Abstract: A pixelation-based approach to summarize downhole inversion results acquires inversion solutions and generates an initial model. Each layered solution is pixelated into pixels where each pixel contains the resistivity value of the initial model. A weighted function that weighs pixels according to their proximity to the logging tool may be used to generate the pixelated model to thereby improve accuracy. A statistical summary study is performed to identify the best pixelated model, which is then used to determine one or more formation characteristics.

Abstract: A system and method for evaluating a subterranean earth formation as well as a method of steering a drill bit in a subterranean earth formation. The system comprises a logging tool that is operable to measure formation data and locatable in a wellbore intersecting the subterranean earth formation. The system also comprises a processor that is in communication with the logging tool. The processor is operable to calculate multiple distance-to-bed-boundary (DTBB) solutions using the measured formation data, identify DTBB solutions that satisfy a threshold, convert the identified solutions into pixelated solutions by dividing the identified solutions into pixels, generate a formation model based on the pixelated solutions, and evaluate the formation using the generated formation model.

Abstract: The disclosed embodiments include devices and methods to perform inversion processing of well log data. In one embodiment, a method to perform inversion processing of well log data includes obtaining an initial model of an earth formation based on a plurality of modeling parameters that includes formation parameters of the earth formation and calibration factors associated with orientations of antennas of a logging tool utilized to measure raw measurements of the earth formation. The method also includes performing a forward modeling of the modeling parameters to obtain a modeling response, and performing a joint cost function of the first modeling response and raw measurements obtained by the logging tool. The method further includes readjusting the initial model if a result of the joint cost function is not below a threshold, and providing the modeling response if the result of the joint cost function is below the threshold.

Abstract: System and methods for geosteering inversion are provided. A downhole tool's response along a path of a wellbore to be drilled through a formation is predicted over different stages of a downhole operation, based on each of a plurality of initial models of the formation. Each initial model represents a different number of formation layers over a specified range. The tool's actual response with respect to one or more formation parameters is determined, based on measurements obtained during a current stage of the operation. The actual response is compared with that predicted from each of the initial models. At least one of the models is selected as an inversion model, based on the comparison and a selection criterion. Inversion is performed for subsequent stages of the operation along the wellbore path, based on the selected model. The wellbore path is adjusted for the subsequent stages, based on the inversion results.

Abstract: Systems and methods for optimized geosteering include creating a parameter matrix, which comprises a formation property for each pair of true vertical depth (TVD) coordinates from a geological model and measured depth (MD) coordinates from a predefined well trajectory; updating the parameter matrix by replacing the TVD coordinates and the MD coordinates for each parameter entry in the parameter matrix with the TVD coordinates and the MD coordinates for an actual well trajectory; and compiling a distance to bed boundary (DTBB) array and one or more other logging while drilling (LWD) arrays using corresponding measurements at the MD coordinates of the actual well trajectory; and calculating a value for each parameter entry in the updated parameter matrix, which is a sum of a geology array, the DTBB array and the one or more other LWD arrays that are each multiplied by respectively assigned or calculated weights.

Abstract: Methods, systems, and computer program products appraise the quality of resistivity LWD data inversion and related earth models. The appraisal uses several quality factors, including signal-to-noise ratio, noise-to-signal ratio, data importance, model parameter importance, and model parameter confidence interval for the resistivity LWD data inversion and related earth models. These quality factors allow a user to determine which data provides useful information, which parts of the earth model may be relied upon, and conversely which parameters in which parts of the model may need to be modified. Such an arrangement is particularly useful in distance-to-bed-boundary (DTBB) inversion for geo-steering and formation evaluation.

Abstract: A logging system includes an electromagnetic logging tool that collects measurements of a subterranean formation as the tool is conveyed along a borehole through the formation. The system further includes a processing system that: generates a first plurality of models of the formation based on at least one first measurement of the formation, the at least one first measurement collected by the tool at a first location of a plurality of locations located along a drilling axis; generates a second plurality of models of the formation based on at least one second measurement of the formation, the at least one second measurement collected by the tool at a second location of the plurality of locations, wherein the second location is adjacent the first location; and selects a model of the first plurality of models based on a spatial continuity of the model with respect to the second plurality of models.

Abstract: The disclosed embodiments include devices and methods to perform inversion processing of well log data. In one embodiment, a method to perform inversion processing of well log data includes obtaining an initial model of an earth formation based on a plurality of modeling parameters that includes formation parameters of the earth formation and calibration factors associated with orientations of antennas of a logging tool utilized to measure raw measurements of the earth formation. The method also includes performing a forward modeling of the modeling parameters to obtain a modeling response, and performing a joint cost function of the first modeling response and raw measurements obtained by the logging tool. The method further includes readjusting the initial model if a result of the joint cost function is not below a threshold, and providing the modeling response if the result of the joint cost function is below the threshold.

Abstract: A transmitter/receiver for use in a dielectric logging tool. The transmitter/receiver generally includes a housing, a septum, a first antenna, and a second antenna. When operated as a transmitter, a first and second electromagnetic signal are emitted by the first and second antenna, respectively. The housing and septum are shaped to combine the first and second electromagnetic signals into a combined signal having varying orientations depending on the phase difference between the first and second electromagnetic signals. When operated as a receiver, an incoming electromagnetic signal is divided into a first and second component signal. The first and second component signals are directed to the first and second antennas, respectively, where they are converted into first and second electrical signals.

Abstract: Methods and systems for determining conductivity of a reservoir formation based on skin effect correction and an analytical model for admittance of the reservoir formation are presented in this disclosure. At least one analytical model of admittance of the formation can be initially built as a function of conductivity of the formation. A plurality of samples for the admittance of the formation can be generated, and one or more parameters of the at least one analytical model can be determined based on the plurality of samples and the at least one model. Then, admittance of the formation can be measured, and conductivity of the formation can be calculated from the measured admittance based on the analytical model with the parameters.

Abstract: An example logging tool may include at least one transmitter antenna and at least one receiver antenna. A first high-impedance metamaterial may be disposed between the transmitter antenna and the receiver antenna. The first high-impedance metamaterial may include a periodic arrangement of patches, each of the patches being electrically coupled to a ground plane using a via.

Abstract: Methods and tools for modifying magnetic tilt angle using a magnetically anisotropic material are disclosed. An electromagnetic logging tool includes an antenna coil oriented at a physical tilt angle relative to a longitudinal axis of the tool and a magnetically anisotropic material that modifies a magnetic tilt angle of the coil relative to the physical tilt angle a coil tilted at a physical tilt angle relative to an axis of the tool.

Abstract: System and methods for geosteering inversion are provided. A downhole tool's response along a path of a wellbore to be drilled through a formation is predicted over different stages of a downhole operation, based on each of a plurality of initial models of the formation. Each initial model represents a different number of formation layers over a specified range. The tool's actual response with respect to one or more formation parameters is determined, based on measurements obtained during a current stage of the operation. The actual response is compared with that predicted from each of the initial models. At least one of the models is selected as an inversion model, based on the comparison and a selection criterion. Inversion is performed for subsequent stages of the operation along the wellbore path, based on the selected model. The wellbore path is adjusted for the subsequent stages, based on the inversion results.

Abstract: A method of real-time impedance matching includes conveying a tool through a borehole where the tool includes a transmit cavity antenna and receive cavity antenna for transmitting and receiving signals through a subsurface formation. The tool also includes a cable for routing signals within the tool and at least one variable inductor or variable capacitor in an impedance-matching circuit. The method further includes measuring a reflection of a signal transmitted through the formation and determining a target impedance based on the impedance of the cable and the reflection. The method further includes adjusting the at least one variable inductor or variable capacitor such that the impedance of the matching circuit substantially equals the target impedance and receiving a signal from the formation via the adjusted impedance of the matching circuit.

Abstract: A pixelation-based approach to summarize downhole inversion results acquires inversion solutions and generates an initial model. Each layered solution is pixelated into pixels where each pixel contains the resistivity value of the initial model. A weighted function that weighs pixels according to their proximity to the logging tool may be used to generate the pixelated model to thereby improve accuracy. A statistical summary study is performed to identify the best pixelated model, which is then used to determine one or more formation characteristics.

Abstract: Electromagnetic sensors which provide high coupling gain between the transmitter and receiver of a dielectric tool include a conductive pad having a cavity filled with dielectric filler, and an electrical conductor that provides electrical current to a conductive feeder placed inside the dielectric filler. During operation, current is fed to the conductive feeder to thereby produce an electric monopole that feeds electromagnetic power into the cavity, which then radiates out into the formation as electromagnetic signals. Because of the design of the electromagnetic sensors, the transmitter/receiver coupling gain and SNR are optimized over the entire range of the dielectric constant (i.e., 5??r?80).

Abstract: A method includes introducing a resistivity logging tool including one or more transmitter coils and one or more receiver coils into a wellbore. First and second signals are then transmitted with a first transmitter coil at first and second frequencies, respectively, and a first receiver coil receives first and second response signals based on the first and second signals. A ratio between the first and second response signals is then calculated to obtain a ratio signal, and the ratio signal is processed in an inversion algorithm. One or more formation characteristics of the subterranean formation may then be determined based on the ratio signal as processed by the inversion algorithm.

Abstract: Systems and methods for optimized geosteering using real-time geological models that are updated with LWD measurements containing data such as, for example, layer boundaries and formation properties.

Abstract: A system and method for evaluating a subterranean earth formation as well as a method of steering a drill bit in a subterranean earth formation. The system comprises a logging tool that is operable to measure formation data and locatable in a wellbore intersecting the subterranean earth formation. The system also comprises a processor that is in communication with the logging tool. The processor is operable to calculate multiple distance-to-bed-boundary (DTBB) solutions using the measured formation data, identify DTBB solutions that satisfy a threshold, convert the identified solutions into pixelated solutions by dividing the identified solutions into pixels, generate a formation model based on the pixelated solutions, and evaluate the formation using the generated formation model.

Abstract: A logging system includes an electromagnetic logging tool that collects measurements of a subterranean formation as the tool is conveyed along a borehole through the formation. The system further includes a processing system that: generates a first plurality of models of the formation based on at least one first measurement of the formation, the at least one first measurement collected by the tool at a first location of a plurality of locations located along a drilling axis; generates a second plurality of models of the formation based on at least one second measurement of the formation, the at least one second measurement collected by the tool at a second location of the plurality of locations, wherein the second location is adjacent the first location; and selects a model of the first plurality of models based on a spatial continuity of the model with respect to the second plurality of models.