DOWNHOLE CALIPER SYSTEM AND METHOD

Description

BACKGROUND

This disclosure relates to systems and methods for a downhole caliper system used in wellbores.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as an admission of any kind.

During the process of extracting hydrocarbons from drilled wells, measurements of one or more characteristics of a well fluid may be obtained using a caliper system. One method of using a caliper system to obtain well fluid measurements involves extending a set of calipers from a tool string such that the calipers contact an inner surface of the wellbore. Unfortunately, this method limits the caliper system to take measurements when the tool string is traveling in one direction through the wellbore. Accordingly, a system for enabling the tool string to receive measurements bi-directionally is desired.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In certain embodiments, a system includes a tool string and a caliper assembly. The caliper assembly includes one or more first calipers rotably coupled to the tool string. The one or more first calipers are circumferentially arrayed about a longitudinal central axis of the tool string. The caliper assembly also includes one or more second calipers rotably coupled to the tool string. The one or more second calipers are circumferentially arrayed about the longitudinal central axis. The caliper assembly also includes a drive element disposed within the tool string and slidably coupled to the tool string. The one or more first calipers extend from the tool string in response to the drive element moving to a first position. The one or more second calipers extend from the tool string in response to the drive element moving to a second position.

In certain embodiments, a system includes a tool string, a caliper assembly, and a controller. The caliper assembly includes one or more first calipers rotably coupled to the tool string. The one or more first calipers are circumferentially arrayed about a longitudinal central axis of the tool string. The caliper assembly also includes one or more second calipers rotably coupled to the tool string. The one or more second calipers are circumferentially arrayed about the longitudinal central axis. The caliper assembly also includes a drive element disposed within the tool string and slidably coupled to the tool string. The controller includes a processor. The controller receives a first signal indicative of a first distance of a first extension of the one or more first calipers. The controller also determines an estimated first distance of the first extension of the one or more first calipers based on the first signal. The one or more first calipers extend from the tool string in response to the drive element moving to a first position. The one or more second calipers extend from the tool string in response to the drive element moving to a second position.

In certain embodiments, a method includes placing a tool string in a wellbore of a well. The method also includes extending a set of first calipers from the tool string. The method also includes lowering the tool string through the wellbore while the set of first calipers is extended. The method also includes retracting the set of first calipers into the tool string. The method also includes extending a set of second calipers from the tool string. The method also includes raising the tool string through the wellbore while the set of second calipers is extended.

Various refinements of the features noted above may be undertaken in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is a schematic diagram of a well system having a downhole caliper system, in accordance with an embodiment of the present disclosure;

FIG. 2 is a flowchart of an example process of operating the downhole caliper system of FIG. 1, in accordance with an embodiment of the present disclosure;

FIG. 3 is a side view of different configurations of the downhole caliper system of FIG. 1, in accordance with an embodiment of the present disclosure;

FIG. 4 is a side cross-sectional view of the downhole caliper system showing a first set of calipers in a radially extended position, in accordance with an embodiment of the present disclosure;

FIG. 5 is a side cross-sectional view of the downhole caliper system showing a second set of calipers in a radially extended position, in accordance with an embodiment of the present disclosure;

FIG. 6 is a side cross-sectional view of the downhole caliper system showing the first set of calipers in a radially retracted position and the second set of calipers in a radially retracted position, in accordance with an embodiment of the present disclosure;

FIG. 7 is a side schematic view of a measurement system for measuring a distance of an extension of a first caliper of the first set of calipers and/or a corresponding second caliper of the second set of calipers, in accordance with an embodiment of the present disclosure; and

FIG. 8 is a series of side schematic views showing different configurations of a sensor of the measurement system of FIG. 7, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Certain embodiments commensurate in scope with the present disclosure are summarized below. These embodiments are not intended to limit the scope of the disclosure, but rather these embodiments are intended only to provide a brief summary of certain disclosed embodiments. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

As used herein, the term “coupled” or “coupled to” may indicate establishing either a direct or indirect connection (e.g., where the connection may not include or include intermediate or intervening components between those coupled), and is not limited to either unless expressly referenced as such. The term “set” may refer to one or more items. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

Furthermore, when introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment,” “an embodiment,” or “some embodiments” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, unless expressly stated otherwise, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B.

Embodiments of the present disclosure relate to systems and methods for a downhole caliper system lowered into wellbores for one or more measurements in from within the wellbore. For example, the downhole caliper system includes a first set of calipers that extend from a tool string when the tool string travels in a first direction (e.g., uphole direction, downhole direction) through the wellbore. The downhole caliper system additionally includes a second set of calipers that extends when the tool string travels in a second direction (e.g., downhole direction, uphole direction) opposite the first direction through the wellbore. Additionally, the downhole caliper system includes a measurement system that includes one or more sensors that receive signals from the first set of calipers and/or the second calipers. The controller may determine one or more first extension distances of the first set of calipers and/or one or more second extension distances of the second set of calipers based on the received signals.

With the foregoing in mind, FIG. 1 is a schematic diagram of a well system 10 having a downhole caliper system 12. The well system 10 may be used to convey a tool string 13 of the downhole caliper system 12 and a caliper assembly 14 of the downhole caliper system 12 through a geological formation 15 via a wellbore 16. In certain embodiments, a casing 18 may be disposed within the wellbore 16, such that the tool string 13 and the caliper assembly 14 may traverse the wellbore 16 within the casing 18. As described in further detail herein, the caliper assembly 14 may be used to make one or more measurements within the wellbore 16. The tool string 13 and the caliper assembly 14 may be conveyed on a conveyance cable 20 via a conveyance cable spooling system 22. Although the conveyance cable spooling system 22 is schematically shown in FIG. 1 as a mobile cable spooling system carried by a truck, the conveyance cable spooling system 22 may instead be substantially fixed (e.g., a long-term installation that is substantially permanent or modular). Any conveyance cable 20 suitable for conveying the tool string 13 and the caliper assembly 14 may be used. The conveyance cable 20 may be spooled and unspooled on a spool 24 and an auxiliary power source 26 may provide energy to the conveyance cable spooling system 22, the tool string 13, and/or the caliper assembly 14.

In certain embodiments, the downhole caliper system 12 may include a controller 28 via any suitable telemetry (e.g., via electrical or optical signals pulsed through the conveyance cable 20, or through the geological formation 15 or via mud pulse telemetry). The controller 28 may be any electronic data processing system that can be used to carry out the functionality described herein. For example, the controller 28 may include one or more processors 30, which may execute instructions 32 stored in memory 34 via circuitry 36. As such, the memory 34 of the controller 28 may be any suitable article of manufacture that can store the instructions 32. The memory 34 may be ROM memory, random-access memory (RAM), flash memory, an optical storage medium, or a hard disk drive, to name a few examples.

FIG. 2 is a flowchart of an example process 60 of operating the downhole caliper system of FIG. 1. The process 60 may be performed by the controller 28 of FIG. 1. Additionally or alternatively, the process 60 may be performed any other suitable computing device(s) or controller(s). Furthermore, the blocks of the process 60 may be performed in the order disclosed herein or in any other suitable order. For example, certain blocks of the process 60 may be performed concurrently. In addition, in certain embodiments, at least one of the blocks of the process 60 may be omitted.

In block 62 of the process 60, the tool string having the caliper system is lowered into a wellbore of a well. As discussed herein, the tool string may be lowered via a conveyance cable suitable for conveying the tool string and the caliper assembly through the wellbore. The conveyance cable may be spooled or unspooled. Additionally or alternatively, the conveyance cable may include electrical, pneumatic, and/or fluid connections.

In block 64 of the process 60, the controller 28 controls a first set of calipers (e.g., fingers) to extend from the tool string. As discussed herein, the first set of calipers may protrude radially outward from an outer housing of the tool string into the wellbore of the well. In certain embodiments, the controller 28 controls an actuator that causes the outward radial extension of the first set of calipers. In certain embodiments, the first set of calipers are extended such that an end portion of the first set of calipers contact an inner surface of casing lining the wellbore.

In block 66 of the process 60, the tool string is lowered through the wellbore while the first set of calipers is radially extended (e.g., radially protruded) from the outer surface of the housing of the tool string. In certain embodiments, the end portions of the first set of calipers contact the inner surface of the casing while the tool string is lowered through the wellbore. The controller 28 may measure a deflection of one or more of the first set of calipers in order to identify and/or measure a state of the casing of the wellbore. For example, based on movement (e.g., extension and/or retraction) of the first set of calipers, the controller 28 may identify and/or measure a corrosion of the casing, a residue buildup deposited inside the casing, casing deformation, and the like.

In block 68 of the process 60, the controller 28 causes the first set of calipers to retract (e.g., into the tool string). Additionally, the controller 28 causes a second set of calipers to radially extend from the tool string. In certain embodiments, the controller causes the second set of calipers to radially extend as the first set of calipers radially retract. As with the first set of calipers, in certain embodiments, the second set of calipers may extend until a portion of the second set of calipers contacts the inner surface of the casing of the wellbore.

In block 70 of the process 60, the tool string is raised though the wellbore while the second set of calipers is extended. In certain embodiments, the end portions of the second set of calipers contact the inner surface of the casing while the tool string is raised through the wellbore. The controller 28 may measure a deflection of one or more of the second set of calipers in order to identify and/or measure a state of the casing of the wellbore. For example, based on movement (e.g., extension and/or retraction) of the second set of calipers, the controller 28 may identify and/or measure a corrosion of the casing, a residue buildup deposited inside the casing, casing deformation, and the like. It may be appreciated that the first set of calipers and the second set of calipers may enable the tool string to bi-directionally measure the state of the wellbore. That is, the caliper system may enable the measurement of the state of the wellbore as the tool string is lowered in the wellbore, as well as raised through the wellbore, thereby enabling more measurements to be logged in a shorter distance of travel of the tool string.

FIG. 3 is a series of side views of different configurations of the downhole caliper system 12 of FIG. 1. As shown, the views 90, 92, and 94 may be described in relation to a radial direction or axis 96, a downhole direction or axis 98, and a circumferential direction or axis 100. As shown, the downhole caliper system 12 includes the tool string 13. In the illustrated embodiment, the tool string 13 includes a first tool string section 102 and a second tool string section 104 coupled via a connector portion 106. Additionally, the tool string 13 includes an electronics section 108 which may house sensors, actuators, the controller, or a combination thereof. The down hole caliper system 12 includes the caliper assembly 14, which includes a first set of calipers 110 (e.g., first set of fingers) having one or more first calipers 112 (e.g., one or more first fingers) as well as a second set of calipers 114 (e.g., second set of fingers) having one or more second calipers 116 (e.g., one or more second fingers). As shown, the first set of calipers 110 extend from the first tool string section 102, and the second set of calipers 114 extend from the second tool string section 104.

In the view 90, both the first set of calipers 110 and the second set of calipers 114 are retracted into the tool string 13. As shown, the one or more first calipers 112 and the one or more second calipers 116 are retracted in recesses 118 formed into an outer housing 120 of the tool string 13. As shown, the one or more first calipers 112 and the one or more second calipers 116 are circumferentially arrayed about a longitudinal central axis 122 of the tool string 13, and the second set of calipers 114 is disposed in the downhole direction 98 relative to the first set of calipers 110.

In the view 92, the first set of calipers 110 are radially extended (e.g., protruded) from the outer housing 120 of the tool string 13. As shown, the one or more first calipers 112 of the first set of calipers 110 are rotably coupled to the tool string 13 at first downhole end portions 124 of the one or more first calipers 112, such that first uphole end portions 126 of the one or more first calipers 112 extend radially outward from the tool string 13. As shown, the one or more first calipers 124 have first contact portions 128 disposed at the first uphole end portions 126. The first contact portions 128 may contact the casing of the wellbore when the one or more first calipers 112 are extended. Additionally, the one or more first calipers 112 include first spring portions 130 and first hooked portions. As described in further detail herein, the first spring portions 130 may at least partially cause the first set of calipers 110 to extend from the outer housing 120 of the tool string 13.

In the view 94, the second set of calipers 114 are radially extended (e.g., protruded) from the outer housing 120 of the tool string 13. As shown, the one or more second calipers 116 of the second set of calipers 114 are rotably coupled to the tool string 13 at second uphole end portions 132 of the one or more second calipers 116, such that second downhole end portions 134 of the one or more second calipers 116 extend radially outward from the tool string 13. As shown, the one or more second calipers 116 have second contact portions 136 disposed at the second downhole end portions 134. The second contact portions 136 may contact the casing of the wellbore when the one or more second calipers 116 are extended. Additionally, the one or more second calipers 116 include second spring portions 138 and second hook portions. As described further herein, the second spring portions 138 may at least partially cause the extension of the one or more second calipers 116 from the outer housing 120 of the tool string 13. As shown, the one or more first calipers 112 rotate relative to the tool string 13 in a first direction of rotation, and the one or more second calipers 116 rotate relative to the tool string 13 in a second direction of rotation, such that the first direction of rotation is opposite the second direction of rotation.

FIG. 4 is a side cross-sectional view of the downhole caliper system 12 showing the first set of calipers 110 in a radially extended position 160. In the illustrated embodiment, the tool string 13 includes a bar 162 (e.g., drive element) disposed in an interior 164 of the tool string 13. As shown, the bar 162 is slidably coupled to the tool string 13 such that the bar 162 slides along a longitudinal direction 166 of the tool string 13. The bar 162 includes a recess 168 (e.g., annular recess, longitudinal recess) formed into an outer radial surface 170 of the bar 162. As shown, the tool string 13 includes an actuator 172 coupled to the bar 162. The actuator 172 is communicatively coupled to the controller 28 such that the controller 28 may control movement of the bar 162 within the tool string 13.

In the illustrated embodiment, the bar 162 is in an uphole position 174 (e.g., first position). As shown, the first set of calipers 110 extend radially outward from the tool string 13 in response to the bar 162 moving to (e.g., reaching, being in) the uphole position 174. Additionally or alternatively, the second set of calipers 114 radially retract into the outer housing 120 of the tool string 13 in response to the bar 162 moving to the uphole position 174.

In the illustrated embodiment, the first spring portions 130 contact inner surfaces 176 of the recesses 118. As shown, in response to the bar 162 sliding into the uphole position 174, first hook portions 131 of the one or more first calipers 112 move (e.g., slide) into the recess 168 formed into the bar 162, thereby causing extension of the first set of calipers 110 due to the first spring portions 130 pressing against the tool string 13. Additionally or alternatively, in response to the bar 162 sliding into the uphole position 174, the second hook portions 139 of the one or more second calipers 116 press against an outer radial surface 178 of a downhole sleeve 180 disposed in the recess 168. The second spring portions 138 exert a moment on the one or more second calipers 116 in a circumferential direction 180 about one or more second pivots 182 that rotably couple the one or more second calipers 116 to the tool string 13.

FIG. 5 is a side cross-sectional view of the downhole caliper system 12 showing the second set of calipers 114 in a radially extended position. In the illustrated embodiment, the bar 162 is in a downhole position 200 (e.g., second position). As shown, the first set of calipers 110 are retracted into the recesses 118 formed into the outer housing 120 of the tool string 13 in response to the bar 162 moving to (e.g., reaching, being in) the downhole position 200. Additionally or alternatively, the second set of calipers 114 are radially extended from (e.g., out of) the outer housing 120 of the tool string 13 in response to the bar 162 moving to the downhole position 200.

In the illustrated embodiment, the second spring portions 138 contact inner surfaces 202 of the recesses 118. As shown, in response to the bar 162 sliding into the downhole position 200, the second hook portions 139 of the one or more second calipers 116 move (e.g., slide) into the recess 168 formed into the bar 162, thereby causing extension of the second set of calipers 114 due to the second spring portions 138 pressing against the tool string 13. Additionally or alternatively, in response to the bar 162 sliding into the downhole position 200, the first hook portions 131 of the one or more first calipers 112 press against an outer radial surface 204 of an uphole sleeve 206 disposed in the recess 168. The first spring portions 130 exert a moment on the one or more first calipers 112 in a circumferential direction 208 about one or more first pivots 210 that rotably couple the one or more first calipers 112 to the tool string 13.

FIG. 6 is a side cross-sectional view of the downhole caliper system 12 showing the first set of calipers 110 in a radially retracted position and the second set of calipers 114 in a radially retracted position. In the illustrated embodiment, the bar 162 is in a central position 230 (e.g., third position). The central position 230 is located in the downhole direction 98 relative to the uphole position, and in an uphole direction 232 relative to the downhole position. As shown, the first set of calipers 110 are retracted into the recesses 118 formed into the outer housing 120 of the tool string 13 in response to the bar 162 moving to (e.g., reaching, being in) the central position 230. Additionally or alternatively, the second set of calipers 114 concurrently retract into the recesses 118 formed into the outer housing 120 of the tool string 13 in response to the bar 162 moving to (e.g., reaching, being in) the central position 230.

In the illustrated embodiment, the first spring portions 130 contact inner surfaces 176 of the recesses 118. As shown, in response to the bar 162 sliding into the central position 230, the first hook portions 131 of the one or more first calipers 112 press against an outer radial surface 204 of an uphole sleeve 206 disposed in the recess 168. The first spring portions 130 exert a moment on the one or more first calipers 112 in the circumferential direction 208 (e.g., opposite the circumferential direction 180) about one or more first pivots 210 that rotably couple the one or more first calipers 112 to the tool string 13.

Additionally or alternatively, in response to the bar 162 sliding into the central position 230, the second hook portions 139 of the one or more second calipers 116 press against the outer radial surface 204 of the second hook portions 139 of the one or more second calipers 116 press against the outer radial surface 178 of the downhole sleeve 180 disposed in the recess 168. The second spring portions 138 exert a moment on the one or more second calipers 116 in the circumferential direction 180 (e.g., opposite the circumferential direction 208) about one or more second pivots 182 that rotably couple the one or more second calipers 116 to the tool string 13.

FIG. 7 is a series of side schematic views (e.g., views 254, 256, and 258) of a measurement system 260 for measuring a distance of an extension of a first caliper 262 of the first set of calipers and/or a corresponding second caliper 264 of the second set of calipers. In the illustrated embodiment, the measurement system 260 includes a plunger 266, a plunger head 268, a sensor 270 (e.g., differential variable reluctance transducer [DVRT] sensor), and a spring 272. In the illustrated embodiment, the plunger 266 is slidably coupled to the sensor 270, and the plunger head 268 is disposed at a distal end 274 of the plunger 266. As shown, the spring 272 is coupled to both the first caliper 262 as well as the second caliper 264. In certain embodiments, the first caliper 262 is circumferentially aligned with the second caliper 264 in the circumferential direction 100 about the longitudinal central axis of the tool string. As shown, the plunger head 268 is coupled to the spring 272, such that the plunger 266 is indirectly coupled to the first caliper 262 and the second caliper 264.

As shown, when both the first caliper 262 and the second caliper 264 are retracted, the plunger head 268 is aligned along a radial axis 278 between the first caliper 262 and the second caliper 264. In response to an extension of the first caliper 262, the first caliper 262 pulls the plunger head 268 (e.g., end portion of the plunger 266) in the uphole direction 232 relative to the radial axis 278. Additionally or alternatively, in response to an extension of the second caliper 264, the second caliper 264 pulls the plunger head 268 (e.g., end portion of the plunger 266) in the downhole direction 98 relative to the radial axis 278.

As shown, the controller 28 is communicatively coupled to the sensor 270. The controller 28 receives a signal from the sensor indicative of a longitudinal position 279 (e.g., along the downhole direction 98) of the plunger head 268 relative to the radial axis 278. The controller 28 determines the longitudinal position 279 of the plunger head 268 based on the received signal. The controller 28 determines a first extension distance 280 of the first caliper 262, a second extension distance 282 of the second caliper 264, or a combination thereof based on the received signal and/or the determined longitudinal position 279 of the plunger head 268.

In certain embodiments, the controller 28 may determine whether the longitudinal position 279 of the plunger head 268 is uphole or downhole relative to the radial axis 278. In response to the longitudinal position 279 being uphole from the radial axis 278, the controller 28 determines the first extension distance 280 of the first extension of the first caliper 262. Additionally or alternatively, in response to the longitudinal position 279 being downhole from the radial axis 278, the controller 28 determines the second extension distance 282 of the second extension of the second caliper 264.

FIG. 8 is a series of side schematic views showing different configurations of the sensor 270 of the measurement system 260. In certain embodiments, the sensor 270 includes a magnetic core 300 coupled to the plunger. In the view 302, the magnetic core 300 is longitudinally centered with respect to the sensor 270, such that a first radial central axis 304 of the magnetic core 300 is aligned with a second radial central axis 306 of the sensor 270 when both the first set of calipers and the second set of calipers are retracted into the tool string.

As shown, when the first radial central axis 304 of the magnetic core 300 is longitudinally offset from the second radial central axis 306 of the sensor 270 in the uphole direction 232 (e.g., first set of calipers is radially extended from the tool string), a magnitude 308 of the signal 307 produced by the sensor 270 is above zero in the left region 309. In certain embodiments, the magnitude 308 is proportional to a position 310 (e.g., displacement) of the first radial central axis 304 relative to the second radial central axis 306. In the illustrated embodiment, when the first radial central axis 304 of the magnetic core 300 is longitudinally aligned with the second radial central axis 306 of the sensor 270 (e.g., first and second sets of calipers are both retracted into the tool string), the magnitude 308 of the signal 307 produced by the sensor 270 is near zero in a middle region 311. Additionally or alternatively, when the first radial central axis 304 of the magnetic core 300 is longitudinally offset from the second radial central axis 306 in the downhole direction 98 (e.g., second set of calipers is radially extended from the tool string), the magnitude 308 of the signal is above zero in the right region 313 and, in certain embodiments, proportional to the position 310 of the first radial central axis 304 relative to the second radial central axis 306. It may be appreciated that the configuration shown in the view 302 increases the range of acquisition, thereby increasing measurement accuracy.

In the view 312, the magnetic core 300 is longitudinally offset with respect to the sensor 270, such that the first radial central axis 304 is longitudinally offset from the second radial central axis 306 when both the first set of calipers and the second set of calipers are retracted into the tool string. As shown, when the first radial central axis 304 of the magnetic core 300 is longitudinally offset from the second radial central axis 306 of the sensor 270 in the uphole direction 232 (e.g., first set of calipers is radially extended from the tool string), a magnitude 308 of the signal produced by the sensor 270 is above zero in the left region 309. In certain embodiments, the magnitude 308 is proportional to a position 310 (e.g., displacement) of the first radial central axis 304 relative to the second radial central axis 306. Additionally or alternatively, when the first radial central axis 304 of the magnetic core 300 is longitudinally offset from the second radial central axis 306 in the downhole direction 98 (e.g., second set of calipers is radially extended from the tool string), the magnitude 308 of the signal is above zero in the right region 313 and, in certain embodiments, proportional to the position 310 of the first radial central axis 304 relative to the second radial central axis 306. As shown, the signal in the right region 313 is continuous with the signal in the left region 309. In the illustrated embodiment, when the first radial central axis 304 of the magnetic core 300 is longitudinally aligned with the second radial central axis 306 of the sensor 270 (e.g., first and second sets of calipers are both retracted into the tool string), the magnitude 308 of the signal produced by the sensor 270 has a nonzero magnitude at a location 314 between the left region 309 and the right region 313. It may be appreciated that the configuration shown in view 312 enables measurement outside of the middle region 311, which may give unpredictable measurements.

Technical effects include two sets of calipers that are rotably coupled to a tool string to be lowered into a wellbore. The first set of calipers rotates relative to the tool string in a first direction of rotation, and the second set of calipers rotates relative to the tool string in a second direction of rotation opposite the first direction of rotation. The first set of calipers is extended during a descent (e.g., or ascent) of the tool string through the wellbore, and the second set of calipers is extended during an ascent (e.g., or descent) of the tool string through the wellbore, thereby enabling the tool string to receive measurements while traveling bi-directionally through the wellbore. Additional technical effects include a measurement system that includes a sensor that receives a signal indicative of a first extension distance of a first caliper of the first set of calipers or a second extension distance of a second caliper of the second set of calipers. The configuration of the measurement system reduces the number of sensors for determining the extension distances of the first and second sets of calipers.

The subject matter described in detail above may be defined by one or more clauses, as set forth below.

According to a first aspect, a system includes a tool string and a caliper assembly. The caliper assembly includes one or more first calipers rotably coupled to the tool string. The one or more first calipers are circumferentially arrayed about a longitudinal central axis of the tool string. The caliper assembly also includes one or more second calipers rotably coupled to the tool string. The one or more second calipers are circumferentially arrayed about the longitudinal central axis. The caliper assembly also includes a drive element disposed within the tool string and slidably coupled to the tool string. The one or more first calipers extend from the tool string in response to the drive element moving to a first position. The one or more second calipers extend from the tool string in response to the drive element moving to a second position.

The system of the preceding clause, wherein the one or more second calipers are positioned in a downhole direction from the one or more first calipers.

The system of any preceding clause, wherein the drive element slides along a longitudinal direction of the tool string.

The system of any preceding clause, wherein the one or more second calipers retract into the tool string in response to the drive element moving to the first position, and the one or more first calipers retract into the tool string in response to the drive element moving to the second position.

The system of any preceding clause, wherein the one or more first calipers rotate relative to the tool string in a first direction of rotation, the one or more second calipers rotate relative to the tool string in a second direction of rotation, and the first direction of rotation is opposite to the second direction of rotation.

The system of any preceding clause, wherein the one or more first calipers retract into the tool string in response to the drive element moving to a third position, and the one or more second calipers concurrently retract into the tool string in response to the drive element moving to the third position.

The system of any preceding clause, wherein the second position is in the downhole direction from the first position, the third position is between the first position and the second position.

The system of any preceding clause, wherein the one or more first calipers include one or more hook portions that contact the drive element.

The system of any preceding clause, wherein the drive element includes a longitudinal recess formed into an outer surface of the drive element.

The system of any preceding clause, wherein the one or more first calipers include one or more spring portions that contact the tool string, wherein the one or more spring portions extend the one or more first calipers from the tool spring in response to the one or more hook portions moving into the longitudinal recess.

According to a second aspect, a system includes a tool string, a caliper assembly, and a controller. The caliper assembly includes one or more first calipers rotably coupled to the tool string. The one or more first calipers are circumferentially arrayed about a longitudinal central axis of the tool string. The caliper assembly also includes one or more second calipers rotably coupled to the tool string. The one or more second calipers are circumferentially arrayed about the longitudinal central axis. The caliper assembly also includes a drive element disposed within the tool string and slidably coupled to the tool string. The controller includes a memory and a processor. The controller receives a first signal indicative of a first distance of a first extension of the one or more first calipers. The controller also determines an estimated first distance of the first extension of the one or more first calipers based on the first signal. The one or more first calipers extend from the tool string in response to the drive element moving to a first position. The one or more second calipers extend from the tool string in response to the drive element moving to a second position.

The system of the preceding clause, wherein the one or more second calipers are positioned in a downhole direction from the one or more first calipers.

The system of any preceding clause, wherein the drive element slides along a longitudinal direction of the tool string.

The system of any preceding clause, wherein the controller receives a second signal indicative of a second distance of a second extension of the one or more second calipers; and determines an estimated second distance of the second extension of the one or more second calipers based on the second signal.

The system of any preceding clause, including: a plunger coupled to: a first caliper of the one or more first calipers; and a second caliper of the one or more second calipers; and a sensor that determines a longitudinal position of the plunger relative to a radial axis disposed between the first caliper and the second caliper.

The system of any preceding clause, wherein the first caliper pulls an end portion of the plunger in an uphole direction relative to the radial axis in response to the first extension of the first caliper, and the second caliper pulls the end portion of the plunger in a downhole direction relative to the radial axis in response to the second extension of the second caliper.

The system of any preceding clause, wherein the controller receives a third signal indicative of the longitudinal position of the plunger; and determine the first distance of the first extension of the first caliper, the second distance of the second extension of the second caliper, or a combination thereof based on the received third signal.

The system of any preceding clause, wherein the controller determines whether the longitudinal position is uphole from the radial axis or downhole from the radial axis; determines the first distance of the first extension of the first caliper in response to the longitudinal position being uphole from the radial axis; and determines the second distance of the second extension of the second caliper in response to the longitudinal position being downhole from the radial axis.

According to a third aspect, a method includes placing a tool string in a wellbore of a well. The method also includes extending a set of first calipers from the tool string. The method also includes lowering the tool string through the wellbore while the set of first calipers is extended. The method also includes retracting the set of first calipers into the tool string. The method also includes extending a set of second calipers from the tool string. The method also includes raising the tool string through the wellbore while the set of second calipers is extended.

The method of any preceding clause, including: receiving, via one or more processors, a signal indicative of a longitudinal position of a plunger disposed inside the tool string; and in response to receiving the signal: determining, via the one or more processors, a first distance of a first extension of a first caliper of the plurality of first calipers based on the signal; determining, via the one or more processors, a second distance of a second extension of a second caliper of the plurality of second calipers based on the signal; or a combination thereof.

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. Moreover, the order in which the elements of the methods described herein are illustrated and described may be re-arranged, and/or two or more elements may occur simultaneously. The embodiments were chosen and described in order to best explain the principals of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated.

Finally, the techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical.