Introduction, Physical Properties, and Natural Occurrences of Hydrate

Pellenbarg, Robert E.; Max, M. D.

doi:10.1007/978-94-011-4387-5_1

Cited by 18 publications

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“…If the temperature and pressure conditions are above the gas hydrate stability boundary, then the protogenic gas hydrates dissociate into water and methane. Gas hydrates are widely distributed in the permafrost of polar regions and the strata of continental deep-sea areas (Kvenvolden 1998;Pellenbarg and Max 2000;Sloan 1998;Milkov 2004) and are considered future potential energy resources.…”

Section: Introductionmentioning

confidence: 99%

Extremely High Methane Concentration in Bottom Water and Cored Sediments from Offshore Southwestern Taiwan

Chuang¹,

Yang²,

Lin³

et al. 2006

Terr. Atmos. Ocean. Sci.

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ABSTRACT1 Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC 2 Institute of Oceanography, National Taiwan University, Taipei, Taiwan, ROC 3 Central Geological Survey, MOEA, Taipei, Taiwan, ROC * Corresponding author address: Prof. Tsanyao Frank Yang, Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC; E-mail: tyyang@ntu.edu.tw It has been found that Bottom Simulating Reflections (BSRs), which infer the existence of potential gas hydrates underneath seafloor sediments, are widely distributed in offshore southwestern Taiwan. Fluids and gases derived from dissociation of gas hydrates, which are typically methane enriched, affect the composition of seawater and sediments near venting areas. Hence, methane concentration of seawater and sediments become useful proxies for exploration of potential gas hydrates in a given area. We systematically collected bottom waters and sedimentary core samples for dissolved and pore-space gas analyses through five cruises: ORI-697, ORI-718, ORII-1207, ORII-1230, and ORI-732 from 2003 to 2005 in this study. Some sites with extremely high methane concentrations have been found in offshore southwestern Taiwan, e.g., sites G23 of ORI-697, N8 of ORI-718, and G96 of ORI-732. The methane concentrations of cored sediments display an increasing trend with depth. Furthermore, the down-core profiles of methane and sulfate reveal very shallow depths of sulfate methane interface (SMI) at some sites in this study. It implies sulfate reduction being mainly driven by the process of anaerobic methane oxidation (AMO) in sediments; thus indicating that there is a methane-enriched venting source, which may be the product of dissociation of gas hydrates in this area.

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Section: Introductionmentioning

confidence: 99%

Extremely High Methane Concentration in Bottom Water and Cored Sediments from Offshore Southwestern Taiwan

Chuang¹,

Yang²,

Lin³

et al. 2006

Terr. Atmos. Ocean. Sci.

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“…Natural gas hydrates refer to the case where the guest gas molecule is a natural gas. In the case of methane hydrate, because the methane molecules are tightly packed in the crystalline lattice, methane in hydrate form has a high energy density of 184,000 btu/ft 3 [1]. This compares with 1150 btu/ft 3 for methane gas (CH 4 ) and 430,000 btu/ft 3 for liquefied natural gas (LNG), the cryogenic liquid form of methane.…”

Section: Physical and Chemical Propertiesmentioning

confidence: 97%

“…There the depth to the base of the stability zone is dependent on the increasing temperature related to the geothermal gradient of approximately 3-4 °C per 100 m in continental slope sediments [1], with the maximum lower limit being about 2000 m below the solid surface [11,16].…”

Section: Geological Occurrencesmentioning

confidence: 99%

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Towards Commercial Gas Production from Hydrate Deposits

Silva

Dawe

2011

Energies

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Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. The general consensus is that there are vast quantities of natural gas trapped in hydrate deposits in geological systems, and this has resulted in the emerging importance of hydrates as a potential energy resource and an accompanying proliferation of recent studies on the technical and economic feasibility of gas production from hydrates. There are then the associated environmental concerns. This study reviews the state of knowledge with respect to natural gas hydrates and outlines remaining challenges and knowledge gaps.

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“…In regions of the seafloor where thermogenic hydrocarbons can migrate up along faults, CH 4 within the sediment can be a mixture from the two sources, in which case its composition falls on a mixing line in (Kvenvolden and Lorenson, 2001). Gas hydrates are isometric crystalline solids which consist of a lattice of water molecules with cages that can accommodate gas molecules that are 3.5-7.5×10 −10 m in diameter (Pellenbarg and Max, 2000). Methane hydrate formation is associated with a fractionation of oxygen isotopes, on the same order as fractionation associated with the formation of sea ice, with a fractionation factor, α (hydrate−sw) , in the range 1.0027-1.0031, so that hydrate is enriched in H 2 18 O by 3 (Matsumoto and Borowski, 2000).…”

Section: Methane Hydratesmentioning

confidence: 99%

The paleoceanography of the Bering Sea during the last glacial cycle

Cook¹

2006

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In this thesis, I present high-resolution stable-isotope and planktonic-fauna records from Bering Sea sediment cores, spanning the time period from 50,000 years ago to the present. During Marine Isotope Stage 3 (MIS3) at 30-20 ky BP (kiloyears before present) in a core from 1467 m water depth near Umnak Plateau, there were episodic occurrences of diagenetic carbonate minerals with very low δ 13 C (−22.4 ), high δ 18 O (6.5 ), and high [Mg]/ [Ca], which seem associated with sulfate reduction of organic matter and possibly anaerobic oxidation of methane. The episodes lasted less than 1000 years and were spaced about 1000 years apart. During MIS3 at 55-20 ky BP in a core from 2209 m water depth on Bowers Ridge, N. pachyderma (s.) and Uvigerina δ 18 O and δ 13 C show no coherent variability on millennial time scales.Bering Sea sediments are dysoxic or laminated during the deglaciation. A high sedimentation rate core (200 cm/ky) from 1132 m on the Bering Slope is laminated during the Bølling warm phase,Ållerød warm phase, and early Holocene, where the ages of lithological transitions agree with the ages of those climate events in Greenland (GISP2) to well within the uncertainty of the age models. The subsurface distribution of radiocarbon was estimated from a compilation of published and unpublished North Pacific benthic-planktonic 14 C measurements (475-2700 m water depth). There was no consistent change in 14 C profiles between the present and the Last Glacial Maximum, Bølling-Ållerød, or the Younger Dryas cold phase. N. pachyderma (s.) δ 18 O in the Bering Slope core decreases rapidly (in less than 220 y) by 0.7-0.8 at the onset of the Bølling and the end of the Younger Dryas. These isotopic shifts are accompanied by transient decreases in the relative abundance of N. pachyderma (s.), suggesting that the isotopic events are transient warmings and sustained freshenings.

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Introduction, Physical Properties, and Natural Occurrences of Hydrate

Cited by 18 publications

References 0 publications

Extremely High Methane Concentration in Bottom Water and Cored Sediments from Offshore Southwestern Taiwan

Extremely High Methane Concentration in Bottom Water and Cored Sediments from Offshore Southwestern Taiwan

Towards Commercial Gas Production from Hydrate Deposits

The paleoceanography of the Bering Sea during the last glacial cycle

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