Abstract:
A reaming tool for use while inserting tubular components into a wellbore includes a motor housing configured to be coupled to one end of a string of tubular components. A motor is disposed in the housing. An output shaft is rotationally coupled to the motor. the output shaft is configured to be coupled to a cutting structure at one end thereof. A lock is selectively engageable to rotationally fix the output shaft to the motor housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND 
       [0003]    This disclosure relates generally to the field of wellbore reaming tools used while inserting tubular (casing or liner) into a wellbore. More specifically, this disclosure relates to wellbore reaming tools having devices to facilitate milling out or drilling out of components of the reaming tool after the tubular are inserted so that lengthening the wellbore may continue. 
         [0004]    U.S. Pat. No. 7,849,927 issued to Herrera describes an apparatus used during insertion (“running”) of wellbore lining tubular, e.g., casing or liner, which includes a cutting structure such as a reamer and at least one of a motor, a drive shaft, bearing elements, a gearbox or other torque transfer device, and a connection for coupling the apparatus to the tubular string, which together provide the means and power to rotate the cutting structure, wherein at least part of the apparatus is ‘sacrificial’, that is at least part of the apparatus remains in its run-in location in the wellbore after placement of the tubular string is completed. 
         [0005]    U.S. Pat. No. 8,074,742 issued to Scott et al. describes an apparatus for cutting a wellbore which includes a motor having a stator and a rotor. The rotor includes an output shaft connected to a cutting structure to drive the cutting structure in use. The stator and rotor are spaced radially outwardly of the axis of the rotor such that at least one of the stator and the rotor has an access bore that extends through the motor to a position adjacent the cutting structure and through which a further object can pass without obstruction from the stator and rotor. The further object includes a further cutting structure. The motor workings are radially outward of the output shaft and the further cutting structure so as not to obstruct passage of the further cutting structure toward the cutting structure, such that the motor workings do not require drilling or removal to allow the further cutting structure access to the cutting structure. 
         [0006]    Using tools such as those described in the foregoing two patents still requires drilling or milling of the cutting structure in order to continue lengthening the wellbore after the tubular string is cemented in place in the wellbore. Because the cutting structure in such tools is coupled to a motor, it is frequently the case that the cutting structure rotates when engaged by the further cutting structure (e.g., a drill bit or milling tool). Such rotation may hinder mill out or drill out of the cutting structure. What is needed is a wellbore reaming tool that facilitates drill out or mill out of the cutting structure on completion of running the tubular string and cementing thereof if cementing is performed, and primarily if cementing is not completed. 
       SUMMARY 
       [0007]    A reaming tool for use while inserting tubular components into a wellbore includes a motor housing configured to be coupled to one end of a string of tubular components. A motor is disposed in the housing. An output shaft is rotationally coupled to the motor. the output shaft is configured to be coupled to a cutting structure at one end thereof. A lock is selectively engageable to rotationally fix the output shaft to the motor housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a sectional side view of an example motor and reaming head. 
           [0009]      FIG. 2  is a sectional side view of another example motor and reaming head. 
           [0010]      FIG. 3  is a more detailed part sectional, part cut away side view of the apparatus of  FIG. 1  showing a further cutting structure in two different positions, with part of the apparatus in phantom. 
           [0011]      FIG. 4  is a more detailed part sectional, part cut away side view of the additional example apparatus of  FIG. 2   
           [0012]      FIG. 5  shows a detailed view of an example motor with a locking clutch to facilitate mill out or drill out operations as explained with reference to  FIGS. 3 and 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Examples of a casing or liner reaming tool having a locking clutch will be explained in terms of an annular motor which enables passage of devices within the interior of the motor. An example of such motor is shown in U.S. Pat. No. 8,074,742 issued to Scott et al. and incorporated herein by reference. It should be understood that other types of motors used for reaming while running wellbore tubular are within the scope of the disclosure and that the example motor described herein is not limiting with respect to the type of wellbore motor. 
         [0014]    Referring initially to  FIG. 1 , a wellbore  1  has been formed by an initial drilling operation. The wellbore  1  is being or already has been lined with a “string” of metal tubular, e.g., in the form of a liner or casing  3  having a lowermost end  4 . An annular void  6  is defined between the outer surface of the casing  3  and the wall of the wellbore  1 . The void  6  is typically filled with concrete once drilling and reaming operations for the particular section of the wellbore  1  are completed. 
         [0015]    A wellbore tubular running and wellbore reaming apparatus  5  comprises a cutting structure which, in this example, is a reamer shoe  7  connected to an output shaft  9 . Rotation of the output shaft  9  rotates the reamer shoe  7 . In the present example the cutting structure can be sacrificed after running the liner or casing  3  is completed. 
         [0016]    The output shaft  9  comprises a rotor of a motor generally indicated  11 . The rotor in this example may be radially inward of a radially outward stator  13  fixedly connected to the lowermost end  4  of the liner or casing  3 . 
         [0017]    The stator  13  may be concentric with and extend around the periphery of the output shaft  9  and is thus of hollow form when viewed from the side or in transverse cross section. The stator  13  is therefore radially spaced from the rotational axis  10  of output shaft  9  such that it does not, when viewed in cross section from the side, extend across the output shaft  9 . The output shaft  9  may be formed with an access bore  15  that extends along the length of the motor  11  from the reamer shoe  7  to the opposite, distal end of the output shaft  9 , that is the end adjacent the lowermost end  4  of the liner or casing  3 . The access bore  15 , in this example, is co-axial with the axis of rotation  10  of the output shaft  9 . The access bore  15  may extend in a direction aligned with but not co-axial with, the axis  10 . 
         [0018]    The access bore  15  may be dimensioned to receive a further object and is arranged such that the further object can be located directly adjacent the reamer shoe  7 . The further object could comprise any desired device which may include, for example, a sensing device to transmit a signal indicative of physical parameters relevant to the cutting process. However, in this example, the further object comprises a further cutting structure comprising a drill bit  17  connected to a drill pipe or string  19 . 
         [0019]    In use of the apparatus  5 , the liner or casing  3  is run into the pre-drilled wellbore  1 . The motor  11  is activated to drive the output shaft  9  to rotate the reamer shoe  7 . Rotating the reamer shoe  7  aids running of the casing  3  into the wellbore  1 . Once the casing  3  has reached the desired depth, the motor  11  is deactivated. The drill bit  17  and drill string  19  are may then be run into the casing  3 . When the drill bit  17  reaches the lowermost end  4  of the liner or casing  3 , the drill bit  17  is run into the access bore  15  of the output shaft  9  so as to effectively pass through the interior of the motor  11 , i.e., the motor workings are radially outward of the output shaft  9  and drill bit  17  and do not obstruct passage of the drill bit  17  toward the reamer shoe  7 . The motor components therefore do not require drilling out or removal to allow the drill bit  17  access to the reamer shoe  7 . 
         [0020]    When the drill bit  17  reaches the reamer shoe  7 , rotation of the drill bit  17  allows the drill bit  17  to cut through the sacrificial reamer shoe  7  so as to project beyond the reamer shoe  7  so as to move into contact with formations below the pre-drilled wellbore  1  so as to drill a subsequent section of wellbore. 
         [0021]    Referring to  FIG. 2 , another example apparatus  21  is shown with like features being given like references to the apparatus  5  described above with reference to  FIG. 1 . In the example of  FIG. 2  a modified output shaft  22  may be concentric with but radially outward of the motor stator. In this example the motor stator may comprise a radially inward tubular stator  23  fixed to the lowermost end  4  of the casing  3 . The tubular stator  23  is formed with an access bore  25  that extends from the reamer shoe  7  to the lowermost end  4  of the casing  3  co-axially with the axis of rotation  10  of the modified output shaft  22 . The further object, which in this example may be the drill bit  17  and drill pipe  19 , is run into the access bore  25  in the tubular stator  23  rather than the access bore  15  formed in the output shaft rotor  9  of the apparatus  5  of  FIG. 1   
         [0022]    Referring to  FIG. 3 , a flared portion  14  of the radially outward stator  13  is locked to the interior surface of the lowermost end  4  of the casing  3 . This can be achieved using any suitable locking means. The radially inward output shaft rotor  9  is rotatably mounted on the stator  13  using a suitable combination of bearings  27 . Additionally a plurality of thrust bearings  29  may be provided to limit axial movement between the rotor  9  and the stator  13  whilst still allowing relative rotation of these components. The thrust bearings  29  can be arranged to allow limited axial movement if desirable. Any desired type, number and position of bearings may be used as required to deal with the loads generated. 
         [0023]    The motor rotor  9  and stator  13  can comprise any desired structure and components to generate power to rotationally drive the rotor  9 . However, in this example, the rotor  9  and stator  13  together comprise a turbine arrangement wherein the rotor  9  comprises turbine blades  30  arranged to deflect fluid pumped between the rotor  9  and stator  13  so as to convert some of the energy of the fluid into rotation of the rotor  9  and hence the reamer shoe  7 . 
         [0024]    The stator  13  comprises a fluid inlet  31  between the external stator  13  and the internal rotor  9 , at the lowermost end  4  of the casing  3 , the fluid inlet  31  being radially outwardly spaced from the axis  10 . A flow diverter  32  (shown in phantom) is provided adjacent the fluid inlet  31  and serves to divert fluid pumped down the casing  3  radially outwardly so as to flow into the fluid inlet  31 . 
         [0025]    The fluid flow path is indicated by arrows ‘A’. Having been diverted by the flow diverter, the fluid enters the inlet  31  adjacent the lowermost casing end  4 . The fluid is pumped in a direction generally parallel to the axis of rotation  10  of the rotor  9  in the void defined between the concentric rotor  9  and stator  13 , and subsequently exits the void and the turbine arrangement radially inwardly through the outlet  33  into the access bore  15 . The fluid then travels along the access bore  15  and subsequently generally radially outwardly and/or downwardly through jetting apertures (not shown) formed in the reamer shoe  7 . The fluid thus functions as a lubricant for the reamer shoe  7  before being forced up the annular void  6  between the casing  3  and the wellbore  1 . The fluid may be a drilling mud slurry comprising the drilling fluid used normally to lubricate the cutting structure. 
         [0026]    Referring additionally to  FIG. 4 , a flared portion  34  of the radially inward stator  23  of the second example apparatus described with reference to  FIG. 2 , at  21 , is locked to the interior surface of the lowermost end  4  of the liner of casing  3 . This can again be obtained using any suitable locking means. 
         [0027]    A seal  37  may be provided adjacent the flared portion  34  of the stator  23  to resist fluid leakage between the radially outward output shaft rotor  22  and the lowermost end  4  of the casing  3 . In this example the seal  37  comprises a rotating elastomeric seal, although any suitable seal could be used. The bearings, turbine arrangement and fluid flow path are otherwise similar to those described above with reference to  FIG. 3  and the apparatus described with reference to  FIG. 1 . In each example, the bearings may be lubricated by the fluid used to drive the turbine arrangement. In each example, the rotor of the motor could be integral with the output shaft or may comprise separate components connected together. Likewise the output shaft may be integral with the cutting structure or that the foregoing may comprise separate components connected together. 
         [0028]    It will be appreciated that the rotor and stator of the motor in each example described herein are spaced radially outwardly of the rotational axis  10  of the rotor so as to define the access bore which may be used for whatever purpose required. The access bore allows unobstructed access to the cutting structure through the motor. This could be to enable access for a further cutting structure such as a narrower diameter drill bit or reamer shoe, or may be to enable access for a position sensing device or any other inspection or testing device as required. 
         [0029]    The cutting structure driven by the motor could be a sacrificial cutting structure adapted to be, for example, drilled through when required. As explained in the Background section herein, in such cases wherein the cutting structure is to be sacrificed by drilling through or milling, the cutting structure may be caused to rotate when contacted by a rotating drill bit ( 17  in  FIG. 2 ) moved through the access bore ( 15  in  FIG. 2 ). Such rotation may hinder the drilling of the cutting structure. Referring to  FIG. 5 , an example apparatus will be explained that can stop unwanted rotation of the cutting structure during drill out thereof. 
         [0030]    In the present example, in order to facilitate drill out, the power output shaft, shown at  102 , having the cutting structure, shown at  106 , attached thereto by threads  107  or the like may be rotationally locked to the motor housing  101 , and thereby to the casing or liner  108  to prevent rotation of the cutting structure  106  with respect to the casing or liner  108 . In the present example, an anti-rotation clutch or lock may be included in the motor. The clutch or lock may be designed to enable free rotation during normal operations of the reaming motor, and may be engaged on demand by one of several possible methods. 
         [0031]    The clutch or lock may be engaged by applying axial force onto the topmost part of the Output Shaft  102  to shear through axial restraints, e.g., shear pins or rings  105 , allowing the clutch or lock to engage. The clutch or lock may also be engaged by increasing the fluid flow rate through the motor to increase the pressure drop in the motor until a predetermined pressure drop is reached. The pressure drop may be converted into an axial loading on the axial restraints, e.g., the shear pins or rings  105  which are sheared through to enable engagement of the clutch or lock. 
         [0032]    In both the foregoing examples when the axial restraints  105  are sheared through an axial movement of all the internal components of the motor facilitate clutch or lock engagement. In one example the clutch or lock may be a cone clutch consisting of an external female cone  103  and a matching taper internal male cone  104  each having a self-locking taper angle of between 0.1 to 10.0 degrees or more. 
         [0033]    When the cone clutch is engaged, the male cone  103 , which is integral with or coupled to the power output shaft  102  is locked into the female cone  104 . The female cone  104  may be integral with or coupled to the motor housing  101 , which is in turn locked to the liner casing string  108  at the lower end thereof by a threaded connection or any other suitable coupling. The axial locking force is equal to the load imparted by either the mechanical or hydraulic force required to shear through axial restraints  105  (e.g., shear pins or rings) this force being sufficient to resist drilling torque imparted by the drill bit ( 17  in  FIG. 2 ). Lock-up of the power output shaft  102  to the motor housing  101  also permits rotation of the cutting structure  106  directly by rotation of the casing or liner  108 . 
         [0034]    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.