METHANE HYDRATE STUDIES: DELINEATING PROPERTIES OF HOST SEDIMENTS TO ESTABLISH REPRODUCIBLE DECOMPOSITION KINETICS.

• Main Authors: Mahajan, Devinder, Jones, Keith W., Feng, Huan, Winters, William J.
• Language: unknown
• Published: 2015
• Subjects: 03 NATURAL GAS; 43 PARTICLE ACCELERATORS; DRYING; ENERGY SOURCES; GAS HYDRATES; GEORGES BANK; HYDRATES; KINETICS; METHANE; PERMAFROST; POROSITY; SEDIMENTS; SYNCHROTRONS; Methane hydrate; permafrost
• Online Access: http://www.osti.gov/servlets/purl/15006838; https://www.osti.gov/biblio/15006838; https://doi.org/10.2172/15006838

The use of methane hydrate as an energy source requires development of a reliable method for its extraction from its highly dispersed locations in oceanic margin sediments and permafrost. The high pressure (up to 70 MPa) and low temperature (272 K to 278 K) conditions under which hydrates are stable in the marine environment can be mimicked in a laboratory setting and several kinetic studies of pure methane hydrate decomposition have been reported. However, the effect of host sediments on methane hydrate occurrence and decomposition are required to develop reliable hydrate models. In this paper, we describe methods to measure sediment properties as they relate to pore-space methane gas hydrate. Traditional geotechnical techniques are compared to the micrometer level by use of the synchrotron Computed Microtomography (CMT) technique. CMT was used to measure the porosity at the micrometer level and to show pore-space pathways through field samples. Porosities for three sediment samples: one from a site on Georges Bank and two from the known Blake Ridge methane hydrate site, from different depths below the mud line were measured by traditional drying and by the new CMT techniques and found to be in good agreement. The integration of the two analytical approaches is necessary to enable better understanding of methane hydrate interactions with the surrounding sediment particles.