David C. Stromswold
Robert D. Wilson
Bendix Field Engineering Corporation
Grand Junction, Colorado
ABSTRACT
Calibration techniques are presented for spectral logging of 40K, 214Bi (a decay product of uranium), and 208Tl (a decay product of thorium) using scintillation detectors. Methods of correcting field data for steel casings and water in boreholes are described along with typical correction factors. Spatial deconvolution parameters for restoring the character of logs at zone changes are discussed both for the iterative technique of GAMLOG based on half-foot anomalies and for the inverse filter technique that uses the exponential fall-off of signals from thin zones of ore. A short description of the U.S. Department of Energy’s calibration facility at Grand Junction,
Colorado is also given as it pertains to spectral calibration and data correction activities.