Abstract:
A downhole tool includes a plurality of segments positioned on a core member. This construction is particularly suitable for sleeves, stabilizers and drill bit gage pads used in the formation of oil and gas wells. Worn or damaged segments can be replaced without the need for replacing the entire unit. The segments may include spiral vanes for directed fluid upwardly to the well head.

Description:
BACKGROUND OF INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention is related to downhole tools used in drilling oil or gas wells. Such tools include, for example, sleeves, stabilizers and drill bits. 
         [0003]    2. Description of Related Art 
         [0004]    Currently downhole tools such as sleeves, stabilizers and drill bits used for various purposes during the course of drilling an oil or gas well are formed as a single piece unit. Such an array of tools is shown in WO2009/073656 A1. The sleeves, stabilizers and drill bits typically include a plurality of spiral vanes with fluid passageways between them to allow for upward flow of drilling fluid. The pitch of the vanes is selected according to the conditions at the bottom of the well and the composition of the well bore at any given vertical or horizontal position. Various portions of the tool are subject to uneven wear which requires replacing the entire unit. Also, the pitch of the vanes once manufactured is fixed in a given unit and can not be altered to create customized fluid flow in different applications associated with a downhole tool used in forming and/or completing wells. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The invention of this application is forming downhole tools in segmented discrete portions. This allows for replacing worn portions of the tool with a new segment rather than replacing the entire unit. This saves time and materials. This also allows for the ability to adjust the flow path of the fluid around the tool by providing segments having vanes with different pitch angles and blade thicknesses. Thus the operator of the drilling rig can vary the flow characteristics depending on varying conditions within the well. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0006]      FIG. 1  is an elevation view of a tool according to an embodiment of the invention. 
           [0007]      FIG. 2  is a perspective view of the tool showing two of the segments separated. 
           [0008]      FIG. 3  is a longitudinal cross sectional view of the tool. 
       
    
    
       [0009]    The drawings are intended to illustrate the various aspects of the invention and are not intending to be limiting, nor are they necessarily drawn to scale. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    As shown in  FIGS. 1 and 2 , the sleeve or stabilizer  10  according to an embodiment of the invention includes a hollow core member  21  having an upper threaded portion  12  which is known in the art as an API connector. Threads are provided at  14  for connection to an interiorly threaded portion of a tubular member which may be the drill tube. Breaker slots  16  are also provided for gripping by an appropriate bit breaker. Also shown in  FIG. 1  is a plurality of stabilizer or sleeve segments  20 . Although four are shown it is understood that any number of segments may be provided in accordance with the invention. Each segment includes plurality of vanes  22 ,  24 ,  26  and  28  respectively. The segments are mounted on the core member which extends from top portion  12  to bottom portion  30 . The lower portion of the core member may be internally threaded as shown in  FIG. 3  to receive a connection portion of another tool such as a drill bit. Lower collar member  32  may be provided with internal threads that engage threads on the lower exterior portion of core member  21 . In lieu of threads, lower collar member  32  may be welded to core member  21 . Upper and lower collar members  18  and  32  serve as transition members between the core and the segments  20 . They may be provided with vanes  19  and  30  that line up with the vanes  22  and  28  of the adjacent segments. 
         [0011]      FIG. 2  illustrates a way to attach the segments to core  21  and to each other. For preventing rotation of the segments with respect to each other, recesses  40  may be provided the top surface of the vanes as shown in  FIG. 2 . Pins  43  shown in  FIG. 3  are adapted to fit within recesses  40  in the lower surface of an adjacent vane. To prevent rotation of the segments about core member  21 , holes  42  are formed in the passageways between the vanes and extend to the inner surface of the segments. A suitable set screw, welded pin, press weld pin, threaded pin or any other known securing means can be inserted into the hole for securing the segment to the core member  21 . It is understood that there are many other techniques and mechanisms that could be used to attach the various components to each other, all of which could be used in the context of this invention. Upper collar member  18  may be welded to core member  21  or secured to it by any well-known arrangement. 
         [0012]      FIG. 3  illustrates an arrangement of the segments and collars on the core. The core includes an upper connection portion  12  known as an API connector and a lower integral portion  21  formed as a hollow cylindrical body. Upper collar member  18  and segments  20  have an internal diameter slightly greater than the external diameter of cylindrical portion  21  of the core so that they can slide over the outer surface of core portion  21 . 
         [0013]    The exterior lower surface of core portion  21  has inwardly extending threads  46  that are adapted to fit corresponding threads  47  provided on the interior surface of lower collar  32 . The lower interior portion of core member  21  has threads  45  that are adapted to receive a standard API connector. In lieu of a threaded connection, lower collar member  32  may simply be welded to core member  21 . 
         [0014]    To assemble the sleeve or stabilizer, top collar  18  is positioned onto core member  21 . Segment members  20  are then fitted on core  21  with the pins  45  aligning with the holes  40  in adjacent segments. A set screw or pin is then inserted through holes  42  to secure the segments to the core member  21 . Finally lower collar is threaded or welded to the lower portion of the core thereby capturing the segments on the core member between the upper and lower collar members. 
         [0015]    If during use one of the segments experiences more wear than the other, the drill string can be withdrawn from the well and only the worn segment need be replaced. 
         [0016]    Also, it is contemplated that a plurality of segments with different pitch angles could be provided at the well site to allow the drill operator the flexibility to choose among several options depending on the drilling conditions. Each segment could also have a different pitch angle and blade thickness. 
         [0017]    Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.