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 a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures...
Published in: | Energies |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
MDPI
2022
|
Subjects: | |
Online Access: | https://hdl.handle.net/10037/24938 https://doi.org/10.3390/en15093156 |
id |
ftunivtroemsoe:oai:munin.uit.no:10037/24938 |
---|---|
record_format |
openpolar |
spelling |
ftunivtroemsoe:oai:munin.uit.no:10037/24938 2023-05-15T18:29:45+02:00 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 Ramachandran, Hariharan Plaza-Faverola, Andreia Daigle, Hugh 2022-04-26 https://hdl.handle.net/10037/24938 https://doi.org/10.3390/en15093156 eng eng MDPI Energies Ramachandran H, Plaza-Faverola A, Daigle H. 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. Energies. 2022;15(9):3156 FRIDAID 2019677 doi:10.3390/en15093156 1996-1073 https://hdl.handle.net/10037/24938 openAccess Copyright 2022 The Author(s) Journal article Tidsskriftartikkel Peer reviewed publishedVersion 2022 ftunivtroemsoe https://doi.org/10.3390/en15093156 2022-05-04T22:58:43Z The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence for an extended free gas zone (FGZ) below the base of the gas hydrate stability zone (BGHSZ), present-day seafloor seepage has been confirmed only on the eastern half of the sedimentary ridge. In this study, we combine the relationships between aqueous phase pressure, capillary pressure, sediment clay fraction, porosity, and total stress to simulate how much gas is required to open preexisting fractures from the BGHSZ towards the seafloor. Data from four specific sites with different lithology and pressure regime along the ridge are used to constrain the simulations. Results demonstrate that fracturing is favored from the FGZ (with gas saturations < 0.1 and gas column heights < 15 m) towards the seafloor. Neglecting the capillary pressure overpredicts the size of the gas column by up to 10 times, leading to erroneous maximum gas vent volume predictions and associated ocean biosphere consequences. Further parametric analyses indicate that variations in the regional stress regime have the potential to modify the fracture criterion, thus driving the differences in venting across the ridge. Our results are in line with independent geophysical observations and petroleum system modeling in the study area, adding confidence to the proposed approach and highlighting the importance of the capillary pressure influence on gas pressure Article in Journal/Newspaper Svalbard Svalbard margin University of Tromsø: Munin Open Research Archive Long Ridge ENVELOPE(73.583,73.583,-53.100,-53.100) Svalbard Energies 15 9 3156 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
description |
The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence for an extended free gas zone (FGZ) below the base of the gas hydrate stability zone (BGHSZ), present-day seafloor seepage has been confirmed only on the eastern half of the sedimentary ridge. In this study, we combine the relationships between aqueous phase pressure, capillary pressure, sediment clay fraction, porosity, and total stress to simulate how much gas is required to open preexisting fractures from the BGHSZ towards the seafloor. Data from four specific sites with different lithology and pressure regime along the ridge are used to constrain the simulations. Results demonstrate that fracturing is favored from the FGZ (with gas saturations < 0.1 and gas column heights < 15 m) towards the seafloor. Neglecting the capillary pressure overpredicts the size of the gas column by up to 10 times, leading to erroneous maximum gas vent volume predictions and associated ocean biosphere consequences. Further parametric analyses indicate that variations in the regional stress regime have the potential to modify the fracture criterion, thus driving the differences in venting across the ridge. Our results are in line with independent geophysical observations and petroleum system modeling in the study area, adding confidence to the proposed approach and highlighting the importance of the capillary pressure influence on gas pressure |
format |
Article in Journal/Newspaper |
author |
Ramachandran, Hariharan Plaza-Faverola, Andreia Daigle, Hugh |
spellingShingle |
Ramachandran, Hariharan Plaza-Faverola, Andreia Daigle, Hugh 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 |
author_facet |
Ramachandran, Hariharan Plaza-Faverola, Andreia Daigle, Hugh |
author_sort |
Ramachandran, Hariharan |
title |
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 |
title_short |
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 |
title_full |
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 |
title_fullStr |
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 |
title_full_unstemmed |
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 |
title_sort |
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 |
publisher |
MDPI |
publishDate |
2022 |
url |
https://hdl.handle.net/10037/24938 https://doi.org/10.3390/en15093156 |
long_lat |
ENVELOPE(73.583,73.583,-53.100,-53.100) |
geographic |
Long Ridge Svalbard |
geographic_facet |
Long Ridge Svalbard |
genre |
Svalbard Svalbard margin |
genre_facet |
Svalbard Svalbard margin |
op_relation |
Energies Ramachandran H, Plaza-Faverola A, Daigle H. 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. Energies. 2022;15(9):3156 FRIDAID 2019677 doi:10.3390/en15093156 1996-1073 https://hdl.handle.net/10037/24938 |
op_rights |
openAccess Copyright 2022 The Author(s) |
op_doi |
https://doi.org/10.3390/en15093156 |
container_title |
Energies |
container_volume |
15 |
container_issue |
9 |
container_start_page |
3156 |
_version_ |
1766213110320857088 |