Wireline depth counter and methods using same

Abstract

A depth counter for measuring depth of a wireline cable is disclosed. The depth counter includes a housing configured to receive a wireline cable therethrough along a first axis. An encoder wheel is rotatably coupled to the housing. The depth counter includes a first pair of idlers, one idler of the first pair of idlers positioned on each side of the encoder wheel. The first pair of idlers are movable relative to the housing along a second axis that is perpendicular to the first axis. The first pair of idlers are spring biased in a first direction along the second axis. The first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis. A second pair of idlers are configured to bias the wireline cable in a second direction, opposite the first direction, along the second axis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 619,787, filed January 11, 2024, the entirety of which is incorporated by reference herein. FIELD

[0002] This disclosure relates to systems and methods for measuring depth of a wireline tool. BACKGROUND

[0003] Conventionally, depth of a downhole tool of a wireline drilling system is determined by lowering the downhole tool with the wireline cable resting against a freely rotating wheel. A rotary encoder is coupled to the freely rotating wheel and measures angular rotation of the freely rotating wheel. The depth of the wireline tool is approximated by the diameter of the wheel and the number of rotations. However, the wireline cable can slip relative to the wheel, thereby rendering inaccurate measurements.

[0004] Further, FIG. 2 shows a conventional wireline depth counter 30, having a wheel 32 along which the cable passes. The conventional wireline depth counter 30 has a rotary encoder that is coupled to the wheel 32. The wireline depth counter 30 has two wheels 36, with one wheel 36 positioned on each side of the wheel 32. The wheels 36 bias the cable against the wheel 32. Because of this arrangement, an arc length of the cable is in contact with the wheel 32. Therefore, the diameter of the wireline cable 14 can introduce error into the measurement, the error being a function of the diameter of the wireline cable 14. Accordingly, this error can vary from drill rig to drill rig and is difficult to account for.

[0005] Accordingly, a way to improve the accuracy of the depth measurement is desirable. SUMMARY

[0006] Disclosed herein, is a depth counter for measuring depth of a wireline cable. In one aspect, the depth counter includes a housing configured to receive a wireline cable therethrough along a first axis. An encoder wheel is rotatably coupled to the housing. The depth counter includes a first pair of idlers. A first idler of the first pair of idlers is positioned on a first side of the encoder wheel. A second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis. The first pair of idlers are movable relative to the housing along a second axis that is perpendicular to the first axis. The first pair of idlers are spring biased in a first direction along the second axis. The first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis. A second pair of idlers are configured to bias the wireline cable in a second direction, opposite the first direction, along the second axis.

[0007] In another aspect, a depth counter includes a housing configured to receive a wireline cable therethrough along a first axis. An encoder wheel is rotatably coupled to the housing. The depth counter includes a first pair of idlers. A first idler of the first pair of idlers is positioned on a first side of the encoder wheel. A second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis. The first pair of idlers are movable relative to the housing along the second axis. The first pair of idlers are spring biased in a first direction along a second axis that is perpendicular to the first axis. The first pair of idlers are configured to bias against the wireline toward the encoder wheel in the first direction along the second axis. An engagement idler is positioned between the first pair of idlers. The engagement idler is movable relative to the housing along the second axis and is configured to bias against the wireline cable, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

[0008] A method of using the depth counter includes the steps of retracting the first pair of idlers; receiving a wireline cable through the housing; and releasing the first pair of idlers so that the first pair of idlers bias the wireline cable toward the encoder wheel.

[0009] Also disclosed herein is a method comprising biasing, using a plurality of idlers, a wireline cable against an encoder wheel so that a segment of the wireline cable in contact with the encoder wheel is substantially linear.

[0010] Additional advantages of the disclosed system and method will be set forth in part in the description which follows, and in part will be understood from the description, or may be learned by practice of the disclosed system and method. The advantages of the disclosed system and method will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary7 and explanatory-only and are not restrictive of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosed apparatus, system, and method and together with the description, serve to explain the principles of the disclosed apparatus, system, and method.

[0012] FIG. 1 is a block diagram of a system as disclosed herein.

[0013] FIG. 2 is a schematic of a conventional depth counter.

[0014] FIG. 3 is a side view of an exemplary depth counter as disclosed herein.

[0015] FIG. 4 is a cross sectional view of the depth counter of FIG. 3, taken in a vertical plane relative to the view of FIG. 3.

[0016] FIG. 5 is a partial perspective view of the depth counter of FIG. 3.

[0017] FIG. 6 is a perspective view of a mounting platform for coupling to the depth counter of FIG. 3.

[0018] FIG. 7 is a perspective view of another exemplary depth counter.

[0019] FIG. 8 is a partial cross-sectional view of the depth counter of FIG. 7. DETAILED DESCRIPTION

[0020] The disclosed system and method may be understood more readily by reference to the following detailed description of particular embodiments and the examples included therein and to the Figures and their previous and following description.

[0021] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention which will be limited only by the appended claims.

[0022] As used herein the singular forms “a,” “an,” and “the” can optionally include plural referents unless the context clearly dictates otherwise. For example, unless the context dictates otherw ise, use of the term “a sensor” can represent disclosure of embodiments in which only a single such sensor is provided, as well as embodiments in which a plurality of such sensors are provided, and so forth.

[0023] “Optional” or “optionally” means that the subsequently described event, circumstance, or material may or may not occur or be present, and that the description includes instances where the event, circumstance, or material occurs or is present and instances where it does not occur or is not present.

[0024] Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, also specifically contemplated and considered disclosed is the range from the one particular value and / or to the other particular value unless the context specifically indicates otherwise. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another, specifically contemplated embodiment that should be considered disclosed unless the context specifically indicates otherwise. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint unless the context specifically indicates otherwise. Finally, it should be understood that all of the individual values and subranges of values contained w ithin an explicitly disclosed range are also specifically contemplated and should be considered disclosed unless the context specifically indicates otherwise. The foregoing applies regardless of whether in particular cases some or all of these embodiments are explicitly disclosed.

[0025] Optionally, in some aspects, when values or characteristics are approximated by use of the antecedents “about,” “substantially,” or “generally,” it is contemplated that values within up to 15%, up to 10%, up to 5%, or up to 1% (above or below) of the particularly stated value or characteristic can be included within the scope of those aspects.

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed apparatus, system, and method belong. Although any apparatus, systems, and methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present apparatus, system, and method, the particularly useful methods, devices, systems, and materials are as described.

[0027] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. In particular, in methods stated as comprising one or more steps or operations it is specifically contemplated that each step comprises what is listed (unless that step includes a limiting term such as "consisting of’), meaning that each step is not intended to exclude, for example, other additives, components, integers or steps that are not listed in the step.

[0028] As used herein, "depth" can refer to distance into a borehole along the borehole path. That is, a borehole can extend vertically downwardly, upwardly, or at any angle. Further, the borehole can be straight or have at least one curve. Depth can be understood to include depth into the borehole in any direction.

[0029] Disclosed herein and with reference to FIG. 1, is a system 10 for determining depth of a wireline tool in a borehole 100. The system 10 can comprise a winch 12 (also referred to as a drum), a wireline cable 14 (also interchangeably referred to herein as a “cable” or a “wireline”) wound around the winch, and a wireline tool 20 that is directly or indirectly coupled to the wireline cable 14. For example, the wireline cable 14 can extend over a pulley 16 of a mast 18, through a wireline depth counter 50 that is coupled to the mast 18, and couple to the wireline tool 20. In operation, the wireline cable 14 is coupled to a wireline tool 20, and the winch rotates to either increase or decrease the operative length of wirehne cable, thereby controlling a position of the wirehne tool 20 with respect to (eg., within) a drill string. As used herein, the term “wireline tool” refers to a mechanical structure comprising an instrument that is deployable and retrievable (e.g., configured to be tripped) within a borehole using a wirehne cable 14. In exemplary configurations, the wirehne tool can include a sensor. Optionally, the wireline tool can comprise a housing or probe structure.

[0030] In some optional aspects, the wireline tool can include running gear as is known in the art. Running gear can include a tool that is configured to deploy a sensor, such as, for example, landing running gear to facilitate landing on and retrieving a core barrel assembly, and / or latching running gear that is used to connect a sensor / tool to an overshot for deployment / retrieval. In exemplary aspects, the landing running gear can attach to an instrument (e.g., a gyro) to protect the instrument from shock on impact at the bottom of a hole. Optionally, the landing running gear can comprise a latch assembly that is configured to latch onto an inner tube assembly. In additional exemplary aspects, the latching running gear can comprise a structure having a distal (farthest from the surface or rig) end that engages a proximal (closest to the surface or rig) end of an instrument housing and further defines a proximal end portion that includes an engagement feature (e.g., a spear point, a groove, a projection, or other structure) that is configured to complementarity engage an overshot or other retrieval device.

[0031] As used herein, the term “cable” can refer to a flexible elongated member that can exert a tensile force during deployment and / or retrieval of a wireline tool. The cable need not provide any electrical communication, although it may. The wireline tool 20 can be any wireline tool. For example, the wireline tool 20 can comprise one or more sensors 24 such as, for example, pressure sensor(s), magnetic sensor(s), radiation (e.g., gamma) detector(s), optical televiewer(s) and / or acoustic televiewer(s), etc. In other aspects, the wireline tool 20 can comprise mechanical tools, such as, for example, a latch for engaging an inner tube assembly of a core barrel assembly.

[0032] Refernng to FIGS. 3-5, a depth counter 50 can comprise a housing 52 configured to receive a wireline cable 14 therethrough so that the wireline cable extends along a first axis 2. An encoder wheel 60 can be rotatably coupled to the housing 52. The depth counter 50 can further comprise a first pair of idlers 62. A first idler 62a of the pair of the idlers 62 can be positioned a first side 61 of the encoder wheel 60. and a second idler 62b of the first pair of idlers 62 is positioned on a second side 63 of the encoder wheel 60 that is opposite the first side of the encoder wheel along the first axis 2. The first pair of idlers 62 can be movable relative to the housing 52 along a second axis 4 that is perpendicular to the first axis 2 (vertically in FIG. 3). The first pair of idlers 62 spring biased in a first direction 6 (downwardly in FIG. 3) along the second axis 4 (e.g., via spring 72). The first pair of idlers 62 can be configured to bias against the wireline cable 14 toward the encoder wheel 60 in the first direction 6 along the second axis 4. As used herein, the term “idler” is used in its conventional sense and, in the context of this disclosure, generally refers to a wheel, pulley, or sheave that does not impart a driving force to the wireline cable.

[0033] The depth counter 50 can further comprise a second pair of idlers 64 that are configured to bias the wireline cable 14 in a second direction 8, opposite the first direction 6, along the second axis 4. The second pair of idlers 64 can be coupled to the housing 52 so that the second pair of idlers are not movable relative the housing 52 along the second axis 4. For example, the second pair of idlers 64 can be coupled to the housing 52 so that they can rotate but are otherwise not movable (i.e., laterally) relative to the housing 52.

[0034] The depth counter 50 can further comprise an engagement idler 66 positioned between the first pair of idlers 62. The engagement idler 66 can be movable relative to the housing 52 along the second axis 4. The engagement idler 66 can be configured to bias against the wireline cable 14 to thereby bias the wireline cable against the encoder wheel 60. Each of the engagement idler 66 and the encoder wheel 60 has a respective rotational axis 68. The engagement idler 66 can be substantially aligned with the encoder wheel 60 along the first axis 2. For example, the engagement idler 66 can be aligned with the encoder wheel 60 along the first axis 2 so that an axis 9 that is parallel to the second axis 4 intersects the rotational axis 68 of the engagement idler 66 and the rotational axis 68 of the encoder wheel 60. In further aspects, the axis 9 that intersects the rotational axis 68 of the encoder wheel 60 can be within 10 mm, within 5 mm, within 4 mm, within 3 mm, within 2 mm, or within 1 mm of the rotational axis 68 of the engagement idler 66.

[0035] The first pair of idlers 62 (and, the engagement idler 66. where included), can be configured to cause the wireline cable 14 to have a substantially linear segment between the first pair of idlers along the first axis 2. For example, between the rotational axes of the first pair of idlers, the wireline cable 14 can have a centerline 15 that extends through the geometric center of the wireline cable. The centerline 15 can have a variation along the second axis 4 of no more than 10 mm. or no more than 5 mm. or no more than 4 mm, or no more than 3 mm, or no more than 2 mm, or no more than 1 mm. Accordingly, the contact between the encoder wheel 60 and the wireline cable 14 can be approximated as a point of contact. In this way, measurements of the depth counter 50 can be independent of the diameter of the wireline cable 14.

[0036] The idlers 62, 64, 66 can comprise pulleys / sheaves that guide the wireline cable 14. The idlers can freely rotate. In some aspects, the idlers can comprise bearings, such as, for example, ball bearings, that promote rotation with minimal friction. In some aspects, the idlers 62, 64, 66 can have a U- or V-shaped circumferential surface in planes parallel to the respective rotational axes 68 of the idlers. The U- or V-shaped circumferential surface can guide the wireline cable 14 toward a middle of the idler (along the respective rotational axis 86) and retain the wireline cable on the idler.

[0037] The first pair of idlers 62 can be coupled to a frame 70. In further aspects, the engagement idler 66 can likewise be coupled to the frame. The frame 70 can be spring-biased in the first direction 6 along the second axis 4 (e.g., via the spring 72). Referring to FIG. 4, the frame 70 can be retracted to receive the wireline cable 14. For example, the frame 70 can be lifted upwardly (relative to the position of the frame shown in FIG. 4) to expose a slot 54 through which the wireline cable 14 can be received. The frame 70 can then be released so that the frame extends over the slot 54 (as shown in FIG. 4), thereby retaining the cable within the housing 52.

[0038] Referring also to FIGS. 7-8, the spring 72 can bias the frame 70 downwardly against a nut 74 that is threadedly coupled to a shaft 76. For example, the spring 72 can extend between a surface 71 of the nut 74 and a surface 81 of the frame 70. In some aspects, the shaft 76 can define a shoulder 73 that engages a corresponding shoulder 75 of the nut. When the shoulder 73 of the shaft 76 engages the shoulder 75 of the nut 74, the surface 71 of the nut 74 and the surface 81 of the frame 70 can be spaced by a predetermined distance that corresponds to a predetermined spring force applied to the wireline cable 14 for a given diameter of the wireline cable.

[0039] An axial position of the nut 74 along the shaft 76 can be adjusted by rotating the nut 74 along the shaft 76. In this way, the frame 70 can be moved toward and away from the encoder wheel 60. For example, the nut 74 can define a feature 77 (e.g., a ridge, shelf, or projection) that engages a corresponding feature 79 (e.g., a ridge, shelf, or projection) of the frame 70 to inhibit or prevent further movement of the frame 70 away from the nut 74 in the first direction 6 along the first axis 4. In one example, the features 77, 79 can have respective stop surfaces that can be positioned in facing contact to prevent further movement of the frame 70 away from the nut 74 in the first direction 6. Accordingly, movement of the nut 74 upwardly along the shaft 76 can lift the frame 70 to permit receipt of the wireline cable 14 within the depth counter 50. The frame 70 can then be lowered by moving the nut 74 along the shaft 76 (e.g., until the shoulder 75 of the nut 74 engages the shoulder 73 of the shaft 76.

[0040] In further aspects, a jam nut 78 can be tightened against the nut 74 to inhibit or prevent movement of the nut 74, thereby preventing shifting or unthreading of the nut. In this way, stability and accuracy of the depth counter 50 can be maintained. The jam nut 78 can have a pair of radial projections that permit hand-tightening and loosening. It is further contemplated that the axial position of the nut 74 along the shaft 76 can be adjusted to modify a biasing force of the spring 72.

[0041] Referring to FIG. 7, in some aspects, the nut 74 can comprise one or more features to permit hand turning. For example, the nut 74 can comprise a plurality of rounded lobes. The nut 74 can further define bores within the rounded lobes to reduce a w eight of the nut.

[0042] In some aspects, each of the engagement idler 66 and the first pair of idlers 62 has a respective rotational axis 68. The engagement idler 66 can be substantially aligned with the first pair of idlers 62 along the second axis 4 so that an axis 11 that is parallel to the first axis 2 intersects the respective rotational axis 68 of each of the engagement idler 66 and the first pair of idlers 62.

[0043] Referring to FIGS. 4 and 5, the frame 70 can comprises a pair of guards 80. Each guard 80 can have an inner surface 82 that opposes a respective idler 64 of the second pair of idlers so that when the first pair of idlers 62 are freely biasing against the wireline cable 14. The inner surface 82 of each guard 80 and the respective idler 62 of the second pair of idlers 64 can sufficiently encircle the wireline cable 14 so that the wireline cable is retained between the pair of guards and the second pair of idlers. That is, when the first pair of idlers are freely biasing against the wireline cable 14, the guards 80 can be spaced from the respective idlers 62 by a distance, d, of no more than the diameter of the wireline cable 14. For example, the wireline cable can have a diameter of ¼ inch. Accordingly, in some aspects, the distance, d, that the guards 80 are spaced from the respective idlers 62 can be less than 'A inch, or less than 1 / 8 inch, or less than 0.1 inch.

[0044] The depth counter 50 can comprise guides 84 that guide movement of the frame 70 along the second axis 4. For example, outer surface of the guards 80 can slide against the guides 84.

[0045] In exemplary aspects, the first pair of idlers 62 can be positioned between the second pair of idlers 64 along the first axis 2. For example, each of the first pair of idlers 62 can be spaced along the first axis 2 from the encoder wheel 60 by a distance from about 1 inch to about 3 inches (e.g., from about 1.25 to about 2 inches). Each of the first pair of idlers 62 can be spaced along the first axis 2 from the encoder wheel 60 by a distance from about 2.5 inches to about 4 inches (e g., from about 3 to about 4 inches). In exemplary aspects, the rotational axis 68 of each of the second pair of idlers 64 can be positioned between the encoder wheel 60 and a respective first idler 62 along the first axis 2.

[0046] In some aspects, when the first pair of idlers 62 are freely biasing against the wireline cable 14, the wireline cable can bend around the second pair of idlers 64 to have, at the first pair of idlers, a concavity toward the first pair of idlers (shown in FIG. 3). This can ensure engagement between the wireline cable 14 and the encoder wheel 60. For example, in the view7 show n in FIG. 4, the wireline cable 14 can bend upw ardly between the first pair of idlers 62 and the second pair of idlers 64. For example, referring to FIG. 4, each idler of the second pair of idlers 64 and the encoder wheel 60 can have respective outer surfaces 69 that are configured to engage the w ireline cable 14. Portions of the outer surface 69 of each idler 64 of the second pair of idlers farthest along the second axis 4 in the first direction 6 are spaced in the first direction along the second axis from a portion of the outer surface 69 of the encoder wheel 60 positioned farthest along the second axis 4 in the second direction 8. This spacing is represented in FIG. 4 between the dash-dot-dashed lines.

[0047] Referring to FIG. 3, the housing 52 can comprise an engagement structure that is configured to permit mounting of the housing to a mounting platform. For example, the engagement structure can comprise a first projection 90 that extends in a first direction along the first axis 2 and a second projection 92 that extends in a second direction, opposite the first direction, along the first axis. In this way, the depth counter 50 can be coupled to a mounting platform that is, in turn, coupled to a drill rig (e.g., the mast 18 (FIG. 1) of the drill rig). More generally, the engagement structure can comprise one or more of a hook, a projection, a socket, a slot, combinations thereof, or any suitable surface for engaging the mounting platform.

[0048] Referring to FIG. 6, a mounting platform 212 can comprise a base 220 that defines a first coupling feature 221. The first coupling feature 221 can be, for example, a first receptacle 222. The mounting platform 212 can comprise a latch 224 that is movably coupled to the base 220 about and between a secured position (e.g., pivoted toward the base) and a release position (pivoted away from the base). The latch 224 can define a second retention feature 226, which can optionally comprise a second receptacle 240. The first projection 90 can be received within the first receptacle 222, and the second projection 92 can be received within the second receptacle 240 to secure the depth counter 50 to the mounting platform 212.

[0049] The mounting platform 212 can be configured to magnetically engage the drill rig. For example, the mounting platform 212 can comprise a switchable permanent magnet fastener 250 having an actuator (e.g., a lever) that is configured to move at least a portion of the plurality of magnets about and between first and second configurations. When in the first configuration, the polarities of the plurality of magnets align to produce a magnetic attraction to a ferromagnetic surface, and in the second configuration, the polarities of the plurality of magnets align to at least partially cancel each other out to reduce or eliminate the magnetic attraction of the switchable permanent magnet.

[0050] Additional details of an engagement structure and an exemplary mounting platform are disclosed in International Patent Application No. WO2023 / 158734, filed February 16, 2023, the entirety' of which is hereby incorporated by reference herein for all purposes.

[0051] A method of using the depth counter 50 can include retracting the first pair of idlers 62, receiving the wireline cable 14 through the housing 52, and releasing the first pair of idlers so that the first pair of idlers bias the wireline cable toward the encoder wheel.

[0052] More generally, a method can comprise the step of biasing, using a plurality of idlers, a wireline cable against an encoder wheel 60 so that a segment of the wireline cable 14 in contact with the encoder wheel is substantially linear. For example, the segment of the wireline cable 14 can be the portion of the wireline cable between the rotational axes 68 of a pair of idlers closest to the encoder wheel 60 on each side of the encoder wheel 60 along the first axis 2, with the wireline cable 14 extending along the first axis 2. In some aspects, the pair of idlers closest to the encoder wheel 60 on each side of the encoder wheel 60 along the first axis 2 can be movable along the second axis 4 that is perpendicular to the first axis 2. In various aspects, substantially linear can mean that the wireline cable 14 extends along the first axis 2 and has variation along the second axis 4 of no more than 10 mm, or no more than 5 mm, or no more than 4 mm, or no more than 3 mm, or no more than 2 mm, or no more than 1 mm.

[0053] In some aspects, the plurality of idlers comprise a first pair of idlers 62, one idler of the first pair of idlers positioned on each side of the encoder wheel 60 along the first axis 2. The first pair of idlers 62 can be movable relative to the housing 52 along the first axis. The first pair of idlers 62 can be spring biased in a first direction along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis.

[0054] An engagement idler 66 can be positioned between the first pair of idlers 62. The engagement idler can be movable relative to the housing 52 along the second axis 2. The engagement idler 66 can be configured to bias the wireline cable 14 against the encoder wheel 60. The engagement idler 66 can be substantially aligned with the encoder wheel along the first axis 2. For example an axis 9 that is parallel to the second axis 4 can intersect the rotational axis 68 of the engagement idler 66 and the rotational axis 68 of the encoder wheel 60. Exemplary- Aspects

[0055] In view of the described apparatuses, systems, and methods and variations thereof, herein below are described certain more particularly described aspects of the invention. These particularly recited aspects should not however be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the "particular" aspects are somehow limited in some way other than the inherent meanings of the language literally used therein.

[0056] Aspect 1: A depth counter comprising: a housing configured to receive a wireline cable therethrough along a first axis; an encoder wheel rotatably coupled to the housing; a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are spring biased in a first direction along the second axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; and a second pair of idlers that are configured to bias the w ireline cable in a second direction, opposite the first direction, along the second axis.

[0057] Aspect 2: The depth counter of aspect 1, further comprising an engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias against the wireline cable, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

[0058] Aspect 3: The depth counter of aspect 2, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

[0059] Aspect 4: The depth counter of any one of the preceding aspects, further comprising a frame, wherein the first pair of idlers are coupled to the frame, wherein the frame is spring-biased in the first direction along the second axis.

[0060] Aspect 5: The depth counter of any one aspects 2-4, wherein each of the engagement idler and the first pair of idlers has a respective rotational axis, wherein the engagement idler is substantially aligned with the first pair of idlers along the second axis so that an axis that is parallel to the first axis intersects the respective rotational axis of each of the engagement idler and the first pair of idlers.

[0061] Aspect 6: The depth counter of any one of aspects 4-5, wherein the frame comprises a pair of guards, each guard having an inner surface that opposes a respective idler of the second pair of idlers so that when the first pair of idlers are freely biasing against the wireline cable, the inner surface of each guard and the respective idler of the second pair of idlers sufficiently encircle the wireline cable so that the wireline cable is retained between the pair of guards and the second pair of idlers.

[0062] Aspect 7: The depth counter of aspect 6, wherein, when the first pair of idlers are freely biasing against the wireline cable, the each guard of the pair of guards is less than ‘A inch of the respective idler of the second pair of idlers.

[0063] Aspect 8: The depth counter of any one of the preceding aspects, wherein the first pair of idlers are positioned between the second pair of idlers along the first axis.

[0064] Aspect 9: The depth counter of any one of the preceding aspects, wherein the first pair of idlers are configured to cause the wireline cable to have a substantially linear segment between the first pair of idlers along the first axis.

[0065] Aspect 10: The depth counter of any one of the preceding aspects, wherein the second pair of idlers are coupled to the housing so that the second pair of idlers are not movable relative the housing along the second axis.

[0066] Aspect 11: The depth counter of any one of the preceding aspects, wherein each idler of the first and second pairs of idlers and the encoder wheel has a respective rotational axis, wherein the rotational axes of the second pair of idlers are betw een the rotational axes of the first pair of idlers and the rotational axis of the encoder wheel along the second axis.

[0067] Aspect 12: The depth counter of any one of the preceding aspects, wherein each idler of the second pair of idlers and the encoder wheel have respective outer surfaces that are configured to engage the wireline cable, wherein portions of the outer surface of each idler of the second pair of idlers farthest along the second axis in the first direction are spaced in the first direction along the second axis from a portion of the outer surface of the encoder wheel positioned farthest along the second axis in the second direction.

[0068] Aspect 13: The depth counter of any one of the preceding aspects, wherein the housing comprises an engagement structure that is configured to permit mounting of the housing to a mounting platform.

[0069] Aspect 14: The depth counter of aspect 13, wherein the engagement structure comprises a first projection that extends in a first direction along the first axis and a second projection that extends in a second direction, opposite the first direction, along the first axis.

[0070] Aspect 15: The depth counter of aspect 4, further comprising: a shaft, wherein the frame is movably coupled to the shaft; a nut that is threadedly coupled to the shaft; a spring that biases against the nut and biases the frame in the first direction; and ajam nut that is threadedly received on the shaft, wherein the jam nut is configured to be tightened against the nut to inhibit movement of the nut.

[0071] Aspect 16: A depth counter comprising: a housing configured to receive a wireline cable therethrough along a first axis; an encoder wheel rotatably coupled to the housing; a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along the second axis, wherein the first pair of idlers are spring biased in a first direction along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; and an engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias the wireline cable against the wireline cable, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

[0072] Aspect 17: The depth counter of aspect 16, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

[0073] Aspect 18: A method of using the depth counter of any one of the preceding aspects, the method comprising: retracting the first pair of idlers; receiving a wireline cable through the housing; and releasing the first pair of idlers so that the first pair of idlers bias the wireline cable toward the encoder wheel.

[0074] Aspect 19: A method comprising: biasing, using a plurality of idlers, a wireline cable against an encoder wheel so that a segment of the wireline Aspect: cable in contact with the encoder wheel is substantially linear.

[0075] Aspect 20: The method of aspect 19, wherein the plurality of idlers comprise: a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along the second axis, wherein the first pair of idlers are spring biased in a first direction along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; and an engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias the wireline cable against the encoder wheel, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

[0076] Aspect 21: The method of aspect 20, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

[0077] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the method and compositions described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A depth counter comprising:a housing configured to receive a wireline cable therethrough along a first axis;an encoder wheel rotatably coupled to the housing;a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are spring biased in a first direction along the second axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; anda second pair of idlers that are configured to bias the w ireline cable in a second direction, opposite the first direction, along the second axis.

2. The depth counter of claim 1, further comprising an engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias against the wireline cable, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

3. The depth counter of claim 2, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

4. The depth counter of claim 1, further comprising a frame, w herein the first pair of idlers are coupled to the frame, wherein the frame is spring-biased in the first direction along the second axis.

5. The depth counter of claim 2, wherein each of the engagement idler and the first pair of idlers has a respective rotational axis, w herein the engagement idler is substantially aligned with the first pair of idlers along the second axis so that an axis that is parallel to the first axis intersects the respective rotational axis of each of the engagement idler and the first pair of idlers.

6. The depth counter of claim 4, wherein the frame comprises a pair of guards, each guard having an inner surface that opposes a respective idler of the second pair of idlers so that when the first pair of idlers are freely biasing against the wireline cable, the inner surface of each guard and the respective idler of the second pair of idlers sufficiently encircle the wireline cable so that the wireline cable is retained between the pair of guards and the second pair of idlers.

7. The depth counter of claim 6, wherein, when the first pair of idlers are freely biasing against the wireline cable, each guard of the pair of guards is less than ¼ inch of the respective idler of the second pair of idlers.

8. The depth counter of claim 1, wherein the first pair of idlers are positioned between the second pair of idlers along the first axis.

9. The depth counter of claim 1, wherein the first pair of idlers are configured to cause the wireline cable to have a substantially linear segment between the first pair of idlers along the first axis.

10. The depth counter of claim 1, wherein the second pair of idlers are coupled to the housing so that the second pair of idlers are not movable relative the housing along the second axis.

11. The depth counter of claim 1, wherein each idler of the first and second pairs of idlers and the encoder wheel has a respective rotational axis, wherein the rotational axes of the second pair of idlers are between the rotational axes of the first pair of idlers and the rotational axis of the encoder wheel along the second axis.

12. The depth counter of claim 1, wherein each idler of the second pair of idlers and theencoder wheel have respective outer surfaces that are configured to engage the wireline cable, wherein portions of the outer surface of each idler of the second pair of idlers farthest along the second axis in the first direction are spaced in the first direction along the second axis from a portion of the outer surface of the encoder wheel positioned farthest along the second axis in the second direction.

13. The depth counter of claim 1, wherein the housing comprises an engagement structure that is configured to permit mounting of the housing to a mounting platform.

14. The depth counter of claim 13, wherein the engagement structure comprises a first projection that extends in a first direction along the first axis and a second projection that extends in a second direction, opposite the first direction, along the first axis.

15. The depth counter of claim 4, further comprising:a shaft, wherein the frame is movably coupled to the shaft;a nut that is threadedly coupled to the shaft;a spring that biases against the nut and biases the frame in the first direction; and ajam nut that is threadedly received on the shaft, wherein the jam nut is configured to be tightened against the nut to inhibit movement of the nut.

16. A depth counter comprising:a housing configured to receive a wireline cable therethrough along a first axis;an encoder wheel rotatably coupled to the housing;a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along the second axis, wherein the first pair of idlers are spring biased in a first direction along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; andan engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias the wireline cable against the wireline cable, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

17. The depth counter of claim 16, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

18. A method of using the depth counter of any one of the preceding claims, the method comprising:retracting the first pair of idlers;receiving a wireline cable through the housing; andreleasing the first pair of idlers so that the first pair of idlers bias the wireline cable toward the encoder wheel.

19. A method comprising:biasing, using a plurality of idlers, a wireline cable against an encoder wheel so that a segment of the wireline cable in contact with the encoder wheel is substantially linear.

20. The method of claim 19, wherein the plurality of idlers comprise:a first pair of idlers, wherein a first idler of the first pair of idlers is positioned on a first side of the encoder wheel, wherein a second idler of the first pair of idlers is positioned on a second side of the encoder wheel that is opposite the first side of the encoder wheel along the first axis, wherein the first pair of idlers are movable relative to the housing along the second axis, wherein the first pair of idlers are spring biased in a first direction along a second axis that is perpendicular to the first axis, wherein the first pair of idlers are configured to bias against the wireline cable toward the encoder wheel in the first direction along the second axis; andan engagement idler positioned between the first pair of idlers, wherein the engagement idler is movable relative to the housing along the second axis, wherein the engagement idler is configured to bias the wireline cable against the encoder wheel, wherein each of the engagement idler and the encoder wheel has a respective rotational axis, wherein the engagement idler is substantially aligned with the encoder wheel along the first axis.

21. The method of claim 20, wherein an axis that is parallel to the second axis intersects the rotational axis of the engagement idler and the rotational axis of the encoder wheel.

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