Abstract: A method for obtaining elemental concentration and determining the formation mineralogy uses a tool having multiple dual-function detectors that can detect both neutrons and gamma rays simultaneously. The method includes emitting neutrons into the formation, detecting neutron and gamma ray signals from the formation and discriminating the neutron signal and the gamma ray signal, obtaining the space, time and energy dependent fluence rates for fast neutrons and thermal neutrons, obtaining gamma ray energy spectra from inelastic scattering and neutron capture reactions from one or more detectors, obtaining the energy spectrum of inelastic gamma rays and/or capture gamma rays from a single element, calculating concentration of the element in the formation using its energy spectrum of inelastic gamma rays or capture gamma rays from one or more detectors and the space, time and energy dependent fluence rate of fast neutrons or thermal neutrons, and determining the formation mineralogy.

Abstract: A method for obtaining a gas saturation value of a subterrain formation involves a tool having multiple dual-function detectors that detect neutrons and gamma rays. The method includes steps of emitting neutrons into the formation, detecting neutrons and gamma ray signals form the formation using the detectors, determining formation parameters including the formation type and formation porosity, and further determining parameters such as the ratio of thermal neutron count rates from at least two of three detectors, the ratio of capture gamma count rates from at least two of three detectors, and calculating the real-time gas saturation value using the determined parameters.