Abstract:
The present invention generally relates to a disconnect for use in a wellbore to separate a tubular string from a stuck wellbore component. In one aspect, the invention includes a disconnect with a first portion and a second portion and a lock nut preventing the separation of the two portions. When a predetermined fluid force is applied to a piston in the disconnect, a tensile sleeve fails and the first and second portions of the disconnect separate, thereby leaving a portion of the disconnect in the wellbore with the stuck component. In one embodiment, the tensile sleeve&#39;s failure permits an annular piston to dislodge a wedge sleeve from the lock nut, thereby permitting separation of the first and second portion of the disconnect.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to an apparatus and method for use in a wellbore. More particularly, the invention relates to a disconnect for separating two or more components in a wellbore.  
           [0003]    2. Description of the Related Art  
           [0004]    In the drilling, completion, and operation of a hydrocarbon wells, various wellbore components are inserted and removed from a previously drilled wellbore on a lower end of a tubular string. Wellbore components include packers (to seal off production zones), motors, pumps, sensors, sliding sleeves (to control flow of fluid in and out of production tubing), hydraulically set liners (for lining during cementing of casing), whipstocks (to divert drill bit while drilling), valves, cement shoe assemblies, and drill bits.  
           [0005]    As wellbore components are delivered and removed from a wellbore, the components or the tubular string they are attached to can become stuck in the wellbore. The problem is exacerbated by non-liner wellbores or previously existing obstructions in the wellbore. In one example, a drill bit on an end of a drill string is used to increase the depth of the wellbore. As the drill rotates at the end of the string, it may become stuck or otherwise jammed in the wellbore. There are conventional wellbore devices that are designed to aid in freeing a component that is stuck in the wellbore. For example, a “jar” can be disposed in the drill string to selectively provide a jarring force to the stuck component. A jar includes a telescopic portion that permits axial elongation of the jar. By operating a jar that is disposed near the stuck component, a force can be developed to possibly free the component.  
           [0006]    In other instances, the use of jars is inadequate to free a stuck component and the component must be exposed in the wellbore in order to remove it with the use of fishing tools. To permit a drill sting or other tubular string to be separated from a stuck component, disconnect devices, are placed at intervals in the drill string. A disconnect is a component that can be selectively separated into two portions. For example, a disconnect disposed in a string of tubulars can permit the string to be separated and the lower part left in the wellbore for accessibility by fishing tools. Likewise, a disconnect disposed between the end of a tubular string and a wellbore component, like a drill bit, permits the selective removal of the string of tubulars if the bit should become stuck.  
           [0007]    Conventional pull type disconnects utilize shear pins to temporarily couple a first and second portion of the disconnect together or to hold an internal piston in a first position. Shear pins are designed to fail when they are subjected to a force, such as a tensile or compressive force developed across the pins. When a wellbore component is stuck and a disconnect is disposed in a tubular string near the component, an upward force applied from the surface can cause the shear pins of the disconnect to fail, permitting the string to be removed from the wellbore. After the tubular string is retrieved to the surface, a fishing tool is used to manipulate the stuck wellbore component.  
           [0008]    Shear pins are sized and numbered based upon the shear force needed to operate a disconnect. While they have been used as temporary connections in wellbores for years, shear pins have limitations. For example, forces other than the intended force may prematurely cause the shear pins to shear, thus making them unreliable. Because the shear pins can shear prematurely, additional fishing operations may be required to retrieve the prematurely disconnected wellbore component, leading to lost production time. For example, shear pins located on a tubular string that includes a perforating gun can shear prematurely from the force generated when the perforating gun is fired. Additionally, shear pins can shear prematurely when a slide hammer bangs on a shifting tool in order to shift the sliding sleeve or when a jarring device is used to dislodge a component.  
           [0009]    Therefore, there is a need for a more reliable disconnect for use in a wellbore. There is a further need for a disconnect that can operate only when a predetermined amount of tension force is applied to a member.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention generally relates to a disconnect for use in a wellbore to separate a tubular string from a stuck wellbore component. In one aspect, the invention includes a disconnect with a first portion and a second portion and a lock nut preventing the separation of the two portions. When a predetermined fluid force is applied to a piston in the disconnect, a tensile sleeve fails and the first and second portions of the disconnect separate, thereby leaving a portion of the disconnect in the wellbore with the stuck component. In one embodiment, the tensile sleeve&#39;s failure permits an annular piston to dislodge a wedge sleeve from the lock nut, thereby permitting separation of the first and second portion of the disconnect. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.  
         [0012]    It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0013]    [0013]FIG. 1 is an elevation view of the disconnect showing a castellation arrangement between a first and a second portions of the disconnect.  
         [0014]    [0014]FIG. 2 is a section view of a disconnect of the present invention.  
         [0015]    [0015]FIG. 3 is an enlarged view of the disconnect in the area around the tensile sleeve.  
         [0016]    [0016]FIG. 4 is an enlarged view of the area of the disconnect surrounding lock nut.  
         [0017]    [0017]FIG. 5 is a section view illustrating the tensile sleeve after it has failed.  
         [0018]    [0018]FIG. 6 is a section view of the disconnect illustrating the position of the components as the device is operated.  
         [0019]    [0019]FIG. 7 is an enlarged section view in the area of the lock nut.  
         [0020]    [0020]FIG. 8 is a section view of the disconnect illustrating the disconnect just prior to separation of the first and second portions.  
         [0021]    [0021]FIG. 9 is a section view showing the first portion of the disconnect removed from the second portion. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    The present invention provides an apparatus and method to disengage a wellbore component from a tubular string. A disconnect device having a first and second portion and a tensile sleeve is provided to disengage the wellbore component from the tubular string. The tensile sleeve includes a notch defining a portion of reduced thickness within the sleeve that can be caused to fail when a predetermined amount of force is applied. Additionally, a lock nut and a wedge sleeve operate to retain the first and second parts of the disconnect together prior to the failure of the tensile sleeve  
         [0023]    [0023]FIG. 1 is an elevation view of a disconnect  100  showing a castellation arrangement between a first  101  and a second  109  portions of the disconnect. The castellation members  169  of a housing  136  and a mandrel  110  prevent the first and second portions  101 ,  109  from rotating in relation to each other. Additionally, a tubular  105  is coupled to an upper sub  102  that is coupled to the mandrel  110 . The housing  136  is coupled to the lower sub  190  that is coupled to a wellbore component  195  or a tubular.  
         [0024]    [0024]FIG. 2 is a section view of a disconnect  100  of the present invention. Specifically visible in FIG. 2 are the first  101  and second  109  portions of the disconnect  100 . The first portion  101  includes upper sub  102 , the mandrel  110  having a bore therethrough, a wash out sleeve  116 , o-rings  108 ,  171 ,  172 , a tensile sleeve  122 , an aperture  127 , and an annular piston  130  with a ball seat  138  at the upper end thereof. The tensile sleeve  122  includes an upper portion  113  with a flange  123  that is shown seated on a shoulder  115  of the mandrel  110 . The second portion  109  includes the housing  136 , a thrust washer  140 , a lock nut  146 , a wedge sleeve  150 , spring  155 , o-rings  173 ,  174 ,  175  and a lower sub  190 . The first portion  101  and the second portion  109  are coupled together by the lock nut  146 .  
         [0025]    As stated above, the first portion  101  includes the upper sub  102  having an upper end  104  threaded to the tubular string  105  and a lower end  106  threaded to the upper end  103  of the mandrel  110 . As shown, a gap  111  is formed between the lower end  106  of the upper sub  102  and the washout sleeve  116  to provide a fluid pathway. Additionally, the upper sub  102  provides a connection between the tubular string  105  and the disconnect  100 . O-ring  108  provides a seal between the mandrel  110  and the upper sub  102  to prevent fluid flow thereinbetween. A lower end  151  of the mandrel  110  is threaded in order to mate with the threads of the lock nut  146 .  
         [0026]    Still referring to FIG. 2, the piston  130  is slideably coupled to an inner surface  178  of the mandrel  110  and moves axially in response to an axial force. O-ring  171  provides a fluid seal between the piston  130  and the mandrel  110 . Additionally, the aperture  127  is provided in a wall of the mandrel  110  to allow fluid from the upper portion  101  of the disconnect  100  to escape to an annulus created between the wellbore and the disconnect  100 . The aperture  127  and its function will become apparent with respect to FIGS. 8 and 9.  
         [0027]    Piston  130  includes the ball seat  138  at an upper end thereof for the seating of a ball (not shown) in order to seal the bore of the disconnect  100  and develop a fluid force above the piston  130 . In another embodiment, the piston  130  may include a restricted bore to create a fluid force. The piston  130  can move axially within the mandrel  110  to engage the wedge sleeve  150 , a portion of the second portion  109  of the disconnect  100 . The spring  155  biases the wedge sleeve  150  against the lock nut  146 , which is in contact via threads with the lower end  151  of the mandrel  110 . The lock nut  146  is a “C” shaped ring and is normally outwardly biased away from the threaded mandrel  110 . When in contact with the lock nut  146 , the wedge sleeve  150  urges the lock nut  146  inwards and into contact with the mating threads of the mandrel  110 , thereby retaining the upper  101  and lower  109  portions of the disconnect  100  together. The wedge sleeve  150  is designed to move axially along an inner wall  133  of the housing  136 , when the piston  130  travel pass gap  125  and engages shoulder  126  (FIG. 7) of the sleeve. In doing so, the outwardly biased lock nut  146  moves out of engagement with the threaded mandrel  110 . O-ring  173  provides a fluid seal between the piston  130  and the wedge sleeve  150 . Thrust washer  140  provides a cushion against jarring forces that can cause the lock nut  146  to jar and damage the housing  136 .  
         [0028]    Still referring to FIG. 2, the housing  136  is threaded at a lower end  137  to an upper end  191  of the lower sub  190 . The housing  136  provides an enclosure for a portion of the mandrel  110 , the piston  130 , the lock nut  146 , the wedge sleeve  150 , the thrust washer  140 , the spring  155 , the o-rings  173 ,  174 ,  175 . O-rings  174 ,  175  provides a seal between the lower sub  190  and the housing  135  and between the piston  130  and lower sub  190 , respectively. Additionally, o-ring  172  provides a fluid seal between the housing  136  and mandrel  110 . The lower sub  190  has the upper end  191  threaded to the lower end  137  of the housing  136  and lower end  192  can be threaded to a wellbore component  195  or a tubular string. A gap  156  provided between the wedge sleeve  150  and the lower sub  190  permits the sleeve to move axially. Additionally, the lower sub  190  has a stop shoulder  157  to prevent the wedge sleeve  150  from moving pass the spring&#39;s  155  elastic limit when the sleeve  150  moves axially.  
         [0029]    [0029]FIG. 3 is an enlarged view of the disconnect  100  in the area around the tensile sleeve  122 . The washout sleeve  116  supports the tensile sleeve  122  that is disposed thereon, and protects the tensile sleeve  122  from being damaged by abrasive fluids that may flow through from the upper sub  102  to the lower sub  190  (not shown) during hydrocarbon production.  
         [0030]    The tensile sleeve  122  may be an annular sleeve having a notch  118  or some other strength reducing formation that divides the tensile sleeve  122  into the upper portion  113  and a lower portion  114 . The upper portion  113  includes the flange  123  that is shown seated on the shoulder  115  of mandrel  110 . The lower portion  114  of the sleeve  122  is threaded to the piston  130 . In this manner, the tensile sleeve  122  is retained between the mandrel  110  and the piston  130  and a tensile force may be applied thereto as the piston is urged downward as will be described. Illustrated in FIG. 3 is a ball  120  seated in the ball seat  138  of the piston  130 . Typically, when the disconnect is  100  to be operated, the ball  120  is dropped from above and lands in the ball seat  138  thereby blocking the flow of fluid in the bore of the disconnect  100  and permitting fluid pressure to be developed above the ball  120  and piston  130 . The depth of the notch  118  determines the amount of force required to separate the upper portion  113  from the lower portion  114  of the tensile sleeve  122  or a predetermined failure force of the notch  118 . When a fluid force acts upon the piston  130  via the ball  120 , the piston  130  places a tensile force on the tensile sleeve  122  because flange  123  of the upper portion  113  is seated in the shoulder  115  of the mandrel  110 . When the predetermined failure force is reached, the sleeve  122  is separated into upper portion  113  and lower portion  114  (FIG. 5). Also visible in FIG. 3 is the gap  111  formed between the upper sub  102  and the washout sleeve  116  providing a fluid pathway into the chamber  112  formed around an outer surface of the tensile sleeve  122 . The chamber  112  permits fluid communication along an outer surface of the sleeve  122  to equalize pressure.  
         [0031]    [0031]FIG. 4 is an enlarged view of the area of the disconnect  100  surrounding lock nut  146 . As illustrated, threaded inner portion of the lock nut  146  is mated with threads formed in the lower end  151  of the mandrel  110 , thereby fixing the lock nut  146  to the mandrel  110 . At an outer surface, the lock nut  146  is controlled by the wedge sleeve  150  and its upper portion  158  and thus urged into contact with the mandrel  110 . Spring  155  urges the wedge sleeve  150  towards the lock nut  146 , thereby keeping the lock nut  146  engaged.  
         [0032]    Another concern of conventional disconnect devices is the possibility of bending movements that can occur where the upper and lower portions  101 ,  109  are connected together. In the present invention, because the wedge sleeve  150  is wedged tightly with the lock nut  146 , any bending movement is severely restricted. Additionally, the wedge sleeve  150  has the shoulder  126  to receive the lower end of the piston  130 , when the piston  130  travels across gap  125 . The thrust washer  140  is disposed between the lock nut  146  and a flange  128  of the housing  136 . Additionally, the o-ring  173  provides a seal between the wedge sleeve  150  and the piston  130 .  
         [0033]    [0033]FIG. 5 is a section view illustrating the tensile sleeve  122  after it has failed. With the ball  120  seated at the top of the piston  130 , fluid pressure is applied to the ball  120  and piston surface. When the predetermined failure force of the tensile sleeve  122  is reached, the sleeve  140  separates into its upper and lower portions  113 ,  114 . Thereafter, the piston  130  is free to move downward in the disconnect  100 .  
         [0034]    [0034]FIG. 6 is a section view of the disconnect  100  illustrating the position of the components as the device is operated. FIG. 7 is an enlarged section view in the area of the lock nut  146 .  
         [0035]    The piston  130 , with the ball  120 , continues to move axially along the inner wall  178  of the mandrel  110  and crosses the gap  125  (not shown) and engages the shoulder  126  of the wedge sleeve  150 . The piston  130  then moves the wedge sleeve  150  axially along the inner wall  133  of the housing  136 , and against the bias force of the spring  155 , thereby compressing the spring  155 .  
         [0036]    When the wedge sleeve  150  moves axially along the inner wall  133  of the housing  136 , it is moved out of the engagement with the lock nut  146  thereby, allowing the nut to move out of engagement with the mandrel  110  and decoupling the first and second portions  101 ,  109  of the disconnect  100  from each other. This relationship is illustrated in FIG. 7. The wedge sleeve  150  continues moving axially due to the movement of the piston  130 , crosses gap  156  (not shown) and engages stop shoulder  157  (not shown) to further compress the spring  155 . However, stop shoulder  157  on the lower sub  190  (not shown) prevents the wedge sleeve  150  from traveling beyond the spring&#39;s  155  elastic limit.  
         [0037]    [0037]FIG. 8 is a section view of the disconnect  100  illustrating the disconnect  100  just prior to separation of the first and second portions  101 ,  109 . As previously described, the piston  130  and ball  120  travel axially downwards in the disconnect  100  after the upper portion  113  and lower portion  114  separate due to fluid pressure. The downward movement of the piston  130  urges the wedge sleeve  150  out of contact with the lock nut  146  and the threads of the mandrel  110  come out of engagement with the threads of the lock nut  146 . Thereafter, as shown in FIG. 8, continued fluid pressure applied to the piston  130  and ball  120  cause axial movement of o-ring  171  past a port  127  formed in a wall of the mandrel  110 . As the fluid is diverted, its pressure necessarily drops and the change in pressure can be measured and noted out of the surface of the well.  
         [0038]    The sudden change in pressure indicates that not only are the threads of the mandrel  110  out of engagement with the threads of the lock nut  146 , but that the mandrel  110  is at an axial position within the housing  136  of the disconnect  100  whereby, re-engagement between the threads will not result. Thereafter, the first portion  101  of the disconnect  100  may be pulled out of the wellbore, leaving the second portion  109 , and any stock component there below, accessible by fishing tools.  
         [0039]    [0039]FIG. 9 is a section view showing the first portion  101  of the disconnect removed from the second portion  109 . Typically, the portion remaining in the wellbore includes a profile or some other formation accessible by a fishing tool.  
         [0040]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.