A method for determining a density may comprise disposing a nuclear density tool into a wellbore. The nuclear density tool may comprise a gamma source and a first gamma detector, wherein the first gamma detector and the gamma source are disposed on a longitudinal axis of the nuclear density tool. The method may further comprise transmitting an energy from the gamma source, detecting the energy reflected with the first gamma detector, recording a count rate of the energy at the first gamma detector, and identifying a density of a first layer from the count rate, a mass attenuation coefficient, and a source-to-detector distance. A system for determining a density may comprise a nuclear density tool. The nuclear density tool may comprise a gamma source configured to transmit an energy and a first gamma detector configured to detect reflected energy. The system may further comprise an information handling system.

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.

Embodiment disclosed herein include systems and methods for azimuthally imaging a borehole, A logging tool having one or more gamma radiation sensors is disposed at a depth position within a borehole, with the one or more gamma radiation sensors positioned to measure gamma radiation within multiple azimuthally offset sectors. The gamma radiation sensors measure gamma radiation at one or more positions within each of the azimuthally offset sectors. A spectral gamma radiation profile is determined for three radioelements at the one or more positions within each of the azimuthally offset sectors based on the gamma radiation measurements. Concentrations of each of the radioelements are determined at the one or more positions based, at least in part, on the spectral gamma radiation profiles, A plurality of color coded points that each encode the combined concentrations of one or more of the radioelements are generated by mapping each of the determined concentrations to an axis point on each of three color coded axes that define a three dimensional display space. The color coded points are rendered in an azimuthal radioelement borehole image.

A method of determining a presence of stratigraphic traps includes obtaining a Gamma ray (GR) log dataset. The GR log dataset includes values for a plurality of wells in an area of interest. The method includes determining a geological time period corresponding to a depth in the GR log dataset; determining a spectrum of Earth’s orbital parameters corresponding to the geological time period; determining peak frequencies of the spectrum of Earth’s orbital parameters; and determining a quantity of orbital cycles per well in the area of interest. The spectrum of Earth’s orbital parameters includes parameters for eccentricity, obliquity, and precession. The orbital cycles may be reflected as sedimentary patterns in a geologic record. The method includes determining a presence of stratigraphic traps, based, at least in part, on differences in quantities of orbital cycles between one or more wells in the area of interest.

In some examples, a computer-readable medium stores executable code which, when executed by a processor, causes the processor to obtain a threshold pulse rate that is based on an average pulse rate of a gamma radiation detector tool and on a desired probability that the threshold pulse rate will not be exceeded by the gamma radiation detector tool. The code also causes the processor to identify instances of pulse from the gamma radiation detector tool that do not exceed the threshold pulse rate, and output an indication of the identified instances of pulses for use in a measurement-while-drilling application.

Systems and methods include a computer-implemented method for creating artificial real-time gamma ray (GR) images for well placement. Real-time azimuthal density data is determined from drilling of a well. An azimuthal density data set is generated using the real-time azimuthal density data. The azimuthal density data set is generated with a greater sampling rate than a real-time sampling rate of the real-time azimuthal density data. An azimuthal density curve depth match is performed using the azimuthal density data set. Performing the azimuthal density curve depth match includes creating a depth shift match table. A high-resolution sector near-bit gamma ray (GR) image is generated using the azimuthal density curve depth match and the depth shift match table. The high-resolution sector near-bit GR image is oriented to a top of a wellbore for the well.

The inelastic and capture ratio is optimized for porosity measurements in downhole applications. Pulsed-neutron data is acquired using a pulsed-neutron downhole tool. At each sampling point or log depth, the inelastic count rates and capture rates are computed. The inelastic count rate is corrected for the capture count background to increase porosity sensitivity. The capture count rate is computed by summing a range of time windows in the decay curve. In this process, the inelastic and capture responses are matched for borehole sensitivity. The ratio of inelastic and capture counts is computed. This ratio is the input to the characterized transform algorithm to compute measured porosity.

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 and system for identifying formation porosity and formation lithology. The method may include disposing a PNL tool into a borehole that is disposed in a formation, emitting a neutron from a neutron source on the PNL tool into the formation, and capturing one or more gammas expelled from formation in response to the neutron from the neutron source to form a plurality of pulsed neutron logging (PNL) measurements in a log. The method may further include identifying a formation porosity and a formation lithology with an artificial neural network that at least partially incorporates the PNL measurements.

In some examples, a computer-readable medium stores executable code which, when executed by a processor, causes the processor to obtain a threshold pulse rate that is based on an average pulse rate of a gamma radiation detector tool and on a desired probability that the threshold pulse rate will not be exceeded by the gamma radiation detector tool. The code also causes the processor to identify instances of pulse from the gamma radiation detector tool that do not exceed the threshold pulse rate, and output an indication of the identified instances of pulses for use in a measurement-while-drilling application.