Abstract:
The present invention generally provides a port collar assembly comprising a housing and a sleeve disposed therein. The sleeve is moveable between a first or opened and a second or closed position relative to the housing. In the closed position, the port collar prevents communication of the fluid between the exterior and interior of the port collar. In the open position, the port collar permits communication of the fluid between the exterior and interior of the port collar. The assembly includes a locking mechanism for the opened and closed positions comprising ratchet teeth formed on the exterior surface of the sleeve and mating ratchet teeth formed on the interior surface of the housing. The mating ratchet teeth are designed to secure the sleeve in a first position within the housing. A second set of mating ratchet teeth secures the sleeve in a second position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to port collars for use in a tubular string. Specifically, the invention relates to a two-position port collar which can be repeatedly opened and closed and securely retained in each position. 
     2. Background of the Related Art 
     Port collars typically have a tubular housing which can be made up into a tubular string to form a part thereof. The port collar has a sliding sleeve disposed therein which may be used to selectively communicate fluid flow between an annular area of the well and an interior of the tubing string. In one example, a port collar is installed in a tubular string in a closed position and the tubular string is then inserted into a wellbore, locating the port collar at a predetermined depth in the well. Packing elements are installed above and below the port collar to isolate a specific zone of the annulus. Thereafter, the sliding sleeve of the port collar is remotely opened and the interior of the tubular is placed into communication with production fluid in the annulus. The port collar may also be used to permit fluid flow from the interior of the tubing string into the annulus of a well. For example, in cementing deep wells, a two-part cementing job is often used wherein the lower portion of a casing or liner string is cemented and then, using a port collar, the upper annulus is cemented to avoid hydrostatic pressures present in the lower portion of the annulus. 
     While many port collar designs have been made and used, certain problems exist with current designs. For example, most port collars rely on shear screws or some other type of mechanically shearable connection to unlock the sleeve from an initial position and permit movement of the sleeve to a second position within the collar. In a typical example, the shearable connection holds the sleeve in a closed position and then, when the collar is in the wellbore and ready to be opened, the shearable members are caused to fail with mechanical or hydraulic force. Once the shearable connection has failed, the sleeve is left prone to accidental shifting in the housing, unless it is permanently locked into either an open or closed position. 
     There is a need therefore, for a port collar that does not rely on a shearable connection to lock the sleeve into position within the housing. There is a further need for a port collar that can be repeatedly shifted and locked into the opened and closed positions. There is yet a further need for an easily shiftable port collar that can be used with other port collars in a single tubular string to create a larger assembly for selectively exposing different areas of an annulus to communication with the interior of the tubing string. 
     SUMMARY OF THE INVENTION 
     The present invention generally provides a port collar assembly comprising a housing and a sleeve disposed therein. The sleeve is moveable between a first or opened and a second or closed position relative to the housing. In the closed position, the port collar prevents communication of the fluid between the exterior and interior of the port collar. The assembly includes a locking system for each position comprising ratchet teeth formed on the exterior surface of the sleeve and mating ratchet teeth formed on the interior surface of the housing. One set of mating ratchet teeth are designed to secure the sleeve in an opened position within the housing and a second set of mating ratchet teeth secures the sleeve in a closed position. In one aspect of the invention, the ratchet teeth on the interior surface of the housing are formed on the inner surface of an inwardly biased C-ring disposed in a groove formed in the interior surface of the housing. A plurality of buttons are disposed within apertures formed in the exterior surface of the sleeve and the buttons can be urged in an outward radial direction by a shifting tool disposed within the sleeve. The buttons urge the C-rings into the grooves of the housing and out of engagement with the mating ratchet teeth formed on the surface of the sleeve. In this manner, the sleeve and housing are unlocked from each other and the tool can be shifted to the other position. 
     In another aspect of the invention, cavities and shifting shoulders are formed on the interior of the sleeve opposite each locking system. Corresponding unlocking and detenting formations are formed on a shifting tool including a formation designed to urge the buttons of the sleeve in a radial outward direction. A shifting surface on the shifting tool, corresponding to a shoulder formed on the interior of the sleeve, allows a force to be applied to move the sleeve to a second location in the housing after being unlocked. 
     In another aspect of the invention, several port collars are installed in a tubular string in a wellbore. Thereafter, in order to open and close the port collars, a number of shifting tools are run into the well on a run-in string in a pre-determined, spaced-apart orientation. The shifting tool at the lowest point on the string opens each port collar as it passes therethrough. In order to close the port collars, the string of shifting tools is pulled upwards and the shifting tool designed to close the port collars closes each collar as it passes therethrough. By accurately spacing the shifting tools along the run-in string, the direction of the string can be reversed in order to open a certain port collar while leaving the others in a closed position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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. 
     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. 
     FIG. 1 is a partial section view showing the port collar of the present invention. in an open position. 
     FIG. 1A is an enlarged view of a locking portion of the port collar of FIG.  1 . 
     FIG. 2 is a partial section view of the port collar in a closed position. 
     FIG. 3 is a perspective, side view of a shifting tool used to open the port collar including an opening portion and a closing portion. 
     FIG. 4 is a section view showing the port collar in the open position with a shifting tool installed therein. 
     FIG. 4A is an enlarged view showing the opening portion of the shifting tool engaged in the sleeve of the port collar. 
     FIG. 5 is a section view showing a collet-like function of the shifting tool. 
     FIG. 5A is an enlarged view thereof. 
     FIG. 6 is a side view of a wellbore showing a plurality of port collars disposed on a string of tubulars. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a side view, partially in section of the port collar  200  of the present invention. The port collar  200  includes a housing  205 , which is typically connected at each end to a tubular string (not shown). The housing  205  includes a plurality of housing apertures  210  formed in a wall thereof and constructed to align with sleeve apertures  212  formed in a wall of a sleeve  206  when the port collar  200  is in an open position as in FIG.  1 . The sleeve  206  is disposed within the housing  205  and is installed therein in a certain rotational orientation which is predetermined and is secured with lock screws or set screws (not shown) between the housing  205  and the sleeve  206 . Axial movement of the sleeve  206  within the housing  205  is limited by stops  215 ,  217  formed at each end of the interior of the housing  205 . The stops prevent axial movement of the sleeve  206  within the housing beyond that movement necessary to locate the sleeve  206  in the open or closed position. 
     The port collar  200  includes a first locking system, generally labeled  300  to retain the sleeve  206  in a closed position and a second locking system  301  to retain the sleeve in an open position. In FIG. 1, locking system  301  is engaged and the port collar  200  is locked in the open position with fluid communication possible between the inside and outside of the port collar  200  through aligned apertures  210 ,  212 . The sleeve  206  is prevented from axial movement in a first direction by stop  217  and in the direction of the closed position by engaged locking system  301 . 
     Each locking system  300 ,  301  includes locking surfaces formed on the perimeter of the sleeve  206  and locking surfaces formed on the inner surface of the housing  205 . The surfaces prevent the sleeve  206  from moving within the housing  205  in one direction. FIG. 1A is an enlarged view showing a portion of engaged locking system  301 . Specifically, the locking surface formed on the sleeve  206  includes ratchet teeth  325  extending around the sleeve perimeter. In the preferred embodiment, the mating locking surface of the housing  205  includes at least one groove  365  formed in the inner surface of the housing with an inwardly biased C-ring  370  disposed therein. On the inside surface of the C-ring  370 , facing the sleeve  206 , ratchet teeth  375  are formed and are designed to interact with ratchet teeth  325  formed on the exterior of the sleeve  206  such that the sleeve  206  is prevented from axial movement in the housing  205  in a first direction when the mating teeth  325 ,  375  of the sleeve and the C-ring are engaged. As depicted in FIG. 1A, the engaged ratchet teeth  325 ,  375  will move across each other with little resistance in a first direction but will interfere with each other preventing movement in a second direction. Specifically, the design allows the ratchet teeth  325 ,  375  to move across each other as the port collar  200  is shifted to the open position shown in FIG.  1 . Thereafter, the interaction of the teeth  325 ,  375  prevent the sleeve  206  from moving back towards the closed position. In the open position therefore, the sleeve  206  is prevented from axial movement in one direction by stop  217  acting between the sleeve  206  and the housing  205  and in the opposite direction by the locking system  301 . 
     Interspersed with the ratchet teeth  325  on the outer perimeter of the sleeve  206  are at least one button  335 , one of which is visible in FIG.  1 A. The buttons  335  are housed in countersunk apertures  336  formed in the sleeve  206  and a head portion  337  of each button  335  is retained on a reduced diameter shoulder  338  formed in each aperture. The buttons can be urged outwardly radially by a shifting tool described hereafter. The placement of apertures  336  with the buttons  335  therein correspond to the location of the ratchet teeth  325  formed on the outer surface of the sleeve  206  such that the buttons  335 , when urged outwards, extend out above the ratchet teeth  325 . By urging the buttons outward, the head portion  337  of the buttons move the inwardly biased C-ring  370  back into the groove  365  and out of engagement with the ratchet teeth  325  of the sleeve. In this manner, the locking system  301  is unlocked and the sleeve  206  can be moved axially within the housing  205 . The number of buttons utilized can be increased for redundancy. Additionally, each locking system can utilize multiple locking surfaces. For example, if a particular tool is run through a port collar and one set of buttons is inadvertently urged outwards thereby disengaging a first C-ring, a second C-ring with its locking surface will remain engaged with corresponding ratchet teeth of the sleeve, thereby preventing premature shifting of the port collar. 
     FIG. 2 is a partial section view showing the port collar  200  in a closed position with the sleeve apertures  212  out of alignment with the housing apertures  210 . In the closed position, there is no fluid communication between the interior and exterior of the port collar  200 . As with locking system  301 , locking system  300  includes ratchet teeth formed on the exterior of the sleeve  206  and ratchet teeth formed on the inside surface of a C-ring housed in a groove formed on the inside surface of housing  205 . In the closed position, the sleeve  206  is prevented from movement in a first axial direction by stop  215  and in the direction of the open position by the engaged locking system  300 . 
     Unlocking and shifting of the port collar  200  between the open and closed positions are performed through the use of a shifting tool. FIG. 3 is a perspective view of shifting tool  400  which is comprised of an opening portion  410  and closing portion  450 , each portion having an opposing orientation along the length of the shifting tool. Portions  410 ,  450 , when run into the wellbore, are independently seated in the interior of the port collar sleeve  206 . FIG. 3 illustrates the opening portion  410  including a tool oriented to open the port collar  200  and closing portion  450  oriented to close the port collar  200 . The spacing between the opening  410  and closing  450  portions is adjustable depending upon operational conditions and requirements. Each portion  410 ,  450  of the shifting tool  400  includes collet-like features with a plurality of slots  436  formed longitudinally within the tool. The slots create fingers  435  therebetween which move in a spring-like manner when force is applied to the surface thereof. In the preferred embodiment, at least four equally spaced fingers  435  are formed around the shifting tool  400 . 
     Considering the opening portion  410  of the tool in greater detail, each finger  435  includes two unlocking formations  412 ,  430  designed to interact with corresponding surfaces on the interior of the sleeve  206 . Unlocking formation  430  also serves to move the sleeve  206  within the housing  205  via engagement between surfaces of the formation  430  and the sleeve  206 . Unlocking formations  412 ,  430  include upper surfaces  413 ,  431  substantially parallel to the surface of finger  435  and three angled surfaces  414 ,  415 ,  433 . Unlocking formation  430  also includes one shifting surface  432  substantially perpendicular to the surface of finger  435 . The shifting surface  432  provides a means to urge the sleeve  206  from the closed to the open position as described hereafter. A detenting formation  420  has one upper surface  421  substantially parallel to finger  435  and two angled surfaces  422 ,  423 . 
     Closing portion  450  similarly includes two unlocking formations  470 ,  480  and are detenting formation  460 . As with the opening portion, formations  480 ,  470  include surfaces  481 ,  471  substantially parallel to the surface of finger  435  and three angled surfaces  483 ,  472 ,  473 . Additionally, shifting formation  480  includes shifting surface  482  substantially perpendicular to finger  435 . A detenting formation  460  includes an upper surface  461  and also a two surfaces  462 ,  463  angled to the surface of finger  435 . 
     Formed in the interior of the sleeve  206 , opposite each locking system  300 ,  301  are cavities constructed and arranged to interact with the formations and surfaces of the shifting tool  400 . FIG. 4 is a partial section view of the port collar  200  showing the closing portion  450  of the shifting tool  400  engaged with the corresponding cavities in the sleeve opposite locking system  301 . With the closing portion  450  of the shifting tool  400  inserted, the sleeve  206  may be urged in the direction of stop  215 , mis-aligning the apertures  210 ,  212  of the sleeve and housing and closing the port collar  200 . As illustrated in FIG. 4A, an enlarged view of locking system  301 , formations  460 ,  470 ,  480  of the closing portion  450  of the shifting tool  400  have engaged corresponding cavities of the sleeve  206 . The interior of the sleeve  206  opposite locking system  301  includes two unlocking cavities  430 ,  436  and one shifting shoulder  440  constructed and arranged to interact with unlocking formations  470 ,  480  and detenting formation  460  formed on the closing portion  450  of the shifting tool  400 . In FIG. 4A, shifting surface  482  of the shifting tool is in contact with shoulder  440  of the sleeve  206 . Surfaces  481 ,  471  of formations  470 ,  480  have contacted the lower surface  338  of buttons  335  disposed in the sleeve  206  and the buttons have been urged outwards in a radial direction. The head portion  337  of each button  335  has contacted and urged the C-rings  370  into the grooves  365  formed on the interior surface of the housing  205 . In this manner, the ratchet teeth  375  have been moved out of engagement with the mating ratchet teeth  325  (not visible) on the exterior of the sleeve  206 . 
     With the ratchet teeth  325 ,  375  out of engagement, force applied against shoulder  440  by shifting surface  482  will cause the sleeve  206  to move axially within the housing  205 . As the sleeve  206  moves into the closed position, axial movement of the sleeve  206  is limited by stop  215  and locking system  301  will prevent axial movement towards the open position, thereby locking the port collar  200  in the closed position. As visible in FIG. 1, there are two cavities  437 ,  434  and a shifting shoulder  436  opposite locking system  300  to interact with formations  412 ,  430  and shifting surface  432  of the opening portion  410  of the shifting tool  400 . Locking system  300  is disengaged in a similar manner as locking system  301  and those skilled in the art will appreciate that the foregoing description is equally applicable to locking system  300 . 
     FIG. 5 is a partial section view of the port collar  200  having been shifted to the open position by the opening portion  410  of the shifting tool  400 . FIG. 5 illustrates the collet-like movement of the fingers  435  allowing the opening portion  410  of the shifting tool  400  to be urged out of engagement with the sleeve  206 . FIG. 5A is an enlarged view showing the interaction of the various surfaces of the shifting tool  410 , sleeve  206  and housing  205 . After the port collar is shifted to the open position and additional axial movement of the sleeve  206  is prevented by stop  217 , continued force applied to the shifting tool will cause a surface  423  of the detenting formation  420  to contact and move downward across an undercut surface  218  of the sleeve  206  formed below stop  217 . The downward component of force exerted upon surface  423  urges the flexible finger  435  downward until shifting surface  432  is no longer in contact with corresponding shoulder  502  of sleeve  206 . In this manner, the shifting tool  400  can be moved out of engagement with the port collar. 
     Typically, a port collar  200  is placed in a well in the closed position whereby the annular area around the port collar  200  is isolated from the interior of the port collar. In order to open the port collar  200 , a shifting tool  400  is run into the well on a run-in string of tubular. The opening  410  and closing  450  portions of the shifting tool  400  allow the port collar  200  to be opened and then closed again at the completion of some downhole operation. As the shifting tool enters the closed port collar, the opening portion  410  passes through the formations opposite the locking system  301  and subsequently, the opening portion  410  interacts with formations opposite the locking system  300  and the shifting tool becomes fixed within the sleeve  206 . In this position, the shifting tool urges the buttons  335  of the locking system  300  outwards thereby moving the C-rings  370  out of engagement with the ratchet teeth  325  of the sleeve. Continued force applied to the shifting tool  400  will then urge the sleeve  206  down and into the open position. Thereafter, continued force upon the shifting tool  400  causes the collet-like fingers of the opening portion  410  of the shifting tool to collapse and come out of engagement with cavities of the sleeve  206 , as illustrated in FIG.  5 A. 
     The present invention can also be used in a wellbore wherein numerous port collars  200  are arranged in series at various depths in the well and are then alternately opened or closed by multiple shifting tools run into the well along a run-in string. FIG. 6 is a side view of a wellbore showing a plurality of port collars  200  disposed on a string of tubulars  220 . For example, port collars  200  can be located adjacent formations and then selectively opened to access production fluid. Subsequently, the port collars  200  can be re-closed isolating the interior thereof from the annular well fluid. In other examples, the port collars  200  are opened to permit cement to be injected into the annular area therearound and then re-closed after the cementing process is complete. 
     As a run-in string with shifting tools installed therein is lowered into a wellbore, the opening tool portion  410  of the shifting tool opens the port collars as it passes therethrough. Closing portion  450  of the shifting tool, because it is designed to operate only while moving in an upward direction through the port collars  200 , passes downward through the port collars  200  with no effect. After the shifting tool  400  has passed through and opened all of the port collars  200 , the run-in string housing the shifting tools can be pulled upwards towards the surface of the well such that the closing portion of a shifting tool  450  will re-close the lower most port collars. Finally, if necessary, the opening portion  410  of the shifting tool  400  can then be lowered back through an intermediate port collar(s), leaving the port collar(s) in the open position. In this manner, port collars are selectively opened and closed in a string of multiple port collars. 
     While foregoing is directed to the preferred embodiment 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.