Abstract:
A wellbore intervention tool for use in penetrating an obstruction in a wellbore includes a cutting tool having at least one rotating cutter member for penetrating the obstruction. A displacement mechanism coupled to the cutting tool sets and adjusts a cutting position of the cutting tool relative to a tool axis. A sweeper coupled to the displacement mechanism deflects the displacement mechanism about the tool axis, and the cutting tool is deflected with the displacement mechanism.

Description:
BACKGROUND 
       [0001]    This disclosure relates to apparatus for penetrating wellbore obstructions. Such obstructions may be, for example, a collapsed wellbore section, a wellbore plug, a failed flapper in a downhole safety valve, and the like. The disclosure also relates to removing a section of wellbore conduit (“tubular”) or penetrating several nested wellbore tubulars to access the wellbore externally to or off such tubulars. 
         [0002]    In the hydrocarbon exploitation industry, there is often a need for penetrating an obstruction in a wellbore, where such an obstruction may be a section of a collapsed wellbore and tubulars, a “fish” in the wellbore that cannot be removed by traditional wellbore milling tools, and the like. Such a “fish” may be a barrier installed, for example, in the form of a wireline plug, a failed flapper in a downhole safety valve, a lost tool string, a logging tool, and so forth. Penetrating such obstructions can be required to bring the well back to normal operation or to obtain access to the wellbore below the obstruction to plug and abandon the well. 
         [0003]    It is common, with various rates of success, to remove or penetrate such wellbore obstructions using lightweight wellbore milling tools deployed by wireline or coiled tubing. In some instances, attempts may be made to remove or penetrate the obstruction with heavier intervention apparatus deployed on jointed pipe; however, such methods are without guaranteed success. 
         [0004]    Hence, there is a need for methods and devices that can be used to mechanically mill away, or to disintegrate, an obstruction sufficiently for this obstruction to fall into the wellbore below an interval of interest or to be retrieved to the surface. 
       SUMMARY 
       [0005]    In one illustrative embodiment, a wellbore intervention tool for use in penetrating an obstruction in a wellbore includes a cutting tool having at least one rotating cutter member for penetrating the obstruction. The wellbore intervention tool includes a displacement mechanism that is coupled to the cutting tool and operable to set and adjust a cutting position of the cutting tool relative to a tool axis. The wellbore intervention tool includes a sweeper coupled to the displacement mechanism. The sweeper is operable to deflect the displacement mechanism about the tool axis, wherein the cutting tool is deflected with the displacement mechanism. 
         [0006]    In another illustrative embodiment, a method of penetrating an obstruction in a wellbore includes lowering a wellbore intervention tool into the wellbore. The wellbore intervention tool includes a cutting tool having at least one rotating cutter member, a displacement mechanism coupled to the cutting tool, and a sweeper coupled to the displacement mechanism. The method includes positioning the at least one rotating cutter member against the obstruction and rotating the rotating cutter member. The method further includes operating the sweeper to deflect the displacement mechanism about the tool axis during at least a portion of rotating the rotating cutter member, thereby deflecting the rotating cutter member about the tool axis. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The following is a description of the figures in the accompanying drawings. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
           [0008]      FIG. 1  shows a wellbore intervention tool for penetrating an obstruction in a wellbore according to one embodiment. 
           [0009]      FIG. 2  shows a cutting tool pivoted relative to a tool axis according to one embodiment. 
           [0010]      FIG. 2A  shows a cutting tool laterally displaced relative to a tool axis according to one embodiment. 
           [0011]      FIG. 3  shows a cross-section of a tool anchor according to one embodiment. 
           [0012]      FIG. 4  shows a cross-section of a stroker according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  illustrates a wellbore intervention tool  10  disposed within a wellbore  12  to penetrate an obstruction  11  in the wellbore  12 . Herein, the term “obstruction” may generally mean any form of unwanted wellbore restriction. As discussed in the Background section herein, examples of obstructions include, but are not limited to, a section of a collapsed wellbore, a section of tubulars, and a fish, e.g., a wireline plug, a failed flapper in a downhole safety valve, a lost tool string, and the like. For the purposes of the present disclosure, an obstruction is illustrated in general form by reference numeral  11  in  FIG. 1 . 
         [0014]    In one embodiment, the wellbore intervention tool  10  may be deployed into the wellbore  12  by a wellbore deployment system capable of transmitting power and control signals to the wellbore intervention tool  10  from the surface and returning data from the wellbore intervention tool  10  to the surface. For example, the wellbore intervention tool  10  may be deployed on the end of an armored electrical cable (“wireline”) or a coiled tubing having an electrical cable implemented therein. As an example,  FIG. 1  shows the wellbore intervention tool  10  deployed on the end of a wireline  13  suspended from a crane or mast (not shown) above a wellhead (not shown). Other means of transmitting data and commands, such as fiber optic cable, may also be used. 
         [0015]    In one embodiment, the wellbore intervention tool  10  includes an anchor  14  for holding the wellbore intervention tool  10  in place during penetration of an obstruction. The anchor  14  may engage a wall of the wellbore  12 , a casing or liner installed in the wellbore  12 , or a tubing within the wellbore  12 . In  FIG. 3 , an example embodiment of the anchor  14  includes an anchor body  16  on which a radially expandable anchor  18  is mounted. The anchor body  16  may have an axial bore  17  for passage of tools, fluids, and the like. The anchor  14  may include a drive mechanism  20  for sliding the radially expandable anchor  18  on the anchor body  16  in order to move the radially expandable anchor  18  between a collapsed position and an expanded position. The drive mechanism  20  may include, for example, a hollow motor  22 , a reduction gear system  24 , and a screw drive  26  mounted on the anchor body  16 . The motor  22  may be, for example, an electrical, pneumatic, or hydraulic motor. 
         [0016]    Returning to  FIG. 1 , the wellbore intervention tool  10  includes a cutting tool  30  for penetrating the obstruction  11  in the wellbore  12 . The cutting tool  30  has one or more cutting members that can be placed against the obstruction  11  and used to grind, mill, and/or apply other cutting action to the obstruction  11 . The cutting members may be blades, drill bits, and the like. 
         [0017]    In one embodiment, the cutting tool  30  may be a dual-blade counter-rotating cutter. Such embodiments include the cutting tool  30  having two blades  31  (only one blade is visible in the drawing) mounted adjacent to each other with a gap between the blades  31  such that the blades  31  do not contact each other when rotating and a drive mechanism (not shown) for rotating the two blades  31  in opposite directions, typically about a common rotational axis (shown at  31 A). The drive mechanism may be operated by a motor  42 , such as an electrical motor, pneumatic motor, or hydraulic motor, included in the wellbore intervention tool  10 . Introducing a counter-rotating cutting feature in the cutting tool  30  will improve the penetration speed and efficiency of the cutting tool  30 , lower the amount of axial force (weight) needed to urge the cutting tool  30  against the obstruction, and significantly reduce the risk of “kickback” due to the blade of the cutting tool  30  becoming stuck, which would damage a wireline deployed tool. 
         [0018]    An example of a dual-blade counter-rotating cutter is disclosed in U.S. Patent Application Publication No. 2013/0048329 filed by Qian (the &#39;329 publication). A dual-blade counter-rotating cutter such as disclosed in the &#39;329 publication or other similar device may be used as the cutting tool  30  in one embodiment. 
         [0019]    In another embodiment, the cutting tool  30  may be a single-blade rotating cutter. In another embodiment, the cutting tool  30  may have more than two rotating blades. In another embodiment, the cutting tool  30  may be a drill bit. 
         [0020]    In one embodiment, a pivoting mechanism  40  is coupled to the cutting tool  30  and may be used to adjust a cutting position of the cutting tool  30 . As an example, the pivoting mechanism  40  may include a pivot pin  35  that the cutting tool  30  may pivot around. The cutting tool  30  may be coupled to the pivot pin  35  such that an offset angle of the cutting tool  30  relative to the tool axis  33  can be set by adjusting the rotational angle of the cutting tool  30  around the pivot pin  35 . This movement may be independently controlled by a suitable rotary drive mechanism in the pivoting mechanism  40 , such as an electric motor and a worm gear. 
         [0021]    In one embodiment, the pivoting mechanism  40  is coupled to a sweeper  45 , which is configured to rotate the pivoting mechanism  40  about the tool axis  33 . The sweeper  45  may rotate the pivoting mechanism  40  through  360  degrees around the tool axis  33 . The sweeper  45  may include, for example, an electrical or hydraulic motor and a gear or gear box. The cutting tool  30  is coupled to the pivoting mechanism  40  and will rotate with the pivoting mechanism  40 . 
         [0022]    In  FIG. 1 , the cutting tool  30  is aligned with the tool axis  33 . The offset angle of the cutting tool  30  relative to the tool axis  33  is therefore 0 degrees. In this position, the rotation axis (shown at  31 A) of the blade(s)  31  of the cutting tool  30  is substantially perpendicular to the tool axis  33 . This will result in a cutting through the obstruction  11  with a diameter substantially the same as the diameter of the cutting blade(s)  31 . 
         [0023]    In  FIG. 2 , the cutting tool  30  is not aligned with the tool axis  33 , and the offset angle θ of the cutting tool  30  relative to the tool axis  33  is therefore greater than 0 degrees. This will result in a cutting through the obstruction  11  with a larger diameter than the diameter of the cutting blade  31 . The diameter of the cutting may be therefore determined by the amount of cutting tool axis angular offset. The pivoting function can be used, for example, to control the location and size of a “window” milled in a tubular. 
         [0024]    The pivoting mechanism  40  is an example of an angular displacement mechanism. In another embodiment, the pivoting mechanism  40  may be replaced with a linear displacement mechanism, such as illustrated at  40 A in  FIG. 2A . The linear displacement mechanism  40 A may be operated to adjust an offset distance d of the cutting tool  30  relative to the tool axis  33 . As an example, the linear displacement mechanism  40 A may include a pin  35 A that slides within a slot  37 . The cutting tool  30  may be coupled to the pin  35 A so that the offset distance d between the cutting tool  30  and the tool axis  33  can be adjusted by sliding the pin  35 A within the slot  37 . When the cutting tool  30  is aligned with the tool axis  33 , the offset distance d will be zero. A suitable drive mechanism in the linear displacement mechanism  40 A can be used to move the pin  35 A within the slot  37 . Also, the linear displacement mechanism  40 A is not limited to a pin-and-slot arrangement and may generally include any arrangement that can be used to displace the cutting tool  30  relative to the tool axis  33 . As in the case of the pivoting mechanism  40 , the linear displacement mechanism  40 A may be coupled to the sweeper  45  and rotated or deflected about the tool axis  33  by the sweeper  45 . 
         [0025]    It is also possible to have a displacement mechanism that selectively provides an angular or linear displacement to the cutting tool  30 . 
         [0026]    Returning to  FIG. 1 , in one embodiment, the wellbore intervention tool  10  may include a stroker  50  for applying an axial force (and movement) along the tool axis  33 . Such an axial force can provide a downward/forward pressure on the cutting tool  30  to assist with the milling of an obstruction. The axial force may be transmitted to the cutting tool  30  through the pivoting mechanism  40  (or through the linear displacement mechanism  40 A in  FIG. 2A ). During a window milling operation where the cutter blade(s)  31  may be moved radially substantially away from the tool axis  33 . The stroker  50  may also generate an upward force/movement of the cutting tool  30 . 
         [0027]    The stroker  50  may have any suitable configuration. In  FIG. 4 , an example stroker  50  includes a stroker body  51 , which may have an axial bore  53  for passage of fluids, tools, and the like. Mounted on the stroker body  51  are a motor  52 , which may be electrical, pneumatic, or hydraulic, a gear box  54 , and a screw drive  56 . A nut  58 , e.g., a ball nut, cooperatively engages the screw drive  56 . The screw drive  56  has an external thread section reaching from its lower end to a downward facing shoulder at its upper end. The nut  58  may have internal threads in its upper end engaged with the external threads of the screw drive  56 . The nut  58  may have external axial key-slots where keys installed in the very lower end of the outer housing  59  are engaged and serve as an anti-rotation device  60 . The motor  52 , gear box  54 , and screw drive  56  may be placed in a pressure balanced chamber  61  to keep them clean and functional. 
         [0028]    Another example of a stroker that may be used in the wellbore intervention tool  10  is disclosed in U.S. Patent Application No. 2010/0126710 to Hallundbaek et al. (the &#39;710 publication). In the &#39;710 publication, the stroker includes a piston mounted on a shaft and disposed in a cylinder. The piston divides the cylinder into two chambers, each of which may be selectively filled with fluid from a pump. The piston moves along the cylinder in response to differential fluid pressure between these two chambers. As the piston moves, the shaft moves along with the piston and provides the desired axial force. 
         [0029]    Returning to  FIG. 1 , in one embodiment, the wellbore intervention tool  10  may include a stabilizer section  64  for centralizing the wellbore intervention tool  10  in the wellbore  12  during penetration of an obstruction. Any suitable stabilizer known in the art of wellbore operations may be used. In general, the stabilizer section  64  may include, e.g., radial fins  66  and the like arranged about the diameter of the wellbore intervention tool  10 . The radial fins  66  may be collapsible, for example, to allow passage of the tool  10  through restricted diameters within the wellbore  12 . 
         [0030]    The cuttings from the wellbore intervention tool  10  may be left in place, or a debris catching feature can be built into the wellbore intervention tool  10 . In one embodiment, the debris catching feature may include circulating fluids through the cutting tool  30  into a so-called “junk basket” mounted externally or internally on the cutting tool  30  or in a module attached above the cutting tool  30 . 
         [0031]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.