Wireline Case-Hole Roller

Abstract

The present invention relates to a wireline cased-hole roller (WCRO) for deployment during a logging operation that reduces slickline or e-line cable contact and drag in the cased hole section of a wellbore. Arrays of WCROs, clamped on the slickline or e-line, reduce logging tensions and improve force transmission from surface down to the tool cable head by significantly reducing the cased-hole cable drag. They also permit the use of lower grade cables or winches in certain environments due to lower logging tensions. Another benefit is the mitigation of cased hole cable wear zones since the cable is suspended above the casing, liner or tubing. In high-angle or horizontal wells, arrays of WCROs aid conveyance and improve tractor performance by reducing the cable drag force which has to be overcome to reach the target zone.

Claims

1. A wireline cased-hole roller (WCRO) comprising: a pair of cable insert halves; a pair of opposing WCRO body halves; a pair of reciprocally-positioned chassis comprising a plurality of roller wheels; and one or more fasteners, wherein the one or more fasteners are configured to couple the pair of cable insert halves, the pair of opposing WCRO body halves, and the pair of chassis together onto a cable, wherein the shape of the WCRO in combination with the plurality of roller wheels allow for both radial and axial movement.

2. The WCRO of claim 1, wherein the pair of cable insert halves are concentrically disposed between the cable and the pair of opposing WCRO body halves, wherein the pair of cable insert halves are in direct contact with the cable and at least partially encased within the pair of opposing WCRO body halves.

3. The WCRO of claim 1, wherein the cable insert halves each comprise flanged ends, a central flange, and an anti-rotation spigot recess, to prevent axial and radial movement of the cable insert halves within the pair of opposing WCRO body halves, wherein the anti-rotation spigot recess receives an anti-rotation spigot disposed on the pair of opposing WCRO body halves.

4. The WCRO of claim 1, wherein the one or more fasteners comprise cable insert fasteners configured to secure the pair of cable insert halves to the pair of opposing WCRO body halves, wherein the cable insert fasteners travel through insert fastener clearance holes disposed on the pair of opposing WCRO body halves and are received by cable insert fastener threads disposed on the pair of cable insert halves.

5. The WCRO of claim 1, wherein the pair of cable insert halves are manufactured from a material comprising aluminum.

6. The WCRO of claim 1, wherein the pair of opposing WCRO body halves comprise dowel pin recesses configured to receive dowel pins, wherein the dowel pin recesses and dowel pins contribute to the coupling of the opposing WCRO body halves onto the cable.

7. The WCRO of claim 1, wherein the one or more fasteners comprise clamping bolts configured to secure the pair of cable insert halves and the pair of opposing WCRO body halves to the cable, wherein the clamping bolts travel through clamping bolt clearance holes disposed on one half of the pair of opposing WCRO body halves and are received by clamping bolt female threads disposed on the other half of the pair of opposing WCRO body halves.

8. The WCRO of claim 1, wherein the pair of opposing WCRO body halves are manufactured from a material comprising stainless steel.

9. The WCRO of claim 1, wherein the pair of chassis are disposed in chassis recess portions, wherein the chassis recess portions are disposed on outer surfaces of the pair of opposing WCRO body halves.

10. The WCRO of claim 10, wherein the chassis recess portions comprise curved recesses which provide clearance for the plurality of roller wheels.

11. The WCRO of claim 1, wherein the one or more fasteners comprise chassis bolts configured to secure the pair of chassis to the opposing WCRO body halves, wherein the chassis bolts travel through chassis bolt clearance holes disposed on the chassis and are received by chassis bolt female threads disposed on the opposing WCRO body halves.

12. The WCRO of claim 1, wherein the pair of chassis are manufactured from a material comprising stainless steel.

13. The WCRO of claim 1, wherein the plurality of roller wheels are disposed on the pair of chassis at a 60° phased offset about the WCRO.

14. The WCRO of claim 1, wherein the plurality of roller wheels are disposed on the pair of chassis in an up/down pattern about the WCRO.

15. The WCRO of claim 1, wherein each of the plurality of roller wheels are mounted to the pair of chassis via an axel, wherein the axel is run through an axel clearance hole disposed on the chassis and through a central bore of each roller wheel, to rest in axel recess.

16. The WCRO of claim 16, wherein the axel is held in position via an axel fixing pin, wherein the axel fixing pin is screwed through an axel fixing pin threading disposed on the chassis and clamped to a groove disposed on the axel.

17. The WCRO of claim 16, wherein the axel comprises a lubrication injection port, a lubrication channel, and a lubrication outlet, wherein a lubricant is injected into the axel at the lubrication injection point, through the lubrication channel, and out the lubrication outlet to facilitate rotation of the plurality of roller wheels.

18. The WCRO of claim 1, wherein the plurality of roller wheels are manufactured from a material comprising stainless steel.

19. A cable assembly comprising: a cable; and a wireline cased-hole roller (WCRO), wherein the WCRO comprises: a pair of cable insert halves; a pair of opposing WCRO body halves; a pair of reciprocally-positioned chassis comprising a plurality of roller wheels; and one or more fasteners, wherein the one or more fasteners are configured to couple the pair of cable insert halves, the pair of opposing WCRO body halves, and the pair of chassis together onto the cable; wherein the shape of the WCRO in combination with the plurality of roller wheels allow for both radial and axial movement.

20. A method for reducing cable drag and tension during wireline or slickline operations comprising: coupling one or more wireline cased-hole rollers (WCROs) to a cable, wherein the one or more WCROs comprise: a pair of cable insert halves; a pair of opposing WCRO body halves; a pair of reciprocally-positioned chassis comprising a plurality of roller wheels; and one or more fasteners, wherein the one or more fasteners are configured to couple the pair of cable insert halves, the pair of opposing WCRO body halves, and the pair of chassis together onto the cable; wherein the shape of the WCRO in combination with the plurality of roller wheels allow for both radial and axial movement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:

[0013] FIGS. 1A and 1B illustrate isometric views of a wireline cased-hole roller in accordance with one embodiment of the present invention;

[0014] FIGS. 2A and 2B illustrate exploded views of a wireline cased-hole roller in accordance with one embodiment of the present invention from opposing perspectives;

[0015] FIG. 3A illustrates a chassis with exploded roller wheel components in accordance with one embodiment of the present invention;

[0016] FIG. 3B illustrates a close-up, internal view of an axel in accordance with one embodiment of the present invention;

[0017] FIG. 4A illustrates a plurality of wireline cased-hole rollers installed on a wireline cable in accordance with one embodiment of the present invention; and

[0018] FIG. 4B illustrates a close-up view of a wireline cased-hole roller in relation to a wellbore wall in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] FIGS. 1A and 1B illustrate an embodiment of a wireline cased-hole roller (WCRO) 2. In embodiments, WCRO 2 may be a device for installation on a wireline or slickline cable above a wellbore logging tool, capable of significantly reducing cable drag in a cased-hole section of a subsurface wellbore. In reducing cable drag, WCRO 2 may reduce logging tensions and improve force transmission from wellbore surface to logging tool cable head during wireline logging operations. In embodiments, WCRO 2 comprises two cable insert halves 4, two opposing WCRO body halves (an upper body 6 and a lower body 8), two chassis 10, and a plurality of roller wheels 13. As illustrated, two cable insert halves 4, upper and lower bodies 6 and 8, two chassis 10, and plurality of roller wheels 13 may be fastened together onto a cable 14. In embodiments, cable 14 may be any suitable cable for use with any wellbore logging tool. As previously mentioned, cable 14 may be, without limitation, a wireline or slickline. Further, coupling of these components onto cable 14 may be accomplished using screws, bolts, anti-shear dowel pins, spigots, or any combinations thereof.

[0020] FIGS. 2A and 2B each illustrate an exploded view of WCRO 2 from opposing perspectives. As illustrated, cable insert halves 4 may be concentrically disposed between cable 14 and upper and lower bodies 6 and 8, such that cable insert halves 4 may be in direct contact with cable 14 and at least partially encased within upper and lower bodies 6 and 8. In embodiments, cable insert halves 4 may mate together to form a central bore in which to pass cable 14 through WCRO 2. Each cable insert half 4 may be in the general shape of a hollow, half cylinder and comprise flanged ends 16 disposed about the end portions of each cable insert half 4 and a central flange 18 disposed about the middle portion of each cable insert half 4. Flanged ends 16 and central flanges 18, alone or in combination, may be used to prevent axial movement of cable insert halves 4 within WCRO 2. In embodiments, flanged ends 16 may be tapered and between about 0.75 cm and about 1.5 cm in length to match the external cone profile of the WCRO 2. Further, flanged ends 16 may extend beyond upper and lower bodies 6 and 8, while the remaining portions of each cable insert half 4, including central flanges 18, may fit into corresponding cable insert recess portions 24 of upper and lower bodies 6 and 8. In embodiments, each central flange 18 may comprise one or more cable insert fastener threads 20 which receive one or more cable insert fasteners 26 and one or more anti-rotation spigot recesses 22 which receive one or more anti-rotation spigots 30. As illustrated, each cable insert half 4 may comprise two cable insert fastener threads 20 to correspond with two cable insert fasteners 26 and one anti-rotation spigot recess 22 to correspond with one anti-rotation spigot 30.

[0021] In embodiments, cable insert halves 4 may be available in various sizes to ensure the central bore diameter of WCRO 2 corresponds to the diameter of cable 14. In embodiments, cable 14 may vary in diameter between about 5.0 mm and about 20.0 mm. During installation of WCRO 2, cable insert halves 4 may be configured to slightly deform around an outer armor of cable 14 to prevent physical damage to the cable. To accomplish this deformity, cable insert halves 4 may be manufactured from any suitable material, such as, without limitation, aluminum and other soft metals. Further, cable insert halves 4 may be disposable. In embodiments, cable insert halves 4 may be manufactured from aluminum, and because aluminum may be considerably softer than the armor of cable 14, there may be a reduced risk of damage to the wireline or slickline during installation of WCRO 2. At installation, cable 14 may be any suitable diameter required for a particular logging operation and may even vary in diameter size along its length, taking into account any manufacturing tolerances and varying degrees of wear or distortion. Therefore, a range of different cable insert halves 4 may be employed for a plurality of WCROs 2 installed on cable 14 to ensure a proper fit along the length of cable 14 and prevent slippage on and/or damage to cable 14. In embodiments, the length of cable insert halves 4 may be between about 10.0 cm and about 20.0 cm, or alternatively between about 10.0 cm and about 15.0 cm.

[0022] As set forth above, cable insert halves 4 may be encased within the opposing WCRO body halves of upper and lower bodies 6 and 8. In embodiments, upper and lower bodies 6 and 8 may be of similar structure and in the general shape of a tapered half cylinder comprising an inner surface 32 and an outer surface 34. Inner surface 32 of both upper and lower bodies 6 and 8 may comprise cable insert recess portions 24 having anti-rotation spigots 30 and insert fastener clearance holes 28. In embodiments, insert fastener clearance holes 28 may extend from inner surface 32 to outer surface 34 of upper and lower bodies 6 and 8. In embodiments, cable insert recess portions 24 may be configured in shape to accurately receive cable insert halves 4, such that anti-rotation spigots 30 fit into anti-rotation spigot recesses 22, thus preventing radial rotation of cable insert halves 4 within WCRO 2. Further, cable insert halves 4 may be secured within cable insert recess portions 24 with cable insert fasteners 26, such that cable insert fasteners 26 may travel through insert fastener clearance holes 28 to be received by or fit into cable insert fastener threads 20, and sit flush with outer surface 34 of upper and lower bodies 6 and 8. In embodiments, cable insert fasteners 26 may be any suitable fasteners, bolts, or screws such as, without limitation, small cap head bolts or screws. In embodiments, cable insert fasteners 26 may have a diameter of 3 mm (i.e., M3 bolts).

[0023] In embodiments, upper and lower bodies 6 and 8, which securely encase cable insert halves 4, may be coupled together onto cable 14. Coupling of upper and lower bodies 6 and 8 onto cable 14 may be accomplished via dowel pins 36 and dowel pin recesses 38. In embodiments, dowel pin recesses 38, configured to receive dowel pins 36, may be disposed on inner surface 32 of both upper and lower bodies 6 and 8. In embodiments, one dowel pin 36 may correspond to two dowel pin recesses 38, one recess being disposed on inner surface 32 of upper body 6 and the other recess being disposed on inner surface 32 of lower body 8. As illustrated in FIGS. 2A and 2B, upper body 6 and lower body 8 may each comprise four dowel pins recesses 38 to receive four dowel pins 36. In embodiments, dowel pins 36 may be 4×8 mm pins. In an alternative embodiment, upper body 6 or lower body 8 may be machined to include pegs acting as dowel pins 36 that are received by corresponding recesses 38 disposed on the opposing body.

[0024] In addition to dowel pins 36 and dowel pin recesses 38, coupling of upper and lower bodies 6 and 8 may be accomplished via clamping bolts 40, clamping bolt female threads 42, and clamping bolt clearance holes 44. In embodiments, clamping bolt female threads 42 may be disposed on upper body 6 or lower body 8 with corresponding clamping bolt clearance holes 44 disposed on the opposing body relative to clamping bolt female threads 42. For instance, as illustrated on FIGS. 2A and 2B, clamping bolt female threads 42 may be disposed on inner surface 32 of lower body 8 and have corresponding clamping bolt clearance holes 44 disposed on upper body 6. In embodiments, clamping bolt clearance holes 44 may extend from inner surface 32 to outer surface 34. Upper body 6 or lower body 8 may comprise four clamping bolt female threads 42 or four clamping bolt clearance holes 44, or any combinations thereof. In embodiments, clamping bolts 40 may travel through clamping bolt clearance holes 44 and may be received by or fit into clamping bolt female threads 42, such that upper and lower bodies 6 and 8, along with cable insert halves 4, may be securely coupled and clamped onto cable 14. During installation, clamping bolts 40 may be torqued to a consistently safe limit with a calibrated torque wrench which in turn may reduce the risk of damage to cable 14 from cable insert halves 4 when clamping bolts 40 may be tightened. In embodiments, clamping bolts 40 may be any suitable fasteners, bolts, or screws such as, without limitation, four large cap head bolts or screws. In embodiments, clamping bolts 40 may have a diameter of 6 mm (i.e., M6 bolts).

[0025] In further embodiments, upper body 6 and lower body 8 may comprise lanyard holes 62 disposed on outer surface 34. Lanyard holes 62 may travel through one of the tapered portions of upper and lower bodies 6 and 8. As illustrated in FIGS. 2A and 2B, upper body 6 may comprise lanyard hole 62 and lower body 8 may comprise another lanyard hole 62. Lanyard holes 62 may be used to connect WCRO 2 to a lanyard during installation or removal onto cable 14 for added security and to avoid dropping the device down the wellbore.

[0026] The two opposing WCRO body halves, upper body 6 and lower body 8, may be manufactured from any suitable material such as, without limitation, stainless steel or other high-performance material. Further, upper and lower bodies 6 and 8 may also be surface hardened (e.g., vacuum hardened) to improve wear resistance during use. Further, upper and lower bodies 6 and 8 may be available in various sizes to accommodate the wellbore in which WCRO 2 may be used. In embodiments, the length of upper and lower bodies 6 and 8 may be between about 10.0 cm and about 15.0 cm, or alternatively between about 12.0 cm and about 13.0 cm. Further, the diameters of upper and lower bodies 6 and 8 may range from about 5.0 cm to 10.0 cm according to the application.

[0027] As set forth above, WCRO 2 may comprise two chassis 10 in addition to cable insert halves 4 and upper and lower bodies 6 and 8. In embodiments, each chassis 10 may be in the general shape of a hollow, half cylinder comprising a plurality of roller wheels 13 and chassis bolt clearance holes 56. In embodiments, each chassis 10 may be disposed on outer surfaces 34 of upper and lower bodies 6 and 8 in a reciprocal fashion. Further, each chassis 10 may comprise three roller wheels 13 phased at a 60° offset in an up/down pattern about the structure. In embodiments, outer surface 34 of both upper and lower bodies 6 and 8 may comprise a chassis recess portion 46 configured in shape to accurately receive chassis 10. Chassis recess portion 46 may be disposed about the middle, non-tapered portion of upper and lower bodies 6 and 8. In embodiments, chassis recess portion 46 may be about 4.0 cm in length, measuring from one tapered portion to the other, and about 2.0 cm in thickness. Further, chassis recess portion 46 may comprise curved recesses 47 to create clearance for plurality of roller wheels 13. Clearance may aid in preventing any debris from becoming lodged in WCRO 2 during operation. In embodiments, outer surface 34 of upper and lower body 6 and 8 at chassis recess portions 46 may comprise both the insert fastener clearance holes 28 and chassis bolt female threads 48. Chassis bolt female threads 48 correspond to chassis bolt clearance holes 56. In certain embodiments, as illustrated in FIGS. 2A and 2B, each chassis recess portion 46 of upper body 6 and lower body 8 may comprise two insert fastener clearance holes 28 and three chassis bolt female threads 48.

[0028] In embodiments, chassis 10 may be secured within chassis recess portions 46 via chassis bolts 50, chassis bolt clearance holes 56, and chassis bolt female threads 48. Chassis bolts 50 may travel through chassis bolt clearance holes 56 and may be received by or fit into corresponding chassis bolt female threads 48. In embodiments, chassis bolts 50 may be any suitable fasteners, bolts, or screws such as, without limitation, small cap head bolts or screws. In embodiments, chassis bolts 50 may have a diameter of 4 mm (i.e., M4 bolts). In certain embodiments, as illustrated in FIGS. 2A and 2B, each chassis 10 may comprise three chassis bolt clearance holes 56 phased at a 60° offset about the structure. Upon full assembly, WCRO 2 may comprise six roller wheels 13 disposed about its circumference. In embodiments, plurality of rollers wheels 13 may be capable of rotating axially in relation to cable 14, thereby allowing WCRO 2 to function as an omni wheel. For instance, WCRO 2 may be capable of moving both circumferentially and axially about an inner surface of a wellbore.

[0029] FIG. 3A illustrates chassis 10 of WCRO 2 comprising plurality of roller wheels 13 mounted to the structure, one of which is shown from an exploded perspective. Each roller wheel 13 may be mounted in a slot 51 of chassis 10 via an axel 53 and an axel fixing grub screw 55. In embodiments, axel 53 may be run through an axel clearance hole 57 disposed on chassis 10 and through a central bore 59 of each roller wheel 13, to rest in axel recess 61. Axel 53 may be about 4.0 cm in length and have an outer diameter of about 0.5 cm. To hold axel 53 in position, axel fixing grub screw 55 may be a fastener screwed through axel fixing pin threading 63 and clamped onto a groove 65 of axel 53. Once properly mounted and secured, each roller wheel 13 may be capable of rotating about axel 53 with a small clearance 67 of about 1 mm present between the external surface of each roller wheel 13 and the surfaces of chassis 10 about slot 51. Each roller wheel 13 may be about 2 cm in length, have a varying outer diameter ranging from about 14.0 mm and about 25.0 mm, and have an inner diameter of about 8.0 mm. In embodiments, a bearing 69 may be disposed within each roller wheel 13 and held in place via circlips 71. Bearing 69 may be any suitable bearing including, without limitation, a needle bearing. In embodiments, bearing 69 may be about 8.0 mm in length, have an outer diameter of about 8.0 mm, and have an inner diameter of about 5.0 mm. Further, bearing 69 may comprise multiple bearings if necessary (e.g., two needle bearings). Circlips 71 may be any suitable fasteners or retaining rings capable of holding bearing 69 in position within each roller wheel 13 and further, may be manufactured from a semi-flexible metal with open ends that may be snapped into place. In embodiments, to facilitate rotation of plurality of roller wheels 13 during operation, lubrication may be applied within each roller wheel 13.

[0030] In embodiments, lubrication of plurality of roller wheels 13 may be accomplished via axel 53. FIG. 3B illustrates a close-up, internal view of axel 53 comprising a lubrication injection port 73, a lubrication channel 75, and a lubrication outlet 77. Prior to operation, a grease gun may be utilized and positioned at lubrication injection port 73 to pump any suitable lubricant (e.g., grease) through lubrication channel 75 and out lubrication outlet 77. In embodiments, lubrication outlet 77 may comprise one or more outlets (e.g., two outlets). As such, the lubricant may be provided to plurality of roller wheels 13 and bearings 69 and thus facilitate rotation during operation. In embodiments, plurality of wheels 13 may be properly lubricated when the lubricant appears at the ends of each roller wheel 13. Further, in embodiments, lubrication injection port 73 may be conically-shaped in order to properly seat the grease gun during injection of the lubricant.

[0031] In embodiments, chassis 10 of WCRO 2 as well as plurality of roller wheels 13 may be manufactured from any suitable material such as, without limitation, stainless steel. The use of stainless steel material for these components may contribute to durability of WCRO 2 during operation. Further during operation, plurality of roller wheels 13 may contribute to low friction of cable 14, therefore minimizing cable drag within a wellbore, reducing logging tensions, and improving force transmission during wireline logging operations. In embodiments, chassis 10 may have any suitable dimensions to allow for proper mounting of plurality of roller wheels 13 as well as proper seating into chassis recess portion 46.

[0032] When fully assembled, referring once again to FIGS. 1A and 1B, WCRO 2 may have an outer diameter of about 5.0 cm or greater (measured from the tip of one roller wheel 13 to another). In embodiments, WCRO 2 may have an outer diameter measuring about 7.4 cm. WCRO 2 may minimize contact area within the wellbore during logging operations and allow for standoff rotation under the action of cable torque. WCRO 2 allows for easy rotation, both axial and radial, should cable 14 rotate when it is deployed and retrieved from the wellbore. The general nature of a wireline or slickline cable during logging operations is to rotate. Rotation may be caused by opposing lay angles of inner and outer armors and induce unequal torsional forces when tensions are applied. As such, the design of WCRO 2 may allow for easy rotation of cable 14 during logging operations, avoiding, for example, the potential for damage if excessive torque was allowed to build up.

[0033] In further embodiments upon full assembly, WCRO 2 may comprise cutouts 54. Sometimes during the disassembly or removal of WCRO 2 from cable 14, WCRO 2 may become stuck or fixed to the wireline or slickline. In such case, a parting tool or special jig may be used to pry WCRO 2 from cable 14. In embodiments, the parting tool may utilize cutouts 54 disposed on inner surface 34 of upper and lower bodies 6 and 8 to achieve leverage when disengaging a stuck WCRO 2 from cable 14.

[0034] FIG. 4A illustrates a generic logging operation that includes a plurality of WCROs 2 coupled to cable 14 in accordance with one embodiment of the present invention. As illustrated, plurality of WCROs 2 may be clamped onto cable 14. Cable 14 may be, for example, stored on a wireline drum 72 and spooled into the well by a winch driver and logging engineer in a logging unit 74. In the illustrated embodiment, logging unit 74 may be fixed to the drilling rig or platform 76, and cable 14 may be deployed through a derrick 78 via at least two sheaves such as an upper sheave 68 and a lower sheave 70 to the maximum depth of the wellbore. The wellbore may be a cased well with cased-hole portion 66. As illustrated, WCROs 2 may be installed on cable 14 in cased-hole portion 66. A logging tool 80 may be connected to the lower end of cable 14 to take, for example, measurements involving the state of tubing, casing, cement, or perforations of the wellbore. The number of WCROs 2, and their positions on cable 14 may be determined by a number of factors, including for example, the length of the cased-hole portion 66, the location at which logging tool 80 needs to reach, and the overall trajectory of the wellbore, which may be deviated or directional in nature. In embodiments, WCROs 2 may be deployed at any suitable distance above a logging tool such that they remain within a casing portion and reduce the drag in that portion. This in turn may permit more pull-down for open-hole tools. Further, WCROs 2 may be used in addition to other cable standoff-type devices. FIG. 4B illustrates a close-up view of a single WCRO 2 attachment to cable 14 taken along circle 82. In the illustration of FIG. 4B, WCRO 2 may be seen in relation to cable 14, a wellbore wall 84, and the wellbore.

[0035] In embodiments in which plurality of WCROs 2 may be used on cable 14, high tension and high drag during wireline logging operations may be significantly reduced by minimizing cable 14 contact over a selected zone(s) of a wellbore. WCROs 2 may be installed on cable 14, for example, to either straddle known dogleg zones where the cutting of casing grooves may be a risk (e.g., eliminating cable contact 100%) or they can be placed at regular intervals along cable 14 to minimize friction, and therefore reduce tension, during logging operations of the wellbore. In certain embodiments, the spacing of WCROs 2 on cable 14 may be from about 3 meters to about more than 35 meters, depending on the requirements for the particular wellbore being logged.

[0036] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.