Abstract:
Downhole fluid jet cutting tools having extendible and retractable arms with cutting heads on the ends are disclosed. The jet cutting tools permit casing and other downhole surfaces to be cut utilizing a cutting fluid forced through a jet nozzle assembly. Movement of a piston slidingly engaged within the passageway of the tool actuates the arms when cutting fluid pressure acts on the piston. As a result, the arms are extended and cutting fluid is forced at high pressure from the passageway to the cutting head where it is expelled through nozzles for cutting casing and the like. The jet cutting tools permit the arms to be extended, retracted, and re-extended or redeployed multiple times without the need for being retrieved from the wellbore.

Description:
BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The present invention is directed to a downhole cutting tool and, in particular, a downhole radially expandable fluid jet cutting tool. 
         [0003]    2. Description of Art 
         [0004]    Various types of cleaning or cutting jet blasting arrangements have been proposed and used for jet blasting or eroding surfaces with abrasive fluids including, by way of example only, steam, water or any other fluid along with or without an abrasive substance in an attempt to accomplish whatever results may be desired. 
         [0005]    Generally the fluids are conducted through a fluid passage in the arrangement and discharged through a restricted orifice in a jetting nozzle to increase the velocity of fluids and abrasive particles in an attempt to increase the cutting or cleaning effect desired. The jetting nozzle is available in a variety of designs and sizes and is normally produced from an extremely hard and/or tough material such as, by way of example only, carbide. It is generally accepted that the closer a jetting nozzle is to the surface to clean or cut the higher the efficiency of the operation. 
         [0006]    One such prior jetting tool apparatus is disclosed in U.S. Pat. No. 5,765,756. The jetting tool apparatus of this patent includes multiple extendible telescoping jetting nozzles that are rotated into position by fluid flowing through the tool. In addition to rotation, the jetting nozzles extend telescopically so as to come in close contact with the cutting surface. After the cutting is completed, however, the nozzles remain extended. They are rotated downward into recesses to facilitate movement of the tool out of the wellbore. In those instances where the tool is to be moved to a new location for continued jetting, the telescopically extended jetting nozzles can not be reconfigured to a lesser extension because the telescoping members cannot be retracted to their original positions. As a result, the tool in U.S. Pat. No. 5,765,756 is limited in its use and requires removal of the tool from the well and resetting of the telescoping jetting nozzles before the tool can be used in a new, narrower, location. As is apparent, removal of the tool for resetting and subsequent repositioning in the well is time consuming and costly. 
       SUMMARY OF INVENTION 
       [0007]    The present invention overcomes the deficiencies of U.S. Pat. No. 5,765,756 while providing additional benefits not found in prior jet cutting tools. For example, the jet cutting tools and methods of cutting a surface of a wellbore of the present invention provide the capability to extend and retract the jetting nozzles for easy and quick relocation and redeployment within a well without the need for removal of the tool from the well; permit the jetting nozzles to be consistently extended to the cutting surface; maintain the jetting nozzles in the appropriate orientation during cutting; permit easy and efficient cutting of casing when passing through a restriction in the casing or when cutting a surface in relatively shallow water depth; permit efficient cutting in multiple locations within conduits having variable inner diameters; and provide the capability of cutting in large diameter conduits and then be redeployed for cutting in small diameter conduits without having to remove the tool from the wellbore. 
         [0008]    Broadly, the present invention is directed to a jet cutting tool having one or more arms that are extendable radially from the body of the tool. Each arm is in fluid communication with a passageway within the tool. An actuating member, such as a piston, is disposed within the passageway. Each arm includes a cutting head disposed on the end. The cutting head may include a metal cutting element such as crushed carbide or other carbide elements. Cutting fluid, such as an abrasive slurry known to persons skilled in the art, is pumped at high pressure down the passageway and moves the piston. The piston in turn extends each of the arms until each arm is in contact with the inner wall surface of the cutting surface or casing of the well. Cutting fluid is also forced into a length of tubing in fluid communication with the passageway and the cutting head. After extension of the arms to the point where the piston is no longer movable by the cutting fluid, the cutting head is positioned next to, and preferably in contact with, the cutting surface. The cutting fluid is then forced through the length of tubing from the passageway to the cutting head and out of the nozzle at a high pressure. The high pressure of the cutting fluid being expelled from the nozzle of the cutting head cuts the casing or other cutting surface. 
         [0009]    After cutting, the pressure of the cutting fluid flowing through the passageway is decreased and the piston is retracted. Accordingly, the arms are also retracted so that the jet cutting tool can be moved to a new location and the arms redeployed for additional cutting. Advantageously, the retraction and the extension of the arms are fully repeatable such that the jet cutting tool can be used in multiple locations having multiple inner diameter, including cutting narrower portions of casing after cutting wider portions of casing. 
         [0010]    In accordance with one aspect of the invention, one or more of the foregoing advantages have been achieved through a downhole jet cutting tool. The downhole jet cutting tool comprises a housing having an upper end for connection to a conduit string for running the downhole jet cutting tool into a well, the housing having a passageway for communicating a cutting fluid pumping down the conduit string to the downhole jet cutting tool; an actuating member operatively associated with the passageway whereby the actuating member is actuable by the cutting fluid, the actuating member having an initial position and a plurality of actuated positions; and a jet nozzle assembly, the jet nozzle assembly comprising an arm operatively associated with the actuating member whereby the arm is moved from a retracted position to one of a plurality of extended positions by the actuating member moving from the initial position to a corresponding actuated position, the arm having a cutting end and pivot end, the pivot end being pivotally connected to the housing, and the cutting end having a nozzle for expelling the cutting fluid, wherein the passageway of the housing and the nozzle of the cutting head are in fluid communication with each other such that the cutting fluid can flow from the passageway and out of the nozzle at a pressure sufficient to cut a cutting surface disposed within the well. 
         [0011]    A further feature of the downhole jet cutting tool is that the cutting head may be pivotally connected to the arm. Another feature of the downhole jet cutting tool is that the housing may have an opening leading from the passageway to an exterior portion of the housing, and the arm may have a portion that extends through the opening into the passageway in engagement with the actuating member. An additional feature of the downhole jet cutting tool is that the passageway and the nozzle may be in fluid communication with each other through a flexible tubing. Still another feature of the downhole jet cutting tool is that the flexible tubing may be in fluid communication with the passageway through a port disposed in the housing above the actuating member. A further feature of the downhole jet cutting tool is that the housing may include a recess for receiving the jet nozzle assembly when the arm is in the retracted position. Another feature of the downhole jet cutting tool is that the actuating member may comprise a piston located in the passageway that is acted on by the cutting fluid flowing down the passageway. An additional feature of the downhole jet cutting tool is that the actuating member may include a biasing member for biasing the actuating member toward the initial position. Still another feature of the downhole jet cutting tool is that the biasing member may comprise a coil spring. A further feature of the downhole jet cutting tool is that the cutting head may include at least one standoff for contact with the cutting surface in the well while the arm is in one of the extended positions. Another feature of the downhole jet cutting tool is that at least one of the at least one standoffs may comprise a roller. An additional feature of the downhole jet cutting tool is that the roller may have an outer surface with at least one groove disposed on the outer surface. Still another feature of the downhole jet cutting tool is that at least one of the at least one standoffs may comprise a carbide dome button. 
         [0012]    In accordance with another aspect of the invention, one or more of the foregoing advantages have been achieved a downhole jet cutting tool for cutting a tubular member in a well. The downhole jet cutting tool comprises a housing having an upper end for connection to a conduit string for lowering the housing into the tubular member, the housing having a passageway; a piston in the passageway for movement between upper and lower positions; a spring in the passageway for urging the piston toward the upper position; an arm having an upper portion pivotally connected to an exterior portion of the housing at a pivot point, the arm having a cam portion that extends through an opening in the housing into the passageway below the piston so that cutting fluid being pumped down the conduit string moves the piston downward from the upper position, causing the piston to push downward on the cam portion of the arm to pivot a lower portion of the arm outward from the housing; a cutting head with a nozzle attached to the lower portion of the arm for engaging the tubular member; and a flexible tube extending from a port in the housing above the piston to the cutting head for delivering cutting fluid being pumped down the conduit string to the nozzle. 
         [0013]    In accordance with still another aspect of the invention, one or more of the foregoing advantages have been achieved a method of cutting a casing disposed within a well. The method comprising the steps of: (a) running a downhole jet cutting tool on a conduit string into a tubular member of a well to a first location, the downhole jet cutting tool having an actuating member biased toward an initial position and an arm with a cutting head, the arm being pivotally movable from a retracted position by movement of the arm from the initial position; (b) pumping a cutting fluid down the string, which exerts a force on the actuating member to move the actuating member from the initial position, causing the arm to pivot from the retracted position and move the cutting head outward into contact with a surface of the tubular member; (c) continuing to pump the cutting fluid down the string, which flows to and out of the cutting head, resulting in the tubular member being cut; and (d) after the tubular member has been cut, stopping the pumping of cutting fluid down the string, which allows the actuating member to return to its initial position and, thus, causing the arm to return to the retracted position. 
         [0014]    A further feature of the method of cutting a casing disposed within a well is that the actuating member in step (a) may comprise a piston. Another feature of the method of cutting a casing disposed within a well is that the method may further comprise the step of moving the downhole jet cutting tool to a second location within the well after completion of step (d) and repeating steps (b) and (c). An additional feature of the method of cutting a casing disposed within a well is that the second location may be narrower than the first location. Still another feature of the method of cutting a casing disposed within a well is that step (a) may comprise pivotally mounting the arm to a housing of the jet cutting tool at a pivot point; and step (b) may comprise exerting a downward force by the actuating member on a portion of the arm inward from the pivot point. 
         [0015]    The jet cutting tools and methods of cutting a surface in a wellbore disclosed herein have one or more of the following advantages: providing the capability of extending and retracting the jetting nozzles for easy and quick relocation and redeployment within a well; permitting the jetting nozzles to be consistently extended to the cutting surface; maintaining the jetting nozzles in the appropriate orientation during cutting; permitting easy and efficient cutting of casing when passing through a restriction in the casing or when cutting a surface in relatively shallow water depth; permitting efficient cutting in multiple locations within conduits having variable inner diameters; and providing the capability of cutting in large diameter conduits and then be redeployed for cutting in small diameter conduits without having to remove the tool from the wellbore. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  is a cross-sectional view of one embodiment of the jet cutting tool of the present invention shown in its retracted or run-in position. 
           [0017]      FIG. 2  is a cross-sectional view of the jet cutting tool illustrated in  FIG. 1  shown in its extended or cutting position. 
           [0018]      FIG. 3  is a top view of a cutting head of one specific embodiment of the jet cutting tool of the present invention. 
           [0019]      FIG. 4  is a top view of another cutting head of one specific embodiment of the jet cutting tool of the present invention. 
           [0020]      FIG. 5  is a perspective view of a roller for one embodiment of the jet cutting tools of the present invention. 
       
    
    
       [0021]    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 INVENTION 
       [0022]    Referring now to  FIGS. 1-2 , jet cutting tool  20  is shown in its retracted or “run-in” position ( FIG. 1 ) and an extended or cutting position ( FIG. 2 ). Jet cutting tool  20  has housing  22  with passageway  24  extending longitudinally into upper end  23  of housing  22 . Upper end  23  is adapted to be connected to string of conduit  10 , such as tubing or drill pipe, through any device or method known to persons of ordinary skill in the art. The lower portion of housing  22  is solid, with passageway  24  having a bottom  25  approximately midway along the length of housing  22 . 
         [0023]    Actuating member such as piston  26  is slidingly engaged within passageway  24  of housing  22 . Resilient seal  28  provides a seal with piston  26  along the wall of passageway  24 . Preferably, a retaining member such as coil spring  30  is disposed adjacent piston  26  for urging piston  26  upward. As discussed in greater detail below, spring  30  is expanded when jet cutting tool  20  is in its retracted position ( FIG. 1 ) and compressed when jet cutting tool  20  is in its extended position ( FIG. 2 ). Therefore, spring  30  is biased for retaining piston  26  in an initial or upper position in which jet cutting tool  20  is in its retracted position. 
         [0024]    Housing  22  also includes a plurality of rectangular openings  32  (only one shown) extending through its side wall, into which part of a jet nozzle assembly  40  is received when jet cutting tool  20  is in its retracted position. Although only one jet nozzle assembly  40  is shown, typically tool  20  has three or more jet nozzle assemblies  40 . Housing  22  also has a recess  33  on its exterior into which the remaining portion of jet nozzle assembly  40  locates. Opening  32  extends from passageway  24  to recess  33  and has a shorter axial length than recess  33 . The lower end of opening  32  coincides with passageway bottom  25 . Housing  22  also preferably includes radially extending flanges  34 ,  36  at its upper and lower ends for protecting jet nozzle assembly  40  when jet cutting tool  20  is in its retracted position. 
         [0025]    Port  38 , which is located above piston  26  in housing  22 , provides fluid communication from passageway  24  to jet nozzle assembly  40 . Jet nozzle assembly  40  comprises arm  42 , tubing  44 , and cutting head  50 . Preferably, tubing  44  is flexible. Tubing  44  is in fluid communication with passageway  24  and cutting head  50 . Couplings  45 ,  46  attach tubing  44  to passageway  24  and to cutting head  50 , respectively. Preferably, cutting head  50  is pivotally attached to arm  42  by a fastener such as pin  47  or any other device that is capable of attaching cutting head  50  to arm  42  and allowing cutting head  50  to rotate or pivot relative to arm  42 . Accordingly, cutting head  50  can pivot about the point of connection with arm  42  to facilitate better contact with the inner wall surface  61  of casing  60  ( FIG. 2 ). 
         [0026]    A pivot end of arm  42  is connected to housing  22  within the upper end of recess  33  by a fastener such as pin  49  or any other device that is capable of attaching the pivot end of arm  42  to housing  22  and allowing arm  42  to rotate or pivot about pivot pin  49 . A lever or cam  48  is integrally formed on the upper end of arm  42  and extends through opening  32  into passageway  24  in contact with the lower end of piston  26 . Cam  48  contacts piston  26  at a point that is radially inward and upward from pivot pin  49 , creating a moment arm. Downward movement of piston  26  pushes downward on cam  48 , causing arm  40  to pivot outward to the position shown in  FIG. 2 . Preferably, flanges  34 ,  36  protect arm  42 , cutting head  50 , and tubing  44  of jet nozzle assembly  40  when arm  42  is in its retracted position ( FIG. 1 ). As shown in  FIG. 1 , in a preferred embodiment, tubing  44  has little or no slack in it when jet cutting tool  20  is in the retracted position. Therefore, the risk of tubing  44  being damaged or broken when jet cutting tool  20  is being run into the well is lessened. 
         [0027]    Cutting head  50  has passage  52  disposed therein. Passage  52  is in fluid communication with coupling  46  and, thus, tubing  44  and passageway  24 . Cutting head  50  also includes opening  54  with, nozzle  56 . As shown in the embodiment of  FIGS. 1 and 2 , passage  52  in cutting head  50  includes plug  59 . Plug  59  is used to close one end of passage  52  when passage  52  is formed by drilling all the way through cutting head  50 . In other words, plug  59  may be included if certain methods of manufacturing cutting head  50  are utilized. 
         [0028]    Cutting head  50  also preferably includes one or more standoffs  58  that engage the wall surface of casing  60  ( FIG. 2 ) and facilitate maintaining cutting head  50  and, thus, jet cutting tool  20  in place. Standoffs  58  preferably also provide guidance of cutting nozzle  56  in the same track. As shown in  FIGS. 1 and 2 , standoffs  58  may comprise dome buttons formed of a hard, wear resistant material such as tungsten carbide. In other embodiments, standoffs  58  are polymer elements. In still other embodiments, shown in  FIGS. 3-5 , standoffs  66  are bearing units such as rollers  58  having grooves  67  (shown in  FIG. 5 ) to facilitate gripping the inner wall surface of casing  60 . 
         [0029]    Standoffs  58  may be arranged in any manner to facilitate the desired type of cut in casing  60 . For example, as shown in greater detail in  FIG. 3 , standoffs  58  are rollers  66  for rolling axially along the inner wall surface of casing  60  ( FIG. 2 ) in the direction of arrow  63  and arrow  65  when cutting tool  20  is making an axial cut. Alternatively, as shown in  FIG. 4 , rollers  66  may be rotated 90 degrees, i.e., perpendicular to rollers  66  shown in  FIG. 3 , such that they rotate and, thus, cut, in the direction of arrows  68  and  69  when cutting tool  20  is making a circumferential cut. In one specific embodiment, standoffs  58  are ball bearings (not shown) capable of rotating in any direction. 
         [0030]    As mentioned above,  FIG. 1  shows jet cutting tool  20  in its initial or “run-in” position. Each arm  42  is retracted and disposed along housing  22 . After jet cutting tool  20  is properly placed within casing  60  of the well (not shown), cutting fluid  62  ( FIG. 2 ) is pumped down conduit string  10  through passageway  24  of jet cutting tool  20 . Cutting fluid  62  forces piston  26  to move downward, i.e., in the direction of arrow  63 . In so doing, spring  30  is compressed and piston  26  pushes on cam end  48  and rotates arm  42  around or about pivot pin  49 , causing arm  42  to extend outwardly from housing  22  until standoffs  58  of cutting head  50  contact the inner wall surface of casing  60  as illustrated in  FIG. 2 . Thus, jet cutting tool  20  is placed in its extended or cutting position. 
         [0031]    After cutting head  50  contacts the inner wall surface of casing  60 , piston  26  can no longer move in the direction of arrow  63 . Therefore, cutting fluid  62  is forced at a greater pressure through tubing  44  to cutting head  50  where it is focused through passage  52  into and through nozzle  56  and out of opening  54  at a high pressure to cut the inner wall of casing  60  as illustrated by cut  64  ( FIG. 2 ). The operator moves conduit string axially to form an axial cut and rotates conduit string  10  to form a circumferential cut. In one specific embodiment (not shown), cutting fluid  62  propels a rotatable cutting member (not shown) to facilitate cutting of the inner wall surface of casing  60 . In other embodiments, all of the cutting is performed by cutting fluid  62  being expelled through nozzle  56  at a high pressure. 
         [0032]    Cutting fluids  62 , and their cutting rates, are known to persons skilled in art. Preferably, cutting fluid  62  is an abrasive cutting fluid such as those having a ratio of 1 pound of abrasive material per gallon of water carrier. Suitable abrasive materials are known in the art such as ground garnet material which is available from many known sources. The water in cutting fluid  62  can be enhanced with polymers to increase the stream holding profile of the cutting fluid  62  to increase cutting efficiency. Typical cutting rates, but by no means the only cutting rates, are expected to be approximately 1 inch per minute using the foregoing cutting fluid  62 . 
         [0033]    After casing  60  has been cut as desired by the operator of jet cutting tool  20 , the operator ceases pumping cutting fluid  62  down conduit string  10 . Accordingly, the force being applied to piston  26  in the direction of arrow  63  ceases. When this occurs, spring  30  expands and, thus, moves piston  26  upward in the opposite direction of arrow  63 . The weight of jet nozzle assembly  40  causes arm  42  to rotate or pivot about cam end  48  until jet nozzle assembly  40  is received within recess  33  of housing  22 . In other words, the removal of the pressure of cutting fluid  62  flowing through passageway  24  of jet cutting tool  20  causes jet cutting tool  20  to return to its run-in position. Subsequently, jet cutting tool  20  can be moved to a new location for additional cutting. Advantageously, the new location can have a smaller diameter and jet cutting tool  20  will properly deploy without the need for removal of jet cutting tool  20  from the well. 
         [0034]    It is to be understood that the invention 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. For example, the cutting head is shown as having a rectangular or square shape; however, cutting head can have any shape desired or necessary for providing the type of cut desired by the operator of the jet cutting tool. Likewise, the arm of the jet nozzle assembly and its corresponding recess can have any shape desired or necessary to permit extension and retraction as described above. Moreover, the tubing can be made of any material desired or necessary to facilitate transportation of the cutting fluid from the passageway to the cutting head. Additionally, the size of the opening from the passageway to the tubing, the size of the tubing, the size of the passageway in the cutting head, the size of the nozzle, and the size of the opening in the cutting head can be any size desired or necessary to provide the desired size and depth of cut in the casing. Further, the cutting surface is not limited to casing. Other types of conduits, tubings, or structures may be cut using the jet cutting tools described herein. In addition, spring can be replaced by a pressurized chamber or another device that is biased toward keeping the piston in the retracted position. Alternatively, hydrostatic pressure could provide the force for biasing the piston toward the retracted position by having the passageway in the housing continuing to the end of the jet cutting tool where it is opened to the wellbore. Moreover, the piston may be replaced with a valve or other actuating member known to persons of ordinary skill in the art. Additionally, the tubing may be inflexible and the couplings of the tubing to the housing and the cutting head may be flexible joints providing 360 degree movement. Further, a top sub may be connected to and placed in communication with the passageway of the housing and the tubing may be in fluid communication with the passageway of the housing through a port in the top sub instead of through a port in the housing. Additionally, a ported collar in fluid communication with the tubing may be secured to the exterior of the top sub to place the tubing in fluid communication with the port in the top sub and, thus, in fluid communication with the passageway. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.