Abstract:
Devices and methods for cleaning or removing cuttings from a cut as cutting is being performed. A pipe cutter includes a housing shaped and sized to be disposed within the tubular member, a rotary cutting blade carried by the housing to cut the tubular member when rotated and an impeller operably associated with the cutting blade to create fluid flow and turbulence proximate a cut being made in the tubular member

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to cutting devices useful for cutting tubular members. 
         [0003]    2. Description of the Related Art 
         [0004]    Pipe cutters are used to cut tubular members. Pipe cutters typically include a circular cutting blade that is mounted upon a spindle. The spindle, in turn, is mounted upon an arm that can be moved radially out through a slot in a surrounding housing to be brought into cutting contact with a surrounding tubular member to be cut. During cutting, the blade can rotate at approximately 100 rpm. Pipe cutters are often used downhole, being run in on a tool string to cut a casing member within a wellbore. Commercially available pipe cutters include the MPC Mechanical Pipe Cutter from Baker Hughes Incorporated of Houston, Tex. 
         [0005]    In operation, the pipe cutter is disposed within a tubular member to be cut, and the cutting blade is rotated by a motor. The arm is them moved so that the cutting blade is placed in cutting contact with the tubular member. The pipe cutter also rotates about it central axis, causing a circumferential cut to be made in the surrounding tubular member. 
         [0006]    Cuttings or filings create a problem during cutting. They can cause damage to the cutting blade or prevent a clean cut from being made. As a cut is made deeper, the cuttings can become trapped within the cut, magnifying the problems. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention provides systems and methods for cleaning or removing cuttings from a cut as cutting is being performed. In a described embodiment, a downhole pipe cutter includes an impeller that is mounted proximate the cutting blade and rotates with the cutting blade. In a described embodiment, the impeller includes one or more paddles that extend radially outwardly from the hub of the spindle. In a particular embodiment, the one or more paddles extend radially outwardly from a central impeller ring. The impeller is rotated with the cutting blade. During cutting, the impeller paddles induce liquid flow and turbulence proximate the area of the tubular being cut. This flow and turbulence will wash and remove cuttings from the cut being made. 
         [0008]    In particular embodiments, the impeller is formed of an elastomer. In alternative embodiments, the impeller is formed of polysiloxane, poly-ether-ether-ketone, polytetrafluoroethylene or another plastic or thermoplastic. In still other embodiments, the impeller is formed of steel or aluminum or another metal. 
         [0009]    In an alternative embodiment, a flow housing is located partially around the impeller. In a described embodiment, the flow housing includes a top plate that lies substantially parallel to the cutting blade and a circumferential side wall that lies radially outside of the paddles. The flow housing helps to improve fluid flow proximate the cut being made. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals designate like or similar elements throughout the several figures of the drawings and wherein: 
           [0011]      FIG. 1  is an isometric view of an exemplary pipe cutter which incorporates an impeller in accordance with the present invention. 
           [0012]      FIG. 2  is an enlarged isometric view of portions of the pipe cutter shown in  FIG. 1 . 
           [0013]      FIG. 3  is an external, isometric view of an exemplary impeller shown apart from the other components of the pipe cutter. 
           [0014]      FIG. 4  is a cross-sectional view showing the pipe cutter cutting an exemplary tubular member. 
           [0015]      FIG. 5  is a cross-sectional view of an alternative embodiment pipe cutter which includes a flow housing proximate the impeller. 
           [0016]      FIG. 6  is an isometric view of the alternative exemplary pipe cutter shown in  FIG. 5 . 
           [0017]      FIG. 7  is a schematic side view of an alternative embodiment wherein an impeller is disposed on both axial sides of a cutting blade. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]      FIGS. 1-4  depict an exemplary pipe cutter  10  which is used to cut tubular members. The pipe cutter  10  generally includes a tubular housing  12  having a tapered nose portion  14 . The housing  12  is shaped and sized to be disposed within a tubular member that is to be cut. As can be seen with reference to  FIG. 4 , a cavity  16  is defined within the housing  12 . The cavity  16  is shaped and sized to retain within a support arm  18  which carries a rotary spindle  20  as well as a circular cutting blade  22 . A circular cutting blade  22  is mounted upon the spindle  20  and can be rotated by a motor (not shown) contained within the pipe cutter  10  in a manner known in the art. The support arm  18  is articulable so that the cutting blade  22  can be moved into or out of the cavity  16  during a cutting operation. 
         [0019]    An impeller  24  is also mounted upon the spindle  20  and is rotated along with the cutting blade  22 . The impeller  24  is preferably affixed to the cutting blade  22  using an adhesive or connectors or in another manner known in the art. In a particular embodiment, the impeller  24  includes one or more paddles  26  that extend radially outwardly along the lo blade from the vicinity of the spindle  20 . In certain embodiments, the impeller  24  includes a central impeller ring  28  from which the paddles  26  extend radially outwardly. In the illustrated embodiment, there are eight paddles  26 . However, there may be more or fewer than eight paddles  26 . 
         [0020]    In a particular embodiment, the impeller  24  is formed of an elastomer. In alternative embodiments, the impeller  24  is formed of polysiloxane, poly-ether-ether-ketone, polytetrafluoroethylene or another plastic or thermoplastic. In still other embodiments, the impeller  24  is formed of steel or aluminum or another metal. The impeller  24  can be formed by molding, water jet cutting, laser cutting, machining or in other ways known in the art. In the depicted embodiment, the impeller  24  is located on the lower side of the cutting blade  22  (i.e., the side that is further downhole), as illustrated in  FIG. 1 . However, it should be understood that the pipe cutter  10  would operate as effectively if the impeller  24  were placed on the upper side of the cutting blade  22 . In addition, the cutting blade  22  might have an impeller  24  on both sides of the cutting blade  22 .  FIG. 7  depicts a cutting assembly wherein there are impellers  24  and  24  placed on both axial sides of a cutting blade  22 . 
         [0021]    During operation, the pipe cutter  10  is submerged within wellbore fluid. Typical wellbore fluids include brine, fresh water, seawater, production hydrocarbons and water or oil-based muds.  FIG. 4  illustrates the pipe cutter  10  being used to cut a surrounding tubular member  30 . As depicted, a cut  32  is being created as the cutting blade  22  is rotated in the direction of arrow  34 . As cutting occurs, the paddies  26  push the fluid to create flow and turbulence in the wellbore fluid proximate the cut  32  in the general area shown at  36  in  FIG. 4 . This flow and turbulence will act to remove cuttings from the cut  32  and the area proximate the cut  32 . 
         [0022]      FIGS. 5 and 6  illustrate an alternative pipe cutter  10 ′ which includes a flow housing or shroud  40  which is located proximate the impeller  24 . The flow housing  40  functions to help increase fluid flow proximate the cut  32 . By containing fluid proximate the paddles  26 , a more directed stream of higher velocity is created. In the depicted embodiment, the flow housing  40  includes a curved, crescent-shaped top plate  42  and a circumferential side wall  44  which are interconnected and form an interior enclosure  46 . In the depicted embodiment, the flow housing  40  is supported by a support arm  48  which retains the flow housing  40  in a fixed position proximate the cutting blade  22  and impeller  24 . The support arm  48  fixes the flow housing  40  in a position such that the top plate  42  is substantially parallel to the cutting blade  22  and the side wall  44  lies radially outside of the paddles  26 . 
         [0023]    A suitable grease can be used to assist cutting of high strength alloys or other materials. In a particular embodiment, the grease is applied to the paddles  26  prior to run-in and cutting. During operation to cut a tubular member, centrifugal force will cause grease to be applied to the cut from the paddles  26 . 
         [0024]    It can be seen that the invention also provides methods for cutting a tubular member. According to an exemplary method of cutting, the pipe cutter  10  or  10 ′ is disposed within a tubular member  30  to be cut. The cutting blade  22  is then rotated to cut the tubular member  30 . The impeller  24  is rotated to cause fluid flow and turbulence proximate the cut being made in the tubular member, thereby helping to remove cuttings from the cut. 
         [0025]    Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.