Effect of seafloor temperature and pressure variations on methane flux from a gas hydrate layer: Comparison between current and late Paleocene climate conditions

2001 ◽  
Vol 106 (B11) ◽  
pp. 26413-26423 ◽  
Author(s):  
Wenyue Xu ◽  
Robert P. Lowell ◽  
Edward T. Peltzer
Keyword(s):  
Gas Hydrate ◽  
Methane Flux ◽  
Climate Conditions ◽  
Hydrate Layer ◽  
Late Paleocene ◽  
Temperature And Pressure

MICROBIAL COMMUNITIES AND DIFFERENTIAL METHANE FLUX IN ARCTIC GAS HYDRATE MOUNDS

2017 ◽  
Author(s):  
Stella C. Ross ◽  
◽  
Scott Klasek ◽  
Wei-Li Hong ◽  
Marta E. Torres ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Gas Hydrate ◽  
Methane Flux

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

Seasonal variability of natural methane seepage offshore Western Svalbard

2021 ◽  
Author(s):  
Manuel Moser ◽  
Knut Ola Dølven ◽  
Bénédicte Ferré
Keyword(s):  
Gas Hydrate ◽  
Bottom Water ◽  
Methane Flux ◽  
Mixing Rate ◽  
Bottom Water Temperature ◽  
Acoustic Data ◽  
Methane Seepage ◽  
Continental Shelves ◽  
Water Conditions ◽  
Methane Fluxes

<p>Natural methane seepage from the seafloor to the water column occurs worldwide in marine environments, from continental shelves to deep-sea basins. Depending on water depth, methane fluxes, and mixing rate of the seawater, methane may partially reach the atmosphere, where it could contribute to the global greenhouse effect. Estimates of annual marine methane fluxes are commonly calculated from hydro-acoustic data collected during single research surveys. These snapshot estimates neglect short (i.e., tide) and long (seasonal) variations.</p><p>Here we compare the seepage activity along the upper limit of the gas hydrate stability zone offshore Western Svalbard in August 2017 (bottom water temperature (BT) ~3.46°C), June 2020 (BT ~1.75°C), and November 2020 (BT ~3.96°C) using high-resolution vessel-based multibeam data. Our results complete annual methane flux estimates by Ferré et al. (2020) and confirm a significantly reduced seepage activity during the cold bottom-water conditions. We investigate short-term variation by comparing a 7.5 km long multibeam section at three phases of the lunar semidiurnal (M2) tide. We will discuss how these processes affect annual methane fluxes estimates offshore Svalbard and further Arctic methane fluxes estimates.</p><p>The research is part of the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) and is supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259 and UiT.</p><p> </p><p>Ferré, B., Jansson, P. G., Moser, M., Serov, P., Portnov, A., Graves, C. A., et al. (2020). Reduced methane seepage from Arctic sediments during cold bottom-water conditions. Nat. Geosci. 13, 144–148. DOI: 10.1038/s41561-019-0515-3</p>

scholarly journals Thermal State of the Blake Ridge Gas Hydrate Stability Zone (GHSZ)—Insights on Gas Hydrate Dynamics from a New Multi-Phase Numerical Model

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3403 ◽  
Author(s):  
Burwicz ◽  
Rüpke
Keyword(s):  
Numerical Model ◽  
Gas Hydrate ◽  
Methane Flux ◽  
Stability Zone ◽  
Free Gas ◽  
Blake Ridge ◽  
Geochemical Profiles ◽  
Multi Phase ◽  
Hydrate Stability

Marine sediments of the Blake Ridge province exhibit clearly defined geophysical indications for the presence of gas hydrates and a free gas phase. Despite being one of the world’s best-studied gas hydrate provinces and having been drilled during Ocean Drilling Program (ODP) Leg 164, discrepancies between previous model predictions and reported chemical profiles as well as hydrate concentrations result in uncertainty regarding methane sources and a possible co-existence between hydrates and free gas near the base of the gas hydrate stability zone (GHSZ). Here, by using a new multi-phase finite element (FE) numerical model, we investigate different scenarios of gas hydrate formation from both single and mixed methane sources (in-situ biogenic formation and a deep methane flux). Moreover, we explore the evolution of the GHSZ base for the past 10 Myr using reconstructed sedimentation rates and non-steady-state P-T solutions. We conclude that (1) the present-day base of the GHSZ predicted by our model is located at the depth of ~450 mbsf, thereby resolving a previously reported inconsistency between the location of the BSR at ODP Site 997 and the theoretical base of the GHSZ in the Blake Ridge region, (2) a single in-situ methane source results in a good fit between the simulated and measured geochemical profiles including the anaerobic oxidation of methane (AOM) zone, and (3) previously suggested 4 vol.%–7 vol.% gas hydrate concentrations would require a deep methane flux of ~170 mM (corresponds to the mass of methane flux of 1.6 × 10−11 kg s−1 m−2) in addition to methane generated in-situ by organic carbon (POC) degradation at the cost of deteriorating the fit between observed and modelled geochemical profiles.

scholarly journals Formation and Collapse of Gas Hydrate Deposits in High Methane Flux Area of the Joetsu Basin, Eastern Margin of Japan Sea

2009 ◽  
Vol 118 (1) ◽  
pp. 43-71 ◽  
Author(s):  
Ryo MATSUMOTO ◽  
Yoshihisa OKUDA ◽  
Akihiro HIRUTA ◽  
Hitoshi TOMARU ◽  
Eiichi TAKEUCHI ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Japan Sea ◽  
Methane Flux ◽  
Eastern Margin ◽  
Gas Hydrate Deposits

scholarly journals A Geophysical Review of the Seabed Methane Seepage Features and Their Relationship with Gas Hydrate Systems

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-26
Author(s):  
Jinxiu Yang ◽  
Mingyue Lu ◽  
Zhiguang Yao ◽  
Min Wang ◽  
Shuangfang Lu ◽  
...  
Keyword(s):  
Climate Change ◽  
Gas Hydrate ◽  
Greenhouse Gas Emission ◽  
Spatial Relationship ◽  
Methane Flux ◽  
Fluid Migration ◽  
Stability Zone ◽  
Methane Seepage ◽  
Migration Pathways ◽  
Hydrate Stability

Seabed methane seepage has gained attention from all over the world in recent years as an important source of greenhouse gas emission, and gas hydrates are also regarded as a key factor affecting climate change or even global warming due to their shallow burial and poor stability. However, the relationship between seabed methane seepage and gas hydrate systems is not clear although they often coexist in continental margins. It is of significance to clarify their relationship and better understand the contribution of gas hydrate systems or the deeper hydrocarbon reservoirs for methane flux leaking to the seawater or even the atmosphere by natural seepages at the seabed. In this paper, a geophysical examination of the global seabed methane seepage events has been conducted, and nearby gas hydrate stability zone and relevant fluid migration pathways have been interpreted or modelled using seismic data, multibeam data, or underwater photos. Results show that seabed methane seepage sites are often manifested as methane flares, pockmarks, deep-water corals, authigenic carbonates, and gas hydrate pingoes at the seabed, most of which are closely related to vertical fluid migration structures like faults, gas chimneys, mud volcanoes, and unconformity surfaces or are located in the landward limit of gas hydrate stability zone (LLGHSZ) where hydrate dissociation may have released a great volume of methane. Based on a comprehensive analysis of these features, three major types of seabed methane seepage are classified according to their spatial relationship with the location of LLGHSZ, deeper than the LLGHSZ (A), around the LLGHSZ (B), and shallower than LLGHSZ (C). These three seabed methane seepage types can be further divided into five subtypes considering whether the gas source of seabed methane seepage is from the gas hydrate systems or not. We propose subtype B2 represents the most important seabed methane seepage type due to the high density of seepage sites and large volume of released methane from massive focused vigorous methane seepage sites around the LLGHSZ. Based on the classification result of this research, more measures should be taken for subtype B2 seabed methane seepage to predict or even prevent ocean warming or climate change.

The response of temperature and pressure of hydrate reservoirs in the first gas hydrate production test in South China Sea

2020 ◽  
Vol 278 ◽  
pp. 115649 ◽  
Author(s):  
Xuwen Qin ◽  
Qianyong Liang ◽  
Jianliang Ye ◽  
Lin Yang ◽  
Haijun Qiu ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Gas Hydrate ◽  
Production Test ◽  
China Sea ◽  
Temperature And Pressure ◽  
Hydrate Reservoirs

Mathematical modelling of injection gas hydrate formation into the massif of snow saturated the same gas

2016 ◽  
Vol 11 (2) ◽  
pp. 233-239 ◽  
Author(s):  
V.Sh. Shagapov ◽  
A.S. Chiglintseva ◽  
S.V. Belova
Keyword(s):  
Diffusion Coefficient ◽  
Mathematical Modelling ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Influence Analysis ◽  
Hydrate Layer ◽  
Gas Hydrate Formation ◽  
Hydrate Saturation ◽  
The Given ◽  
Cold Gas

Considered the problem of gas hydrate formation during injection of cold gas in the snow massif, initially saturated with the same gas. In work some limited scheme according to which, intensity of hydrate formation is limited by diffusion of gas through the hydrate layer formed between the phases of gas and ice, to the boundary of contact ice-hydrate, and is determined by the introduction of only one parameter the given diffusion coefficient. Shows the distributions of pressure, temperature, hydrate saturation and the saturation of the snow at different points in time. Held influence analysis of the effect of the pressure of the injected gas and the permeability of the snow massif on the intensity of hydrate formation.

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