Quantitative nuclear borehole logging based on neutron excited gamma-reactions

The application of the spectrometric neutron-γ method for coal ash and soil salinity quantitative determinations has been described. The results of field tests for ash-in-coal determinations carried out in dry and water-filled boreholes of eight Australian black coal deposits are discussed. The borehole logging system SIROLOG, now commercially available is described. The latest version of SIROLOG neutron-γ probe achieved values of r.m.s. deviation better than 2% ash in most tests, both in water-filled and dry boreholes and for coals of ash content in the range 3-50%. The laboratory measurements and the preliminary field tests for quantitative logging of salinity in soils are described. A spectrometric neutron-γ method using a 252Cf source and a BGO detector was applied. Major constraints affecting salinity logging were identified. The most important of these were simulated in laboratory tests and evaluated. (author)