Abstract:
A cutting assembly for external conduits on a tubing string or main tubular conduit features at least one breakaway in the string that can be severed with a tensile force. Preferably each external conduit is run through a cutter housing that is integral with a passage having threaded end connections. While in some scenarios it is preferred that the main tubular conduit is severed below the cutting assembly thus allowing the cutting apparatus to be retrieved with the upper portions of the cut main tubular conduit and external longitudinal member(s), in other circumstances it may be desired that the main tubular conduit is severed above the cutting assembly allowing the cutting apparatus to be left “downhole” with the lower portion of the cut main tubular conduit and the BHA. The cutter knife assembly chambers or channels can be in banks that are axially spaced using bypass channels to access lower banks. The cutter knife assembly and associated channels can be mirror images so that the external conduits can be cut regardless of where the tubing string is severed and one or more conduits can be cut with a single cutter assembly.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation in part of U.S. patent application Ser. No. 12/469,388, filed on May 20, 2009 entitled Auxiliary Conduit Cutting Apparatus. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of the invention is cutting auxiliary conduits associated with a bottom hole assembly (BHA) when the string supporting the BHA is separated and pulled “out of the hole” from an underground or underwater encasement or caisson. 
       BACKGROUND OF THE INVENTION 
       [0003]    In many applications in oil or gas wells, a main tubular conduit, such as production tubing, is run into the wellbore with a BHA attached. The BHA may have a wireline, control line, vent line, or other such longitudinal member(s) attached to it. Typically, these wireline, control line, vent line, or other such longitudinal member(s) will be run externally to the production tubing. Such longitudinal members will be referred to as external longitudinal members herein. Often, there may be several such external longitudinal members run into the wellbore along with, and external to, the production tubing or other main tubular conduit. 
         [0004]    In some circumstances, it becomes necessary to cut or sever the main tubular conduit at a point downhole, and to pull the tubular conduit back out of the hole, leaving the severed lower portion of tubular conduit, and the BHA attached thereto, in the wellbore. This also necessitates the cutting of the external longitudinal members, preferably without a separate operation for running specialized cutting equipment into the wellbore. It is also desirable to be able to cut the wireline, control line, vent line, or other such longitudinal member(s) somewhere downhole as close as possible to the point at which the tubular conduit is cut, to salvage as much as possible of the external longitudinal member and keep the wellbore as open as possible. While in some scenarios it is preferred that the main tubular conduit is severed below the cutting apparatus thus allowing the cutting apparatus to be retrieved with the upper portions of the cut main tubular conduit and external longitudinal member(s), in other circumstances it may be desired that the main tubular conduit is cut above the cutting apparatus allowing the cutting apparatus to be left “downhole” with the lower portion of the cut main tubular conduit and the BHA. 
         [0005]    A prior design described in U.S. Pat. No. 6,997,262 provided a method and apparatus for severing one or more external longitudinal members, with a cutting tool attached to the main tubular conduit, above the BHA. The cutting tool consisted of a cutter body which was clamped in place on the external surface of the main tubular conduit, such as by capturing the cutter body between two couplers threaded onto the tubular conduit. Inside the cutter body was one cutter knife which slid longitudinally relative to the cutter body. This cutter knife is fixedly attached to the external longitudinal member, such as by being clamped thereto. The external longitudinal member or members are routed through the cutter body so as to be exposed to the cutting edge of the knife or knives. If there are several knives, they can be oriented facing each other, and the external longitudinal member or members are routed between the cutting edges on the cutter knives. A surface on each cutter knife abuts an actuating surface on the cutter body, with this actuating surface sloping downwardly and transversely to the longitudinal axis of the cutting tool. If there are several cutter knives, there can be a single conical actuating surface, or several actuating surfaces. 
         [0006]    If it became necessary to sever the main tubular conduit and retrieve the upper portion, this operation was first accomplished below the cutting tool. The upper portion of the tubular conduit, as well as the cutting tool, is then pulled upwardly, or uphole, to retrieve it from the well. 
         [0007]    After the tubular conduit is severed, pulling upwardly on the tubular conduit will also lift the cutter body upwardly, or in an uphole direction. At the same time, the external longitudinal member to which the cutter knives are attached is still attached to the BHA, thereby holding the cutter knives in place longitudinally in the well bore. The uphole movement of the cutter body relative to the cutter knives caused the sloping actuating surfaces on the cutter body to engage the abutting surfaces on the cutter knives and forced the cutter knives toward each other, or inwardly. This drove the cutting edges of the cutter knives through the external longitudinal member or members, severing them. This allowed the upper portion(s) of the cut external longitudinal member or members and the cutting tool to be simultaneously retrieved from the well bore. 
         [0008]    As shown in  FIG. 1 , the apparatus  10  includes generally a cutter body  12 , and one or more cutter knives  18 ,  20 . The cutter body  12  has a longitudinal bore  14  therethrough, for passage of a tubular conduit TC to which the apparatus  10  of the present invention may be attached. For example, the cutter body  12  can be captured in place longitudinally on the tubular conduit TC by threading of couplers (not shown), as is known in the art, on the ends of the section of tubular conduit TC, above and below the cutter body  12 . 
         [0009]    The cutter body  12  has a generally longitudinal knife chamber  16  in which the cutter knives  18 ,  20  are slidably positioned. The cutter knives  18 ,  20  have clamping bodies  22 ,  24  near their upper ends. The clamping bodies  22 ,  24  can be fastened together, as shown better in  FIG. 2 , to clamp tightly around a longitudinal member, such as a wireline WL, which is positioned externally to the tubular conduit TC. The clamping bodies  22 ,  24  can be bolted together at mating surfaces  50 , as is well known in the art. The bolts and bolt holes are omitted in these views, for the sake of clarity. 
         [0010]    The cutter knives  18 ,  20  have thinner mid-sections  26 ,  28 , which can flex to allow the lower ends of the knives  18 ,  20  to deflect inwardly, as will be explained below. Cutter blades  30 ,  32  are mounted on the knives  18 ,  20  near their lower ends, with the blades  30 ,  32  having cutting edges  34 ,  36  facing each other, or facing inwardly.  FIG. 3  shows this orientation of the cutting edges  34 ,  36 . 
         [0011]    As seen in  FIGS. 1 through 3 , a wireline passage  38  is provided longitudinally through the cutter body  12 , as is a vent line passage  40 . Similarly, a passage could be provided for a control line or any other kind of external longitudinal member that may be in use next to the tubular conduit TC. These longitudinal member passages,  38  and  40 , position the external longitudinal members VL, WL between the cutter knives  18 ,  20 , and specifically between the cutting edges  34 ,  36 . As shown in  FIG. 3 , one cutting edge  36  can be V-shaped to centralize the vent line VL and the wireline WL between the cutting edges  34 ,  36 . 
         [0012]    A set of teeth or serrations  42  can be provided within the wireline passage  38 , to facilitate holding the cutter knives  18 ,  20  in position longitudinally relative to the wireline WL, when the clamping bodies  22 ,  24  are bolted together. The portion of the wireline passage  38  between the clamping bodies  22 ,  24  is dimensioned to slightly squeeze the wireline WL, without collapsing it or otherwise damaging it. The vent line passage  40  is dimensioned to allow passage of the vent line VL without squeezing it. As shown in  FIG. 2 , bolts and bolt holes  44  are provided to bolt together the two halves  12 A,  12 B of the cutter body  12 , in a similar fashion to that contemplated for the clamping bodies  22 ,  24 . Bolting together of the two cutter body halves  12 A,  12 B facilitates positioning of the cutter knives  18 ,  20  within the knife chamber  16 . 
         [0013]    As shown best in  FIG. 1 , one or more sloping surfaces  46 , 48  are provided at the lower end of the knife chamber  16 , sloping longitudinally and inwardly toward the longitudinal members VL,WL passing through the cutter body  12 . The lower ends of the cutter knives  18 ,  20  abut these sloping surfaces  46 ,  48 . Rather than having two distinct sloping surfaces, a conical sloping surface could be used with a plurality of inwardly facing knives. 
         [0014]    The configurations shown in  FIGS. 1 and 3  represent the made-up or run-in configuration of the apparatus  10 . After the tubular conduit TC and the BHA (not shown) are positioned in the wellbore, it may become necessary to sever the tubular conduit TC, the vent line VL, and the wireline WL above the BHA and retrieve them from the wellbore. After the tubular conduit TC is severed, by any means known in the art, the upper portion of the tubular conduit TC is pulled upwardly, or in the uphole direction. 
         [0015]    As shown in  FIG. 4 , this lifts the cutter body  12  in the uphole direction. Since the cutter knives  18 ,  20  are clamped in position longitudinally on the wireline WL, the lower end of which is still attached to the BHA, the cutter knives  18 ,  20  are forced inwardly by the sloping surfaces  46 ,  48  in the cutter body  12 , as the cutter body  12  rises. This forces the cutting edges  34 ,  36  of the blades  30 ,  32  toward each other, through the longitudinal members VL, WL, severing them.  FIG. 5  shows the overlapping of the cutter blades  30 ,  32  after the cutter knives  18 ,  20  have been forced fully inwardly by the sloping surfaces  46 ,  48 . After the severing operation, the upper portions of the external longitudinal members VL, WL can be retrieved from the wellbore. 
         [0016]    There were two main issues with the technique described above and the associated FIGS. One issue was the need to run a line cutter into the string to cut it as the preferred technique to sever a portion of the string from the BHA. This added time, cost, and risk to the operation. Apart from this, was that after the string was cut and picked up and the members VL and WL were cut, what remained below the cut location fell into the well and made subsequent fishing operations more difficult, if not impossible, by getting in the way of the retrieving or fishing tools. 
         [0017]    The invention in the prior application filed May 20, 2009 addresses these problem areas in the prior design of U.S. Pat. No. 6,997,262. It uses a breakaway coupling that comes apart by a tensile force on the string to part the string. Also, the position of the cutter body or bodies and cutter knife assembly or assemblies is inverted from the previous design. When the string is parted and is pulled up, what happens is that the external longitudinal conduit(s) are tensioned, pulling the knives into the cutting mode, but hanging on to the lower cut portion of the external longitudinal conduit(s) from just below the cut location to the fixation location in the BHA, so that there is no loose end that can fall into the wellbore and disturb subsequent fishing or other operations. In an alternative embodiment, the cutter assembly housing, which houses the cutter knife assemblies, can be a single piece that becomes an integral part of the string to allow more flexibility in the size or number of cutter knife assemblies per housing and allows stacking of chambers or channels (for cutter knife assemblies) while maintaining a lower profile using offset pass-through passages for different lines. Additionally, in an another alternate embodiment, the external longitudinal conduits can be severed either by applying an axial tensile force to the cutter body or bodies or by applying an axial tensile force to the external longitudinal conduit(s), depending on whether the string will be severed above all the housing chambers or severed below all the housing chambers in a prior operation. Those skilled in the art will better understand the invention from a review of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is given by the appended claims. 
       SUMMARY OF THE INVENTION 
       [0018]    A cutting assembly for external conduits on a tubing string features a breakaway in the string that can be severed with a tensile force. Alternately, the string can be severed above or below the cutter assembly by creating a mechanical cut through the tubular wall using a cutter that is actuated by mechanical, hydraulic, or other means. Preferably each external conduit is run through a cutter housing that is integral with a passage having threaded end connections. Upon severing of the string and applying a pickup force, a tensile force is applied either to the cutter assembly or assemblies or to each external conduit depending on whether the severing of the string happens above or happens below al the cutter knife assembly chambers or channels. The severing can also happen below the cutter housings. The channels can be in banks that are axially spaced using bypass channels to access lower banks. The cutter knife assembly can be a minor image with knives fashioned to cut lines while moving in either axial direction relative to the cutter assembly, thus allowing for a cut of the external longitudinal conduit(s) regardless of where the main tubular conduit is severed. One or more conduits can be cut with a single cutter assembly. The cutter assembly housing is preferably unitary with an off-center passage for the string leaving more space for cable cutter runs of various sizes. Pass-throughs for lines are offset from the cutter runs so that cutter knife assembly chambers or channels can be stacked while still allowing the cutter assembly or assemblies to pass through limited wellbore drift diameters. Complete cutter assemblies can also be stacked in tandem and provide similar benefits. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a longitudinal section view of a prior art apparatus (couplers not shown), showing its attachment to a tubular conduit, a vent line, and a wireline; 
           [0020]      FIG. 2  is a transverse section view of the apparatus shown in  FIG. 1 , taken at the line  2 - 2 ; 
           [0021]      FIG. 3  is a transverse section view of the apparatus shown in  FIG. 1 , taken at the line  3 - 3 ; 
           [0022]      FIG. 4  is a longitudinal section view of the apparatus showing the actuation of the cutter knife assembly&#39;s cutter blades; 
           [0023]      FIG. 5  is a transverse section view of the apparatus shown in  FIG. 4 , showing the actuation of the cutter knife assembly&#39;s cutter blades; 
           [0024]      FIG. 6  is a view of the invention claimed in the previous application filed May 20, 2009 shown in a run-in position with multiple cutters for external conduits or lines; 
           [0025]      FIG. 7  is the detailed view of  FIG. 6  showing a close-up view of a cutter assembly within which is a cutter knife assembly; 
           [0026]      FIG. 8  is a view of the apparatus shown in  FIG. 7  showing the breakaway separated and the cutter knife assembly&#39;s cutter blades actuated; 
           [0027]      FIG. 9  is a close-up perspective view of  FIG. 6  showing a line going from one cutter assembly housing to another cutter assembly housing, passing through and bypassing the cutter knife assembly; 
           [0028]      FIG. 10  is an alternative embodiment showing the unitary cutter assembly housing in part cutaway perspective view with three illustrated cutter runs of varying sizes; and 
           [0029]      FIG. 11  is part cutaway perspective view showing stacked cutter knife assembly chambers or channels, their respective cutter knife assemblies therein, and bypass channels or runs, all in a unitary cutter assembly housing. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0030]    Referring to  FIG. 6 , a string  60  on a part of which is shown and those skilled in the art will know extends to the surface of a wellbore, features a schematically illustrated breakaway  62  that has an upper component  64  and a sealingly nested lower component  66 . As used herein, “breakaway” includes any feature of the string designed to come apart when force is applied as well as the use of external tools that accomplish the same result of separation. They are releasably secured together preferably by one or more shear fastener(s)  68 . The invention contemplates a variety of designs with the ultimate objective of separation in the string  60 . Accordingly, the separation can be accomplished with an axial force or rotation or combinations of movements such as when a j-slot assembly is used. Alternatively there can be a ball seat on a sleeve that accepts a dropped object to allow pressuring up to accomplish the separation by, for example, breaking a shear fastener in the breakaway  62 . Using fluid pressure for the separation can make the assembly serviceable in wells that have some deviation or are non-vertical. In an application using an electric submersible pump (ESP) there is generally little deviation and a breakaway  62  that separates by a pulling force will generally be workable. More deviated applications will likely require a way to hydraulically disconnect the breakaway  62  in the manner discussed above or equivalent techniques. 
         [0031]    The upper component  64  has a guide  70  through which an external conduit or conduits can be guided. In  FIG. 6  conduits  72  and  74  are shown, but to make the  FIG. 6  clear, only a part of conduit  74  is illustrated. Conduit  72  extends into a cutter assembly housing  76 . It then continues at lower end  78  and bypasses cutter assembly housing  80  to extend to the BHA, which is not shown. Conduit  74  bypasses cutter housing  76  as best shown in  FIG. 9 , and continues to cutter housing  80 . It then has a lower end  82  that continues to the BHA which is not shown. To list a few possibilities, the term “conduit” as used herein can include a variety of structures such as fiber optic cable, power and signal lines, or control lines that covey fluid pressure. While individual conduits are shown associated with a cutter housing  76  and  80 , those skilled in the art will appreciate that a single housing can cut one or more conduits. 
         [0032]    The inset in  FIG. 7  shows cutter housing  76  in more detail. Preferably, all the cutter housings are identical, but they need not be. A tubular  84 , which is part of the string  60 , has a housing  86  surrounding it with a through passage  88  so that the tubular  84  can go through the housing  86  and support it. The housing  86  can be supported by collars positioned on each end, or it can be supported by other means. A second passage  90  has an uphole opening  92  and a downhole opening  94  to allow the conduit  72  to pass through. Contained within passage  90  is a grip assembly  96  used to hold the conduit  72  fixed relative to said grip assembly. Above the grip assembly  96  is the knife assembly  98  which has an opening allowing the conduit  72  to be fed continuously through in a direction from opening  92  toward opening  94  while allowing clearance between the knife assembly  98  and the conduit  72  to avoid damaging the conduit  72 . The knife assembly  98  is designed to slide up taper  100  when there is a pull force on the conduit  72  to bring the opposed knives together to cut the conduit  72 . Grip assembly  96  moves in tandem with knife assembly  98  by virtue of connecting links  102 . When the breakaway  62  separates, the lower ends of the conduits, such as  72 , remain fixed to the BHA, not shown. Continuously pulling on the string  60  will take out any slack and put tension on all the conduits such as  72  and  74  either at the same time or at delayed time intervals and forces the opposed knives in the knife assembly  98  to come together to cut every conduit, such as  72  and  74 , at the same time or at different times. The grip assembly  96  holds on to the lower conduit just cut, such as  72 , so that it cannot come out of the lower opening  94  and obstruct the wellbore. After the conduit, such as  72 , is cut, the upper portion of the cut conduit, such as  72 , will be pulled away from the cutter housing  76  through opening  92 . This is shown in  FIG. 8  with the breakaway  62  apart and the upper portion  64  at a distance from the fixed lower portion  66 . 
         [0033]      FIG. 9  shows that a cover  104  is secured with fasteners  106  to secure the grip assembly  96  and the knife assembly  98  in chamber  90  and allow movement such that when a pull force is applied to the conduit, such as  72 , in the case of  FIG. 9 , the movement of the knife assembly  98  will cut the conduit  72  while the grip assembly  96  will move with the conduit  72  until the prescribed cut is made, at which point it will slide back in chamber  90  while retaining the conduit  72  and preventing it from coming out of opening  94  which has remained stationary during the cutting operation. 
         [0034]    Those skilled in the art will appreciate that using a breakaway  62  above the cutter housings  76 ,  80  allows the removal of the upper string  60  to be used to apply tension to the conduits, such as  72 ,  74  whose lower extensions  78 ,  82  are fixed by attachment at the BHA, not shown. Applied tension on the conduit  72  advances knife assembly  98  in chamber  90  and actuates the knife assembly  98  to cut said conduit  72 . The lower remnants of conduit  72 , after the cut, are retained in chamber  90  by the grip assembly  96 . While a single conduit is shown to be cut and retained in a dedicated housing, those skilled in the art will appreciate that a single housing can cut multiple conduits. While it is preferred that the workings of the assemblies in the cutter assembly housings  76  and  80  are identical, variations among them can be made to suit the need of the specific conduit that needs to be cut in a given housing. The breakaway  62  can be actuated with a variety of mechanical movements of string  60  that break shear fasteners, for example, or it can be hydraulically actuated with a sleeve that can be shifted with fluid pressure to break a fastener that holds the breakaway  62  together and can thereafter be blown through as a ball on seat assembly or the ball can be blown through the seat to the BHA. The end result of the invention is that the string  60  can be quickly separated and there are no cut conduit remnants that can fall in the wellbore and obstruct it to make subsequent fishing or other operations more difficult. 
         [0035]      FIG. 10  illustrates a string joint  110  made as one piece with a cutter assembly housing  112  having a passage  114  that is off-center. The housing has shown three passages  116 ,  118  and  120  that extend longitudinally. Visible at the top  122  are entrances  124  and  126  that lead to passages  118  and  120 . At the bottom  128  are exits  130 ,  132  and  134  that respectively lead from passages  116 ,  118  and  120 . Ends  122  and  130  are tapered to facilitate running into or coming out of the hole. Passage  118  is the widest for the largest cable or line and it located at the 12 o&#39;clock position, where there exists the most room for that passage due to the offset location of passage (opening)  114  on which the threaded connection to which the string is connected is formed. Portions of the passages  116 ,  118  and  120  have respective covers  136 ,  138  and  140  either above or below the cutter knife assemblies  142 ,  144  and  146  depending on the cutter knife assembly placements. There are also covers over the cutter knife assemblies  142 ,  144  and  146  as well. Except for size differences, the cutter knife assemblies  142 ,  144  and  146  are similar in that they have a guide passage  148  that grips the line or cable (not shown) with a pair of extending members  150  and  152  that hold a cutter blade  154  or/and  156  at the ends. The cutter blades  154  and  156  are brought together around the line to be cut that is between them (not shown) as the ramps  158  and  160  get pulled up as the string  110  is severed below as was previously described for the design of U.S. Pat. No. 6,997,262. Depending on the slack of the lines to be cut, the cutting action can be at the same time or at discrete times as the string  110  is picked up after it is severed. 
         [0036]      FIG. 11  shows the same joint  110  made of a single piece with a cutter assembly housing  200  with an off-center opening  202 . As opposed to  FIG. 10  where the housing  112  had but a single row of parallel tracks or passages such as  116 ,  118  and  120 , in  FIG. 11  there are axially spaced banks of passages such as  204  and  206  both at the 12 o&#39;clock position so that they can have a larger size than other passages that can be run parallel to them say at the 10 o&#39;clock or 2 o&#39;clock positions. The one or more passage in the upper bank such as  204  can be bypassed to reach the lower bank with its one illustrated passage  206  through one or more bypass grooves such as  208  which preferably have a dog leg such as  210  so that like sized line cutting passages can be longitudinally aligned regardless of the number of such passages in the lower bank. As between banks, the number of passages can be the same or different and longitudinal alignment is not required. Straps or bands  212  hold in line  214  in bypass passage  208  or in dog leg  210 . The outside diameter of the housing  200  for the particular application and the size of the lines that need to run in the cutting passages will determine the layout and number of banks that will fit in a given application. It should also be noted that the lines can be ganged up in a given passage. For example lines  216  and  218  run together into a cutter knife assembly  220  that is a minor image layout. It has a hub  222  that includes stacked line pass through openings. One or more cutter blades  224  are near the upper end and one or more cutters  226  are near the lower end. Cutter blades  224  interact with ramps  228  and cutter blades  226  interact with ramps  230 . If the break point in the string is below joint  110 , then forcing that separation there and picking up the joint  110  will pick up the ramp surfaces  230  and force together the cutter blade or cutter blades  226 . Alternatively, a second breakaway location can be above the joint  110  and set at a higher break force value before it comes apart. This configuration provides a retrieval contingency for a BHA positioned below a stuck or lodged cutting assembly. When the break in the string is above the joint  110 , picking up on the string pulls tension on the lines  216  and  218  and brings the cutter blade or cutter blades  224  near the tapered surfaces  228  to make the cut in an alternative way. Thus, if necessary, the cutter assembly and any BHA attached thereto can be retrieved with relative ease in a subsequent operation. In the preferred embodiment each cutter assembly  224  or  226  cuts a single line or conduit that is disposed adjacent a blade or blade pair. However, other arrangements are envisioned such as a blade or blade pair at each end of a cutter knife assembly cutting into the same line or cable to ensure it gets cut. More than one cable can be cut at tapers  228  or  230 . 
         [0037]    The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.