Radioactivity Logging

the aggregate of geophysical borehole research methods based on the recording of radioactive—more precisely, ionizing—radiation. There are two basic groups of radioactivity logging methods: gamma-ray logging methods and neutron logging methods. Gamma-ray logging methods include measurement of the intensity and energy spectrum of gamma rays caused by the natural radioactivity of rocks (prospecting and estimation of the value of ores containing U, Th, or K) and measurement of the intensity of secondary gamma radiation originating in rock irradiated by a gamma-ray source (gamma-gamma logging) lowered into a borehole together with a device to detect secondary gamma rays. Gamma-gamma logging is used for determining the density of rocks, especially coal deposits, and testing single-component ores of heavy metals. In spectral gamma-ray logging, ore is irradiated by gamma rays, and the characteristic X-radiation spectrum of the individual elements is measured; this method is used for sampling ores of heavy metals of complex mineral composition. Neutron-gamma logging is used for determining Becontent.