Collett, Timothy S. et al. (2004): Occurrence of gas hydrate and associated free-gas accumulations on Hydrate Ridge, offshore Oregon, USA

Leg/Site/Hole:
ODP 204
Identifier:
2006-030733
georefid

Creator:
Collett, Timothy S.
U. S. Geological Survey, Denver, CO, United States
author

Goldberg, David S.
Lamont-Doherty Earth Observatory, Palisades, NY, United States
author

Janik, Aleksandra
author

Guerin, Gilles
author

Identification:
Occurrence of gas hydrate and associated free-gas accumulations on Hydrate Ridge, offshore Oregon, USA
2004
In: Anonymous, AAPG annual meeting
American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists (AAPG), Tulsa, OK, United States
13
27
Logging while drilling (LWD) tools were deployed at eight (Site 1244-1150) of the nine sites drilled on Hydrate Ridge during Ocean Drilling Program (ODP) Leg 204. The LWD tools used during Leg 204 included Schlumberger's resistivity-at-the-bit (RAB-GVR) tool, the magnetic resonance while drilling (geoVision) tool, and the azimuthal density-neutron (VDN) tool. The downhole log inferred distribution of gas hydrate beneath Hydrate Ridge and the adjacent slope basin is heterogeneous, with downhole RAB images showing gas hydrate occupying fractures and occurring as a disseminated pore-filling material within flat lying stratigraphic units with thicknesses varying from several centimeters to as much as 10 m. The Archie relation was used with resistivity data from the GVR tool and porosity data from the VDN density tool to calculate water saturations at all eight LWD log sites on Hydrate Ridge. The Archie relation yielded water saturations ranging from low values near the crest of the ridge, of about 10% in Hole 1249A, to a more common value of about 90% along the flanks of the ridge. Thus, the Archie derived gas hydrate saturations at the crest of the ridge exceed 90%. Combined Archie and porosity (NMR, density, and neutron) log analysis also reveal the occurrence of free-gas below the gas hydrate stability zone on Hydrate Ridge, with free-gas saturations exceeding 50% in the "Horizon A" turbidite sequence.
English
Coverage:Geographic coordinates:
North:44.3500
West:-125.0900East: -125.0400
South:44.3400

Economic geology, geology of energy sources; East Pacific; gas hydrates; Hydrate Ridge; Leg 204; measurement-while-drilling; natural gas; NMR spectra; North Pacific; Northeast Pacific; Ocean Drilling Program; Oregon; Pacific Ocean; petroleum; porosity; resistivity; saturation; spectra; thickness; turbidite; United States; well logs;

.