Neutron backscatter gravel pack logging sonde with azimuthal scan capability

摘要: An apparatus (sonde) and method of measuring density, or gravel pack quality, in a cased well borehole using fast neutron source one more thermal detectors is described. In embodiment, creates flux which reacts primarily with the material within casing while collocated detector counts number backscattered neutrons. A novel means obtaining azimuthal measurement discrimination provided by rotating shield. instance shield quite substantial, creating narrow window. another instance, only marginally screens detector, large an alternative second spaced distally from first detector. This used to provide borehole's background, environmental activity, can be improve quality sonde's density measurement.