Abstract:
A milling assembly can be delivered downhole on wireline. Once at the desired location, a processor extends centralizing and driving wheels to initially position the assembly. The assembly has a cutter end with one or more mills or cutters that can be selectively radially extended. The entire cutter end can be rotated in an arcuate manner over a predetermined range. One or more cutter can be extended at a time and driven. The wheels are driven either in an uphole or downhole direction at the same time the arcuate motion can take place. Using a processor, different shapes in a surrounding tubular can be made such as windows for laterals, a plurality of openings for production or interior locator surfaces to properly position subsequent equipment with respect to openings already made by the device.

Description:
FIELD OF THE INVENTION 
   The field of the invention is mills for tubulars downhole and more particularly wireline run mills that can produce windows or other openings of desired shape and location in the tubular. 
   BACKGROUND OF THE INVENTION 
   Conventional ways to make outlets in tubulars, commonly referred to as windows, involve setting a diverter, known as a whipstock, and properly supporting and orienting it. The whipstock can also be run attached to a bottom hole assembly that can include one or more mills and orientation equipment for the whipstock and even an anchor for the whipstock that can be set when the desired orientation is obtained for the whipstock. Milling windows incorporates possibilities that something could go different from plan. Mills can bore into the whipstock instead of being urged along its ramped surface until the casing wall is penetrated and an exit is made. Mills can become dull or make too early an exit that can result in the window being too short. The mills can become dull during the window forming procedure or the anchor for the whipstock can prematurely release. Typically windows made by the whipstock need to be very long because ramp angles on the whipstock are very small, in the order of about three degrees or less to avoid bogging down the widow mill with extreme lateral forces to get it to go through the wall. Windows are also made in stages with sequential mills that in series make the window wider than the previous mill. Using such systems of ever larger mills requires the system to withstand bending moments as progressively larger mills get onto the whipstock ramp and start widening the already started window. At times, the stress levels become excessive and connection failures are known to occur between mills. 
   Openings in tubulars are needed for other purposes such as normal production from the surrounding formation. Many times that is accomplished with perforating guns. The problems with perforating guns are the safety concerns of handling explosives and the potential for formation damage from shooting off the guns as well as other subsidiary issues of proper placement and support for the guns and retrieval after they are shot off. 
   While guns can be run in wireline for fast delivery to the desired location, assuming that the well is not too deviated, milling assemblies are run in on a tubular string that is either rotated from the surface or includes a downhole mud motor to rotate the mills. 
   The present invention takes a fresh approach to providing openings in tubulars that avoids many of the issues discussed above. In the preferred embodiment, an assembly is delivered on wireline for rapid deployment into the wellbore. The assembly comprises a processor which can selectively actuate a combination guiding and anchoring system that allows the assembly to be initially positioned in the desired spot and moved longitudinally to fashion any shape of opening or openings desired in a predetermined location or locations. One or more cutters can be extended for milling and the cutters can be moved in a predetermined arc while the assembly is moved uphole or downhole. Spare cutters are envisioned to allow a specific job to be finished without bit change or/and to allow the job to be completed faster. The rate of uphole or downhole movement can be controlled. The assembly can even make locating grooves for proper positioning of subsequent equipment after the desired opening or openings are made. These and other advantages of the present invention will be more apparent to those skilled in the art from a review of the drawings and description associated with the preferred embodiment while recognizing that the full scope of the invention is in the associated claims. 
   SUMMARY OF THE INVENTION 
   A milling assembly can be delivered downhole on wireline. Once at the desired location, a processor extends centralizing and driving wheels to initially position the assembly. The assembly has a cutter end with one or more mills or cutters that can be selectively radially extended. The entire cutter end can be rotated in an arcuate manner over a predetermined range. One or more cutter can be extended at a time and driven. The wheels are driven either in an uphole or downhole direction at the same time the arcuate motion can take place. Using a processor, different shapes in a surrounding tubular can be made such as windows for laterals, a plurality of openings for production or interior locator surfaces to properly position subsequent equipment with respect to openings already made by the device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective of a twin cutter assembly with one cutter extended; and 
       FIG. 2  is a close up view of the downhole end of the tool from  FIG. 1  with the other cutter extended. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a body or main housing  10  that is preferably supported by a wireline  12  to power a processor  30  and other equipment, as will be described below. The body  10  has a set up uphole wheels  16  and downhole wheels  18 . Preferably each wheel set comprises three wheels at 120 degree spacing but other arrangements are possible. Instead of wheels other types of devices that can selectively contact the surrounding tubular, shown schematically as  20  are also envisioned. One example is tracks instead of retractable and driven wheels that are shown. It is preferred that all the wheels be retractable for quick run in and when in the proper location downhole that they are extendable to engage the tubular  20  to not only centralize the housing  10  with respect to tubular  20  but also to allow the housing  10  to be driven uphole or downhole with respect to the tubular  20 . 
   Housing  10  has a rotating component  22  that can be turned with respect to housing  10  when wheels  16  and  18  are extended. This occurs by the turning of a sun gear  24  around a planetary gear  26  (shown only in part and schematically). Thus the rotating component  22  while being coaxial with housing  10  can rotate about its common longitudinal axis with housing  10 . A motor  28  controlled by processor  30  can selectively turn the housing  22  clockwise or counterclockwise. 
   Housing  22  is illustrated with cutters or mills  32  and  34 . Although two mills are shown, one or more mills can be incorporated into the design. The terms cuter, mill, drill or bit and other synonymous terms are intended to be interchangeable for the purposes of this description. The mills  32  or  34  are selectively extended radially by ramps  36  or  38  by virtue of motors  40  or  42  attached to them for translating them. Thus, when raised surface  44  is under cutter  34  the cutter  34  is extended up to a maximum extension shown in  FIG. 2 . The amount of radial extension is controlled by processor  30  regulating motor  42  so that the amount of radial extension can be held constant at a given value or varied with time as the milling progresses at a speed that is dependent on either predetermined patterns or in real time depending on the actual milling progress being made or the resistance experienced by an extended cutter. The ramp assemblies  36  and  38  are mounted to the housing  22  and rotate with it. Similarly, driven shafts  46  and  48  are also supported by the housing  22  and rotate with it. Bevel gears  50  and  52  are mounted respectively on shafts  46  and  48  and they each engage driven gear  54  that is secured to mill  34 . Gear  54  is mounted to housing  22  to move radially when mill  34  is extended by longitudinal movement of ramp assembly  38 , for example. Housing  22  supports gear  54  through a slot (not shown) in ramp assembly  38  so as to allow translation of ramp  38  in opposed longitudinal directions to force mill  34  out or to allow it to back up in the opposed direction, such as for run in or pulling out of the hole. Ramp assembly  38  can be driven in opposed directions by a threaded shaft  56  and the same assembly can be applied to ramp assembly  36 . The shaft such as  56  can act to change the position of either mill between the maximum extended position of either of the mills  32  or  34  and the fully retracted position. Alternatively, motors  40  or  42  can be stepper motors to advance or withdraw an associated ramp in predetermined increments so that the gear  54  and associated mill  34  can be extended or allowed to retract a predetermined amount along ramp  58 , for example. In the preferred embodiment, identical operation is envisioned for mill  32  that is connected to driven bevel gear  60 , which rides on ramp surface  62 . Bevel gears  64  and  66  mounted to shafts  46  and  48  respectively, drive gear  60 . At the uphole end of shafts  44  and  46  are bevel gears  64  and  66  which mesh with gear  68  connected to shaft  70 . Shaft  70  has a gear  72  near its uphole end that is driven by gears  74  and  76  that are respectively driven by motors  78  and  80  that are also controlled by processor  30 . 
   In operation, the tool is run in the hole with the wheels  16  and  18  retracted so that delivery can be accomplished in the shortest time. The processor  30  has features to determine the orientation of the mills  32  and  34  much in the way an MWD tool determines the orientation of a whipstock downhole before it is anchored. Mills  32  and  34  are also retracted for run in and do not turn for run in. When the proper depth is determined using known techniques, the wheels  16  and  18  are extended to centralize the tool in the tubular  20  as well as to get traction for driving the tool uphole and downhole as determined by processor  30 . If a window is to be milled, it can be produced from downhole moving up or from uphole going down or even from opposed ends toward a middle of the window. A single mill, such as  34 , can be extended, as shown in  FIG. 2 . This is done through processor  30  commanding the motor  42  to drive ramp assembly  38  so that ramp  58  can push out gear  54  to extend mill  34 . Processor  30  then can operate motors  78  and  80  to ultimately drive gears  50  and  52  in the manner described before to get mill  34  turning. At this time mill  32  may also be rotating but it is not extended. Processor  30  has the capacity to operate with more than on mill extended at a time. Thus, for example, if a random or ordered hole pattern is required, as a way of avoiding having to perforate, more than one mill can be extended for making round holes. In the embodiment illustrated the rotation of component  22  rotates both mills  32  and  34  a like amount forcing them to be longitudinally aligned at all times. However, a separate drive for each mill is contemplated. Those skilled in the art will appreciate that one portion of housing  22  will need to be rotatable with respect to another and the driving systems from motors  78  and  80  will need to be independently operated. If this is done, even an oblong window can be milled with two mills operating making two different shapes of a typical window at the same time which in the end results in a single window made to the preprogrammed shape specification. As previously stated one mill can simply be a backup for the other mill so that a given opening can be finished if one mill gets dull or breaks without having to trip out of the hole. By preprogrammed regulation of the driving rate for the wheels  16  or/and  18  and the movement of motor  28  that controls the left to right movement of either or both mills  34  or/and  32  while coupled with associated ramp control for mill extension by controlling the associated motor  40  and/or  42  any shaped opening can be produced in any tubular regardless of its wall thickness. 
   The tool of the present invention can perforate a tubular in an ordered or random pattern, to avoid having to use a perforating gun that can have adverse effects on the formation. It can also be used to make a window in the shame shape as a multi-mill bottom hole assembly currently makes it when used in conjunction with a whipstock. For example the window can be wider at the top to approximate the diameter of the largest mill being used while becoming more slender at the bottom to approximate what happens when the mills make a departure from the whipstock ramp. Alternatively, a totally different window shape can be made. Rather than going clean through the tubular wall, only some material can be removed from its inside wall leaving a thinner wall to be penetrated by a milling bottom hole assembly in conjunction with a whipstock. Independently, the tool of the present invention can strategically produce radial grooves in the inner wall of the tubular to act as locators for packers or other downhole tools that need to be positioned with respect to the hole or holes just produced. 
   Other features can be provided that have been left off the drawings for greater clarity of the operation of the milling equipment. Passages can be incorporated though the housing  10  or external grooves that will allow flow with cuttings to be circulated or reverse circulated. A downhole pump can aid in such fluid movements. Alternatively the housing  22  can accept and trap cuttings in a screen basket as long as the rotating components are suitably isolated from the captured cuttings. This method is schematically illustrated as  90 . Such cuttings can be retained with magnets or baskets mounted in housing  22 . While the tool is preferably run in on wireline  12  it can also be delivered on coiled tubing or jointed tubing, either of which will greatly facilitate circulation or reverse circulation for the purpose of capturing cuttings. 
   While longitudinally shifting ramp assemblies  36  and  38  are illustrated, those skilled in the art will appreciate that other equivalent techniques for extending and retracting the mills  32  and  34  can be used. These mills can be operated in tandem or have totally separate controls so that one mill can either back up the other one if there is a problem or both mills can work on a hole or hole pattern at the same time to expedite the job. While two mills are illustrated fewer or additional mills can be used either as backups or at the same time to shorten the operation. 
   The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.