Thermopile probe to measure temperature anomalies in geothermal boreholes

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:7322435

Dennis, B R; Stephani, E L; Todd, B E

The standard thermal well logging tools presently employed by oil well logging service companies use a thermistor probe as the temperature measuring device. The thermistor is normally incorporated as one arm of a Wheatstone bridge circuit. The bridge circuit must be staged for limited temperature ranges and is adequate for most well logging operations where only detection of thermal anomalies is of primary concern and the logging speed is not important. The design of a thermopile sensor using conventional thermocouples and a downhole thermally isolated reference junction has greatly improved the temperature logging capability in a deep geothermal wellbore. The much faster response of the thermopile sensor will allow a logging rate of up to 200 ft/min in contrast to the average rate of 50 ft/min using the thermistor probe. The thermopile sensor is a low impedance device whose characteristics are very well known. The development of a high pressure dewar chamber for use in high temperature downhole instrumentation sondes has provided a suitable environment to employ a downhole reference junction permitting the use of thermocouple measurements in the deep geothermal borehole.

• Research Organization: Los Alamos Scientific Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 7322435
• Report Number(s): LA-UR-77-574; CONF-770418-3
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150303* -- Geothermal Exploration & Exploration Technology-- Exploratory Drilling & Well Logging
BOREHOLES
CAVITIES
CONTAINERS
CRYOGENICS
DESIGN
DEWARS
DRILLING
ELECTRONIC CIRCUITS
GEOTHERMAL SYSTEMS
GEOTHERMAL WELLS
Geothermal Legacy
HOT-DRY-ROCK SYSTEMS
MEASURING INSTRUMENTS
PERFORMANCE TESTING
SEMICONDUCTOR DEVICES
TESTING
THERMISTORS
THERMOCOUPLES
WELL DRILLING
WELL LOGGING
WELLS