A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research Année : 2015

A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin

Bedanta K. Goswami
  • Fonction : Auteur
Karen A. Weitemeyer
  • Fonction : Auteur
Timothy A. Minshull
  • Fonction : Auteur
Martin C. Sinha
  • Fonction : Auteur
Graham Westbrook
  • Fonction : Auteur
Anne Chabert
  • Fonction : Auteur
Timothy J. Henstock
  • Fonction : Auteur
Stephan Ker

Résumé

We acquired coincident marine controlled-source electromagnetic (CSEM), high-resolution seismic reflection and ocean-bottom seismometer (OBS) data over an active pockmark in the crest of the southern part of the Vestnesa Ridge, to estimate fluid composition within an underlying fluid-migration chimney. Synthetic model studies suggest resistivity obtained from CSEM data can resolve gas or hydrate saturation greater than 5% within the chimney. Acoustic chimneys imaged by seismic reflection data beneath the pockmark and on the ridge flanks, were found to be associated with high-resistivity anomalies (+2-4 m). High-velocity anomalies (+0.3 km/s), within the gas hydrate stability zone (GHSZ) and low-velocity anomalies (-0.2 km/s) underlying the GHSZ, were also observed. Joint analysis of the resistivity and velocity anomaly indicates pore saturation of up to 52% hydrate with 28% free gas, or up to 73% hydrate with 4% free gas, within the chimney beneath the pockmark assuming a non-uniform and uniform fluid distribution respectively. Similarly, we estimate up to 30% hydrate with 4% free gas or 30% hydrate with 2% free gas within the pore space of the GHSZ outside the central chimney assuming a non-uniform and uniform fluid distribution respectively. High levels of free-gas saturation in the top part of the chimney are consistent with episodic gas venting from the pockmark.

Dates et versions

hal-04200696 , version 1 (08-09-2023)

Identifiants

Citer

Bedanta K. Goswami, Karen A. Weitemeyer, Timothy A. Minshull, Martin C. Sinha, Graham Westbrook, et al.. A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin. Journal of Geophysical Research, 2015, 120 (10), pp.6797-6822. ⟨10.1002/2015JB012344⟩. ⟨hal-04200696⟩
1 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More