Electrical properties of polycrystalline methane hydrate

Autor:	John C. Pinkston, Jeffery J. Roberts, Laura A. Stern, Steven Constable, Karen Weitemeyer, Wyatt L. Du Frane
Rok vydání:	2011
Předmět:	Materials science Scanning electron microscope Clathrate hydrate Analytical chemistry Mineralogy Activation energy Methane Dielectric spectroscopy chemistry.chemical_compound Geophysics chemistry Electrical resistivity and conductivity General Earth and Planetary Sciences Crystallite Hydrate
Zdroj:	Geophysical Research Letters. 38
ISSN:	1944-8007 0094-8276
DOI:	10.1029/2011gl047243
Popis:	[1] Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (σ). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate σ. We determined the σ of CH4 hydrate to be 5 × 10−5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, σ measurements of samples increased by a factor of ∼4 and Ea increased by ∼50%, similar to the starting ice samples.
Databáze:	OpenAIRE
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