Issue 28, 2014

Quantitative measurement and mechanisms for CH4 production from hydrates with the injection of liquid CO2

Abstract

The recovery of gas from natural gas hydrates under the permafrost and in oceanic sediments is of particular interest in energy and environmental fields because of the attractive process to release methane gas through the injection of CO2. The sequestration of CO2, a notorious greenhouse gas, in hydrates has the potential to be used in enhanced gas recovery techniques, while simultaneously releasing CH4 locked within the gas bearing hydrates. In this study, we present quantitative experiments to investigate results of possible CH4–CO2 exchange kinetics from injection of liquid CO2 through CH4 hydrates. The experiments performed use CH4 hydrate formed from ice particles (75–90 or 125–150 microns in diameter) at approximately 10.34 MPa and 263 K. In order to reduce unexpected errors, nearly full conversion (>95%) of ice particles to hydrates is achieved. Liquid CO2 is injected into the pressure cell to sweep the residual CH4 atmosphere, ensuring no free CH4 is left in the gas phase. After soaking the hydrate for several hours, CH4 is produced from the hydrates by injecting liquid CO2. The final composition and analysis of the produced CH4 is measured by using in-line gas chromatography. We also measure the CH4 moles after hydrate dissociation to confirm the closure of the total mass balance of the experiment. From these data, we infer the mechanism for CH4 production, identify the penetration depth of the dissociation/exchange on the hydrate particles, and propose physical models describing the mechanism for CH4 production. These experiments are essential in the quantification of the production of CH4 from CH4 hydrates with the injection of CO2.

Graphical abstract: Quantitative measurement and mechanisms for CH4 production from hydrates with the injection of liquid CO2

Supplementary files

Article information

Article type
Paper
Submitted
25 Apr 2014
Accepted
02 Jun 2014
First published
09 Jun 2014

Phys. Chem. Chem. Phys., 2014,16, 14922-14927

Author version available

Quantitative measurement and mechanisms for CH4 production from hydrates with the injection of liquid CO2

B. R. Lee, C. A. Koh and A. K. Sum, Phys. Chem. Chem. Phys., 2014, 16, 14922 DOI: 10.1039/C4CP01780C

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