Physical properties of sediment from the 2006 National Gas Hydrate Program
expedition offshore India

Authors: Winters, W.J., (U.S. Geological Survey, speaker), Gomes, M., Giosan, L., Johnson, J., Kastner, M., Torres, M.E., Long, P.E., Schaef, H.T., Rose, K., and the NGHP-01 Shipboard Scientific Party.

Venue: India’s Directorate General of Hydrocarbons’ International Conference on Gas Hydrates in Nodia (New Delhi), India, February 6–8, 2008 (http://www.dghindia.org/site/pdfattachments/upcomingevents/Updated_Programme_gAS[1].pdf [PDF-external site]).

Abstract: The scientific goals of the NGHP Expedition 01 physical properties program are to a) constrain baseline index properties of host sediment; b) ground-truth well-log, seismic, and other shipboard data sets; c) relate textural characteristics to gas hydrate occurrence and small-scale porous media effects; and d) relate index properties and textural analyses to gas hydrate occurrence and regional sedimentologic interpretations. During the shipboard phase of NGHP-01, baseline bulk physical properties, such as water content, grain density, bulk density, and porosity, were determined on more than 1,800 sediment samples from 14 sites located in four study areas. Overall, physical properties change more significantly near the seafloor, then at a much more gradual rate with depth. The transition depth varies between sites but can range from about 12 to as deep as 200 meters beneath the seafloor. In addition, shear strength, electrical resistivity, magnetic susceptibility, thermal conductivity, and acoustic velocity measurements were conducted to further characterize the sediment. These measurements, when combined with sedimentologic and geochemical studies, delineate the role of the host sediment in hydrate formation and occurrence and are used in modeling the response of hydrate-bearing sediment to natural change or drilling operations. Strong correlation typically exists between physical properties determined from shipboard analyses and well-log studies. More than 500 shore-based grain-size analyses have been conducted that indicate that most sediment is characterized as clayey silt to silty clay with a median grain size that is near or slightly greater than the silt-clay boundary. Grain-size analyses are being conducted on samples identified by infrared imaging as having high concentrations of gas hydrate in recovered core samples. These analyses will be used to study porous-media effects and geologic controls on the occurrence of gas hydrate in situ.

Related NETL Project
The USGS conducts scientific studies of natural gas hydrates to support DOE efforts to evaluate and understand methane hydrates, their potential as an energy resource, and the hazard they may pose to ongoing drilling efforts. This project, DE-AI26-05NT42496, extends USGS support to the DOE Methane Hydrate Research Program previously supported under DE-AT26-97FT34342 and DE-AT26-97FT34343.

NETL Project Contacts
NETL – Robert Vagnetti (robert.vagnetti@netl.doe.gov or 304-285-1334)
USGS – Deborah R. Hutchinson (dhutchinson@usgs.gov or 508-457-2263)