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Modelling of the gas hydrate potential in Svalbard's fjords.

Modelling of the gas hydrate potential in Svalbard's fjords.

Authors :
Betlem, Peter
Roy, Srikumar
Birchall, Thomas
Hodson, Andrew
Noormets, Riko
Römer, Miriam
Skogseth, Ragnheid
Senger, Kim
Source :
Journal of Natural Gas Science & Engineering; Oct2021, Vol. 94, pN.PAG-N.PAG, 1p
Publication Year :
2021

Abstract

Large amounts of methane are trapped as natural gas hydrate (NGH) in the sediments of the Arctic. Unlike NGH provinces offshore west of Svalbard (Vestnesa Ridge), NGH potential in Svalbard's fjords and near-shore environment is poorly constrained. In this study we modelled the NGH stability zone (GHSZ) to determine the NGH formation potential within the fjords of Svalbard. We applied a nearest neighbour interpolation method to dynamically derive statistical bottom-water temperature (BWT) trends from available CTD data. The BWT trends along with available geothermal gradient data constrained Svalbard-wide sub-bottom thermobaric models suitable for GHSZ modelling in the near subsurface. Analyses of source rock and fluid seepage data in Isfjorden, including 15 newly identified acoustic gas flares, indicate an active petroleum system with fluid migration reaching the seafloor with significant contributions of higher-order hydrocarbons to the gas feed. A GHSZ is predicted for most fjords at mean BWT conditions and 95:5 methane:ethane gas compositions. Suitable conditions for pure methane NGH formation are only met in the deepest parts of Isfjorden, Hinlopenstretet, Kross- and Kongsfjorden, and Rijpfjorden. Temporal constraints implemented along the well-defined Isfjorden transect indicated a notable negative response to water column warming. The predicted GHSZ across Svalbard's fjords is likely to disappear over the next few decades. [Display omitted] • The gas hydrate stability zone (GHSZ) is modelled for Svalbard's fjords. • Water column temperatures are calculated through a dynamic nearest neighbour approach. • Seeps, pockmarks and gas flares lie within the GHSZ's spatial extent in Isfjorden. • Natural gas in the shallow subsurface is potentially in hydrate form. • Strong temporal variability in hydrate stability is predicted. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
18755100
Volume :
94
Database :
Supplemental Index
Journal :
Journal of Natural Gas Science & Engineering
Publication Type :
Academic Journal
Accession number :
151591384
Full Text :
https://doi.org/10.1016/j.jngse.2021.104127