Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods
The objective of this project was to advance our understanding of gas hydrate systems in nature by characterizing their electrical properties in the field and in the laboratory. In the laboratory measurements, methane hydrate was synthesized from pure water ice and flash frozen seawater, with varyin...
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ftosti:oai:osti.gov:1608233 2023-07-30T04:04:55+02:00 Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods Constable, Steven R. Kannberg, Peter K. Stern, Laura A. Du Frane, Wyatt L. Roberts, Jeffery J. Lu, Ryan 2021-07-28 application/pdf http://www.osti.gov/servlets/purl/1608233 https://www.osti.gov/biblio/1608233 https://doi.org/10.2172/1608233 unknown http://www.osti.gov/servlets/purl/1608233 https://www.osti.gov/biblio/1608233 https://doi.org/10.2172/1608233 doi:10.2172/1608233 58 GEOSCIENCES 03 NATURAL GAS 2021 ftosti https://doi.org/10.2172/1608233 2023-07-11T09:41:01Z The objective of this project was to advance our understanding of gas hydrate systems in nature by characterizing their electrical properties in the field and in the laboratory. In the laboratory measurements, methane hydrate was synthesized from pure water ice and flash frozen seawater, with varying amounts of sand or silt added. Electrical conductivity was determined by impedance spectroscopy, using equivalent circuit modeling to separate the effects of electrodes and to gain insight into conduction mechanisms. Silt and sand increase the conductivity of pure hydrate, inferred to be contaminant NaCl contributing to conduction in hydrate, to a peak conductivity in agreement with peak resistivities observed in well logs through massive hydrate (3,000--10,000 Ωm). The addition of silt and sand lowers the conductivity of hydrate synthesized from seawater, by an amount consistent with Archie's Law. All samples were characterized using cryogenic scanning electron microscopy and energy dispersive spectroscopy, which shows good connectivity of salt and brine phases. Electrical conductivity measurements of pure hydrate and hydrate mixed with silt during pressure-induced dissociation supports previous conclusions that sediment increases dissociation rate. In order to characterize gas hydrate systems in the field, we collected 360 line kilometers of controlled-source electromagnetic data on Walker Ridge 313, Orca Basin (WR100), Mad Dog (GC781), and Green Canyon 955 in the Gulf of Mexico, all areas with known or seismically inferred gas hydrate deposits and which have be drilled or targeted for future drilling. We deep-towed an EM transmitter that generates an alternating electric field which propagates through the seafloor geology. Data were recorded on 6 receivers towed behind the transmitter at distances between 550 and 1550 m. In the presence of conductive geology, the electric fields will be attenuated, and conversely, in resistive geology the fields will be preserved. Our data were inverted using a 2D inversion ... Other/Unknown Material Methane hydrate Orca SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Walker Ridge ENVELOPE(168.367,168.367,-72.567,-72.567) |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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ftosti |
language |
unknown |
topic |
58 GEOSCIENCES 03 NATURAL GAS |
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58 GEOSCIENCES 03 NATURAL GAS Constable, Steven R. Kannberg, Peter K. Stern, Laura A. Du Frane, Wyatt L. Roberts, Jeffery J. Lu, Ryan Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
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58 GEOSCIENCES 03 NATURAL GAS |
description |
The objective of this project was to advance our understanding of gas hydrate systems in nature by characterizing their electrical properties in the field and in the laboratory. In the laboratory measurements, methane hydrate was synthesized from pure water ice and flash frozen seawater, with varying amounts of sand or silt added. Electrical conductivity was determined by impedance spectroscopy, using equivalent circuit modeling to separate the effects of electrodes and to gain insight into conduction mechanisms. Silt and sand increase the conductivity of pure hydrate, inferred to be contaminant NaCl contributing to conduction in hydrate, to a peak conductivity in agreement with peak resistivities observed in well logs through massive hydrate (3,000--10,000 Ωm). The addition of silt and sand lowers the conductivity of hydrate synthesized from seawater, by an amount consistent with Archie's Law. All samples were characterized using cryogenic scanning electron microscopy and energy dispersive spectroscopy, which shows good connectivity of salt and brine phases. Electrical conductivity measurements of pure hydrate and hydrate mixed with silt during pressure-induced dissociation supports previous conclusions that sediment increases dissociation rate. In order to characterize gas hydrate systems in the field, we collected 360 line kilometers of controlled-source electromagnetic data on Walker Ridge 313, Orca Basin (WR100), Mad Dog (GC781), and Green Canyon 955 in the Gulf of Mexico, all areas with known or seismically inferred gas hydrate deposits and which have be drilled or targeted for future drilling. We deep-towed an EM transmitter that generates an alternating electric field which propagates through the seafloor geology. Data were recorded on 6 receivers towed behind the transmitter at distances between 550 and 1550 m. In the presence of conductive geology, the electric fields will be attenuated, and conversely, in resistive geology the fields will be preserved. Our data were inverted using a 2D inversion ... |
author |
Constable, Steven R. Kannberg, Peter K. Stern, Laura A. Du Frane, Wyatt L. Roberts, Jeffery J. Lu, Ryan |
author_facet |
Constable, Steven R. Kannberg, Peter K. Stern, Laura A. Du Frane, Wyatt L. Roberts, Jeffery J. Lu, Ryan |
author_sort |
Constable, Steven R. |
title |
Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
title_short |
Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
title_full |
Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
title_fullStr |
Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
title_full_unstemmed |
Characterizing Baselines and Change in Gas Hydrate Systems using EM Methods |
title_sort |
characterizing baselines and change in gas hydrate systems using em methods |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1608233 https://www.osti.gov/biblio/1608233 https://doi.org/10.2172/1608233 |
long_lat |
ENVELOPE(168.367,168.367,-72.567,-72.567) |
geographic |
Walker Ridge |
geographic_facet |
Walker Ridge |
genre |
Methane hydrate Orca |
genre_facet |
Methane hydrate Orca |
op_relation |
http://www.osti.gov/servlets/purl/1608233 https://www.osti.gov/biblio/1608233 https://doi.org/10.2172/1608233 doi:10.2172/1608233 |
op_doi |
https://doi.org/10.2172/1608233 |
_version_ |
1772816570615070720 |