Abstract:
An expandable wirefinder ( 60 ) for locating a wire downhole comprises a sleeve ( 62 ) and a dual collet assembly ( 72 ). The dual collet assembly ( 72 ) has first and second collet members ( 78, 82 ) each having plurality of collet fingers ( 80, 84 ). The dual collet assembly ( 72 ) is slidable relative to the sleeve ( 62 ) to operate between running and finding positions. In the running position, the first collet member ( 78 ) is partially disposed within the sleeve ( 62 ) with its collet fingers ( 80 ) inwardly radially biased by the sleeve ( 62 ) and the second collet member ( 82 ) is disposed within the first collet member ( 78 ) with its collet fingers inwardly ( 84 ) radially biased by the sleeve ( 62 ). In the finding position, the collet fingers ( 80 ) of the first collet member ( 78 ) radially expand to form gaps therebetween and the collet fingers ( 84 ) of the second collet member ( 82 ) radially expand into the gaps.

Description:
TECHNICAL FIELD OF THE INVENTION 
   This invention relates, in general, to finding the end of a broken wireline disposed within a wellbore and, in particular, to an expandable wirefinder capable of traveling through a restriction within the wellbore then expanding to the diameter of the wellbore to find the end of the broken wireline and a method for use of the same. 
   BACKGROUND OF THE INVENTION 
   Once a well that traverses a subterranean hydrocarbon bearing formation has been drilled, it is common to attach a variety of tools or equipment to the end of a conductive or nonconductive wireline and lower the tools or equipment downhole to perform wireline operations. For example, certain flow control devices such as subsurface safety valves, plugs, packers, gas lift valves and the like are commonly lowered into the wellbore or retrieved from the wellbore via wireline. Similarly, certain downhole devices such as sliding sleeves and the like are commonly actuated using a service tool suspended on a wireline. 
   During any of the above wireline operations, there is always a risk that the wireline may break during the operation. For example, the weight of the tool string sometimes exceeds the breaking strength of the wireline. Alternatively, if the tool string may become stuck in the wellbore, it may be necessary to pull on the wireline to release the tool string. Such excessive tension on the wireline may cause the wireline to break. In addition, in the case of detonating a perforating gun, the shock generated by the perforating gun will sometimes cause the wireline to break. Furthermore, if an out of range pressure condition occurs during a wireline operation, it may be necessary to shut in the well at a set of shear rams or at a subsurface safety valve. In either case, the wireline may be cut during the shut in operation. 
   When such a wireline break occurs, it becomes necessary to find and retrieve the broken wireline from the wellbore. It has been found, however, that it is often difficult to find and retrieve the broken wireline as the wireline typically falls down into the wellbore and coils up against the interior wall of the wellbore. In addition, finding and retrieving such as broken wireline is particularly difficult when a wellbore restriction is present uphole of the broken wireline. 
   Therefore, a need has arisen for a tool that is capable of finding the end of a wireline after the wireline has broken downhole. A need has also arisen for such a tool that can pass through a restriction in the wellbore yet still find the end of the broken wireline. Further, a need has arisen for such a tool that allows for the retrieval of the broken wireline after the end of the wireline has been found. 
   SUMMARY OF THE INVENTION 
   The present invention disclosed herein comprises an expandable wirefinder and a method for using an expandable wirefinder that is capable of finding the end of a wireline after the wireline has broken downhole. The expandable wirefinder of the present invention can pass through a restriction in the wellbore yet still find the end of the broken wireline. In addition, the expandable wirefinder of the present invention allows for the retrieval of the broken wireline after the end of the wireline has been found. 
   The expandable wirefinder comprises a sleeve and a dual collet assembly that includes first and second collet members. Each of the collet members has plurality of collet fingers. The dual collet assembly is slidably moveable relative to the sleeve between a running position and a finding position. In the running position, the first collet member is partially disposed within the sleeve with its collet fingers inwardly radially biased by the sleeve and the second collet member is disposed within the first collet member with its collet fingers inwardly radially biased by the sleeve. In the finding position, the collet fingers of the first collet member radially expanded to form gaps therebetween and the collet fingers of the second collet member radially expanded into the gaps between the collet fingers of the first collet member. 
   More specifically, when the dual collet assembly is in the running position, the ends of the collet fingers of the first collet member form a circular configuration having a diameter substantially the same as a diameter of the sleeve. At the same time, the ends of the collet fingers of the second collet member substantially form a circular configuration having a diameter less than a diameter of the sleeve. 
   Also, when the dual collet assembly is in the finding configuration, the ends of the collet fingers of the first collet member substantially form a gapped circular configuration having a diameter larger than the diameter of the sleeve. Likewise, the ends of the collet fingers of the second collet member substantially form a gapped circular configuration having a diameter substantially the same as the diameter of the ends of the collet fingers of the first collet member. Accordingly, the expandable wirefinder of the present invention can be run downhole and pass through a restriction then expand to the diameter of the tubular in which the broken wireline in located. 
   In one embodiment of the expandable wirefinder of the present invention, the expandable wirefinder is used to locate the end of the broken wireline downhole then reconfigure the end of the broken wireline by bending the wireline, creating one or more loops in the broken wireline and moving the end of the broken wireline away from the inner surface of the tubular. This embodiment of the expandable wirefinder of the present invention is then pulled out of the hole and a wire grab is run into the hole to retrieve the reconfigured broken wireline from the known position. 
   In another embodiment of the expandable wirefinder of the present invention, the expandable wirefinder includes its own wire grab such that the locating and retrieving of the broken wireline may occur during the same trip downhole. 
   In another aspect of the present invention, the expandable wirefinder is operated in accord with a method comprising the steps of running an expandable wirefinder downhole on a conveying device, the expandable wire finder including a sleeve and a dual collet assembly with a wire grab, contacting a restriction downhole with the sleeve, operating the dual collet assembly from a running position to a finding position, proceeding farther downhole with the dual collet assembly in the finding position, finding the wire downhole with the dual collet assembly, grabbing the wire with the wire grab, retrieving the dual collet assembly and the wire uphole to the sleeve, operating the dual collet assembly from the finding position to the running position and retrieving the expandable wirefinder and the wire uphole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
       FIG. 1  is a schematic illustration of an offshore oil and gas platform operating an expandable wirefinder according to the present invention; 
       FIG. 2  is a half sectional view of an expandable wirefinder according to the present invention in its running position; 
       FIG. 3  is a half sectional view of an expandable wirefinder according to the present invention in its running position; 
       FIG. 4  is a perspective view of an expandable wirefinder according to the present invention in its running position; 
       FIG. 5  is a half sectional view of an expandable wirefinder according to the present invention in its finding position; 
       FIG. 6  is a perspective view of an expandable wirefinder according to the present invention in its finding position; 
       FIG. 7  is a half sectional view of an expandable wirefinder having a wire grab according to the present invention in its running position; and 
       FIG. 8  is a half sectional view of an expandable wirefinder having a wire grab according to the present invention in its finding position. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention. 
   Referring initially to  FIG. 1 , an expandable wirefinder of the present invention for locating the end of a wireline that has broken downhole is being operated from an offshore oil and gas platform that is schematically illustrated and generally designated  10 . A semi-submersible platform  12  is centered over a submerged oil and gas formation  14  located below sea floor  16 . A subsea conductor  18  extends from deck  20  of platform  12  to sea floor  16 . A wellbore  22  extends from sea floor  16  and traverse formation  14 . Wellbore  22  includes a casing  24  that is cemented therein by cement  26 . Casing  24  has perforations  28  in the interval proximate formation  14 . 
   A tubing string  30  extends from wellhead  32  to formation  14  to provide a conduit for production fluids to travel to the surface. A pair of packers  34 ,  36  provide a fluid seal between tubing string  30  and casing  24  and direct the flow of production fluids from formation  14  through sand control screen  38 . Disposed within tubing string  30  is a subsurface safety valve  40  that is designed to shut in the flow of production fluids if the flow exceeds a preset rate. Also disposed within tubing string  30  is a wireline operated pressure testing tool  42  that is attached on the far end of a broken wireline  44 . The near end  46  of wireline  44  is positioned against the interior surface of tubing string  30  as wireline  44  has coiled up within tubing string  30  after being cut by subsurface safety valve  40  during an out of range condition that occurred during a pressure testing operation. 
   In the illustrated embodiment, a fishing operation is being conducted wherein expandable wirefinder  48  is being run downhole on a conveyance  50 , such as a wireline, coiled tubing or the like, to find near end  46  of broken wireline  44 . As explained in greater detail below, expandable wirefinder  48  is not only capable of passing through the restriction crated by subsurface safety valve  40 , but is also capable of contacting the interior surface of tubing string  30  beyond the restriction such that near end  46  of broken wireline  44  may be found and wireline  44  including pressure testing tool  42  can subsequently be retrieved. 
   Referring next to  FIG. 2 , therein is depicted an expandable wirefinder of the present invention that is generally designated  60 . Expandable wirefinder  60  includes an axially extending generally tubular sleeve  62 . Sleeve  62  includes an upper sleeve section  64 , a middle sleeve section  66  that is threadably coupled to upper sleeve section  64  and a lower sleeve section  68  that is threadably coupled to middle sleeve section  66 . Upper sleeve section  64  has a profile  70  that is used to latch into a matching profile within a downhole restriction such as the receiving profile within a subsurface safety valve. 
   Positioned within sleeve  62  is a dual collet assembly  72 . Dual collet assembly  72  is initially coupled to lower sleeve section  68  by a plurality of shear pins  74 . Dual collet assembly  72  has a fish neck  76  that is used to couple dual collet assembly  72  to a conveyance. Dual collet assembly  72  includes an outer collet member  78  having a plurality of collet fingers  80  and an inner collet member  82  having a plurality of collet fingers  84 . In the illustrated embodiment, inner collet member  82  is coupled to fish neck  76  with a pin connector  86 . Also, in the illustrated embodiment, outer collet member  78  is coupled to inner collet member  82  with a pin connector  88 . It should be understood by those skilled in the art that other types of connections may be made between inner collet member  82  and fish neck  76  and between outer collet member  78  and inner collet member  82 , such as threaded connections, without departing from the principles of the present invention. 
   Referring now to  FIGS. 3 and 4 , dual collet assembly  72  has a running position wherein outer collet member  78  is at least partially disposed within lower sleeve section  68  and inner collet member  82  is disposed within outer collet member  78 . More specifically, in this running position, collet fingers  80  of outer collet member  78  are inwardly radially biased by lower sleeve section  68  such that collet fingers  80  form a substantially cylindrical configuration. In fact, as best seen in  FIG. 4 , the ends of collet fingers  80  substantially form a circular configuration having a diameter substantially the same as a diameter of sleeve  62 . Accordingly, in the running position, outer collet member  78  can pass through a variety of restrictions within a wellbore including the restriction having the profile that matches profile  70  of upper sleeve section  64 . 
   Also in the running position of dual collet assembly  72 , collet fingers  84  of inner collet member  82  are inwardly radially biased by lower sleeve section  68  such that collet fingers  84  form a substantially cylindrical configuration. More specifically, each collet finger  84  has a radially outwardly extending lug  90  the passes through a respective window  92  of outer collet member  78  and contacts the interior surface of lower sleeve section  68 . Due to the thickness of lugs  90 , collet fingers  84  of inner collet member  82  are biased radially inwardly to a location within outer collet member  78 . In fact, as best seen in  FIG. 4 , the ends of collet fingers  84  substantially form a circular configuration having a diameter smaller than the diameter of the substantially circular configuration of the ends of collet fingers  80  of outer collet member  78 . 
   Referring now to  FIGS. 5 and 6 , dual collet assembly  72  has a finding position wherein dual collet assembly  72  has been released from sleeve  62  by shearing shear pins  74  after profile  70  of upper sleeve section  64  has located its matching profile in the downhole restriction. In the finding position, outer collet member  78  is no longer disposed within lower sleeve section  68 . Accordingly, collet fingers  80  of outer collet member  78  are no longer inwardly radially biased by lower sleeve section  68 . Instead, collet fingers  80  of outer collet member  78  substantially form a conical section having gaps between collet fingers  80 . In fact, as best seen in  FIG. 6 , the ends of collet fingers  80  of outer collet member  78  substantially form a gapped circular configuration having a diameter larger than the diameter of sleeve  62 . 
   Also in the finding position of dual collet assembly  72 , collet fingers  84  of inner collet member  82  are no longer inwardly radially biased by lower sleeve section  68 . Instead, collet fingers  84  of inner collet member  82  also substantially form a conical section having gaps between collet fingers  84 . In fact, as best seen in  FIG. 6 , the ends of collet fingers  84  of inner collet member  82  substantially form a gapped circular configuration having a diameter substantially the same as the diameter of the gapped circular configuration of the ends of collet fingers  80  of outer collet member  78 . 
   In the finding position of dual collet assembly  72 , collet fingers  84  of inner collet member  82  fill the gaps between collet fingers  80  of outer collet member  78  and collet fingers  80  of outer collet member  78  fill the gaps between collet fingers  84  of inner collet member  82 . Accordingly, when the diameter at the ends of collet fingers  84  of inner collet member  82  and collet fingers  80  of outer collet member  78  is substantially the same as the inner diameter of the tubular in which the broken wireline is disposed, the end of the broken wireline will be contacted by dual collet assembly  72  of expandable wirefinder  60  even when the end of the broken wireline is in contact with the inner surface of the tubular. As little or no gap is present between collet fingers  84  of inner collet member  82  and collet fingers  80  of outer collet member  78 , the end of the broken wireline cannot elude dual collet assembly  72  of expandable wirefinder  60 . 
   Furthermore, due to the conical shape of the interior of dual collet assembly  72  in the finding position, when the end of the broken wireline is found, the end can be bent over such that the end will no longer be in contact with the inner surface of the tubular and a conventional wire grab tool may be run downhole on a subsequent wireline trip to grab the end of the broken wireline and retrieve the broken wireline along with any tools attached to the lower end of the broken wireline to the surface. 
   Even though  FIGS. 2-6  have depicted expandable wirefinder  60  as having six collet fingers  80  in outer collet member  78  and six collet fingers  84  in outer collet member  82 , it should be understood by those skilled in the art that outer collet member  78  and inner collet member  82  could alternative have other numbers of collet fingers either greater than or less than six without departing from the principles of the present invention. 
   In operation, dual collet assembly  72  is pinned within sleeve  62  such that outer collet member  78  is at least partially disposed within lower sleeve section  68  and inner collet member  82  is disposed within outer collet member  78 . In this running position, expandable wirefinder  60  may be run downhole on a conveyance such as a wireline. When expandable wirefinder  60  reaches a restriction in the wellbore, such as subsurface safety valve  40  of  FIG. 1 , dual collet assembly  72  as well as lower sleeve section  68  and middle sleeve section  66  can pass through the restrictions. The downward travel of expandable wirefinder  60  is stopped, however, when profile  70  of upper sleeve section  64  is received within a matching profile within the restriction. 
   At this point, shear pins  74  are sheared by appropriate axial jarring such that dual collet assembly  72  including fish neck  76 , outer collet member  78  and inner collet member  82  is disconnected from sleeve  62 . Dual collet assembly  72  is now free to continue its downhole decent as additional length of the conveyance is feed into the well. As dual collet assembly  72  is slidably released from sleeve  62 , dual collet assembly  72  shifts from its running position to its finding position. During the shifting process, collet fingers  80  of outer collet member  78  begin to radially expand such that gaps are formed therebetween. Thereafter, collet fingers  84  of inner collet member  82  begin to radially expand such that gaps are formed therebetween. As dual collet assembly  72  nears the fully expanded or finding position, collet fingers  84  of inner collet member  82  fill the gaps between collet fingers  80  of outer collet member  78  and collet fingers  80  of outer collet member  78  fill the gaps between collet fingers  84  of inner collet member  82  leaving no gaps between any of the collet fingers. 
   In the finding position, collet fingers  84  of inner collet member  82  and collet fingers  80  of outer collet member  78  preferably contact the interior surface of the tubular in which the broken wireline is disposed. Dual collet assembly  72  is then run farther downhole until dual collet assembly  72  contacts the end of the broken wireline. The weight of dual collet assembly  72  and the conveyance are then allowed to act on the end of the broken wireline in, for example, a cyclical manner. Due to the conical interior shape of dual collet assembly  72 , this process bends the end of the broken wireline preferably creating one or more loops in the broken wireline and moving the end of the broken wireline away from the inner surface of the tubular and toward the center of the tubular. 
   Once the end of the broken wireline has been appropriately reconfigured, expandable wirefinder  60  of the present invention may be retrieved to the surface. Specifically, the conveyance is pulled out of the hole until dual collet assembly  72  reaches sleeve  62 . As dual collet assembly  72  slidably enters sleeve  62 , dual collet assembly  72  shifts from its finding position to its running position. Specifically, lugs  90  of collet fingers  84  of inner collet member  82  contact the end of lower sleeve section  68  which inwardly radially biases collet fingers  84  and retracts collet fingers  84  out of the gaps between collet fingers  80  of outer collet member  78 . Further movement of dual collet assembly  72  into sleeve  62  causes collet fingers  80  of outer collet member  78  to contact the end of lower sleeve section  68  which inwardly radially biases collet fingers  80 . 
   Once dual collet assembly  72  has returned to its running position, appropriate tension on the conveyance will cause profile  70  to release from its matching profile in the restriction such that expandable wirefinder  60  may be retrieved to the surface. Thereafter, a suitable wire grab may be attached to the end of the conveyance and run downhole to the known location of the end of the broken wireline which is now in a configuration that is conducive to being caught in the wire grab such that the broken wireline may be retrieved to the surface. 
   Referring next to  FIGS. 7 and 8 , therein is depicted another embodiment of an expandable wirefinder of the present invention in its running position and its finding position, respectively, that is generally designated  160 . Expandable wirefinder  160  includes an axially extending generally tubular sleeve  162 . Sleeve  162  includes an upper sleeve section (not pictured), a middle sleeve section (not pictured) that is threadably coupled to the upper sleeve section and a lower sleeve section  168  that is threadably coupled to the middle sleeve section. As described above with reference to expandable wirefinder  60  in  FIG. 2 , the upper sleeve section of expandable wirefinder  160  has a profile that is used to latch into a matching profile within a downhole restriction such as the receiving profile within a subsurface safety valve. 
   Positioned within sleeve  162  is a dual collet assembly  172 . Dual collet assembly  172  is initially coupled to lower sleeve section  168  by a plurality of shear pins  174 . Dual collet assembly  172  has a fish neck  176  that is used to couple dual collet assembly  172  to a conveyance. Dual collet assembly  172  includes an outer collet member  178  having a plurality of collet fingers  180  and an inner collet member  182  having a plurality of collet fingers  184 . In the illustrated embodiment, inner collet member  182  is coupled to fish neck  176  with a pin connector  186 . Also, in the illustrated embodiment, outer collet member  178  is coupled to inner collet member  182  with a pin connector  188 . 
   Expandable wirefinder  160  operates in a manner that is similar to expandable wirefinder  60  described above, except expandable wirefinder  160  carries its own wire grab mechanism depicted herein as a wireline spear  190 . In the illustrated embodiment, wireline spear  190  is threadably coupled to inner collet member  182 . Wireline spear  190  axially extends into the region surrounded by collet fingers  184  of inner collet member  182  when dual collet assembly  172  is in the running position. When dual collet assembly  172  is in the finding position, wireline spear  190  axially extends into the region surrounded by collet fingers  184  of inner collet member  182  and by collet fingers  182  of outer collet member  178 . In this position, once the end of the broken wireline is found and the weight of dual collet assembly  172  and the conveyance are applied on the end of the broken wireline to bend the wireline and create loops, wireline spear  190  can grab the broken wireline such that it can be found and retrieved to the surface in a single trip of expandable wirefinder  160 . 
   Even though expandable wirefinder  160  has been described as having a wireline spear type wire grab, other types of wire grabs such as a pronged U-shaped wire grab, a dog knot type wire grab or the like may alternatively be used in conjunction with expandable wirefinder  160  without departing from the principles of the present invention. 
   While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.