Abstract:
Disclosed herein is a selectively movable seat arrangement. The seat arrangement includes, one or more seat members movable between a passable position where a member is passable therethrough and an impassable position where the member is prevented from passing therethrough, and a counter in operable communication with the one or more seat members, the counter capable of allowing movement of the one or more seat members to the passable position to allow passage of a member a selected number of times and then to the impassable position thereby preventing passage of another such member for a period of time.

Description:
BACKGROUND 
       [0001]    In industries concerned with earth formation boreholes, such as hydrocarbon recovery and gas sequestration, for example, it is not uncommon for various operations to utilize a temporary or permanent plugging device. Sometimes plugging is desirable at a first location, and subsequently at a second location. Moreover, additional plugging locations may also be desired and the plugging can be sequential for the locations or otherwise. Systems employing droppable members, such as balls, for example, are typically used for just such purpose. The ball is dropped to a ball seat positioned at the desired location within the borehole thereby creating the desired plug. 
         [0002]    In applications where the first location is further from surface than the second location, it is common to employ seats with sequentially smaller diameters at locations further from the surface. Dropping balls having sequentially larger diameters allows the ball seat furthest from surface to be plugged first (by a ball whose diameter is complementary to that seat), followed by the ball seat second furthest from surface (by a ball whose diameter is complementary to that seat) and so on. 
         [0003]    The foregoing system, however, creates increasingly restrictive dimensions within the borehole that can negatively impact flow therethrough as well as limit the size of tools that can be run into the borehole. Systems and methods that allow operators to plug boreholes at multiple locations without the drawbacks mentioned would be well received in the art. 
       BRIEF DESCRIPTION 
       [0004]    Disclosed herein is a selectively movable seat arrangement. The seat arrangement includes, one or more seat members movable between a passable position where a member is passable therethrough and an impassable position where the member is prevented from passing therethrough, and a counter in operable communication with the one or more seat members, the counter capable of allowing movement of the one or more seat members to the passable position to allow passage of a member a selected number of times and then to the impassable position thereby preventing passage of another such member for a period of time. 
         [0005]    Further disclosed herein is a method of selectively allowing one or more members to pass a seat arrangement before preventing a member from passing the seat arrangement. The method includes, engaging the seat arrangement with one or more members, removing the seat arrangement and allowing the one or more members to pass the seat arrangement, engaging the seat arrangement with an additional member, and maintaining the seat arrangement and preventing the additional member from passing the seat arrangement. 
         [0006]    Further disclosed herein is a system. The system includes, a restriction engager, one or more restrictions, and at least one counter configured to permit or prevent passage of a restriction engager through one of the one or more restrictions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0008]      FIG. 1  depicts a cross sectional view of a selectively movable seat arrangement disclosed herein in a resting position; 
           [0009]      FIG. 2  depicts a cross sectional view of the selectively movable seat arrangement of  FIG. 1 , shown in an open position; 
           [0010]      FIG. 3  depicts a cross sectional view of the selectively movable seat arrangement of  FIG. 1 , shown after having passed one restriction engager; 
           [0011]      FIG. 4  depicts a cross sectional view of the selectively movable seat arrangement of  FIG. 1 , shown preventing passage of a restriction engager after having passed a selected number of the restriction engagers; 
           [0012]      FIG. 5  depicts a partial cross sectional view of an alternate embodiment of a selectively movable seat arrangement disclosed herein shown in a restriction engager passing position; 
           [0013]      FIG. 6  depicts a partial cross sectional view of the selectively movable seat arrangement of  FIG. 5  shown in a restriction engager non-passing position; and 
           [0014]      FIG. 7  depicts a partial cross sectional view of the tubular of  FIG. 5  taken at arrows  7 - 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0016]    Embodiments of the selectively movable seat arrangement disclosed herein are positionable within a borehole tubular or open hole and maintain a seat arrangement or restriction to a member or restriction engager after having allowed a selected number of restriction engagers to pass therethrough. When the restriction is maintained, the restriction engager can sealingly engage the restriction thereby sealing the borehole tubular to flow therepast. Such a seal allows for the creation of a pressure differential in the borehole that is usable by operators for such things as actuation of tools and fracturing of formations, for example. 
         [0017]    Referring to  FIGS. 1 and 2 , an embodiment of the selectively movable seat arrangement  10  disclosed herein in a resting position and an open position, respectively. The selectively movable seat arrangement also described herein as a selective landing configuration  10  includes, a member described herein as a restriction engager  14  and illustrated herein as a ball, one of one or more seat arrangements described herein as restrictions  18  and illustrated herein as a ball seat, and a counter  22 . The counter  22  is configured to index each time one of the restriction engagers  14  passes through the restriction  18 . The restriction  18 , of this embodiment, has a plurality of pivot arms  26  that are pivotal about pivot points  28  between an impassable position also referred to herein as a first pivot arm position and a passable position also referred to herein as a second pivot arm position. Each of the pivot arms  26  has a first end  38  and a second end  42 . When in the first pivot arm position (shown in  FIG. 1 ) the first ends  38  are adjacent to one another to form a ring shaped continuous reduced dimension surface  46  with which the restriction engager  14  is engagable. It should be noted that the restriction engager  14  may sealingly engage with the reduced dimension surface  46 , however, it is not required. When in the second pivot arm position (shown in  FIG. 2 ) the first ends  38  are displaced radially outwardly defining an opening  50  sized to permit passage of the restriction engager  14  therethrough. The pivot arms  26  in one embodiment may be rotationally biased by a biasing member (not shown) such as a torsional spring, for example, that biases them toward the first pivot arm position. 
         [0018]    Movement of the pivot arms  26  from the first pivot arm position to the second pivot arm position is accomplished by urging a restriction engager  14  therethrough with pressure, for example. Ramped surfaces  54  on the first ends  38  are configured to cause the first ends  38  to move radially outwardly in response to a restriction engager  14 , such as a ball, being urged thereagainst. Movement of the pivot arms  26  to the second pivot arm position causes the second ends  42  to move radially inwardly. This radial inward movement causes a tooth  58  on each of a plurality of rams  62  to disengage teeth  66  on an outer radial surface  70  of the second ends  42  of the pivot arms  26 . Once the tooth  58  of the ram  62  is disengaged the ram  62  is able to move longitudinally under a biasing load provided by a biasing member  74 , disclosed herein as a compression spring. 
         [0019]    An escapement  78 , illustrated herein as a lever  82  pivotal about pivot point  84 , engages with teeth  86  on an inner surface  90  of a tubular  94 , such as a casing or drillstring, positioned within a wellbore  98 , limits the longitudinal movement of the ram  62 . The lever  82  and teeth  86  are sized and positioned to allow the ram  62  to advance only a specific dimension each time the tooth  58  disengages from the teeth  66 . This dimension coincides with the spacing between the adjacent teeth  66 . In so doing, the escapement  78  assures that the tooth  58  will reengage with the next tooth  66  each time the pivot arms  26  return to the first pivot arm position. The lever  82  can be rotationally biased, in a direction of arrow  100 , by a biasing member (not shown) such as a torsional spring, for example, to assure that the lever  82  engages with the teeth  86 . 
         [0020]    Referring to  FIG. 3 , the lever  82  can also be sized such that it contacts the outer radial surface  70  when the pivot arms  26  are moved back to the first pivot arm position thereby rotating the lever  82  in a direction opposite to the direction of arrow  100 , disengaging the lever  82  from the teeth  86  in the process. (Note: the radial surface  70  also exists between each of the teeth  66 ). By doing so the lever  82  is properly positioned to engage with the next tooth  86  as soon as the pivot arms  26  begin pivoting again toward the second pivot arm position. This sequential indexing of the tooth  58  along the teeth  86  defines the counter  22 . 
         [0021]    Referring to  FIG. 4 , the number of teeth  66  is selected to establish the number of restriction engagers  14  that the counter  22  will allow to pass the restriction  18 . Once the lever  82  is disengaged from the last tooth  66  the lever  82  will continue to be biased against the surface  90 . However, without any additional teeth  66  for the lever  82  to engage there is nothing to stop the ram  62  from moving under the urging of the biasing member  74 . As such, the ram  62  will stroke until contact is made with a stop  104 , shown here on the tubular  94 , although other mechanical features definable of full travel of the ram  62  are contemplated. 
         [0022]    An annular dimension of the first end  38  of the pivot arms  26  is set to essentially fill an annular gap  108  defined between the outer radial surface  70  and the inner surface  90 . By filling the annular gap  108 , the first end  38  prevents any additional radial outward pivoting of the pivot arms  26 . This non-pivoting condition of the pivot arms  26  maintains the restriction  18  thereby preventing passage of the restriction engager  14  and providing a sealing seat for the restriction engager  14  to seal to. The foregoing structure allows an operator to selectively set how many restriction engagers  14  will pass each restriction  18  before the restriction  18  is maintained, thereby preventing additional restriction engagers  14  from passing. 
         [0023]    Referring to  FIGS. 5 and 6 , an alternate embodiment of a selective landing configuration  110  is illustrated. As with the landing configuration  10  the landing configuration  110  permits a selectable number of restriction engagers  114  to pass a restriction  118  before a counter  122  maintains the restriction  118  impassable by additional restriction engagers  114 . The counter  122  is configured to index each time one of the restriction engagers  114  passes through the restriction  118 . The restriction  118 , of this embodiment, has a plurality of deformable arms  126  that are able to elastically deform between an impassable position also referred to herein as a first deformable arm position and a passable position also referred to herein as a second deformable arm position in the fashion of a collet. Each of the deformable arms  126  has a first end  138  and a second end  142 . 
         [0024]    When in the first deformable arm position (shown in  FIG. 6 ) the first ends  138  seal to one another to form a ring shaped continuous reduced dimension surface  146  that is sealingly engagable with the restriction engager  114 . When in the second deformable arm position (shown in  FIG. 5 ) the first ends  138  are displaced radially outwardly defining an opening  150  sized to permit passage of the restriction engager  114  therethrough. An annular recess  154  in an inner radial surface  158  of a tubular  162  within which the landing configuration  110  is positioned, receives the first ends  138  as the deformable arms  126  are deformed. A nonrecessed portion  166  of the inner radial surface  158  maintains the deformable arms  126  in a nondeformed orientation (first deformable arm position) when the first ends  138  are longitudinally aligned therewith. It is precisely this longitudinal alignment between the first ends  138  of the deformable arms  126  and the nonrecessed portion  166  that the counter  122  controls to allow or prevent the passing of the restriction engager  114 . 
         [0025]    The counter  122  includes a rotationally indexable sleeve  170  that is longitudinally movable against a biasing member  182  that longitudinally biases the sleeve  170  and the deformable arms  126  in a direction wherein the nonrecessed portion  166  radially supports the deformable arms  126 . The restriction  118  and the sleeve  170  are therefore longitudinally movable in response to a restriction engager  114  contacting the deformable arms  126  and providing a longitudinal urging against them in response to pressure applied thereto. The biasing member  182  can reset the sleeve  170  and the deformable arms  126  back to the first deformable arm position after the restriction engager  114  has passed therethrough. Ramped surfaces  184  assure the deformable arms  126  return to the first deformable arm position while also preventing them from wedgably engaging within the annular recess  154 . 
         [0026]    Referring to  FIG. 7 , a plurality of slots  186 , with three slots  186 A- 186 C being shown, and a saw tooth stop surface  188  formed in an inner radial surface  190  of the tubular  162  define the extent of the longitudinal movement of the sleeve  170 , the deformable arms  126  and the restriction  118 . A plurality of tabs  194  radially proud of an outer radial surface  198  of the sleeve  170  slidably engages the slots  186 . When the tabs  194  are bottomed against surface  202 A or  202 B from slot  186 A or  186 B, respectively, the longitudinal travel of the sleeve  170  allows the first ends  138  of the deformable arms  126  to move into longitudinal alignment with the annular recess  154 . The deformable arms  126  being radially unsupported are able to deform from the first deformable arm position to the second deformable arm position, thereby permitting the restriction engager  114  passage by the restriction  118 . However, once the sleeve  170  has rotationally indexed to the point that the tab  194  is engaged with the slot  186 C, the bottom  202 C prevents longitudinal movement of the sleeve  170  (and the deformable arms  126 ) such that the first ends  138  of the deformable arms  126  remain radially supported by the nonrecessed portion  166 . The nonrecessed portion  166  thereby preventing deformation of the deformable arms  126  from the first deformable arm position to the second deformable arm position and passage of the restriction engager  114  therethrough. 
         [0027]    Angled surfaces  206  between the slots  186  and angled surfaces  210  on an end  214  of the tabs  194  cause rotational indexing the sleeve  170  when the sleeve  170  is moved toward the bottoms  202 . Similarly, the saw tooth stop surface  188  and the angled surface  218  on the tabs  194  cause the sleeve  170  to rotationally index in response to movement of the sleeve  170  under urging of the biasing member  182 . Rotational stop surfaces  222  on the saw tooth stop surface  188 , act as an escapement  226  to prevent rotation of the sleeve  170  beyond the next slot  186 , thereby assure indexing of only one slot  186  per passage of one of the restriction engagers  114 . 
         [0028]    The foregoing structure provides a well operator with the means to set a restriction  118  to selectively pass a desired number of restriction engagers  114  by forming the tubular  162  with the desired number of shallow slots  186 A and  186 B before a deep slot  186 C. 
         [0029]    While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.