Patent Abstract:
A combination tool for attaching to a stuck wireline tool, then cutting the wireline just above the stuck tool with a hydraulically driven cutter, allowing the wireline to be pulled out of the hole before fishing out the stuck tool. A side door can be provided on the work string, to allow rerouting of the wireline outside the work string, after which the stuck tool can be unstuck and repositioned within the well bore for completion of the downhole operation of the tool, prior to cutting the wireline free from the downhole tool.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional patent application of co-pending U.S. patent application Ser. No. 09/680,579, filed on Oct. 06, 2000, now U.S. Pat. No. 6,763,753 and entitled “Hydraulic Wireline Cutter.” 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is in the field of retrieving stuck tools which are suspended downhole in an oil or gas well on a wireline. 
     2. Background Art 
     During the drilling of an oil or gas well, tools called well logging tools are often run into the well bore suspended on a wireline. These tools can be used for such purposes as measuring various properties of the earth formation at selected depths. While suspended in the well bore, such tools sometimes become stuck, either in an open hole portion of the well bore, or even in a cased portion. It then becomes necessary to retrieve the stuck tool from the well bore. In open hole, this is usually done by cutting the wireline at the earth&#39;s surface, then running a drill pipe into the well over the wireline. An attachment tool, such as a grappling tool, on the lower end of the drill string is attached to the stuck tool. Then, the wireline is pulled until it separates from the cable head on the stuck tool, and the downhole tool is then retrieved with the drill string. In cased hole, the wireline is normally pulled out of the cable head first, then the stuck tool is fished out, either with a wireline fishing tool or a tubing conveyed fishing tool. 
     The retrieval operation is sometimes further complicated by an unplanned separation of the wireline some distance above the tool, rather than at the cable head, leaving some portion of the wireline in the well, suspended above or lying on top of the stuck tool. This unplanned separation of the wireline can also occur when the wireline is pulled in order to loosen or retrieve a stuck tool. 
     Unplanned separation of the wireline can be minimized by including a weak point in the string, just above the suspended tool. This insures that the wireline will break at this weak point, allowing all of the wireline to be retrieved from the well bore before fishing or retrieval of the stuck tool is attempted. Unfortunately, the use of a weak point limits the weight of the tool string that can be suspended from a wireline, as well as the amount of pull the operator can apply in order to free a stuck tool. 
     Unplanned separation of the wireline can also be minimized by including an explosive driven wireline cutter above the downhole tool. Such tools suffer from the disadvantage that they must be installed in the wireline before running in the tool, and they require a separate fishing operation after the wireline is severed. Explosively severing the wireline can also loosen the attachment between a grappling tool and the stuck tool. 
     Even when the retrieval operation goes without complications, since the wireline is severed before unsticking the tool, the stuck tool must be completely removed from the well bore, then a new or reconnected tool run back into the well to complete the logging operation which was originally underway. 
     It would be beneficial, then, to have a combination tool which can attach to a stuck tool, loosen the stuck tool, sever the wireline just above the tool allowing retrieval of the wireline, and then retrieve the tool. It would also be beneficial to be able to attach to the stuck tool, loosen and reposition the tool for completion of its original operation, and then have the ability to sever the wireline if necessary, all with a single tool. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a combination tool including an attachment tool such as a grapple, and a hydraulically driven wireline cutter, both mounted on a tubular work string. The work string is lowered into the well bore over the wireline, and the grapple is attached to the stuck tool. The work string can be raised and lowered slightly, to confirm the attachment. Fluid flow is then increased to drive a piston and wedge, which in turn drives a cutter blade through the wireline, severing it just above the stuck tool. The entire length of the wireline can then be pulled from the well, after which the work string is used to loosen and retrieve the stuck tool. 
     Alternatively, after the grapple is attached to the stuck tool, the wireline can be cut at the well site on the earth surface and routed through a side door in the work string, and reconnected. Then, the work string can be used to loosen the stuck tool and reposition it downhole as required for the completion of the originally planned operation of the tool, such as well logging operations. Then, the entire assembly can be retrieved with the work string, or the wireline can be hydraulically severed at the stuck tool and retrieved, followed by retrieval of the stuck tool itself. 
     The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which: 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a longitudinal section view of the apparatus of the present invention; 
     FIG. 2 is a longitudinal section view of the apparatus shown in FIG. 1, with a wireline passing therethrough; 
     FIG. 3 is a longitudinal section view of the apparatus shown in FIG. 1, with a stuck tool attached to the grappling device; 
     FIG. 4 is a longitudinal section view of the apparatus shown in FIG. 1, after the wireline has been cut; 
     FIG. 5 is a longitudinal section view of the hydraulic cutter device used in the apparatus shown in FIG. 1; 
     FIG. 6 is a transverse section view of the apparatus shown in FIG. 1, showing the cutter blade in its retracted position; and 
     FIG. 7 is a transverse section view of the apparatus shown in FIG. 1, showing the cutter blade in its extended position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIG. 1, the wireline cutting and retrieval apparatus  10  of the present invention includes a grappling device  12  and a hydraulic cutting device  14  mounted adjacent the lower end of a tubular work string  18 . The grappling device  12  can include a grapple  16  as is well known in the art, or any other type of attachment device suited for attaching the work string to the particular wireline tool that may be stuck downhole. 
     A piston  20  is slidably mounted for longitudinal motion in the work string  18 , sealed against the work string  18  by a seal  28 . An upper nozzle  22  is mounted adjacent the upper end  30  of the piston  20 , in a fluid flow path  29  through the piston  20 . The upper nozzle  22  can be retained in the piston  20  by a retainer ring  24 , and sealed by a seal  26 . 
     As more easily seen in FIG. 5, the lower end of the piston  20  abuts the upper end of an upper wedge  32 , which has an inwardly facing ramp  33  sloping outwardly from the axis of the apparatus  10  and downwardly. The inwardly facing ramp  33  on the upper wedge  32  abuts an outwardly facing ramp  35  on a lower wedge  34 . The outwardly facing ramp  35  also slopes outwardly from the axis of the apparatus  10  and downwardly. A cutter blade  36  is oriented transverse to the axis of the apparatus  10 , and mounted to the lower wedge  34 , for example by a fastener  37 . The cutter blade  36  has an inwardly oriented cutting edge  38 . The cutter blade  36  is mounted for transverse motion within a transverse slot  39  in a cutter body  44 . 
     The lower wedge  34  can be attached to the work string  18  by a shearable device, such as a shear screw  40  and nut  42 . The shear screw  40  retains the lower wedge  34 , upper wedge  32 , and piston  20  in place relative to the work string  18 . This maintains the cutter blade  36  in its retracted position as shown in FIGS. 1 and 5. 
     As shown in FIG. 1, a rupturable device, such as a rupture disk  46  is mounted in the wall of the work string  18 , below the piston  20  and the upper nozzle  22 . The rupture disk  46  can be held in place by a retainer nut  48  and control washers  50 ,  52 . The rupture disk  46  separates a fluid flow path  29  through the work string  18  from the well bore annulus surrounding the work string  18 . A debris barrier  54  is mounted in the bore of the work string  18  below the position of the rupture disk  46 , held in place by a retainer  56 . The debris barrier  54  can limit the accumulation of debris in the moving parts of the apparatus  10  as it is lowered into the well bore. A lower nozzle  58  is mounted in the debris barrier  54 , held in place by a retainer  62 , and sealed by a seal  60 . The lower nozzle  58  serves as a guide through the debris barrier  54  for the wireline. 
     FIG. 2 shows the apparatus  10  as it is being run into the well bore over a wireline WL. The wireline WL passes through a passageway  64  through the piston  20 , the cutter body  44 , the debris barrier  54 , and the grapple  16 . At this point, it can be seen that the grapple  16  is still unengaged, the rupture disk  46  is still intact, the piston  20  is still in its upper position, and the blade  36  is still in its retracted position. These components maintain these positions until after the apparatus  10  contacts and attaches to the top of a stuck tool suspended on the wireline WL. Just prior to attachment to the stuck tool, fluid is circulated through the apparatus  10  to clear the grappling device  12  of debris. Then, the apparatus  10  is set down on the tool to engage it with the grapple  16 , or attachment is achieved as appropriate for the particular attachment device used. 
     FIG. 3 shows a stuck tool ST attached at the cable head CH to the wireline WL. The stuck tool ST is engaged by the grapple  16 , as is well known in the art. The weight of the stuck tool ST can now be supported by the work string  18 . The work string  18  can be moved longitudinally in the well bore, to observe changes in the wireline weight, confirming that the apparatus  10  is attached to the stuck tool ST. 
     It can be seen that fluid flow through the grapple  16  can become more constricted, or even blocked. Greater fluid flow may be required, either to control well pressure, or to allow the functioning of the cutter apparatus as described below. Fluid pressure can be increased until the rupture disk  46  is ruptured, allowing increased fluid flow through the wall of the work string  18  into the annulus. 
     FIG. 4 shows the situation where fluid flow has been increased through the fluid flow path  29  in the upper nozzle  22 , building up a hydraulic pressure differential across the piston  20 . The increased flow can be either out the end of the apparatus  10 , or through the fluid flow path  66  established through the rupture disk  46 . This pressure differential causes the piston  20  to press downwardly against the upper wedge  32 , which in turn presses inwardly on the lower wedge  34 , because of the abutment of the ramps  33 ,  35  on the wedges  32 ,  34 . The exertion of this inward force on the lower wedge  34  imposes a tensile stress on the shear screw  40 . When this tensile stress is sufficient to part the shear screw  40 , the lower wedge  34  moves inwardly, and the piston  20  and the upper wedge  32  move downwardly. More importantly, the lower wedge  34  drives the cutter blade  36  transversely across the wireline passageway  64 , cutting the wireline WL near the cable head CH. Other sherable devices could be substituted for the shear screw  40 , to retain the piston  20  in its upper position until cutting of the wireline WL is desired. FIG. 6 shows more clearly the retracted position of the cutter blade  36 , and FIG. 7 shows the extended position of the cutter blade  36 . After the wireline WL is cut, it can be fully removed from the well bore, preventing it from complicating the loosening and retrieval of the stuck tool ST with the work string  18 . 
     As an alternative mode of operation, instead of operating the cutting device  14  as soon as the stuck tool ST is grappled, the wireline WL could be separated at the earth surface, run through a side door in the work string  18 , and reconnected, as is known in the art. Then, the work string  18  could be used to loosen the stuck tool ST and reposition it as desired in the well bore. This allows the wireline tool to complete its originally planned sequence of operations, such as logging the well, on the lower end of the work string  18 . After completion of the operation of the wireline tool, it can be retrieved from the well with the work string  18 , with the hydraulic cutting operation being performed at any desired time in the retrieval operation. Having the hydraulic cutting device  14  in place adjacent the grapple  16  allows the full removal of the wireline WL should this become desirable during the retrieval process, without the risk of dropping the tool, and without the need for running a separate tool. 
     While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.

Technology Classification (CPC): 4