Abstract: A method for characterizing a subsurface formation includes receiving image data of the subsurface formation obtained by a sensor tool and receiving a plurality of non-image data logs, each non-image data log being obtained by a different type of sensor tool. The method also includes performing an electrofacies analysis on the plurality of non-image data logs where the electrofacies analysis includes defining clusters wherein each cluster has a similar property to provide a plurality of electrofacies blocks with each electrofacies block representing a depth interval. The method further includes partitioning the image data into multiple high-resolution depth segments that share a similar property, feature, and/or pattern for each electrofacies block and assigning data from the plurality of non-image data logs into a corresponding high-resolution depth segment to provide a high-resolution data log that characterizes the subsurface formation.

Abstract: A system for analysis of isolated and connected porosities of a porous formation using permittivity is disclosed. An electrical subsystem can provide electrical signals for one or more of the porous formation or a representation of the porous formation; and the system can determine one or more of a rate of permittivity change (RPC) or permittivity ratio (PR) from a first estimation model that relates permittivity measurements and frequencies that are associated with the electrical signals, so that the system can generate a second estimation model using one or more of the RPC or the PR, associated with the isolated and connected porosities, where the second estimation model can be used with a total porosity of the porous formation to estimate or predict an isolated porosity and a connected porosity of a production porous formation.

Abstract: A multi-frequency tuning circuit includes a first branch including a first inductor and a first capacitor arranged in series and a second branch including a second inductor and a second capacitor arranged in series. The circuit is arranged within a circuitry module configured to be positioned between a source and a load, the first branch and the second branch both associated with loads, from the source, having low impedance frequencies. In order to improve transmitter antenna output power for downhole tools, the tuning circuit creates high impedance at operating frequencies between frequencies corresponding to low impedance.

Abstract: A method for characterizing a subsurface formation includes receiving image data of the subsurface formation obtained by a sensor tool and receiving a plurality of non-image data logs, each non-image data log being obtained by a different type of sensor tool. The method also includes performing an electrofacies analysis on the plurality of non-image data logs where the electrofacies analysis includes defining clusters wherein each cluster has a similar property to provide a plurality of electrofacies blocks with each electrofacies block representing a depth interval. The method further includes partitioning the image data into multiple high-resolution depth segments that share a similar property, feature, and/or pattern for each electrofacies block and assigning data from the plurality of non-image data logs into a corresponding high-resolution depth segment to provide a high-resolution data log that characterizes the subsurface formation.

Abstract: A multi-frequency tuning circuit includes a first branch including a first inductor and a first capacitor arranged in series and a second branch including a second inductor and a second capacitor arranged in series. The circuit is arranged within a circuitry module configured to be positioned between a source and a load, the first branch and the second branch both associated with loads, from the source, having low impedance frequencies. In order to improve transmitter antenna output power for downhole tools, the tuning circuit creates high impedance at operating frequencies between frequencies corresponding to low impedance.

Abstract: An example method includes disposing a carrier in a borehole in an earth formation. The carrier includes a logging assembly for performing a formation evaluation of the earth formation using a sensor in proximity to a borehole wall of the borehole, fluid being disposed at least partially between the sensor and the borehole wall. The method further includes estimating an apparent dielectric loss angle of the fluid to determine a stand-off effect caused by the fluid. The method further includes estimating a formation dielectric loss angle and determining a formation resistance based at least in part on the formation dielectric loss angle. The method further includes adjusting the formation evaluation based at least in part on the estimated formation resistance that accounts for the stand-off effect caused by the fluid. The method further includes performing a wellbore operation based at least in part on the adjusted formation evaluation.

Abstract: A method for performing a formation physical action includes: transmitting a first time-domain transient electromagnetic (EM) signal into a borehole and the formation using a downhole EM wave propagation tool, the first EM signal having frequency domain components in a range of at least 1 MHz to 1 GHz; receiving a second time-domain transient EM signal due to the transmitting of the first EM signal, the second EM signal having frequency domain components in the range of at least 1 MHz to 1 GHz; calculating attenuation and phase shift S-parameters as a function of frequency using the first and second EM signals; assigning to the formation at least one of a resistivity value and a permittivity value of a reference that matches or is within a selected range of the attenuation and phase shift S-parameters; and performing the physical action using the at least one of the resistivity value and the permittivity value.

Abstract: An example method includes disposing a carrier in a borehole in an earth formation. The carrier includes a logging assembly for performing a formation evaluation of the earth formation using a sensor in proximity to a borehole wall of the borehole, fluid being disposed at least partially between the sensor and the borehole wall. The method further includes estimating an apparent dielectric loss angle of the fluid to determine a stand-off effect caused by the fluid. The method further includes estimating a formation dielectric loss angle and determining a formation resistance based at least in part on the formation dielectric loss angle. The method further includes adjusting the formation evaluation based at least in part on the estimated formation resistance that accounts for the stand-off effect caused by the fluid. The method further includes performing a wellbore operation based at least in part on the adjusted formation evaluation.

Abstract: Methods, systems and devices for evaluating an earth formation, including an electromagnetic (EM) well logging apparatus for investigating a formation from a fluid-filled borehole intersecting the formation. Apparatus include a carrier body having a pocket formed in an outer surface, the pocket being defined by a plurality of walls and a bottom; a pad configured to emit EM energy, the pad having an outer face, a plurality of sides complementary to the plurality of walls, and an inner face positioned adjacent to the bottom, wherein the pad is movably disposed in the pocket such that a gap separates at least one wall of the plurality of walls and at least one side of the plurality of sides; and at least one electrically conductive member forming an electrical connection between the carrier body and the pad and covering the gap. The pad may be slideably disposed in the pocket.

Abstract: A method for performing a formation physical action includes: transmitting a first time-domain transient electromagnetic (EM) signal into a borehole and the formation using a downhole EM wave propagation tool, the first EM signal having frequency domain components in a range of at least 1 MHz to 1 GHz; receiving a second time-domain transient EM signal due to the transmitting of the first EM signal, the second EM signal having frequency domain components in the range of at least 1 MHz to 1 GHz; calculating attenuation and phase shift S-parameters as a function of frequency using the first and second EM signals; assigning to the formation at least one of a resistivity value and a permittivity value of a reference that matches or is within a selected range of the attenuation and phase shift S-parameters; and performing the physical action using the at least one of the resistivity value and the permittivity value.

Abstract: A method for imaging an earth formation includes estimating an apparent resistivity (AR) value and an apparent distance to a bedding plane (AD2B) value for each of a plurality of samples derived from measurements of a time-dependent transient electromagnetic signal, estimating an inversion-based resistivity value (IB-R) and an inversion-based distance to a bedding plane (IB-D2B) value at a first sample of each consecutive depth interval, wherein each depth interval includes a plurality of consecutive samples, and determining a difference between apparent values and the corresponding inversion-based values. The method further includes generating an image of the earth formation using the AR and AD2B values for the entire interval if the difference is less than a threshold value and generating an image of the earth formation using IB-R and IB-D2B values for the entire interval if the difference is greater than the threshold value.

Abstract: Methods, systems and devices for evaluating an earth formation, including an electromagnetic (EM) well logging apparatus for investigating a formation from a fluid-filled borehole intersecting the formation. Apparatus include a carrier body having a pocket formed in an outer surface, the pocket being defined by a plurality of walls and a bottom; a pad configured to emit EM energy, the pad having an outer face, a plurality of sides complementary to the plurality of walls, and an inner face positioned adjacent to the bottom, wherein the pad is movably disposed in the pocket such that a gap separates at least one wall of the plurality of walls and at least one side of the plurality of sides; and at least one electrically conductive member forming an electrical connection between the carrier body and the pad and covering the gap. The pad may be slideably disposed in the pocket.

Abstract: Methods and apparatus configured to evaluate a volume of interest of an earth formation intersected by a borehole. Apparatus comprise a transceiver electrode on the tool body configured to provide electrical current to the earth formation; a return electrode configured to receive the electrical current returning from the earth formation; a multi-function electrode on the resistivity imager tool; and an electrical system configured to provide current measurements at the transceiver electrode. In the first operational mode, the electrical system maintains the tool body at a first electrical potential, and maintains the multi-function electrode and the transceiver electrode at a second electrical potential; and in the second operational mode, the electrical system maintains the tool body at the first electrical potential, maintains the multi-function electrode at the first electrical potential, and maintains the transceiver electrode at the second potential.

Abstract: Methods and apparatus configured to evaluate a volume of interest of an earth formation intersected by a borehole. Apparatus comprise a transceiver electrode on the tool body configured to provide electrical current to the earth formation; a return electrode configured to receive the electrical current returning from the earth formation; a multi-function electrode on the resistivity imager tool; and an electrical system configured to provide current measurements at the transceiver electrode. In the first operational mode, the electrical system maintains the tool body at a first electrical potential, and maintains the multi-function electrode and the transceiver electrode at a second electrical potential; and in the second operational mode, the electrical system maintains the tool body at the first electrical potential, maintains the multi-function electrode at the first electrical potential, and maintains the transceiver electrode at the second potential.

Abstract: An apparatus for mitigation of torsional noise effects on borehole measurements. The apparatus may include a conveyance device; a sleeve having a sensor section, the sleeve rotatably disposed on the conveyance device; a sensor having at least one component disposed on the sensor section; and a driver coupled to the conveyance device and configured to rotate at least the sleeve sensor section. The driver may rotate the sleeve sensor section independent of the conveyance device. The driver may rotate the sleeve sensor section at a preset substantially constant rotational speed. The sleeve may include at least one arm configured to selectively lock the sleeve to a surface in the borehole. The driver may rotate the sleeve sensor section during measurement by the sensor. The driver may selectively couple the sleeve.

Abstract: Systems, devices, and methods for evaluating an earth formation. Methods may include inducing a current in the formation; measuring a time-dependent transient electromagnetic (TEM) signal induced by the formation responsive to the current; and estimating apparent resistivity values for each of a plurality of samples derived from the TEM measurement, wherein each sample corresponds to a discrete time window of the TEM measurement. Estimating the apparent resistivity values for each of the samples includes determining for each sample a simulated homogeneous formation that provides a best fit for the sample. The apparent resistivity values may be used to estimate distance to an interface. The apparent resistivity values or the estimated distance may be logged and the log displayed. The apparent resistivity values, the estimated distance, or the log may be used to conduct further operations in a borehole, including geosteering.

Abstract: A method for imaging an earth formation includes estimating an apparent resistivity (AR) value and an apparent distance to a bedding plane (AD2B) value for each of a plurality of samples derived from measurements of a time-dependent transient electromagnetic signal, estimating an inversion-based resistivity value (IB-R) and an inversion-based distance to a bedding plane (IB-D2B) value at a first sample of each consecutive depth interval, wherein each depth interval includes a plurality of consecutive samples, and determining a difference between apparent values and the corresponding inversion-based values. The method further includes generating an image of the earth formation using the AR and AD2B values for the entire interval if the difference is less than a threshold value and generating an image of the earth formation using IB-R and IB-D2B values for the entire interval if the difference is greater than the threshold value.

Abstract: An apparatus for determining a distance between a first borehole and a second borehole is provided that in one embodiment includes a rotating magnet on a tool configured for placement in the second borehole for inducing magnetization in a magnetic object in the first borehole, a first coil and a second coil placed radially symmetrically with respect to an axis of the tool, the first coil providing a first signal and second coil providing a second signal responsive to a magnetic flux resulting from the magnetization in the magnetic object in the first borehole, and a controller configured to combine the first signal and the second signal and determining distance between the first borehole and the second borehole using the combined signal.

Abstract: Systems, devices, and methods for evaluating an earth formation. Methods may include inducing a current in the formation; measuring a time-dependent transient electromagnetic (TEM) signal induced by the formation responsive to the current; and estimating apparent resistivity values for each of a plurality of samples derived from the TEM measurement, wherein each sample corresponds to a discrete time window of the TEM measurement. Estimating the apparent resistivity values for each of the samples includes determining for each sample a simulated homogeneous formation that provides a best fit for the sample. The apparent resistivity values may be used to estimate distance to an interface. The apparent resistivity values or the estimated distance may be logged and the log displayed. The apparent resistivity values, the estimated distance, or the log may be used to conduct further operations in a borehole, including geosteering.

Abstract: An apparatus and method for calibrating a multi-component induction logging tool. The method may include orienting a Z-transmitter coil to be substantially orthogonal to at least one Z-receiver coil, positioning an X-transmitter coil disposed on the logging tool so that the X-transmitter coil is substantially parallel to a conducting surface; encompassing the Z-transmitter coil, the X-transmitter coil, and at least one Z-receiver coil of the logging tool with at least one conducting loop of a calibrator; and calibrating the logging tool using the calibrator. The apparatus may include a calibrator configured to receive the logging tool. The Z-transmitter coil and the Z-receiver coil may be located on separate subs that are detachable from one another.