Field evaluation of active and passive direct uranium borehole logging systems
Thirty test holes were placed in a variety of geologic environments and for wide variations in ore zone grade, thickness, and uranium/radium disequilibrium condition. The ore zones of each test hole were core drilled with >90% core recovery. Core samples were analyzed for a number of trace, minor and major elemental constituents, and for several physical properties. A standard suite of geophysical logs was obtained prior to casing the test holes. Direct uranium logs were then obtained by the PGT, Sandia, IRT, and Century Geophysical sondes. All core and logging results have been written to a computerized data base. The data base was then used to produce various comparison plots and other forms of data evaluation. Calculation of the grade-thickness product for each ore zone and sonde type shows that the logging results are widely dispersed about the values obtained from the core assays. Results for the IRT sonde are systematically lower than core results, the Century sonde severely overestimates the grade-thickness product for very low grade zones, and the PGT sonde exhibits a systematic trend toward underestimating grade-thickness for higher grade (>1000 ppM) ore zones. The Sandia sonde shows no such systematic trends and agrees well with core results at the higher grades (1000 to 2500 ppM range). Neglecting the very large discrepancies observed, for example, with Century's sonde at low grade, or with IRT's sonde when malfunction was suspected, the four direct uranium logging sondes exhibited similar dispersions about the core results.Approximately 50 percent of the time the logging sondes are within +-30% of the core results while about 75% of the time they are within +-50%. A certain amount of this dispersion is due to the unfavorable borehole conditions and to the variety of geologic environments sampled.
- Research Organization:
- Bendix Field Engineering Corp., Grand Junction, CO (USA); Continental Oil Co., Falls City, TX (USA)
- DOE Contract Number:
- AC13-76GJ01664
- OSTI ID:
- 6156852
- Report Number(s):
- GJBX-11381; ON: DE81028626; TRN: 81-013683
- Country of Publication:
- United States
- Language:
- English
Similar Records
Reservoir Characterization of Bridgeport and Cypress Sandstones in Lawrence Field Illinois to Improve Petroleum Recovery by Alkaline-Surfactant-Polymer Flood
Geologic Assessment of the Damage Zone from the Second Test at Source Physics Experiment-Nevada (SPE-N)
Related Subjects
47 OTHER INSTRUMENTATION
GAMMA LOGGING
PROBES
NEUTRON LOGGING
COMPARATIVE EVALUATIONS
FIELD TESTS
BOREHOLES
URANIUM DEPOSITS
CAVITIES
GEOLOGIC DEPOSITS
MINERAL RESOURCES
RADIOACTIVITY LOGGING
RESOURCES
TESTING
WELL LOGGING
050200* - Nuclear Fuels- Exploration- (-1987)
440400 - Well Logging Instrumentation