A system, method, and apparatus for wellbore inspection comprise an electron accelerator to generate X-rays, a rotating collimator assembly configured to produce a cone of X-rays, and at least one detector assembly configured to collect backscattered X-rays. A position assembly can be provided to move the electron accelerator, rotating collimator assembly, and detector through a wellbore. A computer system is configured to receive data from the detector and generate an image of the wellbore.

Various apparatus or methods are arranged to operate a tool downhole in a well, where the tool has a detection package operable to detect gamma rays. Deviation of energy spectra of detected gamma rays in each selected energy window of a set of selected energy windows with respect to reference energy spectra of the respective selected energy window can be detected. One or more properties of one or more regions around the tool can be determined from the deviations, the regions being between the tool and a source of the detected gamma rays in a formation around the well. Additional apparatus, systems, and methods having a gamma ray detection package can operate in a variety of applications.

A system includes a logging tool assembly having a geochemical logging tool with a neutron source and a gamma ray detector, wherein the geochemical logging tool collects formation property measurements as a function of position in a borehole. The system also includes a processor that receives the formation property measurements and that derives a geochemical photoelectric log based at least in part on the formation property measurements. The system also includes an output that displays the geochemical photoelectric log to a user.

Methods, tools, and systems for determining porosity in an earth formation are disclosed. Neutrons are emitted into the formation to induce inelastic scattering gamma rays and thermal capture gamma rays in the formation. The induced gamma rays are detected at a proximal gamma detector and a far gamma detector, which are spaced at different axial distances from the neutron source. A measured proximal-to-far inelastic ratio (a ratio of inelastic scattering gammas detected at the proximal and far detector) and a proximal-to-far thermal capture ratio (a ratio of thermal capture gammas detected at the proximal and far detector) are determined and used to calculate the formation porosity. Techniques are disclosed for removing borehole and casing configuration effects from the measured proximal-to-far thermal capture ratio, leaving only porosity dependence.

A method of creating a well image log of a cased well is provided. A passive cased well image logging tool assembly including a logging tool body, a plurality of gamma ray radiation sensors and a spatial positioning device is moved through at least a portion of the wellbore at a logging speed of no greater than 750 feet per hour. Corrected gamma ray radiation data is vertically sampled at a vertical distance sampling rate of once every vertical distance sampling interval, wherein the vertical distance sampling interval is no greater than 1.75 inches. Based on the sampled data, a well image log is prepared. A passive cased well image logging tool assembly for use in a cased well is also provided.

A method to interpret and quantify mineral compositions and concentrations, the method including: determining, with a computer, mineral composition models from a non-linear inversion of core or log elemental and mineral concentration data; and determining, with a computer, mineral concentrations for subsurface region from a linear inversion of core or geochemical log data from the subsurface region or analogous region and the mineral composition models.

The disclosure provides methods of measuring an intrinsic CO ratio in a geological formation by disposing, proximate the formation, a petrophysical tool including at least one gamma-ray detector, reading a carbon gamma-ray peak for the geological formation and an oxygen gamma-ray peak for the geological formation, determining a measured CO ratio of the geological formation from the carbon gamma-ray peak and the oxygen gamma-ray peak, and correcting the measured CO ratio by applying a corrective algorithm specific for the petrophysical tool or the type of petrophysical tool to obtain an intrinsic CO ratio of the geological formation. The corrective algorithm is derived by a mathematical analysis of measured CO ratios of a sample with a known intrinsic CO ratio using the same petrophysical tool or a petrophysical tool representative of a same type of petrophysical tool. Additional methods and systems using this method are provided.

Computing systems, computer-readable media, and methods interpreting well logs, of which the method includes receiving data that comprises one or more well logs acquired using a tool disposed at a plurality of depths 423 in a bore in a subterranean environment, partitioning the data into segments, the individual segments containing data points, representing the segments as representative points in a parameter domain, determining reachability distances for the representative points in the parameter domain, initializing a cluster based on the reachability distances, identifying one or more segments as part of the cluster, and determining a physical feature represented in the one or more well logs based on the cluster.

Computing system assessment of geological similarity of wells employing well-log data includes receiving logs with chronostratigraphic markers, and extracting signatures from the logs using the chronostratigraphic markers. A distance matrix is generated from the signatures using dynamic time warping. Using the distance matrix, a set of clusters are generated. The set of clusters are presented with an image.

A single crystal yttrium aluminum perovskite scintillator has a minimum thickness of at least 5 mm and a transmittance of at least 50% at a wavelength of 370 nm. A method for fabricating the yttrium aluminum perovskite scintillator includes acquiring a yttrium aluminum perovskite single crystal boule, annealing the yttrium aluminum perovskite single crystal boule in an oxygen containing environment to obtain a partially annealed crystal, and annealing the partially annealed crystal in an inert environment or a reducing environment to obtain the yttrium aluminum perovskite single crystal scintillator.