DOWNHOLE DEVICE OF GAMMA-GAMMA LOGGING Russian patent published in 2017 - IPC G01V5/12 

FIELD: petroleum industry.

SUBSTANCE: downhole device of gamma-gamma logging contains a cylinder guarded housing, a cylinder screen coaxial to the guarded housing and including collimating apertures located against a source of gamma-quanta and gamma-detectors; the source of gamma-quanta, gamma-detectors of a small and a large probe are located successively inside the cylinder screen along the axis of the guarded housing, moreover, the small probe includes one gamma-detector coaxial to the guarded housing and located at the distance of L₁≈20 cm from the source of gamma-quanta, and the large probe includes six gamma-detectors similar to the detectors of the small probe and located at the same side from the source of gamma-quanta as the detector of the small probe, uniformly in the transverse plane of the guarded housing at the distance of L₂=2⋅L₁ along the axis of the guarded housing from the source of gamma-quanta, whereupon, the device contains an auxiliary probe including six or more gamma-detectors similar to the detector of the small probe and located in the screen at the distance of L₃≥3⋅L₁ along the axis of the guarded housing from the source of gamma-quanta at the same side from the source of gamma-quanta as the detectors of the large probe uniformly in the transverse plane of the guarded housing.

EFFECT: increasing of measurement accuracy of the density of a cement rock in cased wells.

3 dwg