The characteristics of gas hydrates recovered from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

• Published in: Marine and petroleum geology Vol. 28; no. 2; pp. 411 - 418
• Main Authors: Lu, Hailong, Lorenson, Thomas D., Moudrakovski, Igor L., Ripmeester, John A., Collett, Timothy S., Hunter, Robert B., Ratcliffe, Chris I.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2011
• Subjects: Alaska; Crystal structure; Gas composition; Gas hydrate; Gas hydrates; Geochemistry; Hydrates; Hydration number; Instrumentation; Isotope; Marine; Methane; Natural gas; North Slope; Pressurizing; Sediments; USA, Alaska, North Slope; Gas hydrate; Isotope; Hydration number; Geochemistry; Alaska; Crystal structure; North Slope
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2010.01.002

Systematic analyses have been carried out on two gas hydrate-bearing sediment core samples, HYPV4, which was preserved by CH 4 gas pressurization, and HYLN7, which was preserved in liquid-nitrogen, recovered from the BPXA-DOE-USGS Mount Elbert Stratigraphic Test Well. Gas hydrate in the studied core samples was found by observation to have developed in sediment pores, and the distribution of hydrate saturation in the cores imply that gas hydrate had experienced stepwise dissociation before it was stabilized by either liquid nitrogen or pressurizing gas. The gas hydrates were determined to be structure Type I hydrate with hydration numbers of approximately 6.1 by instrumentation methods such as powder X-ray diffraction, Raman spectroscopy and solid state 13C NMR. The hydrate gas composition was predominantly methane, and isotopic analysis showed that the methane was of thermogenic origin (mean δ 13C = −48.6‰ and δ D = −248‰ for sample HYLN7). Isotopic analysis of methane from sample HYPV4 revealed secondary hydrate formation from the pressurizing methane gas during storage.