Thermal conductivity of rocks associated with energy extraction from hot dry rock geothermal systems

Conference · Sun Jan 01 04:00:00 EST 1978

OSTI ID:6880645

Sibbitt, W L; Dodson, J G; Tester, J W

Results of thermal conductivity measurements are given for 14 drill core rock samples taken from two exploratory HDR geothermal wellbores (maximum depth of 2929 m (9608 ft) drilled into Precambrian granitic rock in the Jemez Mountains of northern New Mexico. These samples have been petrographically characterized and in general represent fresh competent Precambrian material of deep origin. Thermal conductivities, modal analyses, and densities are given for all core samples studied under dry and water-saturated conditions. Additional measurements are reported for several sedimentary rocks encountered in the upper 760 m (2500 ft) of that same region. A cut-bar thermal conductivity comparator and a transient needle probe were used for the determinations with fused quartz and Pyroceram 9606 as the standards. The maximum temperature range of the measurements was from the ice point to 250/sup 0/C. The measurements on wet, water-saturated rock were limited to the temperature range below room temperature. Conductivity values of the dense core rock samples were generally within the range from 2 to 2.9 W/mK at 200/sup 0/C. Excellent agreement was achieved between these laboratory measurements of thermal conductivity and those obtained by in situ measurements used in the HDR wellbores. By using samples of sufficient thickness to provide a statistically representative heat flow path, no difference between conductivity values and their temperature coefficients for orthogonal directions (heat flow parallel or perpendicular to core axis) was observed. This isotropic behavior was even found for highly foliated gneissic specimens. Estimates of thermal conductivity based on a composite dispersion analysis utilizing pure minerallic phase conductivities and detailed modal analyses usually agreed to within 9 percent of the experimental values.

• Research Organization: Los Alamos Scientific Lab., N.Mex. (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6880645
• Report Number(s): LA-UR-78-1240; CONF-770847-7
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150301* -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
COMPARATIVE EVALUATIONS
DENSITY
DIAGRAMS
DRILL CORES
GEOTHERMAL SYSTEMS
GRANITES
Geothermal Legacy
HIGH TEMPERATURE
HOT-DRY-ROCK SYSTEMS
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
INFORMATION
JEMEZ MOUNTAINS
LEVELS
LITHOLOGY
MEDIUM TEMPERATURE
MOUNTAINS
NEW MEXICO
NORTH AMERICA
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
ROCKS
SEDIMENTARY ROCKS
SOUTHWEST REGION
TABLES
TEMPERATURE DEPENDENCE
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
UNDERGROUND
USA
WATER