(127b) Carbon Storage and Methane Production Via Permafrost Gas Hydrate Deposits

Carbon Dioxide Storage and Natural Gas Production via Gas Hydrate Exchange Process: Down Hole Combustion Thermal Stimulation

AIChE 2013 Spring Meeting, April 28-May 2. Hyatt, San Antonio, Texas

Garrett C Fitzgerald, Marco J. Castaldi

Department of Earth and Environmental Engineering, Columbia University, 550 W 120 St., Room 926, New York, NY 10027

Methane hydrates present a vast potential for future alternative natural gas resources and have the unique ability to be combined with CO₂ sequestration to produce a carbon neutral CH₄ fuel source.  CO₂ forms a stable gas hydrate in the same pressure –temperature environment that naturally occurring CH₄ hydrates exist and can be exploited for an exchange process.  This work investigates the exchange process of simulated combustion gasses (CO₂ and N₂) with CH₄ in hydrate bearing porous media systems.  Porous sediments are prepared with CH₄ hydrate saturations of 50% pore volume and exposed to pure CO_2, and variousCO₂-N₂ gas mixtures while being subjected to a point heat source for assisted hydrate dissociation.  This work will present the gas exchange potential of both pure CO₂ and CO₂ –N₂ blends at various heating rates and exchange conditions.  The production of CH₄ is used as a metric to evaluate energy potential of this gas production method, and the extent of gas exchange is used to quantify the degree of carbon intensity of the end use CH₄ fuel. CH₄ production rates via the gas exchange methods are compared to those produced via thermal stimulation alone without the co-injection of any exchange gas as a baseline for benefits/challenges associated with CO₂ storage in CH₄ hydrate bearing porous sediment deposits. Multiple CO₂ injection rates are investigated where flow rates range from the lower limit as the amount of CO₂ that would be released for a given amount of heat energy (CH₄ as a fuel) input to the upper limit where enough CO₂ is injected to replace all available CH₄ hydrate in the formation. The benefits of using N₂ as a co-injectent are relatively unknown in the literature and are proposed to enhance the maximum exchange potential and subsequently produce a greater percentage of the in place CH_4.  The results of these experiments should present a better understanding of associated N₂ potential benefits as well as quantify the ideal blend mixtures to achieve the highest gas exchange efficiency.