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Title: Method and apparatus for determining vertical heat flux of geothermal field

Abstract

A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer comprised of a length of tubing of relatively low thermal conductivity with a thermopile inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k/sub infinity/, from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k/sub infinity/, and the earth's undisturbed verticalmore » temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.« less

Inventors:
Publication Date:
OSTI Identifier:
7015526
Assignee:
Dept. of Energy
DOE Contract Number:  
E(04-3)-1318
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; GEOTHERMAL FIELDS; HEAT FLOW; MEASURING INSTRUMENTS; MEASURING METHODS; POTENTIOMETERS; DESIGN; TEMPERATURE GRADIENTS; THERMAL CONDUCTIVITY; TRANSDUCERS; ELECTRIC MEASURING INSTRUMENTS; ELECTRICAL EQUIPMENT; EQUIPMENT; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; 150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys

Citation Formats

Poppendiek, H F. Method and apparatus for determining vertical heat flux of geothermal field. United States: N. p., 1980. Web.
Poppendiek, H F. Method and apparatus for determining vertical heat flux of geothermal field. United States.
Poppendiek, H F. Tue . "Method and apparatus for determining vertical heat flux of geothermal field". United States.
@article{osti_7015526,
title = {Method and apparatus for determining vertical heat flux of geothermal field},
author = {Poppendiek, H F},
abstractNote = {A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer comprised of a length of tubing of relatively low thermal conductivity with a thermopile inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k/sub infinity/, from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k/sub infinity/, and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1980},
month = {3}
}