Abstract: The disclosure provides a well integrity monitoring tool for a wellbore, a method, using a nuclear tool and an EM tool, for well integrity monitoring of a wellbore having a multi-pipe configuration, and a well integrity monitoring system. In one example, the method includes: operating a nuclear tool in the wellbore to make a nuclear measurement at a depth of the wellbore, operating an EM tool in the wellbore to make an EM measurement at the depth of the wellbore, determining a plurality of piping properties of the multi-pipe configuration at the depth employing the EM measurement, determining, employing the piping properties, a processed nuclear measurement from the nuclear measurement, and employing the processed nuclear measurement to determine an integrity of a well material at the depth and within an annulus defined by the multi-pipe configuration.

Abstract: A calibrator is positioned on a logging tool at an angular orientation with respect to the logging tool. The calibrator has a radioactive source of gamma radiation distributed inside the calibrator. A first detector count rate is determined based on a detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by a first number of degrees. A second detector count rate is determined based on the detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by second number of degrees. A third detector count rate is determined based on the detector in the logging tool detecting gamma radiation. The first, second, and third detector count rates are averaged to determine a calibration gain factor based on the average detector count rate and a known indication of gamma radiation emitted by the calibrator.

Abstract: A non-rotatable, downhole imaging tool, an imaging system including the non-rotatable imaging tool and methods of determining information about a wellbore employing the non-rotatable imaging tool are provided herein. One example of a non-rotatable imaging tool is disclosed that has a central axis and horizontal planes perpendicular to the central axis, and further includes: (1) a radiation detector positioned proximate the central axis and uniquely on one of the horizontal planes, and (2) a collimator configured to limit exposure of the radiation detector to a single azimuthal area along a circumference of the downhole imaging tool on the one of the horizontal planes.

Abstract: A system and method for evaluating integrity of cement in a wellbore with multiple casing strings. The system and method may include at least one source that can emit a field of photons, and at least one photon detector spaced away from the source by a first distance that configures the tool to measure cement integrity in a first annulus, by a portion of the source photons being scattered back to the first detector which can produce photon count rates based on energy levels of received photons. Integrity of cement in the first annulus can be determined by the photon count rates. A second detector spaced a second distance from the source can be included and can measure cement integrity in a second annulus that is radially outside the first annulus by producing photon count rates for photons received from the second annulus.

Abstract: A calibrator is positioned on a logging tool at an angular orientation with respect to the logging tool. The calibrator has a radioactive source of gamma radiation distributed inside the calibrator. A first detector count rate is determined based on a detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by a first number of degrees. A second detector count rate is determined based on the detector in the logging tool detecting gamma radiation. One or more of the calibrator and logging tool is rotated by second number of degrees. A third detector count rate is determined based on the detector in the logging tool detecting gamma radiation. The first, second, and third detector count rates are averaged to determine a calibration gain factor based on the average detector count rate and a known indication of gamma radiation emitted by the calibrator.

Abstract: Methods and systems including establishing a wellbore heterogeneity profiling factor (HPF), establishing a cement quality curve representing a volumetric void space of a completion profile, and comparing the wellbore HPF and the cement quality curve, thereby determining a cement volumetric void space in a wellbore at a target depth having the completion profile.

Abstract: A system and method for evaluating integrity of cement in a wellbore with multiple casing strings. The system and method may include at least one source that can emit a field of photons, and at least one photon detector spaced away from the source by a first distance that configures the tool to measure cement integrity in a first annulus, by a portion of the source photons being scattered back to the first detector which can produce photon count rates based on energy levels of received photons. Integrity of cement in the first annulus can be determined by the photon count rates. A second detector spaced a second distance from the source can be included and can measure cement integrity in a second annulus that is radially outside the first annulus by producing photon count rates for photons received from the second annulus.

Abstract: A non-rotatable, downhole imaging tool, an imaging system including the non-rotatable imaging tool and methods of determining information about a wellbore employing the non-rotatable imaging tool are provided herein. One example of a non-rotatable imaging tool is disclosed that has a central axis and horizontal planes perpendicular to the central axis, and further includes: (1) a radiation detector positioned proximate the central axis and uniquely on one of the horizontal planes, and (2) a collimator configured to limit exposure of the radiation detector to a single azimuthal area along a circumference of the downhole imaging tool on the one of the horizontal planes.

Abstract: A method for material evaluation may include detecting photons from gamma ray interactions with material in an annular region between a geological formation and a casing. An energy spectrum is generated from the detected photons. A difference between materials may then be detected based on a comparison of the generated energy spectrum with a reference spectrum for a known material (e.g., good cement, known fluid).

Abstract: The disclosure provides a well integrity monitoring tool for a wellbore, a method, using a nuclear tool and an EM tool, for well integrity monitoring of a wellbore having a multi-pipe configuration, and a well integrity monitoring system. In one example, the method includes: operating a nuclear tool in the wellbore to make a nuclear measurement at a depth of the wellbore, operating an EM tool in the wellbore to make an EM measurement at the depth of the wellbore, determining a plurality of piping properties of the multi-pipe configuration at the depth employing the EM measurement, determining, employing the piping properties, a processed nuclear measurement from the nuclear measurement, and employing the processed nuclear measurement to determine an integrity of a well material at the depth and within an annulus defined by the multi-pipe configuration.

Abstract: A method may comprise providing a wellbore penetrating a subterranean formation, the wellbore being lined with a pipe and having a cement between the pipe and the wellbore, wherein the cement contains a defect; providing a control spectrum of gamma radiation count rates as a function of energy for a control, wherein the control comprises the cement without the defect; emitting gamma rays into the pipe and the cement having the defect from a source of a nuclear tool disposed in the wellbore; detecting count rates of gamma radiation scattered back from the pipe and the cement having the defect with a detector of the nuclear tool as a function of energy to produce a sample spectrum; and deriving one or more physical attributes related to the defect based on a comparison of the sample spectrum and the control spectrum.

Abstract: Methods including taking a gamma spectrum from a wellbore at a target depth, wherein the wellbore penetrates a subterranean formation and has a completion profile comprising a pipe and an annulus between the pipe and the subterranean formation; determining a cement volumetric void space in the wellbore at the target depth; establishing a cement-void-spatial calibration curve based on obtained gamma spectra representing cement spatial void space locations in the annulus of the completion profile, wherein each cement volumetric void space amount in the wellbore has a characteristic cement-void-spatial calibration curve; comparing the wellbore gamma spectrum and the cement-void-spatial calibration curve; and determining a location of the cement volumetric void space in the wellbore at the target depth.

Abstract: A system and method to determine a characteristic of a wellbore based on count rates of scattered photons. The system and method can include determining at least one characteristic of a material surrounding a wellbore by, emitting photons from a photon source at a location in the wellbore, detecting, via one or more detectors, photons scattered by the material, counting the scattered photons based on an energy level, producing count rates of the detected photons for various energy ranges, and calculating a value of the characteristic based on the count rates. The material can be at least one of mud, mud cake, and earth formation.

Abstract: A tool can include an X-ray tomography device to evaluate cement in a downhole environment. The X-ray tomography device includes an X-ray beam source configured to transmit an X-ray beam at a first predetermined angle. The beam angle may be set by a capillary device coupled to the X-ray beam source. An energy dispersive, multi-pixel photon detector is configured to count detected backscatter photons received at a second predetermined angle and determine an energy spectrum for the detected photons. A density map of the cement may be generated in response to the number of detected photons. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to receive photons at inner surfaces of an array of tubes forming a columnar structure, the tubes including a material with substantially high density, wherein longitudinal axes of the tubes are substantially parallel. Further activities include directing the photons within the columnar structure to a position-sensitive detector to measure the photons, wherein the position-sensitive detector is divided into an array of pixels, and wherein individual ones of the tubes in the array of tubes maintain a fixed mechanical arrangement with individual ones of the array of pixels, to provide collimation of the photons from a first end of the tubes to a second end of the tubes coupled to the position-sensitive detector. Additional apparatus, systems, and methods are described.

Abstract: In some embodiments, an apparatus and a system, as well as a method, may operate to transform photons received at a scintillator into scintillation energy at a light yield efficiency of at least 30% at temperatures above 150 C. Further activities may include converting the scintillation energy to electron-hole pairs within a pixelated array of a position-sensitive detector having a bandgap of at least 2 eV. Additional apparatus, systems, and methods are described.

Abstract: A system and method to determine a characteristic of a wellbore based on count rates of scattered photons. The system and method can include determining at least one characteristic of a material surrounding a wellbore by, emitting photons from a photon source at a location in the wellbore, detecting, via one or more detectors, photons scattered by the material, counting the scattered photons based on an energy level, producing count rates of the detected photons for various energy ranges, and calculating a value of the characteristic based on the count rates. The material can be at least one of mud, mud cake, and earth formation.

Abstract: A method for cement evaluation may include generating a gamma ray, from a radioactive source, into cement disposed between a casing and a geological formation. Photons reflected from the geological formation and the cement are detected on a gamma detector having a collimator. A detector-to-source distance, a collimator angle, and/or a collimator diameter are set to provide an energy spectra independent of the geological formation. The quality of the cement may be determined based on the energy spectra of the detected photons.

Abstract: Evaluation of borehole annulus cement quality is performed by an artificial neural network configured to estimate one or more cement attributes based on a radiation response of the annulus cement. A plurality of attributes indicative of quality of cement in the annulus can be estimated or derived based on gamma radiation response information (such as a gamma spectrum of the annulus cement). The artificial neural network is trained to perform the estimation by provision to the artificial neural network of training data from multiple example boreholes. The training data can include empirical data and/or simulation data.

Abstract: A tool can include an X-ray tomography device to evaluate cement in a downhole environment. The X-ray tomography device includes an X-ray beam source configured to transmit an X-ray beam at a first predetermined angle. The beam angle may be set by a capillary device coupled to the X-ray beam source. An energy dispersive, multi-pixel photon detector is configured to count detected backscatter photons received at a second predetermined angle and determine an energy spectrum for the detected photons. A density map of the cement may be generated in response to the number of detected photons. Additional apparatus, systems, and methods are disclosed.