HR: 17:20h
AN: NS54A-05    [Abstracts]
TI: Natural System Mimics: Development and Evaluation of Formation/Decomposition Methods for Methane Hydrate Hosted in Fine Sediments
AU: * Mahajan, D
EM: dmahajan@bnl.gov
AF: Stony Brook University, Advanced Energy Research & Technology Center/Chemical and Molecular Engineering, Stony Brook, NY 11794, United States
AU: * Mahajan, D
EM: dmahajan@bnl.gov
AF: Brookhaven National Laboratory, Energy Sciences & Technology Department, Upton, NY 11973, United States
AU: Eaton, M W
EM: meaton@bnl.gov
AF: Stony Brook University, Advanced Energy Research & Technology Center/Chemical and Molecular Engineering, Stony Brook, NY 11794, United States
AU: Kerkar, P
EM: pkerkar@bnl.gov
AF: Stony Brook University, Advanced Energy Research & Technology Center/Chemical and Molecular Engineering, Stony Brook, NY 11794, United States
AU: Jones, K W
EM: kwj@bnl.gov
AF: Brookhaven National Laboratory, Environemntal Sciences Department, Upton, NY 11973, United States
AB: Marine hydrates constitute a major fraction of the total global hydrate inventory that to date need further characterization. Pristine samples recovered from several marine hydrate sites share a common feature: they invariably show high variability with respect to methane saturation. A fundamental understanding of host sediment characteristics with and without filled hydrates is sought. Previous studies (Winters et al., 2004) show discrepancies between field and laboratory data that was attributed to factors such as different methods used to reform hydrates in the laboratory. Our studies focus on hydrates in fine-grained natural sediments and discerning the effect of methods used to synthesize them under subsurface-mimic conditions. Our integrated approach involves characterization of host sediments by Computed Microtomography (CMT) at a beamline of the National synchrotron Light Source (NSLS) to establish parameters such as porosity and tortuosity on a grain scale of sediments with and without hydrates. The CMT technique is complemented by a recently constructed unit, namely Flexible Integrated Study of Hydrates (FISH) in which one of the pressure vessels is of 200 mL volume and fitted with a 12" sight glass. The vessel mimics hydrate formation under near-surface marine conditions. We have evaluated a sediment sample from the Gulf of Mexico (GOM) recovered during the DOE-JIP cruise. After fractionation, it was classified as Very Fine Silt (< 10 mm) under the Udden-Wentworth particle-size classification scheme. The CMT data collection was followed by charging the sample to the FISH unit and hydrates were formed by the Static method in which gas was periodically charged to maintain the pressure. Pressure dependency was established by conducting three runs at 900, 1200, and 1500 psi for hydrate formation. Results for our CMT and the formation/decomposition kinetics will be discussed. Keywords: Host sediments, sediment-hydrate interaction, methane hydrate, FISH unit, computed microtomography.
DE: 3004 Gas and hydrate systems
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly