scholarly journals Ocean temperature variability for the past 60 years on the Norwegian-Svalbard margin influences gas hydrate stability on human time scales

2012 ◽  
Vol 117 (C10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Bénédicte Ferré ◽  
Jürgen Mienert ◽  
Tomas Feseker
Keyword(s):  
Time Scales ◽  
Gas Hydrate ◽  
Temperature Variability ◽  
Ocean Temperature ◽  
The Past ◽  
Hydrate Stability

scholarly journals Time scales of upper ocean temperature variability inferred from the PIRATA data (1997-2000)

2003 ◽  
Vol 30 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Ilana Wainer ◽  
Gabriel Clauzet ◽  
Jacques Servain ◽  
Jacyra Soares
Keyword(s):  
Time Scales ◽  
Temperature Variability ◽  
Upper Ocean ◽  
Ocean Temperature

Time Constraints on Seepage Through Fractured Regions on the Vestnesa Ridge off the W-Svalbard Coast

2021 ◽  
Author(s):  
Hariharan Ramachandran ◽  
Andreia Plaza-Faverola ◽  
Hugh Daigle ◽  
Stefan Buenz
Keyword(s):  
Fluid Flow ◽  
Effective Stress ◽  
Gas Hydrate ◽  
Fluid Pressure ◽  
Fracture Network ◽  
The Arctic ◽  
Stability Zone ◽  
Methane Seepage ◽  
Carbonate Formation ◽  
Hydrate Stability

<p>Evidences of subsurface fluid flow-driven fractures (from seismic interpretation) are quite common at Vestnesa Ridge (around 79ºN in the Arctic Ocean), W-Svalbard margin. Ultimately, the fractured systems have led to the formation of pockmarks on the seafloor. At present day, the eastern segment of the ridge has active pockmarks with continuous methane seep observations in sonar data. The pockmarks in the western segment are considered inactive or to seep at a rate that is harder to identify. The ridge is at ~1200m water depth with the base of the gas hydrate stability zone (GHSZ) at ~200m below the seafloor. Considerable free gas zone is present below the hydrates. Besides the obvious concern of amount and rates of historic methane seeping into the ocean biosphere and its associated effects, significant gaps exist in the ability to model the processes of flow of methane through this faulted and fractured region. Our aim is to highlight the interactions between physical flow, geomechanics and geological control processes that govern the rates and timing of methane seepage.</p><p>For this purpose, we performed numerical fluid flow simulations. We integrate fundamental mass and component conservation equations with a phase equilibrium approach accounting for hydrate phase boundary effects to simulate the transport of gas from the base of the GHSZ through rock matrix and interconnected fractures until the seafloor. The relation between effective stress and fluid pressure is considered and fractures are activated once the effective stress exceeds the tensile limit. We use field data (seismic, oedometer tests on calypso cores, pore fluid pressure and temperature) to constrain the range of validity of various flow and geomechanical parameters in the simulation (such as vertical stress, porosity, permeability, saturations).</p><p>Preliminary results indicate fluid overpressure greater than 1.5 MPa is required to initiate fractures at the base of the gas hydrate stability zone for the investigated system. Focused fluid flow occurs through the narrow fracture networks and the gas reaches the seafloor within 1 day. The surrounding regions near the fracture network exhibit slower seepage towards the seafloor, but over a wider area. Advective flux through the less fractured surrounding regions, reaches the seafloor within 15 years and a diffusive flux reaches within 1200 years. These times are controlled by the permeability of the sediments and are retarded further due to considerable hydrate/carbonate formation during vertical migration. Next course of action includes constraining the methane availability at the base of the GHSZ and estimating its impact on seepage behavior.</p>

scholarly journals Late quaternary temperature variability described as abrupt transitions on a 1/<i>f</i> noise background

2015 ◽  
Vol 6 (2) ◽  
pp. 2323-2337
Author(s):  
M. Rypdal ◽  
K. Rypdal
Keyword(s):  
Time Scales ◽  
Late Quaternary ◽  
Scaling Law ◽  
Temperature Variability ◽  
Climate System ◽  
Scaling Analysis ◽  
Noise Background ◽  
Quaternary Climate ◽  
Last Glaciation ◽  
Climate Noise

Abstract. We show that in order to have a scaling description of the climate system that is not inherently non-stationary, the rapid shifts between stadial and interstadial conditions during the last glaciation cannot be included in the scaling law. The same is true for the shifts between the glacial and interglacial states in the quaternary climate. When these events are omitted from a scaling analysis we find that the climate noise is consistent with a 1/f law on time scales from months to 105 years.

Reservoir volume of gas hydrate stability zones in permafrost regions of China

2018 ◽  
Vol 225 ◽  
pp. 486-500 ◽  
Author(s):  
Xiao Wang ◽  
Lin Pan ◽  
Hon Chung Lau ◽  
Ming Zhang ◽  
Longlong Li ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Reservoir Volume ◽  
Hydrate Stability ◽  
Permafrost Regions
Sign in / Sign up

Export Citation Format

Share Document