Natural-gas-hydrate deposits: a review of in-situ properties
The Los Alamos hydrate project has concentrated on: evaluating techniques to produce gas from hydrate deposits to determine critical reservoir and production variables; predicting physical properties of hydrate-containing sediments both for their effects on production models and to allow us to develop geophysical exploration and reservoir characterization techniques; and measuring properties of synthetic hydrate cores in the laboratory. Exploration techniques can help assess the size of potential hydrate deposits and determine which production techniques are appropriate for particular deposits. So little is known about the physical properties of hydrate deposits that it is difficult to develop geophysical techniques to locate or characterize them; but, 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 frozen rocks may be used to estimate the physical properties of hydrate deposits. Resistivities of laboratory permafrost samples are shown to follow a variation of Archie's equation. Both the resistivities and seismic velocities are functions of the unfrozen water content (Sw); however, resistivities are more sensitive to changes in Sw, varying by as much as three orders of magnitude, which may allow the use of electrical resistivity measurements to estimte the amount of hydrate in place. We estimated Sw, assuming that the dissolved salt in the pore water is concentrated as a brine phase as the hydrates form, and the brine content as a function of depth, assuming several temperature gradients and pore water salinities. Hydrate-bearing zones are characterized by high seismic velocities and electrical resistivities compared to unfrozen sediments or permafrost zones.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6917373
- Report Number(s):
- LA-UR-82-2833; CONF-820865-2; ON: DE83000604
- Resource Relation:
- Conference: 6. international ice symposium, Rolla, MO, USA, 1 Aug 1982
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition
METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST
Related Subjects
NATURAL GAS HYDRATE DEPOSITS
ELECTRIC CONDUCTIVITY
RESISTIVITY LOGGING
SONIC LOGGING
PERMAFROST
SEDIMENTS
VELOCITY
ELECTRIC LOGGING
ELECTRICAL PROPERTIES
GEOLOGIC DEPOSITS
PHYSICAL PROPERTIES
WELL LOGGING
030200* - Natural Gas- Reserves
Geology
& Exploration
033000 - Natural Gas- Properties & Composition