Changes in permeability during flow of water through granite subjected to a temperature gradient

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

OSTI ID:892137

Lockner, D; Bartz, D; Byerlee, J

The useful lifetime of a geothermal reservoir as an energy source can depend strongly on the technique used to extract heat. In both naturally occurring geothermal fields and artificial geothermal reservoirs, such as the Los Alamos hot dry rock experimental continuous extraction of heat requires maintenance of a channel of permeable material to and away from the heat source. Since such a system must be recharged to maintain production over a useful period of time, water must be heated and thus transported through rock in the presence of large temperature gradients. We have designed experiments to study permeability changes in rock due to fluid flow along a temperature gradient to further understanding of how heat production in geothermal reservoirs may depend on these effects. Cylindrical samples of Westerly Granite, 8.9 cm long, 7.6 cm in diameter, and containing a 0.66 cm diameter borehole, were used. A resistance heater was placed in the borehole as a heat source, giving a radially symmetric temperature gradient. Confining pressure and pore pressure were applied to the sample; a pore pressure gradient was applied to induce radial flow either toward or away from the borehole. Although permeability may not have remained homogeneous during the experiments, an apparent permeability, averaged over the whole sample, was calculated from Darcy's Law by measuring the pore fluid flow rate.

• Research Organization: US Geological Survey, Menlo Park, CA
• Sponsoring Organization: USDOE
• OSTI ID: 892137
• Report Number(s): SGP-TR-30; CONF-781222-7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
15 GEOTHERMAL ENERGY
BOREHOLES
ENERGY SOURCES
FLUID FLOW
GEOTHERMAL FIELDS
GRANITES
Geothermal Legacy
HEAT SOURCES
HEATERS
LIFETIME
MAINTENANCE
PERMEABILITY
PORE PRESSURE
PRODUCTION
RESERVOIR ENGINEERING
TEMPERATURE GRADIENTS
WATER