental margins where thermodynamic conditions and methane gas (in excess of local solubility) permit its formation. Hydrate deposits are quite possibly the largest reservoir of fossil fuel on Earth, however, their formation and evolution in response to changing thermodynamic conditions, such as global warming, are poorly understood. Upward fluid flow (relative to the seafloor) is thought to be important for the formation of methane hydrate deposits, which are typically found beneath topographic features on the seafloor. However, one-dimensional models predict downward flow relative to the seafloor in compacting marine sediments. The presence of upward flow in a passive margin setting can be explained by fluid focusing beneath topography when sediments have anisotropic permeability due to sediment bedding layers. Even small slopes (10 degrees) in bedding planes produce upward fluid velocity, with focusing becoming more effective as slopes increase. Additionally, focusing causes high excess pore pressure to develop below topographic highs, promoting high-angle fracturing at the ridge axis. Magnitudes of upward pore fluid velocity are much larger in fractured zones, particularly when the surrounding sediment matrix is anisotropic in permeability. Enhanced flow of methane-bearing fluids from depth provides a simple explanation for preferential accumulation of hydrate under topographic highs. Models of fluid flow at large hydrate provinces can be constrained by measurements of naturally-occurring radioactive tracers. Concentrations of cosmogenic iodine, 129-I, in the pore fluid of marine sediments often indicate that the pore fluid is much older than the host sediment. Old pore fluid age may reflect complex flow patterns, such a fluid focusing, which can cause significant lateral migration as well as regions where downward flow reverses direction and returns toward the seafloor. Longer pathlines can produce pore fluid ages much older than that expected with a one-dimensional compaction model. For steady-state models with geometry representative of Blake Ridge (USA), a well-studied hydrate province, pore fluid ages beneath regions of topography and within fractured zones can be up to 70 Ma old. Results suggest that the measurements of 129-I/127-I reflect a mixture of new and old pore fluid. However, old pore fluid need not originate at great depths. Methane within pore fluids can travel laterally several kilometers, implying an extensive source region around the deposit. Iodine age measurements support the existence of fluid focusing beneath regions of seafloor topography at Blake Ridge, and suggest that the methane source at Blake Ridge is likely shallow. The response of methane hydrate reservoirs to warming is poorly understood. The great depths may protect deep oceanic hydrates from climate change for the time being because transfer of heat by conduction is slow, but warming will eventually be felt albeit in the far future. On the other hand, unique permafrost-associated methane hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Arctic hydrates are thought to be a relict of cold glacial periods, aggrading when sea levels are much lower and shelf sediments are exposed to freezing air temperatures. During interglacial periods, rising sea levels flood the shelf, bringing dramatic warming to the permafrost- and hydrate-bearing sediments. Permafrost-associated methane hydrate deposits have been responding to warming since the last glacial maximum ~18 kaBP as a consequence of these natural glacial cycles. This `experiment, ' set into motion by nature itself, allows us a unique opportunity to study the response of methane hydrate deposits to warming. Gas hydrate stability in the Arctic and the permeability of the shelf sediments to gas migration is thought to be closely linked with relict submarine permafrost. Submarine permafrost extent depends on several environmental factors, such as the shelf lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, groundwater hydrology, and the salinity of the pore water. Effects of submarine groundwater discharge, which introduces fresh terrestrial groundwater off-shore, can freshen deep marine sediments and is an important control on the freezing point depression of ice and methane hydrate. While several thermal modeling studies suggest the permafrost layer should still be largely intact near-shore, many recent field studies have reported elevated methane levels in Arctic coastal waters. The permafrost layer is thought to create an impermeable barrier to fluid and gas flow, however, talik formation (unfrozen regions within otherwise continuous permafrost) below paleo-river channels can create permeable pathways for gas migration from depth. This is the first study of its kind to make predictions of the methane gas flux to the water column from the Arctic shelf sediments using a 2D multi-phase fluid flow model. Model results show that the dissociation of methane hydrate deposits through taliks can supersaturate the overlying water column at present-day relative to equilibrium with the atmosphere when taliks are large (> 1 km width) or hydrate saturation is high within hydrate layers (> 50% pore volume). Supersaturated waters likely drive a net flux of methane into the atmosphere, a potent greenhouse gas. Effects of anthropogenic global warming will certainly increase gas venting rates if ocean bottom water temperatures increase, but likely won't have immediately observable impacts due to the long response times.

Fiber Optic Raman Spectroscopy for Detection of Methane Hydrates and Related Species

Fiber Optic Raman Spectroscopy for Detection of Methane Hydrates and Related Species Book
Author : Anonim
Publisher : Unknown
Release : 2001
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

A capillary waveguide fiber optic probe system has been constructed which is capable of rapidly collecting Raman spectra of organic compounds in water. It consists of a dual fiber optic probe coupled to a capillary waveguide designed to increase the volume of sample interrogated by the excitation light. A Nd:YAG laser operating at 532 nm is used to generate Raman scatter at the sample in the capillary which is transmitted by the collection fiber to a notch filter holder and linear array detector. The feasibility of using this system for methane hydrate detection is evaluated through the use of organic surrogate molecules, due to the low solubility of methane in water at atmospheric pressures. The eventual application is the oceanic detection of methane gas, liquid, and solid hydrate at great depths (1000's of meters). Under these conditions, the solubility of methane increases significantly and solid hydrate may be present. The relative Raman cross sections of methane and other organic compounds relative to nitrogen are documented. The benefit of using a capillary waveguide with the dual fiber optic probe is quantitatively shown. The LOD of acetone (as a surrogate for methane) is determined and the LOD of methane under several experimental conditions is calculated. The ability to detect all three states (gas, liquid, and solid) is of great importance to the detection and characterization of ocean floor methane.