Gas hydrates are crystalline structures containing large amounts of methane, often located in climate-sensitive polar environments. They are found in large quantities at Vestnesa Ridge on the western Svalbard Margin, a place also characterized by an extensive occurrence of active gas seepage (primarily of methane) from pockmarks on the seafloor. Gas hydrates hold potential as a ‘fuel of the future’ while simultaneously posing a risk as a geohazard and an accelerator of climate change. While we are only beginning to understand them, it is crucial to determine the location and quantities of gas hydrates that are stored in marine sediments.
This study, conducted by Sunny Signhroha of CAGE, uses various geophysical methods and techniques to detect gas hydrates on the Vestnesa Ridge, including a novel technique that estimates the seismic quality factor Q from broad-bandwidth (20-300 Hz) high-resolution P-Cable 3D seismic data in order to directly detect gas hydrates in marine sediments. Furthermore, the study includes a detailed analysis of P- and S-wave seismic velocities (through travel time and full waveform inversion) as well as an azimuthal velocity analysis using ocean-bottom seismic data. The P- and S-wave velocity models developed in the thesis are used to estimate gas hydrate saturation with the help of the SCA/DEM rock physics model. The combined analysis of these results suggests the occurrence of gas hydrates lying in fractures and faults along the Vestnesa Ridge. The variations in gas hydrate saturation and morphology across these faults indicates a strong structural control of this gas hydrate system.
Singhroha publicly defended his PhD thesis entitled “Distribution and quantification of gas hydrates and free gas in marine sediments of Vestnesa Ridge, offshore W-Svalbard” on June 18th 2019 at UiT The Arctic University of Norway. This work was funded by the Centre for Arctic Gas Hydrate, Environment, and Climate (CAGE) at UiT.
To find out more, read the two academic articles based on the findings of this research: