SPECTRAL GAMMA LOGGING – OVERVIEW.
SPECTRAL GAMMA LOGGING APPLICATION:
Specific concentration analysis of the three main contributors to naturally occurring gamma radiation in rocks – Potassium (K40 1.46MeV), Uranium (Bi214 1.76MeV and Thorium (Th 2.61MeV).
SPECTRAL GAMMA LOGGING METHOD:
Utilises a large sodium iodide crystal, scintillation system and electronic measurement windows with temperature stability control to measure specific count rates in the various electronic windows. The electronic window ranges are set up during data acquisition. The larger crystals and slow logging speed allow maximum counting of gamma photons in an otherwise low count rates formation.
SPECTRAL GAMMA LOGGING CALIBRATION:
Running probe in a model with known concentrations of Potassium, uranium and Thorium. At Borehole Wireline, our spectral gamma probe is calibrated at the Adelaide Models, AM6.
SPECTRAL GAMMA LOGGING VERIFICATION:
Site verification borehole can be used for verification work. At Borehole Wireline, we use a small Ceasium source attached to the probe body to verify the electronic response at 0.660 KeV). Performed prior on daily basis.
SPECTRAL GAMMA LOGGING DATA PROCESSING:
Calibration and standard logging use spectral stripping techniques on the window count rates to establish the concentrations of Potassium, Uranium and Thorium.