Inelastic gamma ray logging system

摘要

An illustrative embodiment of the invention includes a system for providing inelastic neutron gamma ray measurements in a well borehole. A pulsed neutron source is used to irradiate earth formations in the vicinity of the borehole with 14 MEV neutrons. Gamma rays resulting from the inelastic scattering of these fast neutrons are detected by an encapsulated liquid scintillator used in conjunction with a photomultiplier. The resulting representative voltage pulses are input to pulse height analyzing apparatus having energy windows located to embrace the Compton distributions associated with calcium, silicon, oxygen and carbon. The number of counts occurring in each of these energy regions may then be interpreted in terms of quantities of interest with respect to the formations in the borehole vicinity.