Evaluation of formation composition using neutron induced gamma spectroscopy tools

A system for measuring formation properties in downhole operations, the system comprising:

• a neutron source configured to emit neutrons into a downhole formation;
• a detector configured to register photons that are generated by chemical constituents of the downhole formation;
• and
• a computing system configured to:
• measure a response of the photons detected by the detector;
• transform the measured response of the photons into thermal neutron capture probabilities;
• normalize the thermal neutron capture probabilities to unity prior to obtaining the weight concentrations;
• and
• transform the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation.

A method for measuring formation properties in downhole operations, the method comprising:

• generating, at a neutron source, neutrons that are emitted into a downhole formation;
• registering, at a detector, photons generated by chemical constituents of the downhole formation;
• measuring a response of the photons registered at the detector;
• transforming, with a computing system, the measured responses of the photons registered at the detector into thermal neutron capture probabilities, wherein the thermal neutron capture probabilities are linear functions of elemental yields;
• and
• transforming the thermal neutron capture probabilities into weight concentrations of the chemical constituents of the downhole formation.