HR: 11:20h
AN: OS22A-05    [Abstracts]
TI: Growth kinetics and microstructure of methane hydrates formed in porous media
AU: * Falenty, A
EM: afalent@gwdg.de
AF: GZG, Abt. Kristallographie, University of Goettingen, Goldschmidtstrasse 1, Goettingen, 37077, Germany
AU: Klapproth, A
EM: aklappr@gwdg.de
AF: GZG, Abt. Kristallographie, University of Goettingen, Goldschmidtstrasse 1, Goettingen, 37077, Germany
AU: Techmer, K
EM: ktechme1@gwdg.de
AF: GZG, Abt. Kristallographie, University of Goettingen, Goldschmidtstrasse 1, Goettingen, 37077, Germany
AU: Murshed, M M
EM: mmurshe@gwdg.de
AF: GZG, Abt. Kristallographie, University of Goettingen, Goldschmidtstrasse 1, Goettingen, 37077, Germany
AU: Kuhs, W F
EM: wkuhs1@gwdg.de
AF: GZG, Abt. Kristallographie, University of Goettingen, Goldschmidtstrasse 1, Goettingen, 37077, Germany
AB: The occurrence of natural gas hydrates within sediments is known from a large number of locations. They commonly occupy pore spaces cementing sedimentary deposits. Yet, detailed information about the influence of mineral composition on the formation process in porous media is still very limited. Laboratory investigations of the microstructure of gas hydrate in porous media, as a function of p-T conditions, mineral composition and water/gas supersaturation are therefore of considerable interest. Such studies may allow a better understanding of the formation process and even the prediction of accumulation /decomposition rates of some natural gas hydrates in a given geological setting. As a model study, we carried out various reactions with methane gas and water in three types of media: 1) quartz, 2) quartz + kaolinite, 3) quartz + montmorillonite. The progress of the reactions was recorded by gas consumption (pressure drop) at 3°C. Samples recovered at various stages of the formation or decomposition reactions were investigated using field-emission scanning electron microscopes (FE-SEM) equipped with a cryo-stage [1]. In the SEM investigations, methane hydrates appeared between the quartz grains acting as cement. Kaolinite particles were observed as a filigree network on the surface of hydrate cement, while montmorillonite form flakes or crust like features. Each of the minerals may play individual/coupled interaction with water and gas hydrate, and thereby display a characteristic configuration in the SEM images. Dissimilar kinetic features, using different porous media at the investigated conditions, confirm that mineral composition directly influences the progress of gas hydrate formation. Medium 3 shows the fastest hydrate saturation. With increasing water content of the porous media the formation tends to proceed in a multi-stage process with a slower diffusion-limited later stage. Reference: [1] A. Klapproth, K. Techmer, S.A. Klapp, M.M. Murshed and W.F. Kuhs., In Physics and Chemistry of ice (ed. by W. F. Kuhs), RSC Publishing, Cambridge 2007, pp.321-328.
DE: 3004 Gas and hydrate systems
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting