Abstract:
A disconnect apparatus and method for use in a well bore. The apparatus comprises a top sub having a collet, and wherein the top sub has an external seal surface. The apparatus further comprises a bottom sub having a bore, and wherein the external seal surface and the bore cooperate. The apparatus further includes a support piston disposed within the collet, wherein the support piston has a plurality of fins formed on an outer portion of the support piston, and shear device, operatively attached to the top sub and the support piston, for attaching and detaching the top sub from the support piston. In one preferred embodiment, the collet member comprises a plurality of fingers having a gap between each individual finger. Also, the plurality of fingers may have an external thread formed thereon that engage an internal thread formed on the bottom sub.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to an apparatus for disconnecting. More specifically, but without limitation, this invention relates to an apparatus and method for disconnecting a work string from an assembly in a well bore. 
         [0002]    In the course of drilling and producing hydrocarbons from wells, an operator will perform various well operations. The purpose of the operation may vary, but includes drilling, completing, producing, working over, abandonment, etc. Due to many different reasons, a work string that is concentrically disposed within the well bore may need to be withdraw. As well understood by those of ordinary skill in the art, operators may elect to have a portion of the work string, such as a bottom hole assembly, remain in the well bore. In order to withdraw the work string, disconnect devices have been developed. 
         [0003]    Prior art disconnect devices allow for the detachment so that the work string is pulled out of the well bore, but some portion, such as the bottom hole assembly, is left in the well. Prior art devices suffer from many problems including but not limited to complexity of design, unreliable disengagement, and expensive manufacturing cost. The present invention solves these problems, and many others, as will be further described. 
       SUMMARY OF INVENTION 
       [0004]    A disconnect apparatus for use in a well bore is disclosed. The apparatus comprises a top sub having a collet member disposed thereon, and wherein the collet member extends to an engagement end, and wherein the top sub has an external seal surface. The apparatus further comprises a bottom sub having an internal bore, and wherein the external seal surface and the internal bore cooperate. The apparatus further includes a support piston disposed within the collet member, wherein the support piston contains a plurality of fins formed on an outer portion of the support piston, and shear means, operatively attached to the top sub and the support piston, for attaching and detaching the top sub from the support piston. 
         [0005]    In one preferred embodiment, the collet member comprises a plurality of fingers having a gap between each individual finger and wherein each of the fins are configured to fit within each of the gaps of each of the fingers. Also, the plurality of fingers may have an external thread member formed thereon, and wherein the external thread member will engage an internal thread formed within the internal bore of the bottom sub. Additionally, the shear means may include an aperture in the collet member and a groove formed within the support piston. In the most preferred embodiment, the shear means further includes a set of shear pins that will shear at a predetermined force. 
         [0006]    The apparatus may further comprise a ball member operatively associated with a ball seat formed within the support piston. In one embodiment, the top sub is attached to a coiled tubing within the well bore. In another embodiment, the top sub is attached to a drill string within the well bore. 
         [0007]    A method of disconnecting from a bottom hole assembly within a well bore is also disclosed. The method comprises providing a disconnect apparatus within the well bore, the disconnect apparatus being attached to the bottom hole assembly, the disconnect apparatus comprising: a top sub having a collet disposed thereon, and wherein the collet member extends to an engagement end, and wherein the top sub has an external seal surface; a bottom sub having an internal bore, and wherein the external seal surface and the internal bore cooperate; a support piston disposed within the collet, the support piston having formed on an outer portion a plurality of fins; an aperture in the collet and a groove formed within the support piston, and a shear pin set through the aperture and disposed within the groove so that the shear pin attaches the top sub to the support piston. 
         [0008]    The method further includes placing a ball within the internal portion of the support piston, applying a pressure into the internal portion of the support piston, and shearing the pin that attached the top sub to the support piston. The method further comprises pumping the support piston into the inner bore of bottom sub, freeing the collet from the support piston, contracting the collet so that the collet no longer engages the internal thread means. The method further comprises exerting an upward pull force on the top sub so that the top sub is disconnected from the bottom sub. In one preferred embodiment, the collet comprises a plurality of fingers and the step of contracting the collet includes collapsing each finger. 
         [0009]    In the most preferred embodiment, the shear pin is designed to shear at a predetermined shear force, and wherein the step of applying a pressure comprises exerting a predetermined hydraulic pressure, and wherein the step of shearing the pin includes shearing the pin at the predetermined pressure. 
         [0010]    An advantage of the present invention is that the design allows for the apparatus to have a significant tension strength. Another advantage is that the apparatus has a minimum of parts that require movement and cooperation in order to disengage. Yet another advantage is that the apparatus can be used with rotating strings, such as drill strings. Another advantage is that the apparatus can be used with non-rotating strings such as coiled tubing. 
         [0011]    A feature of the present invention is that the collet can expand and contract. Another feature is that the collet has external thread means formed thereon. Yet another feature is that the collet comprises fingers, and wherein the fingers provide for a gap. Another feature is that the fins on the support piston are configured to fit into the gap. Still yet another feature is the ball and ball seat means allow for hydraulic activation of the disconnect mechanism. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1A  is a cross-sectional view of the top sub of the preferred embodiment. 
           [0013]      FIG. 1B  is a cross-sectional view of the top sub taken from line B-B of  FIG. 1A . 
           [0014]      FIG. 1C  is a cross-sectional view of the top sub taken from line A-A of  FIG. 1A . 
           [0015]      FIG. 2  is a cross-sectional view of the bottom sub of the preferred embodiment. 
           [0016]      FIG. 3A  is a side view of the support piston of the preferred embodiment. 
           [0017]      FIG. 3B  is a cross-sectional view the support piston seen in  FIG. 3A . 
           [0018]      FIG. 3C  is a cross-sectional view of the support piston taken from line C-C of  FIG. 3A . 
           [0019]      FIG. 3D  is a cross-sectional view of the support piston taken from line D-D of  FIG. 3A . 
           [0020]      FIG. 4A  is a cross-sectional view of the preferred embodiment of the assembled apparatus of the present invention. 
           [0021]      FIG. 4B  is a cross-sectional view of the assembled apparatus taken from line E-E 
           [0022]      FIG. 4C  is a cross-sectional view of the assembled apparatus taken from line F-F of  FIG. 4A . 
           [0023]      FIG. 5  is a cross-sectional view of the assembled apparatus seen in  FIG. 4A  with the ball seated in the ball seat. 
           [0024]      FIG. 6  is a sequential view of the assembled apparatus seen in  FIG. 5  with the support piston in an intermediate position. 
           [0025]      FIG. 7  is a sequential view of the apparatus seen in  FIG. 6  with the support piston in fully released position. 
           [0026]      FIG. 8A  is a sequential view of the apparatus seen in  FIG. 7  with the collet thread means being disengaged. 
           [0027]      FIG. 8B  is a cross-sectional view of the apparatus taken from line C-C of  FIG. 8A . 
           [0028]      FIG. 9  is a sequential view of the apparatus seen in  FIG. 8A  with the top sub being removed from the well bore. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIG. 1A  is a cross-sectional view of the top sub  2  of the preferred embodiment. The top sub  2  has a first outer cylindrical surface  4  that extends to a second outer cylindrical surface  6 , which in turn extends to the circumferential groove  8 . The second outer cylindrical surface  6  extends to the collet member, seen generally at  10 . The collet member  10  has a plurality of fingers.  FIG. 1A  depicts the fingers  12 ,  14 . The fingers extend to an engagement end; more specifically, the finger  12  extends to the engagement end  16  and the finger  14  extends to the engagement end  18 . The engagement end  16  contains an aperture  20  and the engagement end  18  contains an aperture  22 , and wherein apertures  20 ,  22  will contain shear pins as will be more fully explained later in the application. 
         [0030]      FIG. 1A  also depicts the external thread means formed on the outer portion of the collet member  10 ; more specifically,  FIG. 1A  shows the external thread profile  24  on finger  12  and the external thread profile  26  on finger  14 .  FIG. 1A  also depicts a gap that exist between each finger; for instance, the gap “G” between the finger  12  and finger  14 . Extending radially inward, the inner bore  28  of the top sub  2  is also shown. 
         [0031]    Referring now to  FIG. 1B , a cross-sectional view of the top sub  2  taken from line B-B of  FIG. 1A  will now be described. This view depicts the fingers  12 ,  14  as well as the fingers  30 ,  32 . The inner bore  28  is also depicted.  FIG. 1C  is a cross-sectional view of the top sub  2  taken from line A-A of  FIG. 1A .  FIG. 1C  depicts the engagement end  16  and aperture  20 , engagement end  18  and aperture  22 , engagement end  34  and aperture  36 , and engagement end  38  and aperture  40 . Note that engagement end  34  extends from finger  30  and engagement end  38  extends from finger  32 . 
         [0032]    Referring now to  FIG. 2 , a cross-sectional view of the bottom sub  46  of the preferred embodiment will now be described. It should be noted that like numbers appearing in the various figures refer to like components. The bottom sub  46  contains an outer surface  48  that has a first radial end  50  and a second threaded end  52 . Extending radially inward is the first inner bore  54  that extend to the internal thread means  56  which in turn terminates at the chamferred shoulder  58 . Extending from the chamferred shoulder  58  is the second inner bore  60  that terminates at the radial shoulder  62 . The third inner bore  64  extends from the radial shoulder  62 . 
         [0033]      FIG. 3A  is a side view of the support piston  68  of the preferred embodiment. The support piston  68  is a generally cylindrical member that has a plurality of fins situated about the cylindrical member, such as fins  70 ,  72 ,  74 .  FIG. 3A  also depicts the circular grooves  76 ,  78 , and wherein the grooves  76 ,  78  will receive the shear pins as will be fully set out later in the application. The outer surface  80 , which contains circular grooves  76 ,  78 , extends to the outer surface  82 , and wherein the outer surface  82  contains a circumferential groove  84 , and wherein the groove  84  will contain a seal means such as an o-ring. 
         [0034]      FIG. 3B  depicts a cross-sectional view of the support piston  68  seen in  FIG. 3A . The outer surface  86  of fin  70  and the outer surface  88  of fin  74  are shown.  FIG. 3B  illustrates the inner bore  90  that extends to the chamferred surface  92 , and wherein the chamferred surface  92  is also referred to as the ball seat  92 .  FIG. 3B  also depicts the radial end surface  93 . Referring now to  FIG. 3C , a cross-sectional view of the support piston  68  taken from line C-C of  FIG. 3A .  FIG. 3C  depicts the fin  94  along with fins  70 ,  72 ,  74 . The outer surface  80  and the inner bore  90  is also shown. In  FIG. 3D , a cross-sectional view of the support piston  68  taken from line D-D of  FIG. 3A  depicts the circular grooves  76 ,  78  along with the circular grooves  96 ,  98  for receiving shear pins. The fins  70 ,  72 ,  74 ,  94  and the inner bore  90  are also shown. 
         [0035]    Referring now to  FIG. 4A , a cross-sectional view of the preferred embodiment of the assembled apparatus  99  of the present invention will now described.  FIG. 4A  depicts the top sub  2 , with the support piston  68  being disposed within the second inner bore  60 . Additionally, outer surface  80  will have an engagement end (i.e.  16 ,  18 ) disposed therein. In the position shown in  FIG. 4A , the external thread means  24 ,  26  are engaged with the internal thread means  56 . Hence, the threaded end  52  can be connected to a bottom hole assembly such as a drilling assembly (not shown in this view) and the thread means  100  can be threadly attached to a work string such as a drill string (not shown in this view), so that the drill string is connected to the bottom hole assembly. Note how the engagement ends (i.e.  16 ,  18 ) are attached to the support piston  68 . 
         [0036]    Referring to  FIG. 4B , which is a cross-sectional view of the assembled apparatus taken from line E-E, the fins  70 ,  72 ,  74 ,  94  are placed within the gaps between fingers  12 ,  14 ,  30 ,  32 . The fins  70 ,  72 ,  74 ,  94  act to support and keep the fingers  12 ,  14 ,  30 ,  32  separated, which in turn keeps the threads on the outer portion of the fingers engaged with the internal threads of the bottom sub  46 . 
         [0037]      FIG. 4C , which is a cross-sectional view of the assembled apparatus taken from line F-F of  FIG. 4A , depicts the shear pin  104  operatively associated with the aperture  22  and groove  98 ; the shear pin  106  operatively associated with the aperture  40  and groove  76 ; the shear pin  108  operatively associated with the aperture  20  and the groove  96 ; and the shear pin  112  operatively associated with the aperture  36  and the groove  78 . The shear pins  104 ,  106 ,  108 ,  112  hold the support piston  68  in place relative to the bottom sub  46  and top sub  2 . The shear pins will shear at a predetermined shear force, and wherein the shear force will be applied via a hydraulic force as will be more fully described. 
         [0038]    Referring now to  FIG. 5 , a cross-sectional view of the assembled apparatus  99  seen in  FIG. 4A  with the ball  116  seated in the ball seat  92  will now be described. The ball  116  has been dropped through the work string and through the inner bore  90  of support piston  68 . The operator will then begin increasing the hydraulic pressure within the work string so that the pressure within the apparatus begins to increase. The ball  116  cooperates with the ball seat  92  and creates a seal, and therefore, all pressure within the internal portion of the work string (which includes the apparatus) will be subjected to this pressure. The support piston  68  will be urged downward by the force acting on the ball  116 . Once a predetermined amount of force is reached, the shear pins will shear, as those of ordinary skill in the art will recognize. 
         [0039]      FIG. 6  is a sequential view of the assembled apparatus seen in  FIG. 5  with the support piston  68  in an intermediate position. As noted earlier, the shear pins are set to shear at a predetermined force. Hence, once the pressure rises to a certain level, the shear pins sheared, and the support piston  68  will begin traveling in a direction away from the fingers  12 ,  14 , as seen in  FIG. 6 . Note that in  FIG. 6 , the thread profiles  24 ,  26  are still engaged with the internal thread means  56 . 
         [0040]      FIG. 7  is a sequential view of the apparatus seen in  FIG. 6  with the support piston  68  in the fully released position. As understood by those of ordinary skill in the art, the continued application of pressure causes the support piston  68  travel to the position seen in  FIG. 7 , wherein the radial end surface  93  abuts radial shoulder  62 . Additionally, the continued application of pressure will cause the fingers of the collet member (fingers  12 ,  14  are shown) to begin to contract since the pressure will act in between the external threads (i.e. threads  24 ,  26 ) and internal threads  56 . This contraction of the fingers will disengage the external threads on the fingers (i.e. threads  24 ,  26 ) from the internal threads  56 . 
         [0041]    Referring now to  FIG. 8A , a sequential view of the apparatus seen in  FIG. 7  with the collet thread means (i.e. threads  24 ,  26 ) being disengaged from internal threads  56  is shown. Also, the top sub  2  is being lifted and separated from the bottom sub  46 . The support piston  68  will stay positioned within the bottom sub  46 . In  FIG. 8B , which is a cross-sectional view of the apparatus taken from line C-C of  FIG. 8A , the external threads of the collet (i.e.  24 ,  26 ) have separated from the internal threads  56 , and the collet fingers  12 ,  14 ,  30 ,  32  have contracted thereby allowing for the removal of the top sub  2 . 
         [0042]      FIG. 9  is a sequential view of the apparatus seen in  FIG. 8A  with the top sub  2  being removed from the well bore  204  via a work string  206 , and wherein in one embodiment the work string may be a coiled tubing string and in another embodiment the work string is a drill string.  FIG. 9  further depicts that the bottom sub  46  is connected to a bottom hole assembly  208 , and wherein the bottom hole assembly  108  contains a drill bit means for boring the well bore, as well understood by those of ordinary skill in the art. 
         [0043]    While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the features and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.