Impact of Gas Saturation and Gas Column Height at the Base of the Gas Hydrate Stability Zone on Fracturing and Seepage at Vestnesa Ridge, West-Svalbard Margin

The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host deep-marine gas hydrate and associated seepage system. Geological geophysical observations indicate predominance vertical fluid expulsion through fractures with pockmarks expressed on seafloor along entire ridge. However, despite apparent evidence for an extended free zone (FGZ) below base stability (BGHSZ), present-day has been confirmed only eastern half sedimentary In this study, we combine relationships between aqueous phase pressure, capillary sediment clay fraction, porosity, total stress to simulate how much required open preexisting from BGHSZ towards seafloor. Data four specific sites different lithology pressure regime are used constrain simulations. Results demonstrate fracturing favored FGZ (with saturations < 0.1 column heights 15 m) Neglecting overpredicts size by up 10 times, leading erroneous maximum vent volume predictions ocean biosphere consequences. Further parametric analyses variations in regional have potential modify fracture criterion, thus driving differences venting across Our results line independent petroleum system modeling study area, adding confidence proposed approach highlighting importance influence pressure.