Physical properties of natural gas hydrate deposits
Natural gas hydrates form in polar regions and in ocean bottom sediments and they may represent a considerable energy resource. Unfortunately, so little is known about the physical properties of hydrate deposits that it is difficult to develop geophysical techniques to locate or characterize them. However, because of the strong similarity between hydrates and ice, empirical relationships between ice composition and seismic velocity, electrical resistivity, density, and heat capacity that have been established for partially frozen rocks can be used to estimate the physical properties of hydrate deposits. The electrical resistivities and seismic velocities, estimated using Archie's law and the time-averaged equation, are functions of the unfrozen water remaining in the pores. The unfrozen water content was estimated assuming that the dissolved salt in the pore water is concentrated as a brine phase as the hydrates form. Using this technique, the brine content was estimated as a function of depth assuming several temperature gradients and pore water salinities. The hydrate-bearing zones are characterized by high-seismic velocities and electrical resistivities compared to unfrozen sediments or permafrost zones. Hydrates also lower the densities and heat capacities of sediment, but these effects are comparatively small.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5264061
- Report Number(s):
- LA-9422-MS; ON: DE82018320
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
033000* -- Natural Gas-- Properties & Composition
CRYSTAL STRUCTURE
DATA
DENSITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
GAS HYDRATES
HYDRATES
INFORMATION
MECHANICAL PROPERTIES
NUMERICAL DATA
PHYSICAL PROPERTIES
POISSON RATIO
SHEAR PROPERTIES
SPECIFIC HEAT
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
YOUNG MODULUS