Abstract: Some aspects relate to techniques for calibrating a logging tool. In some implementations, the logging tool may estimate certain unknown properties of a signal based on distances between transmitters and receivers of the logging tool and based on frequencies used by the transmitters and receivers. The logging tool may estimate the unknown properties by interpolating values into a mathematical function related to the above-noted distances and frequencies. After estimating the unknown properties, the logging tool may be deployed into the wellbore, where it may use the estimated properties to process signals received through a subsurface formation.

Abstract: Systems and methods of the present disclosure relate to calibration of resistivity logging tool. A method to calibrate a resistivity logging tool comprises disposing the resistivity logging tool into a formation; acquiring a signal at each logging point with the resistivity logging tool; assuming a formation model for a first set of continuous logging points in the formation; inverting all of the signals for unknown model parameters of the formation model, wherein the formation model is the same for all of the continuous logging points in the first set; assigning at least one calibration coefficient to each type of signal, wherein the calibration coefficients are the same for the first set; and building an unknown vector that includes the unknown model parameters and the calibration coefficients, to calibrate the resistivity logging tool.

Abstract: Borehole images can be corrected using machine-learning models. For example, a system can train a machine-learning model based on a training dataset. The training dataset can include a first set of borehole images correlated to a second set of borehole images, where the second set of borehole images are less precise versions of the first set of borehole images. The system can then execute the trained machine-learning model in relation to an input borehole image to receive a corrected borehole image as output from the trained machine-learning model. The corrected borehole image can be a visually corrected version of the input borehole image. The system may then perform one or more operations based on the corrected borehole image, such as generating a graphical user interface that includes the corrected borehole image for display on a display device.

Abstract: A system and method for evaluating a subterranean formation includes a logging tool that includes transmitter and receiver antennae. The transmitter antenna transmits a first electromagnetic signal into the formation at a plurality of depths. The receiver antenna receives a plurality of second electromagnetic signals emitted by the formation in response to the first signal.

Abstract: A method includes detecting, via first and second receivers of a tool that are oriented at a first and a third tilt angle, respectively, a first and second measurement of a first signal transmitted by a transmitter of the tool that is oriented at a second tilt angle into a substantially non-conductive material. The method includes determining, based on the first and second measurements, a first tensor and conveying the tool into a first wellbore formed in a subsurface formation. The method includes detecting, via the first receiver and the second receiver, a third and fourth measurement, respectively, of a second signal transmitted by the transmitter and determining, based on the third and fourth measurements, a second tensor and determining a third tensor (having values independent of the first, second, and third tilt angles) based on a relationship between the first and second tensors.

Abstract: A method and system for identifying a blind spot in one or more decoupled measurements. The method may comprise disposing an electromagnetic well measurement system into a wellbore. The electromagnetic well measurement system comprise an electromagnetic transmitter and a plurality of electromagnetic receivers. The method may further comprise transmitting electromagnetic fields into a formation with the electromagnetic transmitter, measuring the electromagnetic fields with the plurality of electromagnetic receivers as one or more measurements at one or more depths in the wellbore, decoupling the one or more measurements to form decoupled measurements, identifying if a blind spot is in the decoupled measurements, and performing an inversion with the decoupled measurements.

Abstract: A system can calibrate inconsistencies in a wellbore tool. The system can receive a first set of measurements and a second set of measurements with respect to different electromagnetic antennas. The system can decouple a first multi-components tensor corresponding to the first set of measurements and a second multi-components tensor corresponding to the second set of measurements. The system can determine, using the decoupled first and second multi-components tensors, a scaling factor. The system can apply the scaling factor to a raw measurement received with respect to an electromagnetic antenna of the wellbore tool positioned in a wellbore to decouple a third multi-components tensor or to decoupled components of a fourth multi-components tensor for controlling a wellbore operation.

Abstract: Certain aspects of the present disclosure relate to calibrating a formation signal for a mixed set measurement device. A first air-hang response of a first measurement device for a tubular string associated with a drilling operation can be measured. A second air-hang response of a second measurement device for the tubular string associated with the drilling operation can be measured. The first air-hang response and the second air-hang response can be used to determine a mixed air-hang response of the mixed set measurement device. The mixed air-hang response can be used to calibrate a formation signal for the mixed set measurement device.

Abstract: System and methods for geosteering inversion are provided. Downhole tool responses are predicted for different points along a planned path of a wellbore during a downhole operation, based on each of a plurality of inversion models. Measurements of the downhole tool's actual responses are obtained as the wellbore is drilled over the different points during a current stage of the operation. The inversion models are then clustered using a weighted clustering approached in which a weighted score system is formulated to apply a standard deviation, number of models, and/or misfit of each cluster as key parameters, and used to evaluate the clusters accordingly. The corresponding scores are computed and used to select clusters. The planned wellbore path is adjusted for the subsequent stage(s) of the downhole operation.

Abstract: Some aspects relate to techniques for calibrating a logging tool. In some implementations, the logging tool may estimate certain unknown properties of a signal based on distances between transmitters and receivers of the logging tool and based on frequencies used by the transmitters and receivers. The logging tool may estimate the unknown properties by interpolating values into a mathematical function related to the above-noted distances and frequencies. After estimating the unknown properties, the logging tool may be deployed into the wellbore, where it may use the estimated properties to process signals received through a subsurface formation.

Abstract: This disclosure presents an apparatus and system for lowering the cost of implementing a downhole sensor system using attachable collars. In some aspects, the attachable collar includes a transmitter component, while supporting electronics are included with a main collar, thereby reducing the cost of the attachable collar. The supporting electronics can send a transmission signal, a control signal, a synchronization clock signal, a selected transmission frequency, a sensor orientation and selection, and other instructions to the transmitter in the attachable collar. The receiver in the main collar can receive the output, as reflected by the subterranean formation, and transform the output to subterranean formation evaluation measurements. The measurements can be communicated to other systems. In some aspects, the attachable collar can include the receiver and the main collar can include the transmitter.

Abstract: A method includes detecting, via first and second receivers of a tool that are oriented at a first and a third tilt angle, respectively, a first and second measurement of a first signal transmitted by a transmitter of the tool that is oriented at a second tilt angle into a substantially non-conductive material. The method includes determining, based on the first and second measurements, a first tensor and conveying the tool into a first wellbore formed in a subsurface formation. The method includes detecting, via the first receiver and the second receiver, a third and fourth measurement, respectively, of a second signal transmitted by the transmitter and determining, based on the third and fourth measurements, a second tensor and determining a third tensor (having values independent of the first, second, and third tilt angles) based on a relationship between the first and second tensors.

Abstract: System and methods for geosteering inversion are provided. Downhole tool responses are predicted for different points along a planned path of a wellbore during a downhole operation, based on each of a plurality of inversion models. Measurements of the downhole tool's actual responses are obtained as the wellbore is drilled over the different points during a current stage of the operation. The inversion models are clustered based on a comparison between the actual and predicted tool responses and a randomly selected centroid for each cluster. The inversion models are re-clustered using an average inversion model determined for each cluster as the centroid for that cluster. At least one of the re-m clustered inversion models is used to perform inversion for one or more subsequent stages of the downhole operation along the planned wellbore path. The planned wellbore path is adjusted for the subsequent stage(s) of the downhole operation.

Abstract: A method for formation evaluation may comprise forming one or more model parameters from one or more priori geological information and one or more downhole measurements, identifying one or more inversion controls, and performing a forward model operation using a piecewise polynomial model (PPM). The method may further comprise performing an optimization using at least the forward model operation, the one or more model parameters, and the one or more inversion controls, determining if a misfit between the one or more downhole measurements and the one or more model parameters is greater than or less than a threshold, and updating the forward model operation or the one or more priori geological information based at least in part on the misfit.

Abstract: A method and system for determining a position of a second production wellbore. The method may comprise inducing a first current into a first conductive member with a first source, emitting a first magnetic field generated by the first current from the first conductive member into a formation, inducing a second current into a second conductive member with a second source, emitting a second magnetic field generated by the second current from the second conductive member into the formation, disposing an electromagnetic sensor system into the second production wellbore, recording the first magnetic field with the at least one sensor from the formation, and recording the second magnetic field with the at least one sensor from the formation. The system may comprise a first source, an electromagnetic sensor system, at least one sensor and an information handling system configured to determine the position of the second production wellbore.

Abstract: A ranging system and method uses three-dimensional (“3D”) magnetic field measurements to correct ranging distance and direction. Ghost well interference may also be decoupled from the ranging solutions using 3D magnetic gradient field measurements.

Abstract: A method and system for identifying a blind spot in one or more decoupled measurements. The method may comprise disposing an electromagnetic well measurement system into a wellbore. The electromagnetic well measurement system comprise an electromagnetic transmitter and a plurality of electromagnetic receivers. The method may further comprise transmitting electromagnetic fields into a formation with the electromagnetic transmitter, measuring the electromagnetic fields with the plurality of electromagnetic receivers as one or more measurements at one or more depths in the wellbore, decoupling the one or more measurements to form decoupled measurements, identifying if a blind spot is in the decoupled measurements, and performing an inversion with the decoupled measurements.

Abstract: A method includes generating a ranging model of a drilling wellbore to be drilled and generating a predicted signal along measured depths of the drilling wellbore based on the ranging model. The method includes performing the following operations until the drilling wellbore has been drilled to a defined depth. The following operations include drilling, with a drill string, the drilling wellbore to an increment of the defined depth and detecting, by a sensor positioned on the drill string, an electromagnetic field emanating from a target wellbore. The following operations include determining ranging measurements to the target wellbore at the increment based on the electromagnetic field and calibrating the predicted signal based on the ranging measurements. The following operations include determining ranging accuracy for all deeper depths in the wellbore and making drilling decisions or adjusting drilling operations based on the predicted ranging accuracy for deeper depths.

Abstract: Systems and methods of the present disclosure relate to calibration of a resistivity tool. A method for in-situ calibration of a resistivity logging tool, comprises transmitting signals with transmitters of the resistivity logging tool; measuring voltages at two or more receivers located at different distances to the transmitters of the resistivity logging tool; decoupling two or more sets of multi-component tensors at two or more receivers based on the measured voltages; calculating a ratio signal from two or more sets of multi-component tensors; obtaining an apparent resistivity based on the ratio signal; simulating a dipole response tensor at the first receiver based on the apparent resistivity; comparing the first set of multi-component tensor with the dipole response tensor to acquire an in-situ calibration factor; and applying the in-situ calibration factor to multi-components for an inversion input.

Abstract: A method comprises determining a plurality of responses at a plurality of tilted angles for multiple coils of a collocated antenna assembly based on at least one coil parameter of the collocated antenna assembly, wherein the at least one coil parameter comprises at least one of a number of coil turns, a coil size, and a number of coils. The method includes determining crosstalk between the multiple coils at each of the plurality of tilted angles from the plurality of responses. The method includes determining a signal-to-noise ratio for each of the plurality of tilted angles based on the crosstalk. The method also includes selecting a tilted angle for the collocated antenna assembly corresponding to an optimal signal-to-noise ratio of the determined signal-to-noise ratios.