Downhole health monitoring of survey sensors

Abstract

The invention relates to downhole health monitoring of survey sensors. Specifically, a method for surveying a wellbore includes rotating a wellbore surveying tool in the wellbore. The wellbore survey tool includes a plurality of magnetometers, a plurality of accelerometers, and optionally a plurality of temperature sensors. Sensor measurements are made as the survey tool rotates in the wellbore. A faulty accelerometer or a faulty temperature sensor is automatically detected from an accelerometer measurement or a temperature measurement. A measurement selected from a magnetometer measurement, an accelerometer measurement, and a temperature measurement calculates a corrected sensor measurement for the faulty sensor and uses it for further calculating at least one of a borehole inclination or a borehole azimuth.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 699,199, filed September 26, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The disclosed embodiments relate generally to wellbore surveying methods, and more particularly to downhole health monitoring of survey sensors. BACKGROUND

[0004] In conventional drilling and measurement-while-drilling (MWD) operations, wellbore inclination and wellbore azimuth are measured during drilling operations. Static measurements can be made at a discrete number of longitudinal points along the axis of the wellbore when drilling has been temporarily stopped and the drill string is lifted off the bottom of the wellbore. More recently, methods have been developed to make continuous (or real-time) measurements while drilling (e.g., while the drill string is rotating in the wellbore). Such continuous measurements are sometimes referred to as deterministic dynamic surveying (DDS). In both static and continuous measurements, wellbore inclination and wellbore azimuth can be computed from three-axis accelerometer measurements of the earth’s gravitational field and three-axis magnetometer measurements of the earth’s magnetic field.

[0005] Due to the severe stresses inherent in the downhole drilling process, such as continuous exposure to shock, vibration, and high temperatures, electronics deployed in downhole measurement tools, particularly accelerometers, are subject to degradation or even sudden failure. Detecting such degradation or failure can be challenging during drilling operations. Moreover, when degradation or failure is suspected, current troubleshooting procedures are highly time-intensive, require specialized personnel, and stop drilling to complete rolling tests. Such procedures can result in long periods of non-productive time and increased expense. Still further, sensor degradation or failure can preclude subsequent survey measurements.

[0006] There is a need in the industry for methods for automatic sensor failure detection and sensor failure correction in measurement-while-drilling (MWD) tools. SUMMARY

[0007] In one example embodiment, a wellbore surveying operation includes surveying a wellbore; automatically detecting a failed survey sensor while surveying; computing a corrected sensor measurement value for the failed survey sensor from other survey sensors; and completing the survey using the corrected sensor measurement value (e.g., computing at least one survey parameter, such as wellbore inclination, wellbore azimuth, or dip angle).

[0008] This summary is provided to introduce a selection of concepts, which are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF DRAWINGS

[0009] For a more complete understanding of the disclosed subject matter and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which:

[0010] Figure 1 A drilling rig including the disclosed borehole survey tool is depicted.

[0011] Figure 2 An example borehole survey tool is depicted. Figure 1 The depicted borehole survey tool.

[0012] Figure 3 A flowchart of an example method for diagnosing and correcting navigation sensor faults is depicted.

[0013] Figure 4 A flowchart of another example method for diagnosing and correcting navigation sensor faults is depicted.

[0014] Figure 5 A flowchart of an example method for detecting accelerometer faults is depicted.

[0015] Figure 6 An example sensor correction block for x-axis, y-axis, and z-axis accelerometer corrections is depicted. DETAILED DESCRIPTION

[0016] Systems and methods for surveying a subterranean borehole while drilling are disclosed. In one example embodiment, the disclosed method includes rotating a borehole survey tool in the borehole. The borehole survey tool includes a plurality of magnetometers, a plurality of accelerometers, and optionally a plurality of temperature sensors. Sensor measurements are taken while the survey tool is rotating in the borehole. A faulty accelerometer or a faulty temperature sensor is automatically detected from the accelerometer measurements or the temperature measurements. A corrected sensor measurement is calculated for the faulty sensor from selected ones of the magnetometer measurements, the accelerometer measurements, and the temperature measurements, and the corrected sensor measurement is used in further calculations of at least one of borehole inclination or borehole azimuth.

[0017] Example embodiments disclosed herein can provide various technical advantages and improvements over the prior art. For example, the disclosed embodiments can enable borehole survey measurements to be made even when one of the three-axis accelerometers or temperature sensors deployed in the survey tool is faulty. Thus, the disclosed embodiments can provide improved reliability and operational flexibility in the event of a sensor failure.

[0018] Figure 1 A rig 20 is depicted that includes the disclosed survey tool 80 deployed in a pipe string 30 and disposed within a wellbore 40. The rig 20 can be deployed onshore or offshore (an onshore application is depicted). As known to those of ordinary skill, offshore rigs typically include a platform that is deployed atop a riser that extends from the seafloor to the surface of the sea. A drill string extends downward from the platform, through the riser, and through a blowout preventer (BOP) located at the seafloor into the wellbore. The disclosed embodiments are not limited in these respects. In both onshore and offshore operations, the wellbore 40 can be drilled in the subterranean formation by rotary drilling, slide drilling, or power drilling in a manner known to those of ordinary skill in the art (e.g., by known directional drilling techniques).

[0019] In the depicted embodiment, the rig 20 is positioned above a subterranean formation and can include a derrick and hoisting equipment (not shown) for raising and lowering a drill string 30, as shown, that extends into the wellbore 40 and includes a drill bit 32 and a survey tool 80, which can include, for example, a measurement-while-drilling (MWD) tool 50 or a rotary steerable system (RSS) 60. As known to those of ordinary skill, the drill string 30 can also include other tools such as a downhole drilling motor, a downhole telemetry system (e.g., deployed in or adjacent to the MWD tool 50), and one or more logging-while-drilling (LWD) tools that include various sensors for measuring one or more properties of the formation that the wellbore penetrates, for example, including resistivity, NMR relaxation time, density, porosity, sonic velocity, gamma ray counts, etc. In addition, the MWD tool 50 can be configured to measure one or more properties of the borehole 40 as it is being drilled or at any time thereafter. The physical properties can include, for example, pressure, temperature, wellbore caliper, wellbore trajectory (attitude), tool face angle, etc.

[0020] Those of ordinary skill will appreciate that, Figure 1 The depicted deployment is merely an example, and the disclosed embodiments are expressly not limited in this respect to bottom hole assembly (BHA) configurations. They are also not limited to any particular type of drilling operation. In addition, it should be appreciated that wellbore survey measurements (inclination and azimuth measurements) are typically made in one or both of the MWD tool 50 and the RSS tool 60. While the disclosed embodiments are described in more detail below with respect to downhole survey measurements, it should be appreciated that such measurements can be MWD and / or RSS measurements.

[0021] Figure 2One example embodiment of a survey tool 80 is depicted. The survey tool 80 can include substantially any suitable downhole tool or tool joint configured to take wellbore survey measurements, e.g., including an MWD tool and / or an RSS as described above. The MWD tool is typically deployed at the upper end of a bottom hole assembly (BHA) and is typically configured to rotate with the drill string. While the disclosed embodiments are not limited in this regard, the MWD tool typically also includes a mud pulse telemetry transmitter or another telemetry system and an alternator for generating electrical power. The RSS is typically deployed in a lower BHA and is coupled to the drill bit 32. The RSS typically includes a steering element that can be actuated to control and / or change the direction of the drilled wellbore 40. In embodiments employing an RSS, substantially any system configuration can be used. For example, a PowerDrive rotary steerable system (available from SLB) rotates entirely with the drill string (i.e., the outer housing body rotates with the drill string). A PowerDrive Xceed uses an internal steering mechanism that does not require contact with the wellbore wall and enables the tool body to rotate entirely with the drill string. A PowerDrive X5, X6, and track rotary steerable system utilizes mud-actuated blades (or pads) that contact the wellbore wall. The extension of the blades (or pads) is adjusted rapidly and continuously as the system rotates in the wellbore. The disclosed embodiments are not limited to any particular RSS configuration.

[0022] The survey tool 80 also includes survey sensors, including an accelerometer set 90 and a magnetometer set 95, which can be deployed to rotate with the drill string or can be deployed in a rolling stabilizer housing that can rotate slowly from time to time. The depicted sensor sets can include a tri-axial accelerometer and tri-axial magnetometer navigation sensor set, which can be any suitable commercially available device. Suitable accelerometers for the sensor set 90 can be selected, for example, from substantially any suitable commercially available device known in the art. Suitable accelerometers can alternatively include micro-electromechanical system (MEMS) solid state accelerometers, which tend to be shock resistant, high temperature rated, and inexpensive. Suitable magnetic field sensors for use in the sensor set 95 can include conventional ring core fluxgate magnetometers or conventional magnetoresistive sensors.

[0023] Figure 2 A depiction of a tri-axial accelerometer set 90 and tri-axial magnetometer 95 is also included. Tri-axial means that each sensor set includes three mutually perpendicular sensors, the accelerometers are designated G x , G y , and G z and the magnetometers are designated B x , B y , and B z . By convention, a right-hand system is designated, where the x-axis accelerometer and magnetometer point to the right, the y-axis accelerometer and magnetometer point up, and the z-axis accelerometer and magnetometer point forward. x , G y , and G z and the magnetometers are designated B x , B y , and B z . By convention, a right-hand system is designated, where the x-axis accelerometer and magnetometer point to the right, the y-axis accelerometer and magnetometer point up, and the z-axis accelerometer and magnetometer point forward. and ) are oriented substantially parallel to the tool axis (and thus parallel to the wellbore axis), as indicated. Thus, each of the accelerometer and magnetometer sets can be considered to determine a plane (y and z axes) and a pole (x axis along the axis of the BHA). It should be understood that the disclosed embodiments are not limited to any particular coordinate convention, and another common convention used in the industry designates the tool axis as the z axis.

[0024] By further non-limiting convention, the gravity field is considered to be positive pointing downward (i.e., toward the center of the Earth), while the magnetic field is considered to be positive pointing magnetic north. Further, again by non-limiting convention, the y axis is considered to be the tool face reference axis (i.e., such that when the y axis is uppermost the gravity tool face GTF is equal to zero, and when the y axis points to the projection of magnetic north in the yz plane the magnetic tool face MTF is equal to zero). The magnetic tool face MTF is projected in the yz plane, and can be mathematically expressed as: The angle between the projections of the horizontal projections on the y and z axes: Again, the gravity tool face GTF can be mathematically expressed as: The negative sign in the gravity tool face expression arises due to the non-limiting convention that the gravity vector is positive in the downward direction, and the tool face angle GTF is positive on the high side of the wellbore (the side facing upward).

[0025] It should be understood that the disclosed embodiments are of course not limited to the above-described conventions for defining wellbore coordinates. These conventions can affect the form of certain mathematical equations later in the present disclosure. Those of ordinary skill in the art will be able to readily utilize other conventions and derive equivalent mathematical equations.

[0026] As also noted above, the disclosed embodiments are not limited to MWD deployments, but can also include RSS deployments. Those of ordinary skill will readily recognize that RSS tools include a steering element that can be actuated to control and / or change the direction of the drilled wellbore 40. In embodiments employing rotary steerable tools, substantially any suitable rotary steerable tool configuration can be used. Various rotary steerable tool configurations are known in the art. For example, some rotary steering systems include a substantially non-rotating (or slowly rotating) outer housing that employs blades that engage with the wellbore wall. Engagement of the blades with the wellbore wall is intended to eccentrically bias the tool body, thereby pointing or pushing the drill bit in a desired direction while drilling. A rotating shaft deployed in the outer housing transmits rotational power and axial weight-on-bit to the drill bit during drilling. The accelerometer and magnetometer sets can be deployed in the outer housing, and thus do not rotate or slowly rotate relative to the wellbore wall.

[0027] The PowerDrive rotary steerable system (available from SLB) rotates the entire drill string (i.e., the outer housing rotates with the drill string). The PowerDrive Xceed uses an internal steering mechanism that does not require contact with the wellbore wall and enables the tool body to rotate entirely with the drill string. The PowerDrive X5, X6, and Track rotary steerable systems utilize mud-actuated blades (or pads) that contact the wellbore wall. The extension of the blades (or pads) is adjusted rapidly and continuously as the system rotates in the wellbore. Further, it should be appreciated that the RSS can include a steerable drill bit, such as the NeoSteer drill bit steering system available from SLB, in which steering pads extend outwardly from the drill bit body into contact with the wellbore wall.

[0028] The PowerDrive Archer utilizes a lower steering section that interfaces with an upper section at a swivel. As the bottom hole assembly rotates in the wellbore, the swivel is actively tilted via a piston in order to change the angle of the lower section relative to the upper section and maintain a desired drilling direction. An accelerometer and magnetometer bank can rotate with the drill string, or can alternatively be deployed in an inner rolling stabilizer housing such that they remain substantially stationary (in a bias phase) or rotate slowly relative to the wellbore (in a neutral phase).

[0029] Referring again to Figure 2 The accelerometer bank 90 and the magnetometer bank 95 can be configured for making downhole surveying measurements during drilling operations. Such measurements are well known and are commonly used to determine, for example, wellbore inclination, wellbore azimuth, gravity tool face, magnetic tool face, and dip angle. The accelerometers and magnetometers can be electrically coupled to a digital signal processor (or other digital controller) by respective analog signal conditioning circuits. The signal conditioning circuits can include low pass filter elements that are intended to band limit sensor noise, thus tending to improve sensor resolution and measurement accuracy.

[0030] More recently, methods have been developed for making continuous (or real-time) measurements while drilling. For example, commonly assigned U.S. Patent 11,692,432 discloses a measurement method in which accelerometer measurements and magnetometer measurements are synchronized, for example, to compensate for temperature drift, phase shift, and attenuation of the measurements, and / or distortions caused by magnetic interference. The corrected / synchronized measurements are then used to calculate desired wellbore survey parameters, such as wellbore inclination, wellbore azimuth, and / or dip angle. The advantageous embodiments disclosed herein can be used with such continuous survey measurements.

[0031] The survey tool 80 also includes an electronic controller 85. A suitable controller 85 can include, for example, a programmable processor such as a digital signal processor or other microprocessor or microcontroller and a processor-readable or computer-readable program code embodying logic. For example, the controller can be utilized to automatically perform certain steps in the method embodiments described in more detail below with respect to the accompanying equations. For example, the controller can be configured to cause the tri-axial accelerometer set 90 and the tri-axial magnetometer set 95 to take corresponding accelerometer and magnetometer measurements while the survey tool 80 is rotating in the wellbore to detect sensor degradation or sensor failure, correct faulty sensor measurements, and calculate wellbore survey parameters from the corrected sensor measurements. Figures 3-6

[0032] A suitable controller 85 can also optionally include other controllable components such as other sensors, data storage devices, power sources, timers, etc. The controller 85 is typically provided in electronic communication with the accelerometers 90 and the magnetometers 95, and can also optionally be in communication with other instruments in the drill string, such as a telemetry system that communicates with the surface. A suitable controller can further optionally include volatile or non-volatile memory or data storage devices.

[0033] Figure 3 A flowchart depicting one example method 100 for diagnosing and correcting navigation sensor failures (e.g., accelerometer failures or temperature sensor failures) is depicted. The disclosed method includes surveying a wellbore (e.g., taking wellbore survey measurements while rotating a survey tool in the wellbore during a drilling operation) at 102. As described above, the measurements can be taken, for example, by taking tri-axial accelerometer and magnetometer measurements using corresponding accelerometer and magnetometer sets deployed in a rotating MWD or RSS tool. A sensor failure detection algorithm can be run concurrently with the wellbore survey measurements at 104. When no sensor failures are detected, the drilling and survey operations can continue as planned (e.g., at 102). In the event of a sensor failure, the faulty sensor measurements can be corrected in real-time during the survey operations at 106. Then, at 108, the desired survey parameters (e.g., wellbore inclination, wellbore azimuth, dip angle, etc.) can be calculated using the corrected sensor measurements. Then, at 110, the survey operations can continue uninterrupted with the corrected sensor measurements.

[0034] Figure 4 ​A flowchart depicting another example method 120 for diagnosing and correcting navigation sensor faults (e.g., accelerometer faults or temperature sensor faults) is depicted. The method 120 is similar to the method 100 in that the wellbore survey measurements are taken at 122 while drilling (e.g., deterministic dynamic survey in the depicted example). A fault detection algorithm 124 is run concurrently with the wellbore survey operations, and utilizes the computed survey parameters (taken at 122) and the field references at 126. As described in more detail below with respect to one example embodiment, the fault detection algorithm can compare the total gravity field and inclination measurements taken at 122 with the corresponding field references at 126. The fault detection algorithm can be configured to detect one or more of, for example, accelerometer faults (such as x-axis, y-axis, or z-axis accelerometer faults) or temperature sensor faults (such as magnetometer temperature sensor faults, x-axis, y-axis, or z-axis accelerometer temperature sensor and / or analog-to-digital controller (ADC) temperature sensor faults).

[0035] With continued reference to Figure 4 , the detection of a sensor fault can trigger one or more of several actions. For example, a sensor fault alert can be transmitted uphole to a field engineer 128, who in turn can manually trigger a sensor correction algorithm 130. In another embodiment, the sensor fault can automatically trigger 132 the correction algorithm 130 (with an alert sent to the field engineer 128). The sensor correction algorithm 130 can be configured to correct the faulty sensor measurements to obtain corrected sensor measurements, which in turn can be used to compute the desired wellbore survey parameters at 134 (e.g., wellbore inclination, wellbore azimuth, magnetic inclination, etc.).

[0036] It will be appreciated that, although not shown, the computation of the desired wellbore survey parameters at 134 can also include compensating the tri-axial accelerometer measurements and the tri-axial magnetometer measurements. The compensation can advantageously be performed after the measured values (including the corrected accelerometer measurements, when applicable) are digitized. The compensation can include, for example, removing first and second time lags introduced by the corresponding accelerometer electronics and magnetometer electronics that communicate with the accelerometers and magnetometers. The temperature measurements taken at 122 (including the corrected accelerometer measurements, when applicable) can be used to remove the first and second time lags. The compensation can also include removing a time lag from the cross-axial magnetometer measurements that is caused by eddy currents induced in the tool collar by rotation in the earth’s magnetic field. The eddy current time lag can be estimated from known characteristics of the tool collar, or can alternatively be measured by rotating the collar at different rates. Suitable compensation techniques are disclosed in commonly-assigned U.S. Patents 11,692,432 and 12,123,297.

[0037] Turning now toFigure 5 A flowchart of an example method 200 for detecting accelerometer sensor malfunctions is depicted. As depicted, at 202, tilt angle and total gravity measurements are calculated based on triaxial accelerometer and triaxial magnetometer measurements taken during exploration / drilling. For example, tilt angle... and total gravity The following can be calculated:

[0038]

[0039]

[0040] in This indicates the accelerometer measurement value. This indicates the magnetometer measurement value.

[0041] and angle Let represent the angle between the gravitational field vector and the magnetic field vector in the yz plane, such that:

[0042]

[0043] The tilt error can be obtained by calculating the absolute value of the difference between at least one of the calculated tilt angle and total gravity and the corresponding reference value. and total gravity error When one or both of the error signals ( and / or When the value exceeds the corresponding threshold at 204, it indicates an accelerometer sensor error, for example, as given in equations (3) and (4) below.

[0044]

[0045]

[0046] Unrestricted example thresholds in Figure 5 The value is given at position 204. When two error signals ( and / or When all values ​​are less than the corresponding threshold, the sensor is considered fully operable, and no correction is applied to the survey measurements.

[0047] Upon detecting an accelerometer sensor fault at 204, the method 200 next determines which accelerometer is faulty (i.e., identifies the faulty accelerometer). The x-axis accelerometer is evaluated at 206. The y-axis accelerometer is evaluated at 208. And the z-axis accelerometer is evaluated at 210. In an exemplary embodiment, each accelerometer measurement in the tri-axial measurement set can be back-calculated from the other two accelerometer measurements in the tri-axial measurement set and the total gravity reference. For example, the back-calculated accelerometer measurements for the x-axis, y-axis, and z-axis accelerometers , , may be calculated as follows:

[0048]

[0049]

[0050]

[0051] The back-calculated x-axis, y-axis, or z-axis accelerometer measurements can then be used to calculate the tilt error , , for example, as follows:

[0052]

[0053]

[0054]

[0055] where represents the reference tilt (e.g., in the local oilfield in which the survey measurements are being taken), and , , and is given as follows:

[0056]

[0057]

[0058]

[0059]

[0060] The faulty sensor can then be identified from , , for example, as follows:

[0061]

[0062] The tilt error with the smallest error corresponds to a faulty sensor (i.e., the smallest tilt error identifies a faulty accelerometer). For example, at 212, equation (11) indicates that an x-axis accelerometer fault when is the smallest of the three, indicates that a y-axis accelerometer fault when is the smallest of the three, and indicates that a z-axis accelerometer fault when is the smallest of the three.

[0063] Referring again to Figure 3 and Figure 4 , the fault detection algorithm can also be constructed to detect temperature sensor faults. It will be appreciated that downhole survey tool deployments typically include multiple analog temperature sensors. While there is a temperature gradient within the tool, these multiple temperature sensors should in principle measure similar temperatures (e.g., within a few degrees) given that they are in relatively close proximity to one another. Thus, in example embodiments, a temperature sensor fault can be indicated when the difference between a temperature sensor measurement and the average (or weighted average) output of selected ones of the other temperature sensors exceeds a threshold. Thus, for example, a fault of a first temperature sensor can be indicated when the difference between the output of the first temperature sensor and the average output of the other relevant temperature sensors (e.g., the average output of the second, third, fourth, and fifth temperature sensors) exceeds a threshold, such as 5 degrees Celsius, 10 degrees Celsius, or 15 degrees Celsius. This can be mathematically expressed, for example, as follows:

[0064]

[0065] It will be appreciated that accelerometer fault detection can be enhanced by associating sensor fault hypotheses with corresponding accelerometer temperature sensor measurements. For example, a fault of an x-axis accelerometer temperature sensor can further confirm an x-axis accelerometer fault. Likewise, a y-axis or z-axis accelerometer temperature sensor fault can further confirm a corresponding y-axis or z-axis accelerometer fault.

[0066] Figure 6 An example sensor correction block for x-axis, y-axis, and z-axis accelerometer corrections is depicted, where x-axis accelerometer corrections are indicated at 220, y-axis accelerometer corrections are indicated at 230, and z-axis accelerometer corrections are indicated at 240. At 220, when an x-axis accelerometer fault is indicated, the x-axis accelerometer measurement (computed from the y-axis and z-axis accelerometer measurements) can be corrected. The x-axis accelerometer correction may be given, for example, as follows:

[0067]

[0068] in, and As defined above. Note that in equation (12), the total gravity can be referenced. and triaxial accelerometer measurements The calibrated axial accelerometer measurement is calculated using the cross-axis accelerometer measurement. .

[0069] At point 230, when a y-axis accelerometer malfunction is indicated, the y-axis accelerometer measurement can be corrected (e.g., calculated based on the x-axis accelerometer measurement and the y-axis and z-axis magnetometer measurements). Y-axis accelerometer calibration. For example, it can be given as follows:

[0070]

[0071] in:

[0072]

[0073]

[0074] as well as This indicates the relative position of the y-axis with respect to the transverse magnetic field (which can be calculated from the cross-axis measurements in the triaxial magnetometer readings), and This represents the previous (e.g., most recent) angle between the gravity and magnetic field vectors in the interaxial plane (e.g., the yz plane using instantaneous coordinate conventions). value.

[0075] At point 240, when a fault is indicated in the z-axis accelerometer, the z-axis accelerometer measurement can be corrected (e.g., calculated based on the x-axis accelerometer measurement and the y-axis and z-axis magnetometer measurements). Z-axis accelerometer calibration. For example, it can be given as follows:

[0076]

[0077] in, , ,and As defined above. Note that in equations (13) and (14), the corrected cross-axis accelerometer measurements... and The total reference gravity, the axial measurement from the triaxial accelerometer, and the cross-axis measurement from the triaxial magnetometer (which are used to calculate) can be used to calculate... The previously measured angular values ​​between the gravity and magnetic field vectors in the cross-axis plane and the angle between them. To calculate.

[0078] It will be appreciated that certain DDS variables (dynamic survey variables) can be calculated using corrected y-axis or z-axis accelerometer measurements. Such DDS variables can include, for example, the lateral gravity field and the cosine or sine of angle X. For example, when the y-axis accelerometer measurement is corrected:

[0079]

[0080] Likewise, when the z-axis accelerometer measurement is corrected:

[0081]

[0082] These dynamic survey variables can be used to calculate various wellbore survey parameters, for example, as described in commonly-assigned U.S. Patent 11,692,432.

[0083] Referring again to Figure 3 and Figure 4 a detected temperature sensor failure can be corrected, for example, by calculating an average or weighted average of selected other (healthy) temperature sensors. This can be mathematically expressed, for example, as follows:

[0084]

[0085] It will be appreciated that the methods described herein can be configured to be implemented via one or more controllers deployed downhole (e.g., in a MWD tool or RSS tool). Suitable controllers can include, for example, programmable processors such as digital signal processors or other microprocessors or microcontrollers and processors readable or computer readable program code embodying logic. For example, the method embodiments (or various steps of the method embodiments) described above with respect to Figures 3-6 and the accompanying equations can be executed with a suitable processor. Suitable controllers can also optionally include other controllable components such as other sensors, data storage devices, power sources, timers, etc. The controllers can also be configured to be in electronic communication with the accelerometers and magnetometers. Suitable controllers can also optionally be in communication with other instruments in the drill string, for example, a telemetry system that communicates with the surface. Suitable controllers can further optionally include volatile or non-volatile memory or data storage devices.

[0086] As described above, the disclosed methods can be implemented automatically. For example, the sensor fault detection methods can run automatically in the background, with corresponding sensor corrections implemented automatically only when a sensor fault is detected. The disclosed embodiments can also include an automated system or tool, such as a MWD tool or an RSS tool, configured for making wellbore survey measurements and for automatically detecting and correcting sensor faults, as described above. The system can include computer hardware and software configured to perform the automatic detection and correction routines. The hardware can include one or more processors (e.g., microprocessors) that can be connected to a data storage device (e.g., a hard drive or solid state memory) and a user interface. The software can include processor-executable instructions stored in the data storage device and / or firmware. The disclosed embodiments are of course not limited to the use or configuration of any particular computer hardware and / or software.

[0087] While downhole health monitoring of survey sensors has been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A method for surveying wellbores, comprising: A wellbore exploration tool is rotated within the wellbore. The wellbore exploration tool includes multiple magnetometers, multiple accelerometers, and multiple temperature sensors. When the exploration tool rotates in the wellbore, magnetometer measurements, accelerometer measurements, and temperature measurements are performed. The fault sensor is automatically detected based on the accelerometer measurement value or the temperature measurement value, wherein the fault sensor includes at least one of the plurality of accelerometers and the plurality of temperature sensors; The corrected sensor measurement value for the faulty sensor is calculated based on the selected measurement value from the magnetometer measurement value, accelerometer measurement value, and temperature measurement value. and Use calibrated sensor measurements to calculate at least one of the wellbore inclination or wellbore azimuth.

2. The method according to claim 1, wherein: The fault sensor is at least one of the plurality of temperature sensors; and Automatic fault detection of a sensor includes (i) calculating the difference between the temperature output of a selected temperature sensor among the plurality of temperature sensors and the average value of a selected other temperature sensor among the plurality of temperature sensors, and (ii) detecting a faulty temperature sensor when the absolute value of one of the differences exceeds a threshold.

3. The method of claim 2, wherein the corrected sensor measurement is equal to the average output of the other selected temperature sensors among the plurality of temperature sensors.

4. The method according to claim 1, wherein the magnetometer measurement value includes a triaxial magnetometer measurement value, and the accelerometer measurement value includes a triaxial accelerometer measurement value.

5. The method according to claim 4, wherein: Triaxial accelerometer measurements were performed using a triaxial accelerometer array that included the first, second, and third triaxial accelerometers. Triaxial magnetometer measurements were performed using a triaxial magnetometer group that included the first, second, and third triaxial magnetometers. and The plurality of temperature sensors include at least a first, second, and third temperature sensor configured to measure the temperature of each of the corresponding first, second, and third triaxial accelerometers, a fourth temperature sensor configured to measure the temperature of the triaxial magnetometer, and a fifth temperature sensor configured to measure the temperature of the analog-to-digital controller.

6. The method of claim 4, wherein the automatic fault detection sensor further comprises: Automatically detects faulty accelerometers; and Automatically identify faulty accelerometers from the plurality of accelerometers.

7. The method of claim 6, wherein the automatic fault detection accelerometer further comprises: Calculate the tilt angle or total gravity based on the measurements from the triaxial magnetometer or the triaxial accelerometer. Calculate the first difference between the tilt angle and the reference tilt angle, or the second difference between the total gravity and the reference total gravity; and When the first difference or the second difference exceeds the corresponding threshold, the faulty accelerometer is detected.

8. The method of claim 6, wherein the automatic fault-identifying accelerometer further comprises: Calculate the inverse x-axis, y-axis, and z-axis accelerometer measurements; The first, second, and third tilt angles are calculated using the corresponding inversely calculated x-axis, y-axis, and z-axis accelerometer measurements; and The smallest tilt angle is selected from the first tilt angle, the second tilt angle, and the third tilt angle to identify the faulty accelerometer.

9. The method of claim 4, wherein the calibrated sensor measurements include calibrated axial accelerometer measurements calculated based on a reference total gravity and a cross-axis accelerometer measurement from the triaxial accelerometer measurements.

10. The method of claim 4, wherein the calibrated sensor measurements include calibrated cross-axis accelerometer measurements, which are calculated based on a reference total gravity, the axial accelerometer measurements from the triaxial accelerometer measurements, the cross-axis accelerometer measurements from the triaxial magnetometer measurements, and a previously measured angle X between the gravity vector and the magnetic field vector in the cross-axis plane.

11. A downhole tool, comprising: The downhole tool body is configured to rotate together with the drill string; A triaxial accelerometer assembly, a triaxial magnetometer assembly, and multiple temperature sensors are deployed in the main body of the tool. and The processor is configured to (i) cause the triaxial accelerometer group, the triaxial magnetometer group, and the plurality of temperature sensors to perform corresponding measurements as the downhole tool rotates in the wellbore, (ii) automatically detect a faulty accelerometer or a faulty temperature sensor from the accelerometer measurements or temperature sensor measurements, (iii) calculate a corrected accelerometer or temperature measurement when a faulty accelerometer or temperature sensor is detected, and (iv) use the corrected accelerometer or temperature sensor measurements to calculate at least one of the wellbore inclination or wellbore azimuth.

12. The downhole tool according to claim 11, wherein: The fault sensor is at least one of the plurality of temperature sensors; Automatic detection of the faulty temperature sensor includes (i) calculating the difference between the temperature output of a selected temperature sensor among the plurality of temperature sensors and the average value of the other selected temperature sensors among the plurality of temperature sensors, and (ii) detecting the faulty temperature sensor when the absolute value of one of the differences exceeds a threshold. and The calibrated sensor measurements are set to be equal to the average output of the other selected temperature sensors among the plurality of temperature sensors.

13. The downhole tool of claim 11, wherein the automatic fault detection accelerometer further comprises: Calculate the tilt angle or total gravity based on the measurements from the triaxial magnetometer or the triaxial accelerometer. Calculate the first difference between the tilt angle and the reference tilt angle, or the second difference between the total gravity and the reference total gravity; When the first difference or the second difference exceeds the corresponding threshold, the faulty accelerometer is detected; Calculate the inverse x-axis, y-axis, and z-axis accelerometer measurements; The first, second, and third tilt angles are calculated using the corresponding inversely calculated x-axis, y-axis, and z-axis accelerometer measurements; and The smallest tilt angle is selected from the first, second, and third tilt angles to identify the faulty accelerometer.

14. The downhole tool of claim 11, wherein the calibrated accelerometer measurements include calibrated axial accelerometer measurements calculated based on a reference total gravity and cross-axis accelerometer measurements of the triaxial accelerometer measurements.

15. The downhole tool of claim 11, wherein the calibrated sensor measurements include calibrated cross-axis accelerometer measurements calculated based on a reference total gravity, one axial accelerometer measurement from the triaxial accelerometer measurements, the other cross-axis accelerometer measurement, and the triaxial magnetometer measurement.

16. A method for surveying a wellbore, comprising: Drilling is performed by rotating a drill string in a wellbore, the drill string including a triaxial accelerometer assembly and a triaxial magnetometer assembly, the triaxial magnetometer assembly being deployed in a tool body that rotates with the drill string; The triaxial accelerometer group and the triaxial magnetometer group are used to perform corresponding triaxial accelerometer measurements and triaxial magnetometer measurements while rotating; While performing the triaxial accelerometer measurement and the triaxial magnetometer measurement, the faulty accelerometer in the triaxial accelerometer group is automatically detected; The corrected accelerometer measurement value for the faulty accelerometer is calculated based on the selected measurement value from the triaxial accelerometer measurement value and the triaxial magnetometer measurement value; and Use calibrated sensor measurements to calculate at least one of the wellbore inclination or wellbore azimuth.

17. The method of claim 16, wherein automatically detecting the faulty accelerometer further comprises: Calculate the tilt angle or total gravity based on the measurements from the triaxial magnetometer or the triaxial accelerometer. Calculate the first difference between the tilt angle and the reference tilt angle, or the second difference between the total gravity and the reference total gravity; and When the first difference or the second difference exceeds the corresponding threshold, the faulty accelerometer is detected.

18. The method of claim 17, wherein automatically detecting the faulty accelerometer further comprises: Calculate the inverse x-axis, y-axis, and z-axis accelerometer measurements; The first, second, and third tilt angles are calculated using the corresponding inversely calculated x-axis, y-axis, and z-axis accelerometer measurements; and Select the smallest tilt angle from the first, second, and third to identify the faulty accelerometer.

19. The method of claim 16, wherein the calibrated accelerometer measurements include calibrated axial accelerometer measurements calculated based on a reference total gravity and cross-axis accelerometer measurements of the triaxial accelerometer measurements.

20. The method of claim 16, wherein the calibrated accelerometer measurements include calibrated cross-axis accelerometer measurements calculated based on a reference total gravity, axial acceleration measurements from the triaxial accelerometer measurements, cross-axis magnetometer measurements from the triaxial magnetometer measurements, and a previously measured angle X between the gravity vector and the magnetic field vector in the cross-axis plane.

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