- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- International Conference on Gas Hydrates (ICGH) (6th : 2008) /
- NEPTUNE-CANADA BASED GEOPHYSICAL IMAGING OF GAS HYDRATE...
Open Collections
International Conference on Gas Hydrates (ICGH) (6th : 2008)
NEPTUNE-CANADA BASED GEOPHYSICAL IMAGING OF GAS HYDRATE IN THE BULLSEYE VENT Willoughby, E.C.; Mir, R; Scholl, Carsten; Edwards, R.N.
Abstract
Using the NEPTUNE-Canada cable-linked ocean-floor observatory we plan continuous, real-time monitoring of the gas hydrate-associated, “Bullseye” cold vent offshore Vancouver Island. Our group inferred the presence of a massive gas hydrate deposit there, based on the significant resistivity anomaly in our controlled-source electromagnetic (CSEM) dataset, as well as anomalously heightened shear moduli, from seafloor compliance data. This interpretation was confirmed by drilling by IODP expedition 311 (site U1328), which indicated a 40 m thick gas hydrate layer near the surface. Sporadic venting and variations in blanking in yearly single-channel seismic surveys suggest the system is evolving in time. We are preparing two stationary semi-permanent imaging experiments: a CSEM and a seafloor compliance installation. These are designed not only to assess the extent of the gas hydrate deposit, but also for long-term monitoring of the gas hydrate/free gas system. The principle of the CSEM experiment is to input a particular electromagnetic signal at a transmitter (TX) dipole on the seafloor, and to record the phase and amplitude of the response at several seafloor receiver (RX) dipoles, at various TX-RX separations. The data are sensitive to the underlying resistivity, which is increased when conductive pore water is displaced by electrically-insulating gas hydrate. The experiment is controlled onshore, and can be expanded to include a downhole TX. Repeated soundings at this site, over several years, will allow measurement of minute changes in resistivity as a function of depth, and by inference, changes in gas hydrate or underlying free gas distribution. Similarly, the displacement of pore fluids by solid gas hydrate will affect elastic parameters. Thus, seafloor compliance data, the transfer function between pressure and seafloor displacement time series, most sensitive to shear modulus as a function of depth, will be gathered continuously to monitor the evolution of the gas hydrate distribution.
Item Metadata
Title |
NEPTUNE-CANADA BASED GEOPHYSICAL IMAGING OF GAS HYDRATE IN THE BULLSEYE VENT
|
Creator | |
Contributor | |
Date Issued |
2008-07
|
Description |
Using the NEPTUNE-Canada cable-linked ocean-floor observatory we plan continuous, real-time monitoring of the gas hydrate-associated, “Bullseye” cold vent offshore Vancouver Island. Our group inferred the presence of a massive gas hydrate deposit there, based on the significant resistivity anomaly in our controlled-source electromagnetic (CSEM) dataset, as well as anomalously heightened shear moduli, from seafloor compliance data. This interpretation was confirmed by drilling by IODP expedition 311 (site U1328), which indicated a 40 m thick gas hydrate layer near the surface. Sporadic venting and variations in blanking in yearly single-channel seismic surveys suggest the system is evolving in time. We are preparing two stationary semi-permanent imaging experiments: a CSEM and a seafloor compliance installation. These are designed not only to assess the extent of the gas hydrate deposit, but also for long-term monitoring of the gas hydrate/free gas system. The principle of the CSEM experiment is to input a particular electromagnetic signal at a transmitter (TX) dipole on the seafloor, and to record the phase and amplitude of the response at several seafloor receiver (RX) dipoles, at various TX-RX separations. The data are sensitive to the underlying resistivity, which is increased when conductive pore water is displaced by electrically-insulating gas hydrate. The experiment is controlled onshore, and can be expanded to include a downhole TX. Repeated soundings at this site, over several years, will allow measurement of minute changes in resistivity as a function of depth, and by inference, changes in gas hydrate or underlying free gas distribution. Similarly, the displacement of pore fluids by solid gas hydrate will affect elastic parameters. Thus, seafloor compliance data, the transfer function between pressure and seafloor displacement time series, most sensitive to shear modulus as a function of depth, will be gathered continuously to monitor the evolution of the gas hydrate distribution.
|
Extent |
586475 bytes
|
Subject | |
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2008-07-21
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
|
DOI |
10.14288/1.0040987
|
URI | |
Affiliation | |
Citation |
Willoughby, E.C.; Mir, R.; Scholl, C.; Edwards, R.N. 2008. NEPTUNE-CANADA BASED GEOPHYSICAL IMAGING OF GAS HYDRATE IN THE BULLSEYE VENT. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, CANADA, July 6-10, 2008.
|
Peer Review Status |
Unreviewed
|
Copyright Holder |
Willoughby, E.C.
|
Rights URI | |
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International