In-situ thermal stimulation of gas hydrates

Gas hydrates are increasingly considered a potential energy resource. Various methods of exploiting gas hydrates (thermal stimulation, depressurization, inhibitor injection, etc.) have been proposed so far, but each of them has some drawbacks. To overcome some of these drawbacks, we propose a new technology for producing methane from gas hydrates. The method uses in situ thermal stimulation by introducing a specially designed hydrate heating apparatus into a horizontal borehole drilled into a gas hydrate zone (GHZ). Instead of using water or other hot fluid injected from the surface or another location away from the GHZ, an air/gas fuel mixture is introduced into a combustion vessel from the surface via a fuel injection tubing string directly into GHZ. Burning the fuel mixture results in the heat necessary to dissociate gas hydrate. The freed natural gas is then conveyed to the surface via a casing that is lining the wellbore. This technology has the advantage of permitting the dissociated gas to be produced through the same wellbore through which the air/gas fuel mixture is injected, thereby avoiding the need of using two wells (injection and exploitation). An estimated energy gain efficiency of the proposed method shows that only about 1.1 to 1.7% of gas produced will have to be burned to decompose hydrates. Previous estimates of other thermal decomposition methods, for example steam injection, show that about 50% of gas produced will have to be burned just to decompose hydrates. An added advantage is that the produced natural gas is not mixed with the combustion gases, thus avoiding the problem of the resulting gas having a BTU content that is too low.

[1]  Kishore K. Mohanty,et al.  1-D Modeling of Hydrate Depressurization in Porous Media , 2005 .

[2]  H. David.  Geoscientists in the Peace Corps; a strategic revisit , 2004 .

[3]  Ji-Ho Yoon,et al.  Hydrate Phase Equilibria of the Carbon Dioxide, Methane, and Water System , 2001 .

[4]  K. Ohgaki,et al.  Exploitation of CH_4 Hydrates under the Nankai Trough in Combination with CO_2 Storage , 1994 .

[5]  George J. Moridis,et al.  Toward Production From Gas Hydrates: Current Status, Assessment of Resources, and Simulation-Based Evaluation of Technology and Potential , 2008 .

[6]  George J. Moridis,et al.  Numerical studies of gas production from several CH4 hydrate zones at the Mallik site, Mackenzie Delta, Canada , 2004 .

[7]  Keun-Pil Park,et al.  Sequestering carbon dioxide into complex structures of naturally occurring gas hydrates , 2006, Proceedings of the National Academy of Sciences.

[8]  I︠u︡. F. Makogon.  Hydrates of Hydrocarbons , 1997 .

[9]  Yash Paul Handa,et al.  Compositions, enthalpies of dissociation, and heat capacities in the range 85 to 270 K for clathrate hydrates of methane, ethane, and propane, and enthalpy of dissociation of isobutane hydrate, as determined by a heat-flow calorimeter , 1986 .

[10]  Carolyn A. Koh,et al.  Clathrate hydrates of natural gases , 1990 .

[11]  Wonmo Sung,et al.  Numerical Study for Production Performances of a Methane Hydrate Reservoir Stimulated by Inhibitor Injection , 2002 .

[12]  L. Stern,et al.  Thermal Regulation of Methane Hydrate Dissociation: Implications for Gas Production Models , 2005 .

[13]  Kiyoteru Takano,et al.  Methane Exploitation by Carbon Dioxide from Gas Hydrates—Phase Equilibria for CO2-CH4 Mixed Hydrate System— , 1996 .

[14]  Michael D. Max,et al.  Natural gas hydrate : in oceanic and permafrost environments , 2000 .

[15]  P. Mcguire.  Methane hydrate gas production by thermal stimulation , 1981 .

[16]  K. Kvenvolden.  Natural gas hydrate; introduction and history of discovery , 2003 .

[17]  Gerald D. Holder,et al.  A Thermodynamic Evaluation of Thermal Recovery of Gas From Hydrates in the Earth (includes associated papers 11863 and 11924 ) , 1982 .

[18]  Yongwon Seo,et al.  Recovering methane from solid methane hydrate with carbon dioxide. , 2003, Angewandte Chemie.

[19]  K. Ohgaki,et al.  Natural gas exploitation by carbon dioxide from gas hydrate fields—high-pressure phase equilibrium for an ethane hydrate system , 1998 .

[20]  Gerald D. Holder,et al.  The Potential of Natural Gas Hydrates as an Energy Resource , 1984 .

[21]  Naval Goel,et al.  In situ methane hydrate dissociation with carbon dioxide sequestration: Current knowledge and issues , 2006 .

[22]  W. Borowski,et al.  In situ methane concentrations at Hydrate Ridge, offshore Oregon: New constraints on the global gas hydrate inventory from an active margin , 2003 .

[23]  W. Dillon,et al.  OCEANIC METHANE HYDRATE: THE CHARACTER OF THE BLAKE RIDGE HYDRATE STABILITY ZONE, AND THE POTENTIAL FOR METHANE EXTRACTION , 1998 .