An example apparatus includes a drill bit body and a leg extending from the drill bit body. A journal may extend from the leg, with a gamma ray detector at least partially within the journal. In certain embodiments, the gamma ray detector may be confined within a pressure protective cavity at least partially within the arm of the journal. In certain embodiments, the gamma ray detector may be a scintillator aligned with at least one of a photomultiplier, photodiodes, or phototransistors.

Systems, methods, and devices for evaluating an earth formation intersected by a borehole. Apparatus may include at least one radiation detector configured to generate an analog electrical signal responsive to a plurality of radiation events, comprising absorption of incident ionizing radiation at a corresponding energy level, and an ionizing radiation spectrometer configured to convert each analog electrical signal from the at least one radiation detector into a plurality of digital signal pulses corresponding to the radiation events and resolve the plurality of digital signal pulses into radiation count information representative of the radiation events. Spectrometers include an input channel for each detector of the at least one radiation detector comprising an analog-to-digital converter (ADC) and configured to convert the analog electrical signal for each detector into the plurality of digital signal pulses; and at least one processor configured to generate the radiation count information.

Systems, methods, and devices for evaluating an earth formation intersected by a borehole. Apparatus may include at least one radiation detector configured to generate an analog electrical signal responsive to a plurality of radiation events, comprising absorption of incident ionizing radiation at a corresponding energy level, and an ionizing radiation spectrometer configured to convert each analog electrical signal from the at least one radiation detector into a plurality of digital signal pulses corresponding to the radiation events and resolve the plurality of digital signal pulses into radiation count information representative of the radiation events. Spectrometers include an input channel for each detector of the at least one radiation detector comprising an analog-to-digital converter (ADC) and configured to convert the analog electrical signal for each detector into the plurality of digital signal pulses; and at least one processor configured to generate the radiation count information.

A method for adjusting a gain of a gamma detector comprises detecting gamma radiation using the detector, recording the detected radiation as count rates in channels, wherein the last channel accumulates all counts above the maximum recorded energy; comparing the last channel count rate (LCCR) to a threshold X and, if LCCR>X, decreasing the gain by a preset amount Y. If LCCR≤X, establishing a first estimate of a needed voltage HV1 using tool temperature and a temperature lookup table, and establishing a second estimate of a needed voltage HV2 using a backscatter peak value and a backscatter lookup table; comparing |HV1−HV2| to a threshold Z; if |HV1−HV2|<Z, adjusting the gain of the gamma detector by HV2 or, if |HV1−HV2|≥Z, adjusting the gain of the gamma detector by HV1.

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.

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 system is disclosed for correcting Uranium-free gamma logs. The system may receive data about a subterranean formation from a gamma-ray-logging process in a wellbore. The system may apply a photoelectric-suppression estimator to the data to determine a photoelectric-suppression factor using stored mud parameters and a wellbore diameter value. The data may be corrected by the system by using the photoelectric-suppression factor to generate a Uranium-free, gamma-ray log. The system may output the Uranium-free, gamma-ray log for determining characteristics of the subterranean formation.

A method may include obtaining, by a computer processor, seismic data regarding a geological region of interest. The method may further include obtaining, by the computer processor, well log data from a wellbore within the geological region of interest. The method may further include determining, by the computer processor, a formation top depth using the seismic data, the well log data, a stratigraphic column, and a machine-learning model. The stratigraphic column may describe an order of various formations within the geological region of interest. The machine-learning model may assign a feature among the seismic data and the well log data to a formation among the formations in the stratigraphic column to determine the formation top depth.

A method may include obtaining, by a computer processor, seismic data regarding a geological region of interest. The method may further include obtaining, by the computer processor, well log data from a wellbore within the geological region of interest. The method may further include determining, by the computer processor, a formation top depth using the seismic data, the well log data, a stratigraphic column, and a machine-learning model. The stratigraphic column may describe an order of various formations within the geological region of interest. The machine-learning model may assign a feature among the seismic data and the well log data to a formation among the formations in the stratigraphic column to determine the formation top depth.

Systems and methods for determining the thermal maturity of a rock formation from isotopic values in gases are provided. Isotope values may be obtained from mud gas isotope logging, vitrinite reflectance equivalence values may be determined from core samples using known techniques. A relationship between vitrinite reflectance equivalence and isotopic values, such as carbon-13 methane values, may be determined. The vitrinite reflectance equivalence may then be determined from isotopic values to determine the thermal maturity of rock formations accessed by drilling additional exploration wells.