Multiple episodes of fluid flow in the SW Barents Sea (Loppa High) evidenced by gas flares, pockmarks and gas hydrate accumulation

2012 ◽  
Vol 331-332 ◽  
pp. 305-314 ◽  
Author(s):  
S. Chand ◽  
T. Thorsnes ◽  
L. Rise ◽  
H. Brunstad ◽  
D. Stoddart ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Gas Hydrate ◽  
Barents Sea ◽  
Gas Flares ◽  
Multiple Episodes

Controls on gas hydrate system evolution in a region of active fluid flow in the SW Barents Sea

2015 ◽  
Vol 66 ◽  
pp. 861-872 ◽  
Author(s):  
Sunil Vadakkepuliyambatta ◽  
Matthew J. Hornbach ◽  
Stefan Bünz ◽  
Benjamin J. Phrampus
Keyword(s):  
Fluid Flow ◽  
Gas Hydrate ◽  
Barents Sea ◽  
System Evolution ◽  
Active Fluid

scholarly journals Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

2019 ◽  
Vol 20 (2) ◽  
pp. 630-650 ◽  
Author(s):  
M. Waage ◽  
A. Portnov ◽  
P. Serov ◽  
S. Bünz ◽  
K. A. Waghorn ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Gas Hydrate ◽  
Barents Sea ◽  
The Barents Sea

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>

Susceptibility assessment of gas hydrate dissociation occurrence along European continental margins and adjacent areas. GARAH project (GeoERA)

2021 ◽  
Author(s):  
Ricardo León ◽  
Christopher Rochelle ◽  
André Burnol ◽  
Carmen Julia Giménez- Moreno ◽  
Tove Nielsen ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Gas Hydrate ◽  
Control Factor ◽  
Continental Margins ◽  
Baseline Scenario ◽  
Submarine Landslides ◽  
Susceptibility Assessment ◽  
Map Algebra ◽  
Hydrate Dissociation ◽  
Density Map

<p>The Pan-European gas-hydrate relate GIS database of GARAH project has allowed assessing the susceptibility of seafloor areas affected by hydrate dissociation. This study has been applied as a first step for the hydrate related risk assessment along the European continental margins. Several factors and variables have been taken into account. They have been defined by their relationship with the presence of hydrates below seafloor and weighted depending on the confidence of finding hydrates in this site. The maximum weight (or confidence) has been given to the recovered samples of gas hydrates or hydrate-dissociation evidences such as degassing or liquation structures observed in gravity cores. Seismic indicators of the presence of gas hydrate or hydrocarbon seabed fluid flow such as BSR, blanking acoustic, amplitude anomalies or the presence of geological structures of seabed fluid flow in the neighbouring of the GHSZ have been weighted with a lower value. The theoretical gas hydrate stability zone (GHSZ) for a standard composition for biogenic gas has been taken into account as another control factor and constrain feature. Seafloor areas out of the theoretical GSHZ have been excluded as potential likelihood to be affected by hydrate dissociation processes. The base of GHSZ has been classified as a critical area for these dissociation processes.</p><p>The proposed methodology analyses the geological hazard by means of the susceptibility assessment, defined by the likelihood of occurrence of hydrate dissociation, collapses, crater-like depressions or submarine landslides over seafloor. The baseline scenario is that gas hydrate occurrence is only possible in seafloor areas where pressure (bathymetry) and seafloor temperature conditions are inside the theoretical GHSZ. Inside GHSZ, the occurrence of gas hydrate is directly related to the presence of its evidences (direct samples of hydrates) or indicators (eg. pore water and velocity anomalies, BSR, gas chimneys, among others), as well as the occurrence of hydrocarbon fluid flow structures inside GHSZ. Finally, the likelihood of the seafloor to be affect gas hydrate dissociation processes will be major at the base of the GHSZ and in the neighbouring of the gas hydrate evidences and indicators. In order to proof this initial hypothesis, a susceptibility assessment has been carried out throughout map algebra in a GIS environment from a density map of evidences and indicators and the Pan-European map of the GHSZ over seafloor. Specifically, it has been conceived as a segmentation in three levels by quantiles resulting of the addition of the density map of evidences and indicators and the weighted map of the GHSZ over seafloor.</p><p> </p><p><strong>Acknowledgment</strong></p><p>GARAH project. GeoERA - GeoE.171.002</p>

scholarly journals Control of the geomorphology and gas hydrate extent on widespread gas emissions offshore Romania

2017 ◽  
Vol 188 (4) ◽  
pp. 26 ◽  
Author(s):  
Vincent Riboulot ◽  
Antonio Cattaneo ◽  
Carla Scalabrin ◽  
Arnaud Gaillot ◽  
Gwénaël Jouet ◽  
...  
Keyword(s):  
Water Column ◽  
Black Sea ◽  
Gas Hydrate ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
The Black Sea ◽  
North East ◽  
Bottom Simulating Reflectors ◽  
Gas Flares ◽  
Sea Fan

The Romanian sector of the Black Sea deserves attention because the Danube deep-sea fan is one of the largest sediment depositional systems worldwide and is considered the world's most isolated sea, the largest anoxic water body on the planet and a unique energy-rich sea. Due to the high sediment accumulation rate, presence of organic matter and anoxic conditions, the Black sea sediments offshore the Danube delta is rich in gas and thus shows Bottom Simulating Reflectors (BSR). The cartography of the BSR over the last 20 years, exhibits its widespread occurrence, indicative of extensive development of hydrate accumulations and a huge gas hydrate potential. By combining old and new datasets acquired in 2015 during the GHASS expedition, we performed a geomorphological analysis of the continental slope north-east of the Danube canyon compared with the spatial distribution of gas seeps in the water column and the predicted extent of the gas hydrate stability zone. This analysis provides new evidence of the role of geomorphological setting and gas hydrate extent in controlling the location of the observed gas expulsions and gas flares in the water column. Gas flares are today considered an important source of the carbon budget of the oceans and, potentially, of the atmosphere.

Methane hydrate mobilization by ice stream erosion during the last glacial

2020 ◽  
Author(s):  
Pavel Serov ◽  
Henry Patton ◽  
Malin Waage ◽  
Calvin Shackleton ◽  
Jurgen Mienert ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Methane Hydrate ◽  
Barents Sea ◽  
Ice Sheet ◽  
Permafrost Degradation ◽  
Last Glacial ◽  
The Barents Sea ◽  
Ice Stream ◽  
Geophysical Imaging ◽  
The Last Glacial

<p>During the past ~2.6 Ma, some 30 glaciations have caused episodic high pressure and low temperature conditions and forced growth and decay of extensive subglacial methane hydrate accumulations globally. Research on Arctic methane release has primarily focused on warm, interglacial episodes when hydrates became unstable across territories either abandoned by former ice sheets or affected by permafrost degradation. Here we present a new mechanism – the subglacial erosion of gas hydrate-bearing sediments – that actively mobilizes methane in hydrate and dissolved form and delivers it to the ice sheet margin. We investigate this mechanism using geophysical imaging and ice sheet/gas hydrate modeling focused on a study site in Storfjordrenna, that hosted large ice stream draining the Barents Sea ice sheet. During the last glacial, we find that this ice stream overrode an extensive cluster of conduits that supplied a continuous methane flux from a deep, thermogenic source and delivered it to the subglacial environment. Our analysis reveals that 15,000 to 44,000 m<sup>3</sup> of gas hydrates were subglacially eroded from the 17 km<sup>2</sup> study site and transported to the shelf-edge. Given the abundance of natural gas reservoirs across the Barents Sea and marine-based glaciated petroleum provinces elsewhere, we propose that this mechanism had the potential to mobilize a substantial flux of subglacial methane throughout multiple Quaternary glacial episodes.</p>

Sign in / Sign up

Export Citation Format

Share Document