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Numerical Simulation of Methane Hydrate in Sandstone Cores

Numerical Simulation of Methane Hydrate in Sandstone Cores. K. Nazridoust, G. Ahmadi and D.H. Smith Department of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY 13699-5725 National Energy Technology Laboratory U.S. Department of Energy, Morgantown, WV 26507-0.

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Numerical Simulation of Methane Hydrate in Sandstone Cores

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  1. Numerical Simulation of Methane Hydrate in Sandstone Cores K. Nazridoust, G. Ahmadi and D.H. SmithDepartment of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY 13699-5725National Energy Technology LaboratoryU.S. Department of Energy, Morgantown, WV 26507-0

  2. Gas Hydrates • Ice-like Crystalline Substances Made Up of Two or More Components • Host Component (Water) - Forms an Expanded Framework with Void Spaces • Guest Component (Methane, Ethane, Propane, Butane, Carbon Dioxide, Hydrogen Sulfide) - Fill the Void Spaces • Van der Waals Forces Hold the Lattice Together

  3. A 1 m3 block of hydrate at normal temperature and pressure will release ~ 164 m3 of methane • Methane hydrate energy content of ~ 6855.90 MJ/m3 • Methane gas – 42.0 MJ/m3 • Liquefied natural gas 16,025.90 MJ/m3 Energy Content

  4. Importance of Gas Hydrates • Potential Energy Resources • Potential Role in Climate Change • Issues During Oil and Gas Production • CO2 Sequestration Objectives • To Provide A Fundamental Understanding of Species Flow During Hydrate Dissociation • To Assess the Reservoir Conditions During Hydrate Dissociation • To Develop a Module for Simulation of Gas Hydrates Dissociation to be Incorporated in FLUENT™ Code

  5. Three-Phase Flow in Methane Hydrate Core, Depressurization

  6. Hydrate Core

  7. Governing Equations Continuity: Darcy’s Law: Saturation: Hydrate Dissociation - (Kim-Bishnoi, 1986) Kinetic Model: Intrinsic Diss. Constant = 124 kmol/Pa/s/m2, and Activation Energy ∆E = 78151 J/kmol

  8. Governing Equations Energy Equation Effective Thermal Conductivity Hydrate Dissociation Heat Sink Masuda, et al. (1999), c = 56,599 J/mol, d = -16.744 J/mol.K.

  9. Governing Equations Equilibrium Pressure Makagon (1997), A = 0.0342 K-1, B = 0.0005 K-2, C = 6.4804 Ambient Temperature Outlet Press.

  10. Initial Conditions Boundary and Ambient Conditions

  11. 0.375 cm 15 cm 22.5 cm 29.625 cm Hydrate Core

  12. Tamb.=275.15K Simulation

  13. Tamb.=275.15K Simulation

  14. Temperature: Comparison with Data

  15. Cumulative Gen./Diss.: Comparison with Data - Case (2)

  16. Aquifer Zone Five-spot Technique • Four wells to form a square where steam or water is pumped in • Gas is pushed out through the 5th well in the middle of the square

  17. Simulation

  18. Conclusions • Depressurization method under favorable conditions is a feasible method for producing natural gas from hydrate. • Gas generation rate is sensitive to physical and thermal conditions of the core sample, the heat supply from the environment, and the outlet valve pressure. • Porosity and relative permeability are important factors affecting the hydrate dissociation and gas generation processes. • For the core studied the temperature near the dissociation front decreases due to hydrate dissociation and then increases by thermal convection. • Increasing the surrounding temperature increases the rate of gas and water production due to faster rate of hydrate dissociation. • Decreasing the outlet valve pressure increases the rate of hydrate dissociation and therefore the rate of gas and water production increases.

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