DOE/Simplec magnetic susceptibility logging system
A magnetic susceptibility logging system has been developed which is relatively stable under normal field logging conditions and which produces logs that accurately represent in situ variations in magnetic susceptibility. However, both field and laboratory tests indicate the need for further improvement of temperature stabilization and bridge compensation; a new generation system designed by Simplec may fill that need. A cubic granite block with a magnetic susceptibility of 385 ..mu..CGS is designated as the primary calibration standard and is available for public use at the DOE facility in Grand Junction, Colorado. Models are also available for characterization of magnetic susceptibility systems. These include models to provide borehole size correction factors, thin layer interpretation parameters, reproducibility limits, longitudinal resolution, and radius of investigation. The DOE/Simplec system has a 99-percent radius of investigation, approximately equal to the coil length (15 inches), and a 99-percent thickness of investigation, approximately equal to two coil lengths. The true magnetic susceptibility and thickness of isolated layers less than two coil lengths in thickness can be obtained through use of parameters measured from their log responses. Field tests show that the system has a reproducibility of at least 5 ..mu..CGS and that logging at 25 ft/min is a good compromise between speed of operation and keeping the probe on the sidewall. Comparison of log and core magnetic susceptibility measurements confirms the fact that the logging system samples a rather large volume and that interpretive aids are necessary to unfold the true variation of magnetic susceptibility with depth. Finally, logs from known uranium-favorable environments show that magnetic susceptibility measurements can give an indication of the degree of geochemical alteration, which is one of the uranium-favorable haloes sought by exploration geologists.
- Research Organization:
- Bendix Field Engineering Corp., Grand Junction, CO (United States); Simplec Manufacturing Co., Inc., Dallas, TX (USA)
- DOE Contract Number:
- AC13-76GJ01664
- OSTI ID:
- 6466035
- Report Number(s):
- GJBX-75(81); TRN: 81-008697
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
URANIUM DEPOSITS
EXPLORATION
WELL LOGGING EQUIPMENT
DESIGN
PERFORMANCE TESTING
BOREHOLES
CALIBRATION
GRANITES
MAGNETIC SUSCEPTIBILITY
MINERALS
CAVITIES
EQUIPMENT
GEOLOGIC DEPOSITS
IGNEOUS ROCKS
MAGNETIC PROPERTIES
MINERAL RESOURCES
PHYSICAL PROPERTIES
PLUTONIC ROCKS
RESOURCES
ROCKS
TESTING
440400* - Well Logging Instrumentation
050200 - Nuclear Fuels- Exploration- (-1987)