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: One or more first formation measurements sensitive to around a sensor string of a drill string deployed in a subsurface formation is received, A 1-D inversion of the first formation measurements is performed at a first reference point. One or more second formation measurements sensitive to ahead of a drill bit of the drill string deployed in the subsurface formation is received. A 1-D inversion of the second formation measurements is performed at a second reference point ahead of the drill bit of the sensor string to determine formation properties ahead of the drill bit, wherein the 1-D inversion of the second formation measurements is based on inversion results associated with the 1-D inversion of the first formation measurements.

Abstract: Methods and systems for decoupling a component signal. A method may include disposing a logging tool in a wellbore, capturing a signal response with the logging tool from a formation, wherein the logging tool includes a first receiver, a second receiver, and a third receiver, averaging the first receiver and the third receiver to generate a first pseudo antenna, generating a second pseudo antenna which includes an azimuth offset, employing an attenuation factor and expansion factor to generate a pseudo collocated antenna. Furthermore combining responses from a transmitter, the first pseudo antenna, the second pseudo antenna, and the pseudo collocated antenna to decouple a component, which may determine the boundaries of a formation from the component. A well measurement system for decoupling a component may include a logging tool, conveyance, and information handling system. The logging tool may include a first downhole tool, a receiver, and a transmitter.

Abstract: A logging tool includes a mandrel having a tool axis, a first loop antenna including first windings wrapped about the mandrel, a second loop antenna co-located with the first loop antenna and including second windings wrapped about the mandrel, and a shield secured to the mandrel. The first loop antenna is in a first orientation and the first windings are wrapped at a first angle. The second loop antenna is in a second orientation opposite the first orientation and the second windings are wrapped at a second angle. The shield includes first slots overlapping and along the first loop antenna and second slots overlapping and along the second loop antenna. The first slots define a first trace angle with respect to the tool axis and different from the first angle. The second slots defines a second trace angle with respect to the tool axis and different from the first angle.

Abstract: Systems, methods, and computer-readable media for in-situ calibration of magnetic field measurements. In some examples, a method can involve generating a magnetic field via a magnetic field source that is coupled to a downhole tool. The magnetic field source can be located within a fixed distance from one or more sensors coupled to the downhole tool. The method can also involve obtaining respective field measurements of the known magnetic field from the one or more sensors, and comparing the respective field measurements from the one or more sensors with respective reference measurements previously obtained from the one or more sensors to yield respective comparisons. The method can then involve determining, based on the respective comparisons, a respective sensitivity drift for each of the one or more sensors.

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 system and method of evaluating a subterranean earth formation using a statistical distribution of formation data. The system comprises a logging tool and a processor in communication with the logging tool. The logging tool comprises a sensor operable to measure formation data and is locatable in a wellbore intersecting the subterranean earth formation. The processor is operable to calculate inversion solutions to the formation data, wherein each inversion solution comprises values for a parameter of the formation, and generate a statistical distribution of the parameter along one or more depths in the subterranean earth formation using the inversion solutions. The processor is also operable to identify peaks within the statistical distribution and select the inversion solutions corresponding to the identified peaks, generate a formation model using the selected inversion solutions; and evaluate the formation using the formation model to identify formation layers for producing a formation fluid.

Abstract: A logging tool and a method for in-situ, independent calibration of receiver amplifier electronics separately from transmitter electronics. A logging tool can perform in-situ gain and phase calibration on one or more receiver assemblies, each consisting of at least a receiver amplifier electronics and a receiver antenna, and based on a calculated gain and phase of the receiver assembly, determine the true antenna amplitude and phase associated with a measurement made by the receiver assembly. The logging tool can perform in-situ crosstalk measurement and calibration, by determining a crosstalk matrix for all of the receiver assemblies and for each receiver assembly, removing the crosstalk interference from the measurement made by the receiver assembly.

Abstract: An antenna assembly includes a tool mandrel having a tool axis and a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis. An antenna shield is secured to the tool mandrel and positioned radially outward from the coil. The antenna shield defines a plurality of slots extending perpendicular to the coil at any angular location about a circumference of the tool mandrel and the plurality of slots is provided in two or more dissimilar lengths.

Abstract: A system and method for determining an uncertainty of a distance to bed boundary (DTBB) inversion of a geologic formation. The system or method includes receiving logging data from a borehole tool, performing a first DTBB inversion using the logging data to calculate first DTBB solutions, adding quantified noise to the logging data to produce an adjusted signal, performing a second DTBB inversion using the adjusted signal to calculate second DTBB solutions, comparing the first DTBB solutions to the second DTBB solutions to determine an uncertainty of the first DTBB solutions based on a relationship of the quantified noise and the difference between the first DTBB solutions and the second DTBB solutions.

Abstract: A method for calibrating a resistivity-logging tool using air-hang calibration is provided. The method may include performing an air-hang measurement using the resistivity-logging tool and performing a first measurement decoupling operation on the air-hang measurement. The first measurement decoupling operation may include generating correcting factors based on a physical model and calculating an air-hang calibration matrix based on the correcting factors. Additionally, the method may include performing a formation measurement using the resistivity-logging tool and performing a second measurement decoupling operation on the formation measurement to generate a decoupled formation measurement matrix. Further, the method may include calibrating the resistivity-logging tool to generate a calibrated formation measurement matrix by subtracting the air-hang calibration matrix from the decoupled formation measurement matrix.

Abstract: An electromagnetic induction tool and method. The electromagnetic induction tool may comprise a tool body, a gap sub may separate different sections of the tool body and may be positioned to at least partially hinder the flow of an axial current and an azimuthal current on the tool body. A coil antenna may be disposed over the gap sub. A method of increasing an electromagnetic field may comprise providing an electromagnetic induction tool. The electromagnetic induction tool may comprise a tool body, a gap sub may separate different sections of the tool body and may be positioned to at least partially hinder flow of an axial current and an azimuthal current on the tool body. A coil antenna may be disposed over the gap sub. The method may further comprise placing the electromagnetic induction tool into a wellbore and operating the coil antenna.

Abstract: A ranging system using spatially continuous filtering techniques to constrain ranging measurements, thereby improving ranging calculations between a bottom-hole-assembly and at least one target well. By taking advantage of the spatial continuity of the wellbore geometry, a quality check of a ranging measurement is performed using ranging measurements acquired at prior depths. Thus, the methods described herein provide improved ranging and direction estimates, as well as prediction of ranging and direction of the target well ahead of the bottom-hole-as sembly.

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.

Abstract: A modular downhole logging system includes a transmitter module having a local frequency, wherein the transmitter module transmits interrogation signals into a formation based on the local frequency. The downhole system also includes a receiver module axially-spaced from the transmitter module and that receives response signals corresponding to the interrogation signals, wherein the receiver module includes sampling logic and sync estimation logic. The sync estimation logic is configured to perform sync estimation operations including estimating the local frequency of the transmitter module based on analysis of response signal Fourier transform results corresponding to different frequencies. The sampling logic/clock is configured to sample the response signals based on the estimated local frequency of the transmitter module, wherein a processor derives formation property values using the sampled response signals.

Abstract: Methods to configure a downhole electromagnetic tool and downhole electromagnetic tool calibration systems are disclosed. A method to configure a downhole electromagnetic tool includes obtaining a first calibration measurement of a first tool configuration and a second calibration measurement of a second tool configuration of a downhole electromagnetic tool, and determining a first ratio of the first calibration to the second calibration. The method further includes obtaining a first synthetic response of the first tool configuration from a first model of the downhole electromagnetic tool, and obtaining a second synthetic response of the second tool configuration from a second model of the downhole electromagnetic tool, and determining a second ratio of the first synthetic response to the second synthetic response.

Abstract: A method may comprise: inserting into a wellbore penetrating a subterranean formation a tool comprising: a transmitter sub assembly comprising a transmitter; and a receiver sub assembly comprising a receiver; generating an electromagnetic wave at the transmitter; propagating the electromagnetic wave through the subterranean formation; receiving the electromagnetic wave in the receiver; generating a response signal in the receiver; calculating a distance to a bed boundary position in a TVDp direction, wherein the TVDp direction is a direction where an angle between the TVDp direction and a tool axis is equal to a tool inclination from a true vertical direction (TVD), wherein TVD is a direction with respect to gravity; calculating a distance to bed boundary in a TST direction, wherein the TST direction is a true stratigraphic thickness direction in a direction towards a bed boundary; calculating a distance to bed boundary in a TVD direction; generating a formation characterization comprising a visual representa

Abstract: Methods to accurately plan and optimize clamped source excitation in ranging or telemetry operations approximate a well having a complex pipe structure as a simple solid pipe (“effective model”) with an effective pipe cross-section and resistance. The simple solid pipe is then treated as a thin wire and analyzed using a FAST Code.

Abstract: A method for selecting initial models or inversion solutions during an inversion process from electromagnetic measurements may comprise disposing an electromagnetic well measurement system into a wellbore, transmitting electromagnetic fields into a formation with the electromagnetic transmitter, measuring the electromagnetic fields with the electromagnetic receiver as measurements at a depth in the wellbore, forming initial models for the inversion process based on the measurements and performing an inversion, filtering an inversion solution, forming a solution database from the filtered inversion solutions, building a reference model, calculating a similarity between the reference model and one or more models in the solution database, selecting one or more results from the solution database with the similarity larger than a threshold, and generating a final inversion model image from the one or more results.

Abstract: A system and method for electromagnetic measurements. The system may comprise an electromagnetic transmitter, wherein the electromagnetic transmitter is an antenna and is operable to transmit a low frequency electromagnetic field into a formation or a high frequency electromagnetic field into the formation. The system may further comprise an electromagnetic receiver, wherein the electromagnetic receiver is an antenna and is operable to record the high frequency electromagnetic field or the low frequency electromagnetic field. The method may comprise transmitting a high frequency electromagnetic field, recording a high frequency electromagnetic field, transmitting a low frequency electromagnetic field, recording a low frequency electromagnetic field, performing a shallow inversion on the low frequency electromagnetic field and the high frequency electromagnetic field to form a formation resistivity model, and running the deep inversion with the random initial guesses that have the misfit.