Abstract:
The tubular cutting tool for severing downhole tubulars, the tool having a drive system, a pivoting system, a cutting head, a cutting member, and a lubricant delivery system. Cutting may be accomplished by rotatingly actuating the cutting head with an associated motor and extending the cutting member away from the cutting head. The lubricant delivery system lubricates the respective contacting surfaces of the cutting member and the tubular and is actuated when the cutting member extends from the cutting head.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of and claims priority from co-pending U.S. application having Ser. No. 12/541,035, filed Aug. 13, 2009, which is a continuation-in-part of and claims priority from U.S. application having Ser. No. 11/728,461, filed Mar. 26, 2007, (now U.S. Pat. No. 7,628,205, issued on Dec. 8, 2009), the full disclosures of which are hereby incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The disclosure herein relates generally to the field of severing a tubular member. More specifically, the present disclosure relates to an apparatus for cutting downhole tubulars. Yet more specifically, described herein is a method and apparatus for optimizing cutting tubulars wherein lubrication is maintained between the cutting member and the tubular. 
         [0004]    2. Description of Related Art 
         [0005]    Tubular members, such as production tubing, coiled tubing, drill pipe, casing for wellbores, pipelines, structural supports, fluids handling apparatus, and other items having a hollow space can be severed from the inside by inserting a cutting device within the hollow space. As is well known, hydrocarbon producing wellbores are lined with tubular members, such as casing, that are cemented into place within the wellbore. Additional members such as packers and other similarly shaped well completion devices are also used in a wellbore environment and thus secured within a wellbore. From time to time, portions of such tubular devices may become unusable and require replacement. On the other hand, some tubular segments have a pre-determined lifetime and their removal may be anticipated during completion of the wellbore. Thus when it is determined that a tubular needs to be severed, either for repair, replacement, demolishment, or some other reason, a cutting tool can be inserted within the tubular, positioned for cutting at the desired location, and activated to make the cut. These cutters are typically outfitted with a blade or other cutting member for severing the tubular. In the case of a wellbore, where at least a portion of the casing is in a vertical orientation, the cutting tool is lowered into the casing to accomplish the cutting procedure. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    Disclosed herein is a cutting tool and method wherein lubrication is delivered during cutting. The system employs a rotating blade and a lubrication system for dispensing lubrication between the blade&#39;s cutting surface and the tubular to be cut. In an example embodiment the cutting tool includes a cutting member that can be moved between a stowed position within the housing and a cutting position in cutting contact with the tubular. The tool further includes a lubricant dispenser a reservoir for storing lubricant. The lubricant can be discharged through a passage that is directed towards the cutting member when the cutting member is in the cutting position. Control of lubricant flow can be maintained by a lubricant shuttle valve assembly that includes a valve body with a bore, a port through the body for communicating the lubricant with the bore, a shuttle member selectively moveable in the bore from a closed position to an open position and a recess in an outer surface of the shuttle member that registers with the port when the shuttle member is in the closed position and when the shuttle member is in the open position, the recess registers with the port and the inlet end of the lubricant discharge, so that the lubricant reservoir and discharge end of the lubricant discharge are in communication. An optional spring can be included for biasing a piston in the reservoir to urge lubricant from the reservoir and through the shuttle valve assembly. In an example embodiment, the recess defines an annulus between the shuttle member and the bore. The outer surface of the shuttle member, that is adjacent the bore, can project radially outward into sealing contact with an inner surface of the bore. This sealing contact can form a flow barrier between the annulus and the lubricant discharge when the shuttle member is in the closed position. In an example embodiment, the shuttle member is mechanically coupled to the cutting member when the cutting member is in the stowed position thereby retaining the shuttle member in the closed position. Alternatively, when the cutting member moves into the cutting position, a biasing spring in the bore urges the shuttle member into the open position. Optionally, a piston can be provided in the reservoir with an end attached to a fill tube for refilling the reservoir with lubricant and a check valve in the piston that defines a flow barrier through the piston for retaining lubricant in the reservoir. A housing may optionally be included the cutting member is mounted on a cutting assembly that pivots on the housing from a stowed into a cutting position, and wherein the cutting assembly includes a channel for directing lubricant from the discharge end of the lubricant discharge onto a side of the cutting member. The cutting tool can be deployed from the surface on wireline. 
         [0007]    In another example embodiment, the cutting tool includes a housing, a cutting assembly with a cutting blade that moves between stowed and cutting positions, a reservoir for storing lubricant therein, passage having an inlet and a discharge directed towards the cutting member when the cutting member is in the cutting position, and a lubricant shuttle valve assembly. In an example embodiment, the shuttle valve assembly is made of a valve body with a smaller bore and an enlarged bore. The enlarged bore is adjacent to and coaxial with the smaller bore. A port is included through the body adjacent the smaller bore. Also included is a shuttle member with a smaller diameter section that forms an annulus between the shuttle member and the smaller bore. A larger diameter section on the shuttle member and adjacent the smaller diameter section is in sealing contact with the smaller bore when the within the smaller bore. When the shuttle member is positioned so the smaller diameter section is within both the smaller bore and the enlarged bore, the port and passage are in communication thereby providing lubrication communication to the cutting member. Alternatively, a piston is included in the reservoir that is biased with a spring towards the lubricant shuttle valve assembly to urge lubricant through the lubricant shuttle valve assembly. A cap may be provided on the cutting member to retain the shuttle member in the closed position when the cutting member is in the stowed position. A spring can be included and positioned so it is biased against the shuttle member for axially urging the shuttle member into the open position when the cutting member moves into the cutting position and disengages the cap from the shuttle member. The respective surfaces of the cap and shuttle member that are in contact may be profiled with a substantially similar slope. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0008]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1 . is a partial sectional view of a cutting tool cutting a tubular in a wellbore. 
           [0010]      FIG. 2  is a side sectional view of a portion of the cutting tool of  FIG. 1 . 
           [0011]      FIG. 3  is a side partial sectional view of a lubricant shuttle valve assembly in a closed position. 
           [0012]      FIG. 4  is a side partial sectional view of the lubricant shuttle valve assembly of  FIG. 3  in an open position. 
           [0013]      FIG. 5  is a is a side partial sectional view of an example of refilling a lubricant reservoir. 
       
    
    
       [0014]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be through and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
         [0016]    It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims. 
         [0017]    Described herein is a method and apparatus for cutting and severing a tubular. While the apparatus and method described herein may be used to cut any type and length of tubular, one example of use involves severing tubing disposed within a wellbore, drill pipe, wellbore tubular devices, as well as wellbore casing. Shown in a side partial cut away view in  FIG. 1  is an embodiment of a cutting tool  10  in a tubular  12  that is inserted into a wellbore  14 . The tubular  12  can be any annular member, such as production tubing, drill pipe, or well casing. 
         [0018]    The cutting tool  10  of  FIG. 1  includes a substantially cylindrical body  16  in which is housed a motor  18  (shown in dashed outline) that rotates a cutting head  20  shown provided on a lower end of the cutting tool  10 . A drive shaft  23  couples the motor  18  to the cutting head  20 . Pivoted out from the cutting head  20  is a cutting assembly  24  that is made up of a blade drive assembly  26  and an attached circular cutting blade  28  for severing or machining the tubular  14 . Power from the motor  18  can be delivered through the shaft  23 , or other gearing means (not shown) for rotating the cutting head  20 . A feed rod  22  ( FIG. 2 ) transfers power for pivoting the cutting assembly  24  from a stowed position within the cutting head  20  into a cutting position and for rotating the cutting blade  28 . On the lowermost portion of the cutting tool  10  is a lubricant dispenser section  30  for retaining and dispensing a lubricant  32  that enhances the cutting and machine process of the tubular  14 . 
         [0019]    A controller  34  disposed at surface may be employed for relaying commands to or otherwise controlling the cutting tool  10 . The controller  34  may be a surface truck (not shown) disposed at the surface as well as any other currently known or later developed manner of controlling a wellbore tool from the surface. The controller  34  can communicate with the cutting tool  10  via a wireline  36  shown attached to an upper end of the cutting tool  10 . Optionally, the cutting tool  10  can be deployed on tubing, coiled or otherwise, slickline, or cable. Also illustrated schematically is a power supply  38  shown disposed on the surface above the wellbore  12  and also in communication with the wireline  36 . The power supply  38  can selectively provide power to the cutting tool  10  via the wireline  36 . Included optionally is an information handling system  40  that may be coupled with the controller  34  either in the same location or via some communication either wireless or hardwire. Other means may be used for disposing the cutting tool  10  within a particular tubular. Examples of these include drill pipe, line pigs, and tractor devices for locating the cutting tool  10  within the tubular  14 . 
         [0020]    Referring now to  FIG. 2 , a side sectional view is shown of the lubricant dispenser section  30  of  FIG. 1 . Here the feed rod  22  is shown projecting along the axis of the cutting tool  10  and having an end attached to the cutting head  20 . A blade drive shaft  42 , has a lower end coupled to the blade drive assembly  26  for delivering rotational power to the cutting blade  28 . Power for the pivot shaft  42  can be provided directly from the motor  18 , or through a gearing arrangement (not shown) between the pivot shaft  42  and drive shaft  22 . A cavity within the lubricant dispense section  30  defines a lubricant reservoir  44  for housing and storing the lubricant  32  of  FIG. 1  as the cutting tool  10  is being deployed within the tubular  14 . An annular piston  46  is coaxially provided within the reservoir  44  and biased towards the cutting assembly  24  by a spring  48  that is also coaxially set within the lubricant dispenser section  30 . 
         [0021]    Further illustrated in  FIG. 2  is a lubricant shuttle valve assembly  50  that has an end projecting into the reservoir  44 . In an example embodiment, the shuttle valve assembly  50  regulates the flow of lubricant from the reservoir  44  and adjacent to the cutting blade  28 . The shuttle valve assembly  50  includes a shuttle valve body  52  that as illustrated has a largely annular configuration. A cylindrically shaped shuttle valve  54  is shown that is selectively movable axially through the shuttle valve body  52 . Optionally, a biasing spring  56  is set within the valve body  52  on an end of the shuttle member  54  that biases the shuttle member  54  towards the cutting assembly  24 . Radial ports  58  extend through a side wall of the shuttle valve body  52  to provide communication between the reservoir  44  and within the shuttle valve body  52 . An annular bulkhead  60  is shown in that defines an upper end of the lubricant dispenser section  30  and in which an end of the shuttle valve assembly  50  opposite the reservoir  44  is anchored. A passage  62  is formed through the bulkhead from the side adjacent the shuttle valve assembly  50  and to the blade drive assembly  26 . 
         [0022]    Referring now to  FIG. 3 , the shuttle valve assembly  50  is illustrated in a partial side sectional view and in what is referred to as a closed position. When in the closed position, the shuttle valve assembly  50  provides a flow barrier between the lubricant reservoir  44  and the passage  62 . Also shown with more specificity is a bore within the shuttle valve body  52  that is made up of a smaller bore  64  adjacent the reservoir  44  and an enlarged bore  65  proximate the portion of the valve assembly  50  facing the bulkhead  60 . Within the smaller bore  64  a snap ring  66  is set within a groove. The spring  56  can be supported by the snap ring  66  so it can apply the biasing force against the shuttle member  54 . A transition  68  defines the border between the enlarged bore  65  and smaller bore  64 . In the embodiment of  FIG. 3 , the transition area is circumscribed by the bulkhead  60 . 
         [0023]    In the example embodiment of  FIG. 3 , the shuttle member  54  diameter changes to thereby define a smaller diameter section  69  and an annulus is formed between the smaller diameter section  69  and the inner circumference of the smaller bore  64 . The diameter of the shuttle member  54  transitions radially outward and forms a larger diameter portion  71  that is in sealing engagement with the smaller bore  64 . The sealing engagement between the larger diameter portion  71  and smaller bore  64  provides the barrier to prevent flow communication from the reservoir  44  into the passage  62 . 
         [0024]    A cap nut  72  is shown on a side of the blade  28  and facing the valve assembly  50 . In the embodiment of  FIG. 3 , the blade drive assembly  26  is in the stowed position, so that the cap nut  72  axially retains the shuttle member  54  within the valve assembly  50 . While retained in the valve assembly  50  by the cap nut  72 , the shuttle member  54  is in a closed configuration that prevents lubricant flow through the valve assembly  50 . In the example embodiment of  FIG. 3 , an insert  74  is shown provided on an upper end of the shuttle member  54  and in contact with the cap nut  72 . Optionally, the contacting surfaces between the cap nut  72  and insert  74  have corresponding profiles as shown. Further illustrated in the example embodiment of  FIG. 3  is a recess  76  (shown in dashed outline) formed in a lower facing surface of the blade drive assembly  26  and disposed adjacent an exit end of the passage  62 . 
         [0025]    In  FIG. 4 , the shuttle valve assembly  50  is illustrated in an open position thereby allowing flow of lubricant from the reservoir  44  through the passage  62  for delivery onto a cutting surface. The recess  76  provides a flow path that can direct the lubricant onto a surface of the blade  28  that is oppositely facing from the reservoir  44 . In the example embodiment of  FIG. 4 , the blade drive assembly  26  has been pivoted away from the stowed position and into the cutting position, thereby disengaging the cap nut  72  from the insert  74  and allowing the shuttle member  54  to move axially within the valve assembly  50 A as upwardly biased by the spring  56 A. The axial movement of the shuttle member  54  repositions the larger diameter portion  71  away from the smaller bore  64  thereby removing the sealing barrier of the larger diameter portion  71  and smaller bore  64 . The moved shuttle member  54  of  FIG. 4  is in a position where its smaller diameter section  69  extends from the radial ports  58  and past the transition  68  so at least a portion of the smaller diameter section  69  is circumscribed by the enlarged bore  65 . As such, the lubricant flows into the annulus  70  from within the reservoir  44 , into the enlarged bore  65 , the passage  62 , the recess  76 , where it is then delivered to the cutting surface within the tubular  14 . An advantage of the similarly sloped profiles on the cap nut  72  and insert  74  that when the blade drive assembly  26  is pivoted inward to the stowed position, it can then slide across the insert  74  and gradually urge the shuttle member  54  axially into the closed position of  FIG. 3 . 
         [0026]    Shown in  FIG. 5  is a sectional view of the lubricant dispenser section  30  wherein a majority of the lubricant  32  has been discharged from the reservoir  44  and the piston  46  is adjacent the shuttle valve assembly  50 . The reservoir may be refilled through a fill tube  78  shown inserted coaxially through the lower end of the dispenser section  30  and having an end set into a lower end  80  of the piston  46 . In the embodiment of  FIG. 5 , the piston  46  further includes a main body  82  having an outer circumference that extends radially outward to the inner surface of the reservoir  44  and past the outer periphery of the lower end  80  of the piston  46 . A bore  84  extends axially through the piston  46  and transitions radially outward within the lower end  80  and profiled to receive a check valve  86  therein. Axial ports  88  through the check valve  86  allow lubricant to flow through the check valve during the refilling process. Ultimately, lubricant flows through the ports  88  and the check valve  86 , through the upper end of the bore  84  to urge the piston  46  into contact with the spring  48 . Moreover, the check valve prevents loss of lubricant through the inlet  90  that projects through the lower end of the dispenser section  30 . Accordingly, by use of the fill tube  78 , the lubricant can be quickly recharged into the lubricant dispenser section  30  and the cutting tool  10  quickly redeployed for additional operations. 
         [0027]    Examples of lubricants include hydrogenated polyolefins, esters, silicone, fluorocarbons, grease, graphite, molybdenum disulfide, molybdenum sulfide, polytetrafluoroethylene, animal oils, vegetable oils, mineral oils, and petroleum based oils. Lubricant  40  inserted between the blade  28  and the inner surface of the tubular  14  enhances machining and cutting of the tubular  14 . 
         [0028]    The present disclosure further includes using a cutting tool with a lubricant to cut tubulars with increased chrome amounts, as well as alloying elements such as nickel, vanadium, molybdenum, titanium, silicium. This method is also applicable to cutting in environments with water, salt water, air, gas, and drilling fluids. 
         [0029]    The improvements described herein, therefore, are well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While presently preferred embodiments have been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present disclosure and the scope of the appended claims.