System and method for monitoring integrity of a wellbore

An inspection tool for monitoring integrity of a wellbore, comprising:

• a radiation source;
• a detector assembly disposed proximate the radiation source, wherein the detector assembly comprises:
• a plurality of scintillators configured to generate a light signal in response to an impinging backscatter signal from a volume of interest in an object, wherein the plurality of scintillators is arranged in a first pattern, and wherein each scintillator of the plurality of scintillators has a first end and a second end;
• a plurality of first detectors, wherein each first detector of the plurality of first detectors is optically coupled to the first end of a corresponding scintillator and configured to receive a first portion of a light signal from the corresponding scintillator, and wherein the plurality of first detectors is arranged in a second pattern that is aligned with the first pattern of the plurality of scintillators;
• a plurality of second detectors, wherein each second detector of the plurality of second detectors is disposed adjacent a corresponding scintillator and optically coupled to the second end of the corresponding scintillator and configured to receive a second portion of the light signal from the corresponding scintillator, and wherein the plurality of second detectors is arranged in a third pattern;
• a scintillator collimator configured to selectively receive the backscatter signal, wherein a first portion of the scintillator collimator is opaque to the backscatter signal, and wherein a second portion of the scintillator collimator comprises a plurality of openings that is transparent to the backscatter signal;
• and
• a processing unit operatively coupled to the detector assembly, wherein the processing unit comprises at least a processor configured to process signal data from the plurality of first detectors and the plurality of second detectors to determine a condition of the wellbore.

A method for inspecting a wellbore, the method comprising:

• positioning an inspection tool in the wellbore, wherein the inspection tool comprises:
• a radiation source;
• a radiation shield disposed adjacent the radiation source;
• a detector assembly disposed proximate the radiation source, wherein the detector assembly comprises:
• a plurality of scintillators configured to generate a light signal in response to an impinging backscatter signal from a volume of interest in an object, wherein the plurality of scintillators is arranged in a first pattern;
• a plurality of first detectors configured to receive a first portion of a light signal from the corresponding scintillator, wherein the plurality of first detectors is arranged in a second pattern that is aligned with the first pattern of the plurality of scintillators;
• a plurality of second detectors, wherein each second detector of the plurality of second detectors is disposed adjacent a corresponding scintillator, and wherein the plurality of second detectors is arranged in a third pattern;
• a scintillator collimator comprising a first portion and a second portion and configured to selectively receive the backscatter signal, wherein the first portion of the scintillator collimator is opaque to the backscatter signal, and wherein the second portion of the scintillator collimator comprises a plurality of openings that is transparent to the backscatter signal;
• irradiating the volume of interest in the object with a radiation signal generated by the radiation source;
• receiving, by the plurality of scintillators via the plurality of openings in the scintillator collimator, a backscatter signal from the volume of interest;
• obtaining a first set of signal data from the plurality of first detectors;
• obtaining a second set of signal data from the plurality of second detectors;
• and
• processing, by a processing unit, the first set of signal data and the second set of signal data to provide a depth resolution and an azimuthal resolution, a defect size, a defect type, or combinations thereof corresponding to a condition of the wellbore.