Abstract: Disclosed are apparatus, systems, and methods for determining the completeness of the cement sheath or gravel-pack annulus of a borehole based on gamma counts or count rates measured with a pulsed neuron tool deployed in the borehole in conjunction with a quantitative relationship between certain gamma count (rate) ratios and a parameter of completeness. In various embodiments, the determination utilizes the ratio of the net long inelastic count (rate) and the near capture count (rate), or the ratio of the net near inelastic count (rate) and the long capture count (rate). Additional apparatus, systems, and methods are disclosed.

Abstract: Disclosed are apparatus, systems, and methods for determining the completeness of the cement sheath or gravel-pack annulus of a borehole based on gamma counts or count rates measured with a pulsed neuron tool deployed in the borehole in conjunction with a quantitative relationship between certain gamma count (rate) ratios and a parameter of completeness. In various embodiments, the determination utilizes the ratio of the net long inelastic count (rate) and the near capture count (rate), or the ratio of the net near inelastic count (rate) and the long capture count (rate). Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, apparatus and systems, as well as methods, may operate to irradiate a portion of a geological formation with neutrons in a neutron burst generated by a switchable electronic source, to measure (with one or more detectors) a flux of gamma rays to provide a measured flux, at least a portion of the gamma rays being generated by the neutrons, and to determine one or more of a neutron porosity, a density, and/or a photoelectric factor of the geological formation based on the measured flux. Other apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, apparatus and systems, as well as methods, may operate to irradiate a portion of a geological formation (94) with neutrons in a neutron burst generated by a switchable electronic source (84), to measure (with one or more detectors (86) a flux of gamma rays to provide a measured flux, at least a portion of the gamma rays being generated by the neutrons, and to determine one one or more of a neutron porosity, a density, and/or a photoelectric factor of the geological formation based on the measured flux.