Quadratic corrections for the Z-effect applied to the inversion of broadband gamma ray logs from uraniferous zones
R. H. Duffin
Journal name: Geophysical Prospecting
Issue: Vol 30, No 6, December 1982 pp. 855 - 865
Info: Article, PDF ( 501.07Kb )
Nonlinear correction parameters have been determined to correct broadband gamma ray logs for the effects of photoelectric absorption in zones of high-grade uranium mineralization. These corrections have been determined empirically by logging artificial test pits. The corrections are a function of grade of mineralization, hole casing thickness, hole medium, and probe energy thresholds. Comparisons between core assays from a high-grade mineralized zone and corrected log inversions recorded with both low-threshold and high-threshold filtered probes are made. The best correlations were obtained between assays and inversion solutions for the low-threshold probe. This reflects the superior counting statistics of this type of probe. Filtered probes reduce z-effect errors but do not eliminate them, and have poorer counting statistics than unfiltered probes.