Abstract:
A self-lubricating swage expands tubulars and includes a primary swaging tool supported on a mandrel that has a lubricious capacity or a primary swaging tool supported on a mandrel and a nose swage member supported on an end of the mandrel. In the latter the nose swage member is fabricated of, is coated with or otherwise includes and applies a lubricious material that smears onto a surface coming into contact with the nose swage member. The smearing of the lubricious material facilitates the sliding of the swaging member as it contacts the inner walls of the tubular.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of an earlier filing date from U.S. Provisional Application Serial No. 60/225,460 filed Aug. 15, 2000 which is fully incorporated herein by reference. 
     
    
     
       BACKGROUND  
         [0002]    1. Field  
           [0003]    The disclosure relates to oilfield downhole operations. More particularly, the disclosure relates to a self-lubricating swage device for expanding a tubular in a wellbore.  
           [0004]    2. Prior Art  
           [0005]    As is well known to those of skill in the art, expandable tubulars such as reformable deformed junctions have been known to the oilfield art. One will recognize the benefit of the exemplary deformed junction in that the junction is easily transported through the casing of a cased wellbore or through an open hole wellbore to its final destination at a junction between a primary and lateral borehole. Once the junction is properly positioned it is reformed into a Y-shaped junction to assist in completing the wellbore. In the fully reformed condition of the junction, the outer dimensions are generally greater than the ID of the casing or open hole. Thus of course it would be rather difficult to install the junction in its undeformed condition. Many methods have been used to expand tubulars or reform a deformed junction in the borehole. One of the prior art methods has been to employ a swaging device. Swaging devices generally comprise a conical or frustoconical hardened member having an outside diameter (OD) as large as possible while being passable through the wellbore casing or the open hole. This swage is urged to travel through a tubular or previously positioned deformed junction whereby the tubular or junction is reformed into an operational position. Where the tubular or junction is located in a vertical or near vertical wellbore, setdown weight alone often is sufficient to generate the approximately 100,000 pounds of force required to expand the tubular or reform the junction. Where the tubular or deformed junction is being placed in a highly deviated wellbore or a horizontal wellbore however, setdown weight might not be sufficient to force the swage device through the junction. In this event, one of skill in the art will recognize the hydraulic procedure alternative to setdown weight which includes an expansion joint located above the swage device, a drill tube anchor located above the expansion joint and a ball seat located below the expansion joint such that by dropping a ball, pressure can be applied to the tubing string whereby the expansion joint is forced to expand downhole which urges the swage device through the tubular or junction. Expansion joints are well known in the art, as are anchors and ball seats.  
           [0006]    One of the problems encountered in swaging any tubular in a wellbore is the high frictional resistance that results from the contact between the swage and the contacted surface. Oftentimes the cross-sectional shape of the pipe is elliptical and not round. Swaging such a cross-sectional shape generates extremely high contact forces, which can cause galling and tearing of either or both of the swage and the pipe, which can in turn increase the force required to push the swage through the tubular.  
           [0007]    Traditional methods of reducing friction include the use of conventional lubricants. In the application at hand, the use of conventional lubricants is limited because the lubricant must be applied to the surfaces immediately before the swage contacts the junction or the pipe. The biggest drawback to this type of application is the cost of placing the lubricant into a position where it can be utilized. Furthermore, since conventional lubricants typically have an adverse effect on cement used in the vicinity within the wellbore, such lubricants must be removed from the area before the cementing operation is commenced. There is a high cost associated with removing the lubricant prior to the application of the cement. Although a multitude of downhole lubricants and friction reducers are commercially available, hole depths and pipe configurations almost always render their use uneconomical.  
           [0008]    Similar drawbacks are experienced during the removal of the prior art swaging devices. The obstacles encountered with respect to lubrication to force the swaging devices into a wellbore are the same as the obstacles encountered in the removal of the swaging devices from the wellbore. The metal (or other material) of the tubulars being expanded generally has a certain amount of resilience such that after the swage device has been forced through the tubular to expand it, the tubular itself will rebound to a smaller ID than the OD of the swage device by several thousandths of an inch. Because of the rebound, nearly as much lifting force is required on the swage device to remove it from the wellbore as is needed to initially urge the swage through the tubular. In the absence of any type of lubrication, this lifting force can be as much as 100,000 pounds. Although a drilling rig can easily pull ten times this weight, in a highly deviated or horizontal wellbore, the friction created on the curvature of the well can be high enough to absorb all of the force imparted at the surface and leave none available for the swage. Thus the tool is stuck. The amount of force necessary to pull the swage through the newly expanded and unlubricated tubular can also be sufficient to damage other well tools or tubulars. Such damage can of course cost significant sums of money to repair and require significant time both to diagnose and to repair.  
         SUMMARY  
         [0009]    The self-lubricating swage avoids the above drawbacks by creating a self-lubricating single or two-part swage device. The single part device comprises a lubricious material associated with the swage. The two-part device comprises a primary swaging tool and second expansion device positioned ahead of the primary swaging tool for expanding a tubular in a wellbore. For simplicity, the second expansion device is termed a “nose swage”. It will be understood that this term is not known to the applicants hereof to have any specific meaning in the art and is selected for use only to describe what is taught herein and the equivalents thereof. The self-lubricating nose swage can be utilized with any type of primary swaging tool. The primary swaging tool is supported on a mandrel, and the nose swage member is supported on an end of the mandrel. The nose swage member may be fabricated of a first lubricious solid material, which is preferably a smearable material such as bronze. Alternatively, the nose swage may be constructed primarily of a different first material and coated with a layer of lubricious material. Additionally or alternatively, the nose swage may contain a plurality of grooves disposed therein, which may be filled with a second lubricious material such as polytetrafluoroethylene. The self-lubricating swage device of the present invention is employable in place of a conventional swage, the function of which being fully assimilated. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Referring now to the drawings wherein like elements are numbered alike in the several figures:  
         [0011]    [0011]FIG. 1 is a side view of the swage in a swaging position;  
         [0012]    [0012]FIG. 1A is a side view of the nose swage, which has disposed within it a plurality of grooves for accommodating a lubricious material;  
         [0013]    [0013]FIG. 2 is a side view of the device wherein the swage cup has been moved to a second position, which is the retrieving position;  
         [0014]    [0014]FIG. 3 is a cross section view of a second embodiment; and  
         [0015]    [0015]FIG. 4 is a side view of an alternative single-part embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring to FIG. 1, a self-lubricating swaging device is shown generally at  10 . Swaging device  10  comprises a forward surface or nose swage shown generally at  12  and a primary swaging tool shown generally at  14 .  
         [0017]    Nose swage  12  is a tool of a cup-like structure having a head surface  16 , a cavity opposing head surface  16 , and an outer side surface  18  that defines a frustoconical shape of nose swage  12 . A box thread  20  is provided for threadedly attaching nose swage  12  to a pin thread  23  on a mandrel  22 . Nose swage  12  is locked into place on mandrel  22  by at least one setscrew  24 , which is received in a groove  26  on mandrel  22 .  
         [0018]    One purpose of nose swage  12  is to act as a pre-expanding swage to begin the expansion process of a tubular. As swaging device  10  is forced through a hole (not shown) of the tubular (the inside surface of which is illustrated schematically in phantom lines) the outer side surface  18  of nose swage  12  begins to expand the tubular through contact with an inside surface  28  (shown in phantom lines) of the tubular. As nose swage  12  is pushed farther into the tubular, outer side surface  18  further pushes away inside surface  28  of the tubular to expand the tubular.  
         [0019]    Another purpose of nose swage  12  is as a lubricator. To this end nose swage  12  is fabricated from a smearable low friction bearing material such as bronze (or coated in such material to a sufficient thickness to provide the needed lubrication, which is preferably about one quarter of an inch or greater thickness). As swaging device  10  is forced through the tubular, the contact force between outer side surface  18  of nose swage  12  and inside surface  28  of the tubular causes the material of nose swage  12  to smear onto inside surface  28 . If swaging device  10  is being forced through a non-circular hole, the material of nose swage  12  smears off primarily onto inside surface  28  at the point of contact between outer side surface  18  and inside surface  28 .  
         [0020]    In an alternate embodiment, as shown in FIG. 1A, nose swage  12 , still being composed of the smearable material, further contains a plurality of grooves  21  disposed therein. Grooves  21  may extend concentrically around nose swage  12 , or they may extend from head surface  16  toward primary swaging tool  14  either longitudinally across outer side surface  18  or in a spiral configuration (illustrated). Grooves  21  are packed with a lubricant (not shown), which is typically a thin film bonded lubricant, such as polytetrafluoroethylene, molybdenum disulfide, graphite, or a similar material. When nose swage  12  contacts inside surface  28  and the surface of nose swage  12  is smeared away, the lubricant is also smeared onto inside surface  28  to further facilitate the sliding of swaging device  10  through the junction. If, on the other hand, nose swage  12  is fabricated of a non-smearable material, then grooves  21  may be packed with a smearable material, such as bronze, or a thin film bonded lubricant, such as polytetrafluoroethylene, molybdenum disulfide, graphite, or a similar material. It will be appreciated that the point of the nose swage is to effectively apply the lubricious material to the ID of the tubular being expanded. The nose swage may be constructed of any material that supports that purpose. This includes metals, plastics, etc.  
         [0021]    In another embodiment, nose swage  12  is not used but rather the primary swage  14  is provided with a groove pattern (illustrated as  21  a in FIG. 4) or a lubricious coating on a surface thereof (not shown). The materials may be any of those disclosed hereinabove or similar acting materials. In FIG. 4, the primary swage with a helical pattern of grooves thereon is illustrated.  
         [0022]    Referring back to FIG. 1, primary swaging tool  14  is shown mounted on mandrel  22  by a threaded connection  30  and a plurality of setscrews  32 . Each setscrew  32  is received in a groove  34 , the combination of which with threaded connection  30  prevents movement of a support  36 . Support  36  is preferably a frustoconical annular element of a single piece, although multiple pieces could be used to achieve the desired result. Support  36  is provided with at least one port  38 , the outlet of which is positioned uphole of a point of contact of swaging device  10  with inside surface  28  of the junction being deformed. Preferably, several ports  38  are positioned on support  36 . Port  38  also intersects an upper bore  40  extending axially through support  36 , of which there are preferably several configured within support  36 . Upper bore  40  is open to an annular space  42 . As should be understood, there may be several bores  40  opening into annular space  42 .  
         [0023]    Support  36  is shown in FIG. 1 supporting a swage cup  44  and thereby preventing the deflection of swage cup  44  toward mandrel  22 . Swage cup  44  extends outwardly from a swage cup base  46 . A lower bore  48  extends axially through swage cup base  46 , opens on the downhole end of swage cup base  46 , and is configured to receive well fluid (not shown) downhole of a contact area  50  of swage cup  44 . Lower bore  48  extends to an uphole end that communicates with annular space  42 . Annular space  42  ensures communication between lower bore  48  and upper bore  40  thus effecting through passage of well fluids from below the contact point  50  of swage cup  44  with inside surface  28  (which forms a metal-to-metal seal) to port  38  above contact point  50 . By this provision, a hydraulic lock is avoided under swage cup  44 , which would otherwise prevent movement of swaging device  10  through the tubular. If provision for fluid flow-through was not provided, it might become more difficult to move swaging device  10  through the junction since overcoming a hydraulic lock would be extremely difficult without an outlet for fluid pressure.  
         [0024]    Swage cup  44  and swage cup base  46  are located on mandrel  22  by shear screws  52  only. Swage cup  44  and swage cup base  46  are preferably fabricated so as to be a single annular component that is slideable along mandrel  22 . Therefore, a means of holding swage cup  44  and swage cup base  46  in the swaging position on support  36  is needed. One embodiment of such means is shear screws  52  that are received in groove  54 . It will be recognized by one of ordinary skill in the art that since shear screws  52  are the only means in this embodiment which hold swage cup  44  and swage cup base  46  in place, swage cup  44  and swage cup base  46  may rotate 360° around mandrel  22  relatively freely. The significance of annular space  42  then is to ensure that lower bore  48  is in fluid communication with upper bore  40  no matter what orientation the swage cup  44  and swage cup base  46  have relative to support  36 .  
         [0025]    In the condition shown in FIG. 1, one of ordinary skill in the art should appreciate that swaging device  10  being forced through a tubular will quite effectively expand the tubular similarly to prior art swages. Once the expansion is complete and it is desirable to remove the swaging tool from the wellbore, an upward pull is necessary. The configuration of the tool as it is being pulled up the wellbore is shown in FIG. 2. Referring now to FIG. 2, upon pulling swaging device  10  in the upward direction point  56  of swage cup  28  will contact the inside diameter (not shown) of the tubular due to the resilience of the tubular as discussed hereinbefore. The pressure on point  56  will tend to prevent swage cup  44  from moving uphole. This force is translated through swage cup base  46  to shear screws  52  (or other retaining arrangement) that will then shear under that force (or release in some other way). One of skill in the art will recognize that the particular amount of force required to shear the screws is engineerable in advance and should be matched to an appropriate amount of force to indicate that withdrawal of swaging device  10  is desired. Upon shearing of screws  52 , swage cup base  46  and swage cup  44  move downhole until swage cup base  46  is in contact with a swage stop  58 . It should be briefly noted at this point that swage stop  58  is connected to mandrel  22  via a regular thread  60  and a plurality of setscrews  62 . Swage stop  58  further includes an o-ring  64  to seal swage stop  58  against mandrel  22 .  
         [0026]    Upon shifting swage cup  44  and swage cup base  46  downhole into contact with swage stop  58 , a gap  66  is formed between swage cup  44  and support  36 . Because of gap  66 , continued pulling on swaging device  10  causes swage cup  44  to deflect toward mandrel  22  to a degree that is sufficient to allow it to slide through the junction. A desired mount of deflection to achieve the stated result is several thousandths of an inch. Gap  66  may be anywhere from several thousandths of an inch to a larger gap. The deflection of swage cup  44  will merely be what is necessary for it to move through the junction at a significantly reduced force as it is being withdrawn from the wellbore.  
         [0027]    Referring now to FIG. 3, a second embodiment of the invention is shown generally at  110 . The general mode of operation remains but the way in which it is carried out is slightly different. Since each of the components of this embodiment is slightly different than each of the counterparts in the first described embodiment, the components of the new embodiment are numbered in multiples of one hundred.  
         [0028]    At the downhole end of swaging device  110 , a self-lubricating nose swage  112  is threadedly attached to a mandrel  122  at a thread  120  and is locked in place by at least one setscrew  124 , which is received in a groove  126 . Nose swage  112 , in addition to acting as a pre-forming swage to open tight tubulars, prevents a shear ring (release ring)  142  from falling off the end of mandrel  122  after a shear screw (or other release)  150  is sheared.  
         [0029]    In the operational condition, with shear screw  150  intact, the space between the uphole end of nose swage  112  and downhole end of shear ring  142  is preferably sufficient to allow full shearing of shear screw  150  by displacement of shear ring  142  in the downhole direction before the noted surfaces interengage. This prevents a partial shearing condition which may impede performance to some degree although should not completely prevent swaging device  110  from performing.  
         [0030]    Mandrel  122  supports the swaging device and, through its movement, activates the same. In the running position (shown), a swage ring support  136  is in position to support a swage ring  144 . Both swage ring support  136  and swage ring  144  in this embodiment “float” on mandrel  122  (i.e., swage ring support  136  and swage ring  144  are not attached to mandrel  122 ). At the uphole end, swage ring support  136  is prevented from moving further uphole by a retaining ring  137 . Retaining ring  137  is threadedly connected to mandrel  122  by a thread  130  and is prevented from moving on thread  130  by at least one setscrew  132 , which is received in a groove  134 . In a preferred embodiment, mandrel  122  is “turned down” from a shoulder  141  to be positioned even with the uphole end of retaining ring  137  and extending to the downhole end of swaging device  110 . This provides more annular area between the mandrel surface and the borehole or junction so that thicker swage components may be used. The “turn down” from shoulder  141  also provides extra stability to retaining ring  137 .  
         [0031]    Swage ring support  136  abuts retaining ring  137  at an interface  139  and includes a fluid bypass  138 . Support for swage ring  144  is along an interface  145 . As a unit, swage ring support  136  and swage ring  144  function as they did in the previous embodiment and indeed as do those of the prior art to expand a tubular. It is with the recovery of swaging device  110  that its unique construction is evident and beneficial. It should be noted that swage ring  144  includes at least one fluid bypass conduit  147  that communicates with an annulus  149 .  
         [0032]    Located downhole of swage ring  144  is shear ring  142 . Swage ring  144  is abutted against shear ring  142  at an interface  143 . Shear ring  142  is prevented from longitudinal movement on mandrel  122  by a plurality of shear screws  150 , which engage a groove  151  on mandrel  122 . Shear ring  142 , in conjunction with retaining ring  137 , maintains swage ring support  136  and swage ring  144  in the operative running and reforming position. It should be noted that slots  153  are provided on both the uphole and downhole sides of shear ring  142  in a preferred embodiment to allow for fluid bypass. While only the uphole end of shear ring  142  requires slots  153  to allow fluid bypass, placing slots  153  on both ends assures that fluid bypass will occur even in the event that swaging device  110  is assembled backwards.  
         [0033]    Once swaging device  110  has been forced through the tubular being expanded, it is normally withdrawn or pulled uphole. In the event that swaging device  110  encounters significant resistance, the features disclosed herein will be set in motion. Since both swage ring support  136  and swage ring  144  are not connected to mandrel  122 , resistance provided by the deformed junction is translated directly to shear screw  150 . At a predetermined amount of force, shear screw  150  will shear and allow mandrel  122  to move uphole. At this point, shear screw  150  has sheared, but swage ring support  136  has not been moved relative to swage ring  144 . Thus, the frictional engagement therebetween is rendered independent and not cumulative with respect to the amount of force necessary to shear screw  150 . Upon movement of mandrel  122  uphole, a snap ring  164  impacts a shoulder  166  on swage ring support  136  and will move snap ring  164  out of its support position under swage ring  144 . This, as in the previous embodiment, allows swage ring  144  to flex, thereby allowing retrieval of swaging device  110 . In practice, the disengagement of swage ring support  136  with swage ring  144  is assisted by a jarring action that normally results from the sudden shear of screw  150 . It should be noted, however, that a straight pull on swaging device  110  would also dislodge swage ring support  136  from swage ring  144 . The jamming action is a likely mode of operation; however, it is not a required mode of operation. Overcoming the friction generated by the flexible swage ring  144  being urged into contact with swage ring support  136  by the junction is all that is necessary. After shearing, swage ring  144  and shear ring  142  will rest on nose swage  112  while support shoulder  166  will rest on snap ring  164 . In this condition, support for swage ring  144  is not available and swage ring  144  is free to flex, thereby allowing swaging device  110  to be recovered from the junction. Commonly, the flexing that will occur is into a slight oval shape.  
         [0034]    It should be appreciated that in both embodiments of the invention the shear release or other release mechanism may not be used in all conditions. The swaging device  10  may pull through the junction without needing to be flexible. Because the tools of each embodiment incorporate the invention, swaging device  10  of either embodiment is retrieved whether or not swaging device  10  gets stuck in the junction. If swaging device  10  does get stuck, shear screw(s)  52  will shear on continued pickup of swaging device  10  and swaging device  10  will operate as hereinbefore described.  
         [0035]    While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.