Abstract:
The casing cutter disclosed herein is useful for severing downhole tubulars and includes a body, a cutting head, cutting blades, and actuators for operating the cutting head and cutting blades. Cutting is accomplished by rotatingly actuating the cutting head with an associated motor, and then radially extending the cutting blades away from the cutting head. In one embodiment, the cutting head includes a cutting member that pivotally extends from the cutting head upon rotation of the cutting head. In another embodiment, cutting members extend from the cutting head due to centrifugal forces associated with rotating the cutting head.

Description:
RELATED APPLICATIONS 
   This application is a divisional of and claims priority from U.S. Application having Ser. No. 11/585,447 filed Oct. 24, 2006, having issued as U.S. Pat. No. 7,478,982, the full disclosure of which is hereby incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   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. 
   2. Description of Related Art 
   Tubular members, such as 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. The device is also configured to rotationally advance the blade against the tubular and cut it from the inside. In the case of a wellbore, where at least a portion of the casing is in a vertical orientation, the cutting tool is lowered (such as by wireline, tubing, or slickline) into the casing to accomplish the cutting procedure. 
   BRIEF SUMMARY OF THE INVENTION 
   The present disclosure includes a cutting tool for cutting a tubular comprising, a drive system, a cutting head mechanically coupled to the drive system, and a cutting member pivotally mounted on the cutting head, wherein the cutting member is in mechanical communication with the drive system. 
   Also included herein is a cutting tool for severing a tubular downhole comprising, a power delivery system, a rotatable cutting head mechanically coupled with the power delivery system, and a cutting assembly disposed on the cutting head, the cutting assembly comprising a transmission and a cutting member, wherein the cutting assembly pivotally extends into a cutting position during rotation of the cutting head. 
   Yet another embodiment disclosed herein includes a tubular cutting device comprising, a power system, a cutting head, a tubular cutting system disposed on the cutting head, and a tubular cutting positioning mechanism coupled to the cutting system. 
   The present disclosure also includes a tubing cutter comprising, a body and a cutting element disposed on the body, wherein the cutting element is put into a cutting position by the centrifugal force resulting from rotation of the body. More than one cutting element may be included with the body. Also included is an optional synchronizing element coupled to the cutting element. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  illustrates a partial cut-away view of a cutting tool. 
       FIGS. 2   a  and  2   b  are partial cut-away perspective views of a cutting tool. 
       FIG. 3  demonstrates a cutting tool in a tubular. 
       FIGS. 4   a  and  4   b  are cut-away side views of an embodiment of a cutting tool. 
       FIGS. 5   a - 5   c  are perspective views of an embodiment of a cutting tool. 
       FIG. 5   d  is a bottom view of a cutting tool. 
       FIG. 5   e  is a cut-away view of a cutting tool. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The device disclosed herein is useful for cutting tubulars, including those disposed within a hydrocarbon producing wellbore. The device, referred to herein as a cutting tool, is capable of being inserted into a wellbore and of being secured therein. The cutting tool is equipped with a cutting member extendable from the body of the device for cutting a tubular wall in a radial configuration thereby severing the tubular. The cutting member can then be retracted from the cutting position and the device removed from within the tubular. 
   With reference now to  FIG. 1  one embodiment of such a cutting tool  10  is disclosed in a partial cut-away view. As shown, the cutting tool  10  comprises a body  11  formed to receive a cutting head  14  coaxially on one of its ends and a cutting system  15  coupled to the free end of the cutting head  14 . Coaxially disposed within the body  11 , and coaxially extending along the axis A X  of the cutting head  14  is a drive system  12 . The drive system  12  (also referred to herein as a power delivery system) comprises a drive shaft  24  connected on one end to a rotational motive source for rotating the drive shaft  24  and terminates approximate to the free end of the cutting head  14 . The drive system  12  however can include any device or system for delivering mechanical energy to the devices herein described. Asymmetrically disposed within the body  11  and proximate to the upper end of the cutting head  14  is an upper transmission  28 . The upper transmission comprises a first gear  30 , a second gear  32 , and a third gear  34 . The first gear  30  is disposed substantially parallel to the drive shaft  24 , corresponding gear teeth are formed along the outer circumference of the first gear  30  and drive shaft  24  for rotational cooperative mating between these two elements. Similarly, the second gear  32  is disposed substantially parallel to the first gear  30  and also has a series of gear teeth formed for mating with the gear teeth of the first gear  30 . The second gear  32  is mechanically coupled to the third gear  34  via a shaft that runs substantially coaxially between these two gears. The third gear  34  lies substantially parallel to the cutting head and is disposed adjacent the upper end of the outer circumference of the cutting head  14 . Corresponding mating gears are formed on the outer surface of the third gear  34  to mate with the gears formed on this outer surface of the upper end of the cutting head  14 . Optionally, an additional second gear  13  and third gear  34  may be included oppositely disposed within the housing  11 . In yet another embodiment, more sets of second and third gears may be built-in, wherein the sets of second and third gears are radially located within the housing  11  substantially equidistant apart. Bearings  36  may be disposed in a space defined by the outer circumference of the upper portion of the cutting head  14  and the inner circumference of the body  11 . Optionally a bulkhead  19  may be provided along a portion of the drive shaft  24 . In the embodiment shown, the bulkhead has a substantially disk like configuration with an aperture formed through its axis formed to receive the drive shaft  24 . Additionally the bulkhead  19  may serve as a structural support for the first and second gears ( 30 ,  32 ). 
   In the embodiment of  FIG. 1 , the diameter of the free end of the cutting head  14  is largely the same as the diameter of the housing  11 . The cutting head  14  diameter is reduced at its upper end so that it can be inserted into the body  11 . Additionally, a coaxial aperture is provided along the length of the cutting head  14  formed for positioning the drive shaft  24  there through. 
   The cutting system  15 , as shown, comprises a gear train  20  coupled with a lower transmission  18  and a cutting member  16 . The gear train  20  comprises an inner gear  21  shown affixed to the terminal end of the drive shaft  24 . A radial gear  23  is provided in substantially the same plane as the inner gear  21  and wherein corresponding gear teeth are formed on the outer surfaces of these two gears ( 21 ,  23 ) for mating cooperation between these two gears. The radial gear  23  is coaxially affixed to a shaft  25  shown extending into the free end of the cutting head  14 . On the opposite end of the shaft  25  the radial gear  23  is coupled with the lower transmission  18 . Although not shown herein, as its name suggests the transmission  18  comprises a series of gears for adjusting the rotational torque and velocity between the radial gear  23  and the first cutting member gear  27 . 
   On the end of the lower transmission  18  opposite where it couples with the gear train  20  is the cutting member  16  and its associated gears. More specifically a first member cutting gear  27  is shown joined to the output of the lower transmission  18 . Gearingly coupled with the first cutting member gear  27  is the second cutting member gear  29 , wherein the first and second cutting member gears ( 27 ,  29 ) lie in substantially the same plane. A post  31  is coaxially situated within the second cutting member gear  29  on which the cutting member  16  is mounted. It should be pointed out that the cutting member  16  may comprise a circular blade, a grinding disk, a milling disk, a sawing disk, or any other apparatus suitable for the cutting or severing of a tubular. 
     FIGS. 2   a  and  2   b  provide examples of how the cutting system  15  may pivot with respect to the cutting head  14 . More specifically,  FIG. 2   a  represents the configuration of the cutting tool  10 , and its associated cutting system  15 , as the tool  10  is moved in and out of a tubular. Whereas,  FIG. 2   b  portrays how the cutting system  15  might be eccentrically pivoted into a cutting position for the cutting of a tubular. Once the tool  10  is disposed within a tubular where a cut is desired the drive system  12  can be activated. Activation of the drive system  12  causes rotation of the drive shaft  24  wherein rotation of the drive shaft in turn can cause rotation of the cutting head  14  as well as rotation of the cutting member  16 . As previously discussed, the drive shaft  24  is coupled with the upper transmission  28  via gear teeth formed on their respective surfaces. Thus upon rotation of the drive shaft  24  the rotational energy is transferred from the drive shaft  24  through the upper transmission  28  via the aforementioned gear teeth. Arrows provided on  FIG. 1  serve to illustrate an example of how this rotational energy is passed from the drive shaft  24  through this upper transmission  28 . More specifically, rotation of the drive shaft  24  thereby produces corresponding rotation in the first gear  30 , that in turn through its coupling with the second gear  32  causes rotation of the second gear  32 . Because the shaft  33  couples the second gear  32  to the third gear  34 , second gear  32  rotational torque is passed onto the third gear  34  via the shaft  33 . As noted above, the corresponding teeth on the third gear  34  and the upper end of the cutting head  14  allow mechanical coupling between the third gear  34  and the cutting head  14  that when rotation of the third gear  34  occurs a corresponding rotation of the cutting head  14  will similarly occur. The inner friction of the gear train  20  causes the cutting system  15  to pivot. Thus no minimum rotational velocity of the cutting head  14  is required for the cutting system  15  to pivot out into the asymmetric alignment as illustrated in  FIG. 2   b . The cutting system  15  starts pivoting as soon as rotation begins. An end stop  22  is provided on the face of the cutting head for limiting the pivoting range of the cutting system  15 . The position of the end stop  22  can be adjusted to provide a maximum cutting angle when the cutting member  16  is engaged with a tubular. 
   The above-described drive shaft  24  rotation similarly rotates the cutting member  16  through the mechanical coupling provided by the gear train  20  and its associated lower transmission  18 . In more detail, the inner gear  21  of the gear train  20  that is affixed to the drive shaft  24  rotates due to rotation of the drive shaft  24 . Rotation of the inner gear  21  in turn produces corresponding rotation of the radial gear  23 . Since the radial gear  23  is mechanically attached to the lower transmission  18 , it imparts a rotational force into the inlet of the lower transmission  18 . Similarly the first and second cutting member gears ( 27 ,  29 ), that are disposed at the outlet of the lower transmission  18 , receive the rotational torque delivered by the lower transmission  18 . The first and second cutting member gears ( 27 ,  29 ) transfer the rotational torque output of the lower transmission  18  onto the cutting member  16 . 
   With reference now to  FIG. 3  an illustration is provided demonstrating use of an embodiment of the cutting tool  10  for cutting a tubular. In the example of  FIG. 3 , the tubular is a wellbore casing  5 . It should be pointed out that the motive force used to provide rotation of the drive shaft  24  is a motor  26 . The motor  26  can be electric, hydraulic, or driven by any now known or later developed means. Moreover the tool  10  is shown disposed within a wellbore via wireline  7  and is anchored within the casing by an anchor system  38 . The anchor system  38  is not limited to a mechanical linkage system like that shown, but can also include other anchoring systems such as those hydraulically actuated in the form of a packer. 
   With reference now to  FIGS. 4   a  and  4   b  another embodiment of a cutting tool  10   a  is provided in a cross-sectional view. The tool  10   a  of  FIGS. 4   a  and  4   b  is comprised of a cutting head  14   a  rotationally coupled on one end of a body  11   a . Disposed on the free end of the cutting head  14   a  is a cutting assembly  50 . In this embodiment the drive system comprises a flexible shaft  56  coupled to a cutting member  16   a  and a shaft  60  in mechanical cooperation with the cutting head  14   a . More specifically the shaft  60  extends through the body  11   a  and parallel to the cutting head  14   a  wherein a pinion gear  62  is formed on the lower end of the shaft  60 . The pinion gear  62  with its mating teeth is formed to cooperatively mate with similar gear teeth fashioned on an inner circumference of the cutting head  14   a . The shaft  60  and pinion gear  62  make up the cutting head transmission assembly  58 . Also as shown is a sleeve  68  provided around the flexible shaft  56  extending along a portion of the shaft  56 . The sleeve  68  extends from within the housing  11   a  and terminates on its lower end within the upper section of the cutting head  14   a . Disposed along the lower end of the sleeve  68  is the pivoting transmission  70 . The pivoting transmission  70  is comprised of a pinion gear  72  disposed substantially parallel to the sleeve  68 , wherein the pinion gear  72  has corresponding mating teeth formed on its outer circumference. These teeth of the pinion gear  72  are made to mesh with similar gears formed on the outer surface of the sleeve  68 . Coaxially formed with the pinion gear  72  is a shaft  74  that extends further into the cutting head  14   a  and terminates at a pivoting mechanism  40 . The pivoting mechanism  40  comprises a worm gear  42 , a bevel/worm gear  44 , and a helical gear  46  disposed on a shaft  48 . The worm gear is affixed on the lower most end of the shaft  74  and is mated with the bevel/worm gear  44  via gear teeth formed on their respective outer surfaces. The bevel/worm gear  44  is disposed substantially perpendicular to the axis of the cutting tool  10   a  and is gearingly coupled on its other end with a helical gear  46 . The shaft  48  extends from the helical gear  46  within the cutting head  14   a  (substantially parallel with the axis of the cutting tool  10   a ) and on its lower most end where it is affixed to the cutting assembly  50 . Optionally a bolt  54  may be provided on the lower most end of the flexible shaft  56  configured to mate with the threads on the end of the shaft  56  to secure the cutting member  16   a  on the shaft  56 . The flexible shaft  56  and the shaft  60  can be driven by a single motor, or each have their own dedicated motors or other means of rotational motivation. 
   In operation of the embodiment of the cutting tool  10   a  provided in  FIGS. 4   a  and  4   b , the cutting assembly  50  can be taken from the non-cutting position, i.e., substantially aligned with the cutting head  14   a  and/or body  11   a  into a cutting position wherein the outer edges of the cutting member  16   a  are put into cutting contact with a tubular. Pivoting or rotating the cutting assembly  50  can occur simultaneously with rotation of the cutting head  14   a . The pivoting action is accomplished via providing rotational torque to the pivoting transmission  70 . The sleeve  68  is coupled with the flex shaft  56 , thereby rotation of the flex shaft  56  will impart a rotational torque onto the sleeve  68 . Since the pinion gear  72  is gearingly coupled with the outer surface of the sleeve  68 , rotation of the flex shaft  56  necessarily causes rotation of the pinion gear  72 . As previously discussed, the shaft  74  is coaxially affixed to the pinion gear  72 , such that any rotation of the pinion gear  72  necessarily rotates the shaft  74 . As the shaft  74  rotates it rotates the worm gear  42  that then puts a rotational torque on the bevel/worm gear  44 . Rotating the bevel/worm gear  44  rotates the helical gear  46  that causes rotation of the shaft  48  and thereby pivoting the cutting assembly  50  out of the coaxial position and into a symmetric position for cutting a tubular. Arrows are provided on  FIG. 4   b  illustrate how forces are transferred from the flexible shaft  56  for pivoting the cutting assembly  50 . As shown in  FIG. 4   a , the flex shaft can bend along its length thereby accommodating this pivoting action of the cutting assembly  50 . Coupling the flex shaft with the cutting member  16   a  results in rotation of the cutting member  16   a  upon rotation of the flex shaft  56 . 
   Imparting a rotational torque onto the shaft  60  in turn rotates the pinion gear  62  to produce cutting head rotation; mating gears on the inner circumference of the cutting head  14   a  transmit force for rotating the cutting head  14   a . Thus rotational torque applied to both the flex shaft  56  in conjunction with the shaft  60  can take the cutting assembly  50  of  FIGS. 4   a  and  4   b  into cutting engagement with a tubular and impart a radial cut onto a tubular engaged by this cutting tool  10   a . Bearings  64  are shown disposed in a cavity formed at a portion of the interface between the cutting head  14   a  and the body  11   a . In one embodiment, monitoring the revolutions of the cutting head controls the pivoting angle of the cutting assembly  50 . Recording cutting head revolutions enables calculating the cutting head  14  position. 
     FIGS. 5   a  through  5   e  provide yet another embodiment of a cutting tool  10   b  in accordance with the description provided herein. With respect now to  FIGS. 5   a  through  5   c , an embodiment of a cutting tool  10   b  is provided comprising a housing  11   b  with a rotating cutting head  14   b  disposed one end of the body  11   b . On the cutting head  14   b  is shown a cutting member  16   b . The cutting member  16   b  of this embodiment comprises cutting elements  78 , wherein the cutting elements lie substantially in a plane that is perpendicular to the axis of the cutting tool  10   b . The cutting members as shown are disposed on the face of the cutting head  14   b  at a radial distance away from the cutting head axis. The cutting elements  78  are pivotingly attached to the cutting head  14   b , this pivoting capability is illustrated in  FIGS. 5   a  through  5   c.    
   With specific regard now to  FIG. 5   a , the cutting elements  78  are shown in a fully retracted configuration where the outer surface of the cutting elements  78  do not extend outside the outer radius of the cutting head  14   b . The pivoting action is sequentially demonstrated in  FIGS. 5   a  and  5   c , i.e.  FIG. 5   a  shows fully retracted elements  78 ,  FIG. 5   b  has partially extended elements  78 , and  FIG. 5   c  demonstrates fully extended elements  78 . With regard now to  FIG. 5   b , the cutting elements  78  are extending just past the outer radius of the cutting head  14   b  on their pivoting attachment and  FIG. 5   c  illustrates a fully extended cutting element  78  wherein the outer diameter of the cutting elements is substantially at their maximum point. 
   A bottom view of the tool  10   a  at the face of the cutting head  14   b  is provided in  FIG. 5   d . Also shown is an optional synchronizing member  80  that is in synchronizing contact with both of the cutting members  78 . It should be pointed out however that while these figures provide two cutting elements  78 , one cutting element, or more than two cutting elements, could be used with the embodiments of these figures. The synchronizing member  80  optionally could be fitted with a series of gear teeth formed for mating cooperation with the outer surface of the cutting elements  78 . The presence of the synchronizing member  80  serves to ensure that the cutting elements  78  pivot from their retracted position of  FIG. 5   a  and advance outward into their fully extended position as shown in  FIG. 5   c  at substantially the same rate of extension. Controlling the rate of extension of the cutting elements  78  is accomplished by virtue of their synonymous coupling with the synchronizing member  80 . 
   With reference now to  FIG. 5   e  a cut away view of an embodiment of the cutting tool  10   b  is provided. This depiction illustrates that the body  11   b  is formed to coaxially receive the cutting head  14   b  along one of its ends. Bearings  82  can be provided in the space between the outer surface of the cutting head  14   b  and the inner circumference of the housing  11   b  to facilitate rotation of the cutting head  14   b  with respect to the body  11   b  thereby minimizing any rotational friction there between. In this embodiment, the cutting elements  78  are shown in their maximum extended position. Moreover corresponding teeth  84  are provided for illustration to demonstrate how one example of the synchronizing effect between each cutting element  78  and the synchronizing member  80 . Substantially cylindrical recesses are provided for receiving the shaft portion ( 79 ,  81 ) of each cutting element  78  as well as the synchronizing member  80 . 
   Operation of the embodiments shown in  FIGS. 5   a  through  5   b  is accomplished by providing rotational torque to the cutting head  14   b . This rotational torque, via centrifugal force of the cutting elements, outwardly pivots the cutting elements  78  into cutting engagement with a tubular member. The outer surface  83  of the cutting elements  78  can be formed in the angular fashion as shown to provide a lower frictional cut for enhancing the cutting of the tubulars. The arrow provided in  FIG. 5   d  is one example of rotational torque direction that could be imparted onto the cutting head for the cutting head of a tubular. The outer surface  83  of the cutting elements  78  can be formed into a beveled shape having a blade like configuration for cutting, and optionally can have other abrasive surfaces for grinding, cutting, sawing, and/or milling a tubular. 
   The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the device is not limited to being wireline conveyed, but can be suspended by any known means, such as tubing, coiled tubing, or slickline as well as any later developed means. Additionally, the device can be used in conjunction with downhole drilling or other boring operations. Moreover, it should be pointed out that the force and/or torque transmission systems heretofore described are not limited to the embodiments described, but can also include belt systems, pulleys, linkages, and any other manner of transferring kinetic (rotational, translational, or otherwise) energy from one member to another. 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 invention disclosed herein and the scope of the appended claims.