Antenna concept for increasing measurement accuracy of resistivity tools

Abstract

An apparatus includes a carrier, a first antenna coupled to the carrier, a second antenna coupled to the carrier, and at least one processor configured to generate, based on processing a first signal received at the first antenna and a second signal received at the second antenna, a third signal. A third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal. The at least one processor is configured to calculate a value of at least one target parameter measured by the carrier based on the third signal.

Description

65REL-510596-WO-2 (INT1034PCT)ANTENNA CONCEPT FOR INCREASING MEASUREMENT ACCURACY OF RESISTIVITY TOOLSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of an earlier filing date from U.S. Provisional Application Serial No. 63 / 711,486, filed October 24, 2024, the entire disclosure of which is incorporated herein by referenceBACKGROUND

[0002] Logging while drilling (LWD) is a technique of conveying well logging tools into a well borehole as part of a bottom hole assembly (BHA). Some applications may include using antennas on measurement tools (e.g., resistivity tools). Techniques for achieving effective measurement accuracy by the measurement tools are desired.SUMMARY

[0003] Embodiments of the present disclosure are directed to an apparatus including: a carrier; a first antenna coupled to the carrier; a second antenna coupled to the carrier; and at least one processor configured to: generate, based on processing a first signal received at the first antenna and a second signal received at the second antenna, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and calculate a value of at least one target parameter measured by the carrier based on the third signal.

[0004] Embodiments of the present disclosure are also directed to a method including: generating, based on processing a first signal received at a first antenna coupled to a carrier and a second signal received at a second antenna coupled to the carrier, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy-associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and calculating a value of at least one target parameter measured by the carrier based on the third signal.65REL-510596-WO-2 (INT1034PCT)

[0005] Embodiments of the present disclosure are also directed to a non-transitory computer-readable medium product having stored thereon instructions that, when executed by at least one processor, cause the at least one processor to perform a method including: generating, based on processing a first signal received at a first antenna coupled to a carrier and a second signal received at a second antenna coupled to the carrier, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and calculating a value of at least one target parameter measured by the carrier based on the third signal,

[0006] Further aspects supported by the present disclosure and features of example embodiments are illustrated in the accompanying drawings and / or described in the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0008] FIG. 1 is a diagram illustrating an example embodiment of a system for performing energy industry operations in accordance with aspects of the present disclosure.

[0009] FIG. 2 illustrates an example diagram of a resistivity tool configured for deployment in a borehole in accordance with one or more embodiments of the present disclosure.

[0010] FIG. 3 illustrates example diagrams described with reference to processing signals received at a first antenna and a second antenna of a resistivity tool in accordance with one or more embodiments of the present disclosure.

[0011] FIG. 4 illustrates example diagrams described with reference to processing the signals received at the first antenna and the second antenna of the tool in accordance with one or more embodiments of the present disclosure.

[0012] FIG. 5 illustrates an example flowchart of a method in accordance with one or more embodiments of the present disclosure.

[0013] FIG. 6 illustrates an example diagram illustrative of the relationship between μr and μeff for some antennas in accordance with one or more embodiments of the present disclosure.65REL-510596-WO-2 (INT1034PCT)

[0014] FIG. 7 illustrates an example flowchart of a method in accordance with one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0015] Logging while drilling (LWD) is a technique of conveying well logging tools into a well borehole as part of a bottom hole assembly (BHA). Some applications may include using antennas on measurement tools (e.g., resistivity tools), in which the antennas are optimized or tuned to provide a maximum of magnetic dipole moment, which may increase signal levels of electromagnetic measurements downhole. In some cases, materials having high magnetic permeability may be used as a core in the design of the coils for the antennas. In some cases, however, the materials may have relative high sensitivity to temperature, pressure, and vibration due to the high magnetic permeability. Accordingly, for example, electrical properties of the antennas may change when the antenna is subjected to some downhole conditions, which may directly impact the measurement accuracy of the tools.

[0016] Some approaches have invested in maximizing antenna moments in association with maintaining stability simultaneous with changes in antenna / dipole moment, for example, in the range of up to a few percent over temperature and pressure. Such approaches may support effective measurement accuracy for cases of low resistivity formations but may be ineffective (e.g., due to limited accuracy) for cases of high resistivity formations. Some other antenna approaches may incorporate ferrite or nanocrystalline materials in the antennas for increasing effective measurement accuracy, which may increase design complexity, overhead costs, and maintenance efforts significantly. Antenna approaches which improve the resistivity measurement accuracy of extra-deep reading tools in high resistive formations are desired.

[0017] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

[0018] According to one or more embodiments of the present disclosure, the systems and techniques described herein support measurement tools having increased resistivity measurement accuracy in high resistive formations. Example aspects of a resistivity tool and an antenna assembly in accordance with one or more embodiments of the present disclosure are described herein.

[0019] FIG. 1 is a diagram illustrating an example embodiment of a system 100 in accordance with aspects of the present disclosure.65REL-510596-WO-2 (INT1034PCT)

[0020] The system 100 is configured to perform any suitable energy industry operation, such as, for example, a drilling operation, a stimulation operation, a measurement operation and / or a production operation. However, example aspects of techniques supported by the system 100 as described herein are not limited to energy industry operations and an associated downhole environment.

[0021] The system 100 includes a borehole 135 in a subsurface formation 130. A borehole string 140 (also referred to herein as a drill string) is disposed in the borehole 135 that penetrates the formation 130. The borehole 135 may be an open hole, a cased hole or a partially cased hole. In one embodiment, the borehole string 140 is a stimulation or injection string that includes a tubular, such as a coiled tubing, pipe (e.g., multiple pipe segments) or wired pipe, that extends from a wellhead at a surface location (e.g., at a drill site or offshore stimulation vessel).

[0022] As described herein, a “string” refers to any structure or carrier suitable for lowering a tool or other component through a borehole or connecting a drill bit to the surface, and is not limited to the structure and configuration described herein.

[0023] In one embodiment, the system 100 is configured as a hydraulic stimulation system. As described herein, “hydraulic stimulation” includes any injection of a fluid into a formation. A fluid may be any flowable substance such as a liquid or a gas, and / or a flowable solid such as sand. In this embodiment, the borehole string 140 includes a stimulation assembly that includes one or more tools 150 or components to facilitate stimulation of the formation 130. Non-limiting examples of the tools 150 included in the borehole string 140 include a fracturing assembly (e.g., a fracture or “frac” sleeve device), a perforation assembly (e.g., shaped charges, torches, projectiles and other devices for perforating the borehole wall and / or casing), and isolation or packer subs.

[0024] The tools 150 may support various processes including formation drilling, geosteering, and formation evaluation (FE) for measuring versus depth and / or time one or more physical quantities in or around a borehole 135. The tools 150 may be included in or embodied as a BHA, drillstring component, or other suitable carrier. A “carrier” as described herein means any device, device component, combination of devices, media and / or member that may be used to convey, house, support or otherwise facilitate the use of another device, device component, combination of devices, media and / or member. Example non-limiting carriers include drill strings of the coiled tubing type, of the jointed pipe type and any combination or portion thereof. Other carriers include, but are not limited to, casing pipes, wirelines, wireline sondes, slickline sondes, drop shots, downhole subs, bottom-hole assemblies, and drill strings.65REL-510596-WO-2 (INT1034PCT)

[0025] One or more of the tools 150 may include suitable electronics (e.g., electronics 175) or processors configured to communicate with a surface processing unit (e.g., a computing device 105), control the respective tool 150 or assembly, and / or process data acquired by the respective tool 150 or assembly. Additionally, or alternatively, the electronics (e.g., electronics 175) may be included in the BHA 145 and electronically coupled to the tool 150.

[0026] BHA 145, which may include a drill bit, is coupled to the tubular of the borehole string 140. The BHA 145 includes a resistivity tool 150 configured to sense resistivity of the formation 130 surrounding the borehole 135. The term “resistivity tool” can encompass one or more different types of resistivity tools as known in the art. In one or more embodiments, the resistivity tool 150 is an induction tool that senses resistivity deeper into the formation 130 than other types of resistivity tools.

[0027] The system 100 may include other types of shallow-reading or deep-reading resistivity tools, used individually or in combination. It is well understood that, for resistivity or conductivity measurement tools, a distinction may be made between apparent resistivity and true resistivity, and the system 100 may support performing processing or a transformation operations which convert tool readings from apparent resistivities into true formation resistivities.

[0028] In an embodiment, the resistivity tool 150 includes upper and lower longspaced and short-spaced transmitters (not illustrated) surrounding a central pair of receivers (not illustrated). Antenna spacings in one or more embodiments can range from 23 to 35 inches but are not limited thereto. Aspects of the present disclosure support smaller or larger antenna spacings. In an example, two receivers of the central pair may measure the phase shift and attenuation of signals (e.g., 2 MHz and 400 kHz signals) broadcast by each transmitter to yield a total of eight logs.

[0029] Aspects of the present disclosure support varying the processing schemes of raw data received at the receivers, and the amount of delivered logs may be based on the processing schemes of the raw data. For example, different processing algorithms may yield different amounts of logs. Aspects of the present disclosure support other frequencies of broadcast signals different from the examples described herein.

[0030] In another embodiment, the resistivity tool 150 may include a first module (a first transceiver device) including a transmitter and, in some cases, a receiver. The resistivity tool 150 may further include a second module (a second transceiver device) including a transmitter and two receivers, in which the two receivers operate at different respective frequencies (e.g., 20 kHz and 50 kHz, but not limited thereto). For example, each of the two65REL-510596-WO-2 (INT1034PCT)receivers included in the second module may operate at both a first frequency (e.g., 20 kHz, but not limited thereto) and a second frequency (e.g., 50 kHz, but not limited thereto). In an example, the modules are spaced apart on the borehole string 140 according to a distance that supports achieving an increased depth of detection. Aspects of the present disclosure support any suitable number of modules and any suitable transmission frequencies supportive of the techniques described herein.

[0031] In another embodiment, the resistivity tool 150 may include a first module (a first transceiver device) including a tri-axial transmitter and receiver and a second module (a second transceiver device) including a tri-axial transmitter and receiver, in which each of the two receivers operate at several different frequencies between 100 Hz and 100 kHz. In an example, the first module and the second module are spaced apart on the borehole string 140 according to a distance that supports achieving an increased depth of detection. Aspects of the present disclosure support any suitable number of modules and any suitable transmission frequencies supportive of the techniques described herein.

[0032] In another embodiment, the BHA 145 may include the resistivity tool 150 (e.g., operating at 2 MHz and 400 kHz) and a modular resistivity tool 150 (not illustrated) (e.g., operating at 20 kHz and 50 kHz), in which the resistivity tool 150 and the modular resistivity tool 150 are both in operation.

[0033] The resistivity tool 150 is sensitive to contrasts in the electrical resistivity of formations around and away from the wellbore and is capable of providing a distribution of resistivity values (e.g., resistivity values and corresponding locations) within the formation around a borehole 135. Accordingly, the depth of detection depends on the resistivity contrast between the penetrated and the remote layer to be evaluated. In an example, deep-reading herein may refer to measurements reading in a radius larger than 0.5 meters. In some examples, the tool 150 may support deep readings of up to 30 meters, but is not limited thereto. The depth of detection and / or depth of investigation may be based on the wavelength and / or frequency of the resistivity tool 150 and the formation properties of the formation 130. Accordingly, for example, the depth of detection and / or depth of investigation can be different for different tool configurations and / or BHA configurations.

[0034] Referring to FIG. 1, the BHA 145 may include an acoustic tool 165 that is configured to obtain information about subsurface structures and / or acoustic wave propagation velocities using acoustic waves. For clarity purposes, acoustic wave frequencies used by an acoustic tool may also include seismic wave frequencies so that an acoustic tool may also be referred to as a seismic tool. Acoustic waves transmitted by the acoustic tool 16565REL-510596-WO-2 (INT1034PCT)are transmitted into the formation 130 and then are reflected at boundaries with high acoustic impedance contrast close enough to be reachable by the acoustic waves and finally are recorded by acoustic receivers which are also positioned in the BHA 145. This method may be referred to as deep shear wave imaging or deep compressional wave imaging. The acoustic tool 165 provides an image clearly illustrating geological structures in the formation or reservoir if impedance contrasts exist. In addition, acoustic waves traveling along the borehole wall (refracted waves) and / or acoustic waves guided by the borehole (guided waves) may be used to determine the acoustic wave propagation velocity at the vicinity of the borehole. Borehole guided waves (e.g., Stoneley waves) might also be used for imaging of structures crossing the wellbore. Converted waves (e.g., PS waves) may also be considered of imaging.

[0035] The BHA 145 may also include one or more other sensing tools 167 that are configured to sense other parameters. Non-limiting embodiments of the other sensing tools 167 include a neutron tool (which can have a neutron emitter and a gamma-ray detector and / or a neutron detector for detecting radiation due to formation interaction with the emitted neutrons), a natural gamma-ray detector, a dielectric tool, and a gravity tool, a magnetic resonance tool, a seismic-while-drilling tool.

[0036] Electronics 175 (also referred to herein as downhole electronics) are configured to operate tools in the BHA 145 and / or act as an interface with telemetry to communicate sensed data to surface equipment 110 such as, for example, to a computing device 105 or to receive commands from the surface equipment 110. Non-limiting embodiments of telemetry include mud-pulse telemetry and wired drill pipe. Data processing functions and / or control functions may be accomplished downhole by the electronics 175, at the surface by the computing device 105, or by a combination thereof.

[0037] The embodiment of FIG. 1 may be referred to as logging-while-drilling (LWD). In other embodiments, the downhole tools or sensors in the BHA 145 may be carried or conveyed by an armored wireline in an embodiment referred to as wireline logging. The tools sense formation properties as a function of distance into the borehole and the output of a tool, sensed property value versus depth or drilled distance, may be referred to a log. A log may be a one-dimensional property sensed versus depth or time or a multi-dimensional property sensed versus depth or time.

[0038] The system 100 includes surface equipment 110 for performing various energy industry operations. For example, the surface equipment 110 is configured for injection of fluids into the borehole 135 in order to, e.g., fracture the formation 130. In one or more65REL-510596-WO-2 (INT1034PCT)embodiments, the surface equipment 110 includes an injection device such as a high pressure pump 115 in fluid communication with a fluid tank 120, mixing unit or other fluid source or combination of fluid sources. The pump 115 injects fluid into the borehole string 140 or the borehole 135 to introduce fluid into the formation 130, for example, to stimulate and / or fracture the formation 130. The pump 115 may be located downhole or at a surface location.

[0039] One or more flow rate and / or pressure sensors 125 may be disposed in fluid communication with the pump 115 and the borehole string 140 for measurement of fluid characteristics. The sensors 125 may be positioned at any suitable location, such as proximate to (e.g., at the discharge output) or within the pump 115, at or near the wellhead, or at any other location along the borehole string 140 or the borehole 135. The sensors described herein are exemplary, as various types of sensors may be used to measure various parameters.

[0040] A computing device 105 (e.g., computing device 105-a) may be disposed in operable communication with components such as sensors 125 located above the surface, the pump 115, and / or downhole components. For example, the computing device 105 may be in operable communication with sensors (e.g., pressure sensors, temperature sensors, vibration sensors, gas sensors, and the like) located below the surface and / or in the borehole string 140. In some examples, the computing device 105-a may be in operable communication with a tool 150 (or multiple tools).

[0041] The system 100 supports communication between the computing device 105 and other devices of the system 100 via wired communication protocols, wireless communication protocols (e.g., electromagnetic (EM) signals, WiFi, Bluetooth™, ZigBee™, Ubiquiti™, 3G, 4G, LTE, and the like), and / or combinations including one or more of the foregoing.

[0042] The system 100 supports telemetry techniques capable of transmitting data from components located downhole to the surface and / or surface equipment 110. Non-limiting examples of the telemetry techniques include acoustic telemetry or mud pulse (MP) telemetry-supportive of transmitting information by generating vibrations in fluid in the borehole 135, electromagnetic (EM) telemetry supportive of transmitting information by way of signals that propagate at least in part through the earth (e.g., through formations 130). Other non-limiting examples of telemetry techniques supported by aspects of the present disclosure include the use of hardwired drill pipe, fibre optic cable, or drill collar acoustic telemetry to carry data to the surface and / or surface equipment 110.

[0043] The system 100 may include one or more access nodes 170 supportive of communicating data along the borehole string 140 (e.g., up or down the borehole string 140).65REL-510596-WO-2 (INT1034PCT)In one or more embodiments, the access nodes 170 may be implemented in the borehole 135 or a communication borehole (not illustrated) separate from the borehole 135. In some examples, the one or more access nodes 170 may provide functionality as wireless access nodes for relaying data from a tool 150 to the surface (e.g., to a computing device 105).

[0044] In one or more embodiments, the system 100 may include a chain of access nodes 170 spaced apart along the borehole string 140, and the chain of access nodes 170 may support repeating of data in a unidirectional (e.g. downhole to surface or surface to downhole) or bidirectional manner. For example, an access node 170 (or chain of access nodes 170) may support the communication of data between a computing device 105, a tool 150, and the like.

[0045] Accordingly, for example, the communication protocols and telemetry techniques supported by the system 100 enable communication between computing devices 105 (e.g., computing device 105-a, computing device 105-b. and the like) and downhole components.

[0046] The computing device 105 is configured to receive, store and / or transmit data generated from components (e.g., pump 115, fluid tank 120, sensors 125, and the like) included in the surface equipment 110 and / or downhole components (e.g., a tool 150, downhole sensors, and the like). The computing device 105 includes processing components configured to analyze received data (e.g., data received from the pump 115, fluid tank 120, sensors 125, a tool 150, and the like). The computing device 105 includes processing components configured to provide data (and / or control signals to other components of the system 100. The computing device 105 includes any number of suitable components, such as processors, memory, communication devices and power sources.

[0047] The computing device 105 may include processing circuitry capable of executing instructions stored on a memory of the computing device 105 in association with performing one or more functions described herein.

[0048] FIG. 2 illustrates an example diagram 200 of a resistivity tool 150 configured for deployment in a borehole 135 in accordance with one or more embodiments of the present disclosure. The tool 150 may be included in BHA 145 as described herein. The tool 150 may be part of a drilling sensor subassembly 146. The BHA 145 has a longitudinal axis 147.

[0049] In the example diagram 200, the tool 150 may include transmitters (not illustrated) and receivers (not illustrated) disposed at different locations along the tool 150 (or BHA 145). However, the quantity and configurations of the transmitters and the receivers are not limited thereto, and embodiments of the present disclosure support any suitable quantity or configuration supportive of the techniques described herein.65REL-510596-WO-2 (INT1034PCT)

[0050] In an embodiment, the tool 150 may be configured to measure various parameters of the formation 130 and / or borehole 135. For example, the tool 150 may be configured for formation evaluation measurements and / or other parameters of interest relating to the formation 130, borehole 135, geophysical characteristics, borehole fluids and boundary conditions. Non-limiting examples of the parameters of interest include resistivity, dielectric constant, water saturation, porosity, density and permeability.

[0051] The tool 150 may include sensors 152 configured to measure environmental parameters such as temperature, pressure, and vibration. In some embodiments, the sensors 152 may be configured to measure directional characteristics (e.g., inclination, azimuth, or the like). Examples of such directional characteristics include inclination and azimuth, curvature, strain, and bending moment.

[0052] The tool 150 may broadcast (transmit) signals towards formation 130 (or portions of the formation 130) via one or more transmitters (not illustrated) and one or more corresponding antennas 156. The transmitters may include electronics suitable for generating processing the signals. The transmitters may be standalone transmission devices or transceiver devices capable of transmitting and receiving signals.

[0053] The tool 150 may receive, at one or more receivers (not illustrated) and one or more corresponding antennas 161 (e.g., one or more of antenna 161-x through antenna 161-z) signals based on the broadcasted signals. The receivers may include electronics suitable for receiving the signals. The receivers may be standalone receiving devices or transceiver devices capable of transmitting and receiving signals. The tool 150 may provide a formation property measurement (e.g., resistivity) associated with the formation 130 based on the received signals, example aspects of which are described herein.

[0054] Each transmitter may include a corresponding antenna 156 (e.g., a directional antenna). Each receiver may include a corresponding antenna 161 (e.g., a directional antenna). The tool 150 may include transmitter-receiver pairs in which a transmitter and a receiver are oriented orthogonal to one another.

[0055] The transmitters and / or receivers may be collocated or non-collocated. Herein, the term “collocated” refers to two or more transmitters / receivers that use intertwined coils or separate coils in such proximity as to behave as a point transmitter / receiver as understood by one of skill in the art. Two receiver / transmitter positions may be considered collocated if the signals received, due to energy emitted by the transmitter(s), at the both positions are substantially identical within the selected measurement accuracy. Non-collocated transmitters / receivers are not intertwined and are separated by sufficient distance as to behave65REL-510596-WO-2 (INT1034PCT)as individual transmitters / receivers as understood by one skill in the art. Thus, two receiver / transmitter positions may be considered non-collocated if signals received, due to energy emitted by the transmitter(s), at both positions are different within the selected measurement accuracy.

[0056] In some non-limiting embodiments, a transmitter (and corresponding antenna 156-x) may be oriented in the X-direction, a transmitter (and corresponding antenna 156-y) may be oriented in the Y-direction, and a transmitter (and corresponding antenna 156-z) may be oriented in the Z-direction. In some non-limiting embodiments, a receiver (and corresponding antenna 161 -x) may be oriented in the X-direction, a receiver (and corresponding antenna 161-y) may be oriented in the Y-direction. and a receiver (and corresponding antenna 161-z) may be oriented in the Z-direction. In some non-limiting embodiments, a transmitter or a receiver may be tilted, such that the transmitter or the receiver is oriented at an angle from the z-axis that is between 0° and 90°.

[0057] The transmitters and receivers may be oriented in any orientation combination such as, for example, combinations with a triaxial antenna such a Z-transmitter with an XYZ-receiver (not shown). In some embodiments, oriented transmitters may be configured such that the coil(s) of corresponding antennas 156 are wound around each other and / or spaced with such proximity as to be collocated as would be understood by one of skill in the art. Similarly, for example, oriented receivers may be configured such that the coil(s) of corresponding antennas 161 are wound around each other and / or spaced with such proximity as to be collocated as would be understood by one of skill in the art. Some embodiments may use a single transmitter and a single receiver. Some embodiments may use multiple transmitters and a single receivers. Some embodiments may include a single transmitter and multiple receivers.

[0058] According to one or more embodiments of the present disclosure, aspects of the tool 150 and receiving antennas 161 support improved resistivity measurement accuracy for extra-deep reading in high resistive formations.

[0059] For example, in some other approaches, a resistivity tool may be equipped with antenna coil assemblies consisting of significant amounts of a material having high magnetic permeability and optimized per design to a maximum of magnetic dipole moment. Such a type of antenna may be most suitable for applications within low resistive formation conditions where EM signals may be strongly attenuated. A disadvantage of such antennas may include sensitivity to environmental conditions (e.g., temperature, pressure, vibration, and the like), for example, due to the physical properties of the magnetic high-permeability material. In some65REL-510596-WO-2 (INT1034PCT)cases, inductance and moment of such antennas may change in response to the environmental conditions, reducing measurement accuracy.

[0060] For low resistive formations, a loss of measurement accuracy may be acceptable as the electronic noise floor may be the primary measurement uncertainty. For high resistive formations, however, the impact of a loss of measurement accuracy may be relatively greater. In some cases, a remote boundary may induce a small change in the signal level, only if the change is larger than the calibration accuracy it can safely be attributed to the remote boundary.

[0061] In some embodiments, as a signal subjected to high resistive formation experiences a minimum attenuation, embodiments of the present disclosure include using antennas (e.g., receiving antennas, for example, antennas 161) with lower dipole moments. In an example, instead of optimizing an antenna (e.g., a ferrite antenna) for all possible resistivity conditions, embodiments of the present disclosure may include implementing one or more antennas (e.g., an antenna 161) which is absent material with high magnetic permeability. For example, in some embodiments, the tool 150 may include a first antenna (e.g., antenna 161-x)) of a first type (e.g., including a material with high magnetic permeability) and a second antenna (e.g., antenna 161-y) of a second type of (e.g., including a material without high magnetic permeability), which may support providing an optimized antenna response for a wider resistivity range.

[0062] In some embodiments, aspects of the present disclosure support using the antennas 161 (e.g., antenna 161-x, antenna 161-y, and / or antenna 161-z) individually, independent of expected formation conditions, or in parallel. In some embodiments, where two antennas (e.g., first antenna (e.g., antenna 161-x), second antenna (e.g., antenna 161-y) are placed on the circumference of the body of the tool 150, one of the antennas can be replaced by a modified antenna type as described herein (e.g.. using materials without high magnetic permeability), which may reduce costs, improve reliability, and improve measurement accuracy. Aspects of the present disclosure support incorporating any combination of suitable antenna approaches described herein in a common antenna assembly.

[0063] Accordingly, for example, aspects of the present disclosure support using different types of antennas, optimized to certain formation resistivity conditions. The techniques described herein support conducting tool measurement on all types of antennas in parallel or on a specific antenna chosen based on formation properties. In an example, instead of running an antenna design approach based on high permeable core materials in which a one fit for all resistivities antenna is implemented, the techniques described herein include using65REL-510596-WO-2 (INT1034PCT)antenna without high permeable core materials, which may support effective measurements in high resistive formations.

[0064] In an example, for a first antenna (e.g., antenna 161-x) of a first type including a relatively high permeable core material and a second antenna (e.g., antenna 161-y) of a second type without a relatively high permeable core material, aspects of the present disclosure described herein further include antenna design and / or connected electronics which may equalize both the antenna types with respect to moment and inductance loss.

[0065] An example implementation associated with tool 150 and signals received at a first antenna (e.g., antenna 161-x) and a second antenna (e.g., antenna 161-y) of the tool 150 is described herein with reference to the following figures. In the example, the first antenna (e.g., antenna 161-x) provides relatively higher precision but lower accuracy, and the second antenna (e.g., antenna 161-y) provides relatively lower precision but higher accuracy.

[0066] In some embodiments, differences in precision and accuracy between the first antenna (e.g., antenna 161-x) and the second antenna (e.g., antenna 161-y) may be based on characteristics associated with each of the first antenna (e.g., antenna 161-x) and second antenna (e.g., antenna 161-y) such as, for example, magnetic permeability of materials included in the antennas, antenna geometry, and quantity of winding turns for the antennas.

[0067] FIG. 3 illustrates example diagrams described with reference to processing signals received at the first antenna (e.g., antenna 161-x) of the tool 150 and the second antenna (e.g., antenna 161-y) of the tool 150 in accordance with one or more embodiments of the present disclosure.

[0068] FIG. 4 illustrates example diagrams described with reference to processing the signals received at the first antenna (e.g., antenna 161-x) of the tool 150 and the second antenna (e.g., antenna 161-y) of the tool 150 in accordance with one or more embodiments of the present disclosure.

[0069] FIG. 5 illustrates an example flowchart of a method 500 in accordance with one or more embodiments of the present disclosure and is described with reference to FIGS. 1 through 4. The method 500 may be implemented by the example aspects of a system 100, a computing device 105, and / or a tool 150 as described herein.

[0070] In the example described herein, antenna 161-x is described as the first antenna, and antenna 161-y is described as the second antenna, but aspects of the present disclosure are not limited thereto. For example, aspects of the present disclosure may be applied to different combinations of the antennas 161 (e.g., antenna 161-x and antenna 161-z as respective first and second antennas, antenna 161-y and antenna 161-z as respective first and second antennas).65REL-510596-WO-2 (INT1034PCT)

[0071] At 505, the method 500 may include broadcasting (transmitting) a signal by a transmitter (or multiple transmitters) of the tool 150. For example, the method 500 may include broadcasting the signal towards a formation (e.g., formation 130) via one or more of antennas 156 (e.g., antenna 156-x and antenna 156-y, antenna 156-z). In a non-limiting example, the frequency of the broadcasted signal may be about 100 Hz to about 5 MHz, but is not limited thereto.

[0072] At 510, the method 500 may include receiving signals at the receiver of the tool 150 based on the broadcasted signal. For example, the method 500 may include receiving a first signal at a first antenna (e.g., antenna 161-x) based on the response of the formation (e.g., formation 130), and further, receiving a second signal at second antenna (e.g., antenna 161-y) based on the response of the formation.

[0073] At 515, the method 500 may include the tool 150 measuring the phase shift and attenuation of the broadcast signal, based on the received signals. As described herein, aspects of the method 500 may include generating corresponding log data based on processing the received signals, for example, in which the processing includes correcting one or more of the signals for accuracy, correcting one or more of the signals for precision, or generating a third signal based on the first signal and the second signal.

[0074] In the example, the first antenna (e.g., antenna 161-x) and the second antenna (e.g., antenna 161-y) are receiving the same formation response. However, in the example, the first antenna (e.g., antenna 161-x) receives a relatively higher formation signal magnitude compared to the second antenna (e.g., antenna 161-y). In an embodiment, the relatively higher formation signal magnitude may be due to a relatively high permeable core material in the first antenna (e.g., antenna 161-x), which results in a higher magnetic moment at the first antenna (e.g., antenna 161-x). For example, the magnetic moment at the first antenna (e.g., antenna 161-x) may be several times higher than the magnetic moment at the second antenna (e.g., antenna 161-y).

[0075] FIG. 3 illustrates, at diagram 300, a signal response 301 -a of the first signal received at the first antenna (e.g., antenna 161-x) and a signal response 302-a of the second signal received at the second antenna (e.g., antenna 161-y). In the example, the first signal received at first antenna (e.g., antenna 161-x) has a relatively higher signal-to-noise ratio compared to the second signal received at second antenna (e.g., antenna 161-y), but has a higher amount of signal drift over temperature. In an example, the signal response 302-a of the second signal is a drift free response. In some examples, the amount of signal drift may be less than a target threshold drift response.65REL-510596-WO-2 (INT1034PCT)

[0076] At 520, the method 500 may include performing signal correction. In an example, both the first signal and the second signal may include the same information and are shifted by 90° if placed at the same position on the tool circumference of the tool 150.

[0077] In an example, at 525, the method 500 may include correcting the accuracy of the first signal received at the first antenna (e.g., antenna 161-x), using the drift-free signal response 302-a of the second signal from second antenna (e.g., antenna 161-y). For example, at 525, the method 500 may include generating a corrected signal response 301-b for the first signal, an example of which is illustrated at diagram 400 of FIG. 4.

[0078] Additionally, or alternatively, at 530, the method 500 may include correcting the precision associated with the second signal based on the higher accuracy signal response 301-a of the first signal. For example, at 530, the method 500 may include generating a corrected signal response 302-b for the second signal, an example of which is illustrated at diagram 405 of FIG. 4.

[0079] Additionally, or alternatively, at 535, the method 500 may include generating a third signal based on processing the first signal received at the first antenna (e.g., antenna 161-x) and the second signal received at the second antenna (e.g., antenna 161-y).

[0080] In an example, the generated third signal may have an accuracy which ranges from the first accuracy (e.g., the lower accuracy) associated with the first signal to the second accuracy (e.g., the higher accuracy) associated with the second signal. In an example, the generated third signal may have a precision level which ranges from the first precision level (e.g., the higher precision level) associated with the first signal to the second precision level (e.g., the lower precision level) associated with the second signal.

[0081] In an example implementation, the generated third signal may have an accuracy equal to the second accuracy (e.g., the higher accuracy) associated with the second signal and / or a precision level equal to the first precision level (e.g., the higher precision level) associated with the first signal. In another example implementation, the generated third signal may have an accuracy which is about equal to the second accuracy (e.g., the higher accuracy) associated with the second signal and / or a precision level which is about equal to the first precision level (e.g., the higher precision level) associated with the first signal.

[0082] The terms “about” or “approximately” as used herein are inclusive of the stated value and include a suitable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement or calculation in question and the error associated with the measurement or calculation.65REL-510596-WO-2 (INT1034PCT)

[0083] At 540, the method 500 may include providing a formation property measurement (e.g., resistivity) associated with the formation 130. In an example, the method 500 may include calculating the formation property measurement based on the corrected signal response 301 -b of the first signal. Additionally, or alternatively, the method 500 may include calculating the formation property measurement based on the corrected signal response 302-b of the second signal. Additionally, or alternatively, the method 500 may include calculating the formation property measurement based on the signal response of the third signal generated at 535.

[0084] In some embodiments, the tool 150 may support transitioning between a correction mode (e.g., as described with reference to 520 through 535) and standalone mode. For example, at 517, the tool 150 may monitor and compare a signal-to-noise ratio associated with the second signal received at the second antenna (e.g., antenna 161-y) (e.g., lower sensitivity antenna) to a threshold value.

[0085] In an example, the second signal may be at the noise floor associated with the system 100 (e.g., the noise floor associated with the signal measurements by the tool 150), and accordingly, the signal-to-noise ratio associated with the second signal may fail to satisfy the threshold value.

[0086] In response to determining (at 517) that the signal-to-noise ratio associated with the second signal fails to satisfy the threshold value (‘SNR ratio > threshold value = NO’), the method 500 may include the tool 150 (or system 100) switching to a standalone mode. For example, the method 500 may include providing (at 540) the formation property measurement (e.g., resistivity) associated with the formation 130 based on the first signal received at the first antenna (e.g., antenna 161-x), without using the second signal. Expressed another way, when the signal-to-noise ratio associated with the second signal fails to satisfy the threshold value, compensation breaks down, and the method 500 proceeds to using the first signal (of a higher magnitude) in a standalone mode for providing the formation property measurement (e.g., resistivity). In an example, in the standalone mode, the method 500 may include applying a predetermined drift correction factor to the first signal, example aspects of which are later described herein.

[0087] In some alternative and / or additional embodiments, the determining (at 517) may be a smooth transition between the standalone mode and the correction mode in contrast to a yes / no decision. For example, the method 500 may include a linear transition between the standalone mode and the correction mode based on threshold values Vail and Val2. In an example, Vail may be a ‘standalone mode value’ associated with implementing the standalone65REL-510596-WO-2 (INT1034PCT)mode, and Val2 may be a ‘correction mode value’ associated with implementing the correction mode.

[0088] In an example, a relationship between the threshold value Vail and the threshold value Val2 is as follows: Val2 = X*Val1 + (1-x)* corrected value, where x is scaled linearly from 1 to 0, going from Vail to Val2. The described transition is not limited to a linear transition, and embodiments of the present disclosure support implementing transitions between the standalone mode and the correction mode based on other functions such as, for example, a polynomial function, an exponential function, or the like, or further statistical analysis of the dataset.

[0089] Example aspects of the signal processing of the first signal received at the first antenna (e.g., antenna 161-x) and the second signal received at the second antenna (e.g., antenna 161-y), for example, in association with generating the corrected signal response 301-b and the corrected signal response 302-b are further described herein with reference to FIGS.3 and 4. In the example descriptions, u 1 (mt) refers to the first signal received at the first antenna (e.g., antenna 161-x), and u2(mt) refers to the second signal received at the second antenna (e.g., antenna 161-y).

[0090] An example method of correcting u2(mt) (e.g., correcting the precision of the second signal at 530) in accordance with one or more embodiments of the present disclosure is described herein for a combination of X- and Y-receivers. The signal received at both receivers varies with toolface TF as follows: X-receiver ul (mt, TF) = ul(mt)*cos(TF), Y-receiver u2(mt, TF) = u2(mt)*sin(TF).

[0091] Correcting u2(mt, TF) may include shifting u2(mt, TF) by 90° such that u2(mt, TF) is in phase with ul (mt, TF). in accordance with Equation (1).u2(mt, TF-90°)* = u2(mt)*sin(TF- 90°) (1)

[0092] For simplicity, the toolface dependence can be dropped after the rotation operation (1). The method may include calculating the difference between the phase shifted signal u2(mt)* and ul(mt) in association with removing the formation signal within u2(mt)* and revealing contained noise spectrum, in accordance with Equation (2) and diagram 305 of FIG. 3.ul(mt) - u2(mt)* (2)

[0093] The method may include performing a spectral analysis (e.g., FFT) to remove noise from u2(mt)*, in accordance with Equation (3) and diagram 315 of FIG. 3.FFT (ul(mt) - u2(mt)*) (3)65REL-510596-WO-2 (INT1034PCT)

[0094] The method may include, based on the FFT, defining a suitable low pass filter (LPF) and applying the filter to u2(mt)* to remove noise, as illustrated at diagram 320 and diagram 325 of FIG. 3. In some embodiments, the method may include deriving parameters for the low pass filter under an assumption the noise spectrum will not change significantly over time or rotation, but aspects of the present disclosure are not limited thereto. For example, aspects of the present disclosure support updating or rederiving the parameters for the low pass filter in response to one or more criteria (e.g., changes to the noise spectrum).

[0095] The method may include, once u2(mt)* is cleaned up from noise, correcting ul(mt) for drift. Based on known moment ml of the first antenna (e.g., antenna 161-x) and known moment m2 of the second antenna (e.g., antenna 161-y), the ratio of ul(mt) / u2(mt)* received under same environmental conditions is equal to ratio of antenna moments.

[0096] Based on an example assumption that u2(mt)* has less drift (e.g., compared to ul(mt)) or driftless, it can be followed that any deviation of ul(mt) / u2(mt)* from the ratio of underlying antenna moments m1 / m2 will result from drift of the first antenna (e.g., antenna 161-x).

[0097] The method may include correcting ul(mt) based on the ratio of moments ml / m2 and ratio, in accordance with Equation (4).

[0098] In the same manner, the systems and techniques described herein include, based on subjecting the tool 150 (respectively, for example, the first antenna (e.g., antenna 161-x) and the second antenna (e.g., antenna 161-y)) to specific changing environmental parameters in a testing environment (e.g., a lab environment), predetermining a drift correction function to be used in association with the first antenna (e.g., antenna 161-x). The systems and techniques described herein support applying the predetermined drift correction function in association with correcting ul (mt) downhole, based on corresponding downhole environment parameters (e.g., temperature, pressure, vibration, and the like). In an example, the correction function may be stored in a memory (not illustrated) of the tool 150 for real-time data correction. Additionally, or alternatively, the correction function may be stored in a memory (not illustrated) of a computing device 105 and / or in a database, and the systems and techniques described herein may include applying the predetermined drift correction function in association with signal postprocessing.65REL-510596-WO-2 (INT1034PCT)

[0099] In some embodiments, the systems and techniques described herein may include applying the predetermined drift correction function to the ul(mt) in accordance with a standalone mode as described herein (e.g., with reference to 517 of the method 500).

[0100] In some embodiments, when moving from a high resistive environment to a lower resistive environment, noise performance of the second antenna (e.g., antenna 161 -y) (lower moment antenna) may decrease. Accordingly, for example, the reduction in noise performance may introduce extra random noise into the corrected ul(mt). The noise derived for the second antenna (e.g., antenna 161-y) by FFT (or other process) can give rise to a quality estimator Q. In some embodiments, the quality estimator Q may include a carrier-to-interference ratio (CIR) or a signal-to-interference ratio (SIR).

[0101] In an example, the method may include deriving a corrected ulq as a weighted average, in accordance with Equation (5).ulcorrected,q(n>t) = ul(tOt) ■ (1 - Q) + U lconected(mt) ■ Q (5)

[0102] In some embodiments, the systems and techniques described herein may include deriving a corrected ulq in accordance with a standalone mode as described herein (e.g., with reference to 517 of the method 500).

[0103] Accordingly, for example, the systems and techniques described herein support deriving the response having the best compromise of accuracy and precision.

[0104] The antenna configurations, signal correction techniques, and signal generation techniques described herein may be implemented at antennas of a tool (e.g., tool 150, acoustic tool 165, or other one or more other sensing tools 167) of the system 100 for improving measurements by the tool.

[0105] In an example described with reference to FIGS. 1 and 2, (illustrated inpart), aspects of the techniques described herein may be fit to a tool 150, in which a transmitter (transmitter) includes a first transmission antenna (Z direction) (e.g., antenna 156-z) and a second transmission antenna (X direction) (e.g., antenna 156-x) and a receiver (e.g., transmitter / receiver) includes a transmission antenna (Z direction) (e.g., antenna 161-z) and a receiving antenna (Y direction) (e.g., antenna 161-y).

[0106] In an example supportive of implementing antennas supportive of the signal correction techniques and improved measurements described herein, a configuration including one transmitting antenna and two receiving antennas is implemented. The receiving antennas will record the same formation signal while excluding the different respective noise / stability characteristics at the receiving antennas. In an example implementation, the65REL-510596-WO-2 (INT1034PCT)configuration may include a rotating tool including a combination of a Z-transmitter (capable of transmitting in the Z direction), an X-receiver (capable of receiving in the X direction), and a Y-receiver (capable of receiving in the Y direction). This also works with X-TX and X / Y-RXs. In another example implementation, a configuration may include a rotating tool including a combination of an X-transmitter (capable of transmitting in the X direction), an X-receiver (capable of receiving in the X direction), and a Y-receiver (capable of receiving in the Y direction).

[0107] In another example implementation, a configuration may include a rotating tool including a combination of an X-transmitter (capable of transmitting in the X direction), a Y-transmitter (capable of transmitting in the Y direction), and a single receiver (e.g., a Z-receiver or an X / Y-receiver), in which the X-transmitter and the Y-transmitter transmit according to different respective signal strengths. Accordingly, for example, for a given configuration, two antennas (e.g., an X-antenna and a Y-antenna) with different sensitivity or signal strength are geometrically at the same position of the BHA.

[0108] Aspects of the present disclosure support configurations including tilted antennas. In an example, a configuration may include three antennas, in which the first antenna is tilted 45° with respect to the Z-direction and pointing in the X-direction, the second antenna is tilted 45° with respect to the Z-direction (e.g., ensuring geometrically the same position) but pointing in the Y-direction, and the third antenna is in any orientation (e.g., longitudinal, tilted, or transverse).

[0109] In some embodiments, the systems and techniques described herein may support replacing one of the transverse antennas (X / Y), which may provide increased accuracy in a wider resistivity range for measurements involving X / Y-antennas.

[0110] In some embodiments, the systems and techniques described herein may be extended such that the tool 150 includes a low-moment, high-stability antenna (also referred to herein as a pilot antenna), in which the antenna is in a tilted or off-center configuration. The systems and techniques described herein may include processing signals (data signals) received at the pilot antenna to separate out azimuthal and non-azimuthal signal strength to compute a calibration drift correction for both the X- / Y- and Z-antennas, respectively.

[0111] In some aspects, for a configuration in which antennas are used that are not at the same geometric position, because of the different locations of the antennas on the body of the tool 150, the systems and techniques described herein may further include a correction for changing antenna distance. In an example, embodiments of the present disclosure65REL-510596-WO-2 (INT1034PCT)may include placing two low-moment antennas symmetrically about the high-moment antenna to be corrected, which may create a virtual midpoint of the two low-moment antennas. That is, for example, correction for the position creates a virtual midpoint.

[0112] In some embodiments, each of the first antenna (e.g., antenna 161-x) and the second antenna (e.g., antenna 161-y) may include the same electromagnetic permeable material or materials of the same magnetic permeability. For example, each of the first antenna (e.g., antenna 161-x) and the second antenna (e.g., antenna 161-y) may include the same electromagnetic high permeable material, with one of the antennas being tuned for stability at the expense of magnetic moment. In some aspects, μeff of the antennas / coils is based on respective geometries of the antennas / coils.

[0113] Aspects of the present disclosure include designing the antennas described herein (e.g., axial antennas (coils)) based on ratio m of Equation (6).m = coil length / coil diameter (6)

[0114] In an example, m is small (e.g., below a threshold value), which results in low μeff and supports the μr of the used magnetic material changing over a wide range without changing the μeff of the antenna response (e.g., maintaining the magnetic moment). Aspects of the present disclosure include transferring the principle to antennas with more complex design geometries and using 3D electromagnetic analysis software to assess or prove the stability.

[0115] FIG. 6 illustrates an example plot diagram 600 illustrative of the relationship between μr and μeff for some other antennas different from the embodiments of the present disclosure.

[0116] Aspects of the antenna features described herein provide several advantages. Using an antenna with lower moment but improved stability supports increasing tool performance in high resistive formations. In some aspects, antenna costs may be reduced as the amount of permeable core material is reduced. In some aspects, any aging effects of antenna parameters (e.g., due to exposure to stress downhole) are removed, reducing reliance on recalibration of the tool and reducing maintenance costs. Aspects of the antenna features described herein support reduced interference of tool electronics with antenna measurements, which may increase immunity of an antenna against electronic interference.

[0117] FIG. 7 illustrates an example flowchart of a method 700 in accordance with one or more embodiments of the present disclosure. The method 700 is an example computer-implemented method that may be implemented by the example aspects of a system 100, a computing device 105, and / or a tool 150 as described herein.65REL-510596-WO-2 (INT1034PCT)

[0118] At 705, the method 700 includes generating, based on processing a first signal received at a first antenna coupled to a tool and a second signal received at a second antenna coupled to the tool, a third signal, where a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal.

[0119] At 710, the method 700 includes calculating a value of at least one target parameter measured by the tool based on the third signal.

[0120] In some aspects, the method 700 includes determining a signal-to-noise ratio of the second signal; and generating (at 705) the third signal based on the first signal and the second signal, based on comparing the signal-to-noise ratio of the second signal to a threshold signal-to-noise ratio.

[0121] In some aspects, the method 700 includes determining a signal-to-noise ratio of the second signal; and generating (at 705) the third signal based on the first signal and the second signal, based on the signal-to-noise ratio of the second signal satisfying a threshold signal-to-noise ratio.

[0122] In some aspects, the method 700 includes determining a signal-to-noise ratio of the second signal; and generating (at 705) the third signal based on the first signal, based on the signal-to-noise ratio of the second signal failing to satisfy a threshold signal-to-noise ratio.

[0123] In the descriptions of the flowcharts herein, the operations may be performed in a different order than the order shown, or the operations may be performed in different orders or at different times. Certain operations may also be left out of the flowcharts, one or more operations may be repeated, or other operations may be added to the flowcharts.

[0124] Set forth below are some embodiments of the foregoing disclosure:

[0125] Embodiment 1. An apparatus comprising: a carrier; a first antenna coupled to the carrier; a second antenna coupled to the carrier; and at least one processor configured to: generate, based on processing a first signal received at the first antenna and a second signal received at the second antenna, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and calculate a value of at least one target parameter measured by the carrier based on the third signal.65REL-510596-WO-2 (INT1034PCT)

[0126] Embodiment 2. The apparatus as in any prior embodiment, wherein: the first precision level is higher than the second precision level; and the third precision level is equal to the first precision level. In some aspects, the first precision level may be substantially different from than the second precision level.

[0127] Embodiment 3. The apparatus as in any prior embodiment, wherein the second accuracy is higher than the first accuracy; and the third accuracy is equal to the second accuracy. In some aspects, the second accuracy may be substantially different from than the first accuracy.

[0128] Embodiment 4. The apparatus as in any prior embodiment, wherein: the first antenna comprises one or more first materials of a first magnetic permeability; and the second antenna comprises one or more second materials of a second magnetic permeability equal to the first magnetic permeability.

[0129] Embodiment 5. The apparatus as in any prior embodiment, wherein the first antenna is not coupled to the second antenna.

[0130] Embodiment 6. The apparatus as in any prior embodiment, wherein the first antenna is magnetically, galvanically, or capacitively coupled to the second antenna. In some cases, an interference associated with the coupling between the first antenna and the second antenna satisfies a threshold value. For example, the coupling may be implemented such that the coupling does not negatively impact or invalidate (e.g., based on a threshold interference value, based on a resultant SNR, or the like) the accuracy improvement techniques and implementations described herein.

[0131] Embodiment 7. The apparatus as in any prior embodiment, wherein a first geometry associated with the first antenna is different from a second geometry associated with the second antenna. In some cases, an interference between the first antenna and the second antenna based on the first geometry of the first antenna and the second geometry of the second antenna satisfies a threshold value. For example, based on the first geometry of the first antenna and the second geometry of the second antenna, a susceptibility of the first antenna to environmental conditions is reduced, a susceptibility of the second antenna to the environmental conditions is reduced, or both.

[0132] Embodiment 8. The apparatus as in any prior embodiment, wherein: the first antenna comprises a first coil comprising a first quantity of turns; and the second antenna comprises a second coil comprising a second quantity of turns different from the first quantity of turns.65REL-510596-WO-2 (INT1034PCT)

[0133] Embodiment 9. The apparatus as in any prior embodiment, wherein a first signal-to-noise ratio associated with the first signal is greater than a second signal-to-noise ratio associated with the second signal.

[0134] Embodiment 10. The apparatus as in any prior embodiment, wherein a first dipole moment of the first antenna is greater than a second dipole moment of the second antenna.

[0135] Embodiment 11. The apparatus as in any prior embodiment, wherein a second susceptibility to drift by the second antenna with respect to one or more environmental parameters is less than a first susceptibility to drift by the first antenna with respect to the one or more environmental parameters.

[0136] Embodiment 12. The apparatus as in any prior embodiment, wherein the at least one processor is further configured to: determine a signal-to-noise ratio of the second signal; and generate the third signal based on the first signal, based on the signal-to-noise ratio of the second signal failing to satisfy a threshold signal-to-noise ratio.

[0137] Embodiment 13. The apparatus as in any prior embodiment, wherein the at least one processor is further configured to generate the third signal by applying a drift correction function to the first signal, wherein the drift correction function is based on one or more environment parameters comprising temperature, pressure, and vibration.

[0138] Embodiment 14. A method comprising: generating, based on processing a first signal received at a first antenna coupled to a carrier and a second signal received at a second antenna coupled to the carrier, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and calculating a value of at least one target parameter measured by the carrier based on the third signal.

[0139] Embodiment 15. A non-transitory computer-readable medium product having stored thereon instructions that, when executed by at least one processor, cause the at least one processor to perform a method comprising: generating, based on processing a first signal received at a first antenna coupled to a carrier and a second signal received at a second antenna coupled to the carrier, a third signal, wherein at least one of: a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; or a third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision65REL-510596-WO-2 (INT1034PCT)level associated with the second signal; and calculating a value of at least one target parameter measured by the carrier based on the third signal.

[0140] As have been described herein, aspects of the present disclosure support an apparatus including a carrier body, in which multiple types of antennas are coupled to the carrier body. The apparatus improves the resistivity measurement accuracy of extra-deep reading tools in high resistive formations. The apparatus provides an optimized antenna response for a wider resistivity range.

[0141] The apparatus may include different types of antennas (e.g., Antenna 1 and Antenna 2) which are, in some examples, optimized to certain formation resistivity conditions. Tool measurement can be conducted on all types of antennas in parallel or on a specific antenna chosen based on the formation properties. The approaches described herein are different from other antenna design approaches which use a “one fit for all resistivities” antenna including core materials of high magnetic permeability.

[0142] In an example, Antenna 1 includes a high magnetic permeability material and has a higher signal-to-noise ratio and higher magnetic dipole moment compared to Antenna 2. Antenna 2 includes material of lower magnetic permeability and is less susceptible to drift effects over temperature, pressure, and / or vibration compared to Antenna 1.

[0143] Signals received at Antenna 1 and Antenna 2 may include the same information. The apparatus supports correcting accuracy of the first signal received at Antenna 1 using the drift free signal response at Antenna 2. The apparatus supports correcting precision of the second signal received at Antenna 2 using the signal response at Antenna 1.

[0144] The material in Antenna 2 is less sensitive to changes in pressure, temperature, and vibration compared to the material in Antenna 1 and improves antenna stability. Implementing Antenna 2 without materials of high magnetic permeability achieves reduced costs, improves reliability, and improves measurement accuracy. The features can be adapted to extra-deep reading tools. The implementations described herein of pairing a high sensitivity I low accuracy sensor with a high accuracy / low sensitivity sensor may be applied to other measurements alternative and / or additional to the measurements described herein. For example, a present disclosure support implementing a resistivity imaging tool in which a large diameter button (e.g., low resolution / high accuracy) is paired with a small diameter button (e.g., high resolution / low accuracy).

[0145] In some alternative and / or additional embodiments, the apparatus may include a matching network (e.g., electrical circuit) connected to Antenna 2 configure to improve the SNR of the Antenna 2. In this case, for example, the matching may be implemented65REL-510596-WO-2 (INT1034PCT)such that the matching improves the SNR but does not negatively impact (e.g., based on a threshold value) or invalidate the accuracy improvement techniques and implementations described herein.

[0146] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “about”, “substantially” and “generally” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and / or “substantially” and / or “generally” can include a range of ± 8% of a given value.

[0147] While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.

Claims

65REL-510596-WO-2 (INT1034PCT)CLAIMSWhat is claimed is:

1. An apparatus characterized by:a carrier (150);a first antenna (161-x) coupled to the carrier;a second antenna (161 -y) coupled to the carrier; andat least one processor configured to:generate, based on processing a first signal received at the first antenna (161-x) and a second signal received at the second antenna (161-y), a third signal, wherein at least one of:a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; ora third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; andcalculate a value of at least one target parameter measured by the carrier based on the third signal.

2. The apparatus of claim 1, wherein:the first precision level is higher than the second precision level; andthe third precision level is equal to the first precision level..

3. The apparatus of claim 1, wherein:the second accuracy is higher than the first accuracy; andthe third accuracy is equal to the second accuracy.

4. The apparatus of claim 1, wherein:the first antenna (161-x) comprises one or more first materials of a first magnetic permeability; andthe second antenna (161-y) comprises one or more second materials of a second magnetic permeability less than or equal to the first magnetic permeability.

5. The apparatus of claim 1, wherein the first antenna (161-x) is not coupled to the second antenna (161-y).

6. The apparatus of claim 1, wherein:the first antenna (161-x) is magnetically, galvanically, or capacitively coupled to the second antenna (161-y).65REL-510596-WO-2 (INT1034PCT)7. The apparatus of claim 1, wherein:a first geometry associated with the first antenna (161-x) is different from a second geometry associated with the second antenna (161-y).

8. The apparatus of claim 1, wherein:the first antenna (161-x) comprises a first coil characterized by a first quantity of turns; andthe second antenna (161-y) comprises a second coil characterized by a second quantity of turns different from the first quantity of turns.

9. The apparatus of claim 1, wherein a first signal-to-noise ratio associated with the first signal is greater than a second signal-to-noise ratio associated with the second signal.

10. The apparatus of claim 1, wherein a first dipole moment of the first antenna (161-x) is greater than a second dipole moment of the second antenna (161-y).

11. The apparatus of claim 1, wherein a second susceptibility to drift by the second antenna (161-y) with respect to one or more environmental parameters is less than a first susceptibility to drift by the first antenna (161-x) with respect to the one or more environmental parameters.

12. The apparatus of claim 1, wherein the at least one processor is further configured to:determine a signal-to-noise ratio of the second signal; andgenerate the third signal based on the first signal, based on the signal-to-noise ratio of the second signal failing to satisfy a threshold signal-to-noise ratio.

13. The apparatus of claim 1, wherein the at least one processor is further configured to generate the third signal by applying a drift correction function to the first signal, wherein the drift correction function is based on one or more environment parameters characterized by temperature, pressure, and vibration.

14. A method characterized by:generating, based on processing a first signal received at a first antenna (161-x) coupled to a carrier and a second signal received at a second antenna (161-y) coupled to the carrier, a third signal, wherein at least one of:a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; ora third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; and65REL-510596-WO-2 (INT1034PCT)calculating a value of at least one target parameter measured by the carrier based on the third signal.

15. A non-transitory computer-readable medium product having stored thereon instructions that, when executed by at least one processor, cause the at least one processor to perform a method characterized by:generating, based on processing a first signal received at a first antenna (161-x) coupled to a carrier and a second signal received at a second antenna (161-y) coupled to the carrier, a third signal, wherein at least one of:a third accuracy associated with the third signal ranges from a first accuracy associated with the first signal to a second accuracy associated with the second signal; ora third precision level associated with the third signal ranges from a first precision level associated with the first signal to a second precision level associated with the second signal; andcalculating a value of at least one target parameter measured by the carrier based on the third signal.

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