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BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   Embodiments of the present invention generally relate to methods and apparatus to sealably close and open a tubular within an oil and gas wellbore. More particularly, embodiments of the present invention generally relate to methods and apparatus for creating a fluid seal used to produce a pressure differential that is utilized to actuate a hydraulic tool downhole. 
   2. Description of the Related Art 
   Hydrocarbon wells typically begin by drilling a borehole from the earth&#39;s surface to a selected depth in order to intersect a hydrocarbon-bearing formation. Steel casing lines the borehole formed in the earth during the drilling process. This creates an annular area between the casing and the borehole that is filled with cement to further support and form the wellbore. Thereafter, the borehole is drilled to a greater depth using a smaller diameter drill than the diameter of the surface casing. A liner may be suspended adjacent the lower end of the previously suspended and cemented casing. This liner overlaps the casing enough to provide gripping engagement between the casing and liner when hung or suspended and extends to the bottom of the borehole. 
   In the completion of oil and gas wells, downhole tools are mounted on the end of a drill support member, commonly known as a work string. The work string may be rotated or moved in an axial direction from a surface platform or rig. Illustrative work strings include drill strings, landing strings, completion strings and production strings. Wellbore tubular members such as casing, liner, tubing, and work string define the fluid flow path within the wellbore. Commonly, a need arises to temporarily obstruct one or more of these fluid flow paths within the wellbore. An obstruction that seals the fluid flow path allows the internal pressure within a section of the tubular conduit to be increased. Hydraulically driven tools operate from this increased internal pressure. For example, a hydraulically operated liner hanger can be utilized to hang the liner to the well casing. However, a subsequent step in the completion of the oil or gas well may require the obstructed fluid path to be reopened without requiring the removal of the tubing string from the well in order to clear the obstruction. 
   Sealably landing a ball on a ball seat provides a common means of temporarily blocking the flow through a tubular conduit in order to operate a hydraulic tool thereabove. Thereafter, increasing pressure above the ball seat causes a shearable member holding the ball seat to shear, releasing the ball seat to move down hole with the ball. However, this leaves the ball and ball seat in the well bore, potentially causing problems for subsequent operations. 
   Another method of reopening the tubular conduit occurs by increasing the pressure above the ball seat to a point where the pressure forces the ball to deformably open the seat and allow the ball to pass through. In theses designs, the outer diameter of the ball represents the maximum size of the opening that can be created through the ball seat. This potentially limits the size of subsequent equipment that can pass freely through the ball seat and further downhole without the risk of damage or obstruction. 
   Hydraulic tools located above a ball seat are set to operate at a pressure below the pressure that opens or releases the ball seat. Internal pressures can become quite high when breaking circulation or circulating a liner through a tight section. In order to avoid premature operation of the tool at these times, the pressure required to open or release a ball seat needs to be high enough to allow for a sufficiently high activation pressure for the tool. 
   For example, predetermined open or release pressures that are set when the ball seat is assembled can exceed 3000 psi. Stored energy above the ball seat results from the compressibility of the fluid and any entrained gases along with the energy stored from the ballooning in the tubular conduit. Therefore, releasing or opening a ball seat by increased pressure can cause the ball to pass through the drill pipe at a relatively high velocity and prematurely release ball seats or shift sleeves located downhole. The large surge pressure created by the ball seat&#39;s release can also undesirably damage formations or cause hydraulic tools below the ball seat to actuate prematurely. 
   Even with precision manufacturing and extensive quality control, occasional malfunctions occur in the activation mechanisms of the tool and the release or opening mechanisms of the ball seat due to these devices&#39; dependency on hydraulic pressure. For example, when the ball seat opens or releases at a lower pressure than planned, the hydraulically operated tool may not have activated or completed its function. Similarly, if the hydraulically operated tool does not function at its desired pressure, the ball seat may reach its release or opening pressure before the tool is activated. 
   Since the ball seat is a restriction in the wellbore, it must be opened up, moved out of the way, or located low enough in the well to not interfere with subsequent operations. Commonly, the ball seat is moved out of the way by having it drop down hole. Unfortunately, this may require the removal of both the ball and ball seat at a later time. Ball seats made of soft metals such as aluminum provide easier drill out; however, they may not properly seat the ball due to erosion caused by high volumes of drilling mud being pumped through the reduced diameter of the ball seat. Interference from the first ball seat being released downhole may also prevent the ball from sealably landing on another ball seat below. Current collet style mechanisms open up in a radial direction when shifted past a larger diameter grove. However, these ball seats are more prone to leaking than the solid ball seats, and the open collet fingers exposed inside the tubular create the potential for damaging equipment used in subsequent wellbore operations. 
   Wiper plugs often possess ball catchers that capture the ball when it is released. Thus, they must withstand the shock force imparted when the ball is released and subsequently caught. If a ball seat is alternatively placed in or at the bottom of the wiper plugs, then they must withstand the added force of the pressure acting on the ball seat. However, wiper plugs are built from materials that can be easily drilled in order to minimize drill out times. This requires a balance of strength versus drillability. Placing the ball seat above the wiper plugs provides an acceptable solution only if the released ball and ball seat do not interfere or obstruct the tubular passage during subsequent wellbore operations. 
   Therefore, there exists a need for an improved apparatus and method for temporarily blocking a fluid path in a wellbore in order to operate a hydraulic tool. There is a further need for a ball seat that does not depend on hydraulic pressure for release, that releases without causing a surge in the tubular below, that can be placed above the wiper plugs, that withstands an impact of a ball released above, that withstands erosion, and that leaves a substantially unobstructed passage through the bore once opened. 
   SUMMARY OF THE INVENTION 
   The present invention generally relates to a method and apparatus for obstructing the passage of fluid within a fluid flow conduit and subsequently reconfiguring the tool to allow substantially full-bore passage therethrough. Pressure developed upstream of the obstruction can be utilized to operate pressure actuated tools such as liner hangers. Equipment used in subsequent wellbore operations such as drill pipe darts can pass undamaged through the opened port. In one embodiment of the invention, the flow through a tubular is obstructed by placing a ball on an expandable ball seat, developing a pressure differential across the ball seat, equalizing the pressure after the hydraulically actuated tool completes its function, and mechanically manipulating the drill string to open the expandable ball seat and allow the ball to pass through. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention, and other features contemplated and claimed herein, 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. 1A  is a longitudinal section view of an embodiment of the invention as it would appear when run in a well bore. 
       FIG. 1B  is an enlarged partial view of a rack and pinion assembly that rotates a multiposition valve shown in the section view of FIG.  1 A. 
       FIG. 1C  is an enlarged view of  FIG. 1A  rotated 90° to better illustrate the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 2A  is a view of the embodiment as shown in  FIG. 1A  with a ball positioned within the multiposition valve to close the axial fluid delivery bore. 
       FIG. 2B  is a view of  FIG. 2A  rotated 90° to better illustrate the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 3A  is a view of the embodiment as shown in  FIG. 1A  during the first stage of the mechanical opening of the multiposition valve. 
       FIG. 3B  is a view of  FIG. 3A  rotated 90° to better illustrate the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 4A  is a view of the embodiment as shown in  FIG. 1A  immediately after rotation of the multiposition valve opens the axial fluid delivery bore. 
       FIG. 4B  is an enlarged partial view of the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 4C  is a view of  FIG. 4A  rotated 90° to better illustrate the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 5A  is a view of the embodiment as shown in  FIG. 1A  during the stage following the rotation of the multiposition valve. 
       FIG. 5B  is a view of  FIG. 5A  rotated 90° to better illustrate the rack and pinion assembly that rotates the multiposition valve. 
       FIG. 6  is an enlarged longitudinal section view of an alternative embodiment of the multiposition valve as it would appear when run in the well bore. 
       FIG. 7  is a longitudinal section view of an alternative embodiment of the invention as it would appear in a well bore after seating a ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 8  is a view of the embodiment in  FIG. 7  with a stab raised during the first stage of the ball seat opening. 
       FIG. 9  is a view of the embodiment in  FIG. 7  after the ball support member has been moved axially away from the ball seat support member in a second stage of the ball seat opening. 
       FIG. 10  is a view of the embodiment in  FIG. 7  after the stab is raised in a subsequent stage of the ball seat opening. 
       FIG. 11  is a view of the embodiment in  FIG. 7  with an open axial fluid delivery bore after the stab opened the ball seat. 
       FIG. 12  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 13  is a section view across plane  15  of FIG.  12 . 
       FIG. 14  is a view of the embodiment in  FIG. 12  at a first stage in the opening of the ball seat. 
       FIG. 15  is a view of the embodiment in  FIG. 12  with an open axial fluid delivery bore after the stab opened the ball seat. 
       FIG. 16  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 17  is a view of the embodiment in  FIG. 16  at a stage after raising the retaining member in order to release the ball and ball seat member. 
       FIG. 18  is a view of the embodiment in  FIG. 16  at a stage when the ball and ball seat member have moved axially downhole. 
       FIG. 19  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 20  is a view of the embodiment in  FIG. 19  at a stage after raising the retaining member in order to release the ball and ball seat member. 
       FIG. 21  is a view of the embodiment in  FIG. 16  at a stage when the ball and ball seat member have moved axially downhole. 
       FIG. 22  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 23  is a view of the embodiment in  FIG. 22  with the inner sleeve raised during the first stage of the ball seat opening. 
       FIG. 24  is a view of the embodiment in  FIG. 22  with an open axial fluid delivery bore. 
       FIG. 25  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 26  is a view of the embodiment in  FIG. 25  at a stage after raising the retaining member in order to release the ball and ball seat member. 
       FIG. 27  is a view of the embodiment in  FIG. 26  at a stage when the ball and ball seat member have moved axially downhole. 
       FIG. 28  is a longitudinal section view of another alternative embodiment of the invention as it would appear in a well bore after seating the ball in the ball seat to close the axial fluid delivery bore. 
       FIG. 29  is a view of the embodiment in  FIG. 28  at a stage after raising the retaining member in order to release the ball and ball seat member. 
       FIG. 30  is a view of the embodiment in  FIG. 29  at a stage when the ball and ball seat member have moved axially downhole. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention generally relates to an apparatus and method for temporarily sealing a fluid flow conduit within a wellbore in order to operate hydraulic tools therein.  FIG. 1A  illustrates an embodiment of the present invention as it would appear positioned inside a liner  100  within a wellbore  102 . Visible in  FIG. 1A  is a telescoping sleeve  104  held within a sub  106  that is connected to a work string  108 , an expandable c-ring  110  that circumscribes the sub, a biasing member  112  that acts on the telescoping sleeve, a multiposition valve  114  with a ball seat  116 , and a slideable inner sleeve  118  positioned inside an outer member  120 . The axial position of the outer member is fixed relative to the liner  100 .  FIG. 1C  provides a cross section view of the tool shown in  FIG. 1A  as it would appear rotated ninety degrees. An enlarged view of one embodiment of the multiposition valve as seen from the angle displayed in  FIG. 1A  is visible in FIG.  1 B. Axial movement of the work string  108  can be performed from the surface of the well. In the run in position of  FIG. 1 , the rotation of the multiposition valve  114  is positioned so that the ball seat  116  within the multiposition valve is opposite an aperture in the multiposition valve that forms the first fluid flow pathway  122 . Therefore, a channel is created through the multiposition valve that provides a substantially open bore and allows fluid to flow though the multiposition valve. When the tool is in the run in position, a telescoping sleeve  104  is located within the first fluid flow pathway  122  in the multiposition valve and rests on a portion of the multiposition valve adjacent to the ball seat. The telescoping sleeve  104  is held within the lower portion of the sub  106  by an outwardly biased shoulder  124  on the telescoping sleeve that travels within a cavity  126  created by an increased inner diameter of the sub. A biasing member  112  is located above the outwardly biased shoulder  124  on the telescoping sleeve  104  and within the cavity  126  formed by the telescoping sleeve  104  and the portion of the sub  106  with an increased inner diameter. Therefore, the biasing member  112  acts downward on the telescoping sleeve and allows for tolerance between the telescoping sleeve and the surfaces on the multiposition valve that it contacts. The inserted telescoping sleeve  104  within the multiposition valve  114  acts as a guide by preventing the ball  200  and fluid from entering other apertures  128  and  130  within the multiposition valve. 
     FIG. 1B  illustrates an embodiment providing for the means of rotating the multiposition valve shown in FIG.  1 A and  FIG. 1C  by a rack and pinion assembly  135 . Two arms  132  extend from opposite sides of the inner sleeve&#39;s lower end. The ends of each arm possess teeth  134  that are aligned and positioned to engage gears  136  that are attached to the multiposition valve  114 . Both the gears and the multiposition valve rotate in the same axis of rotation.  FIG. 1B  shows the position of the inner sleeve  118  as illustrated in FIG.  1 A and FIG.  1 C. Other known techniques known in the art may be utilized to provide the means of rotation for the multiposition valve  114 . These techniques include but are not limited to linkage, levers, cams, torsion spring, and hydraulics. 
   An enlarged view of the tool shown in  FIG. 1A  is illustrated in  FIG. 2A  with a ball  200  seated on the ball seat  116 . After the tool was in position and at a predetermined time, a ball  200  was dropped or pumped through the tubular from the surface. Since the inner diameter of the ball seat  116  is smaller than the outer diameter of the ball  200 , the ball landed on the ball seat and obstructed the axial fluid flow path  202  to create a fluid seal above the ball and ball seat. Pressure above the ball seat can be increased to actuate a hydraulic tool such as a liner hanger (not shown). The pressure differential can be equalized once the hydraulic tool has been actuated. A small downward movement of the work string  108  is often utilized to disengage the setting tool upon completion of suspending the liner. This downward movement is transposed down through the work string  108 , sub  106 , and telescoping sleeve  104 . Therefore, the biasing member  112  that keeps the telescoping sleeve in contact with the multiposition valve accommodates this movement. In the embodiment shown in  FIG. 1A , the biasing member  112  is a spring. 
     FIG. 3A  shows the device in  FIG. 1A  after the work string  108  has been moved up from the surface of the well. Support of the liner&#39;s weight is transferred to the casing (not shown) after the liner hanger (not shown) suspends the liner. Releasing the liner running tool from the liner  100  (shown in  FIG. 1A ) allowed relative motion between the work string  108  and the liner. Axial movement of the work string  108  moved the sub  106  and telescoping sleeve  104  within the tool. Therefore,  FIG. 3  shows the tool after the work string  108  has been raised a distance greater than the measure between the c-ring  110  and the top of the inner sleeve  118  when in the run in position. At this point, checking the weight on the work string verifies that the liner is properly hung off since the work string should be free of the load created by the liner. The upward movement of the work string  108  raised the telescoping sleeve  104  to a position above the multiposition valve  114 . In the run in position of the tool, the c-ring  110  is held in a compressed state within a preformed profile  138  on the sub  106  by the inner diameter of the inner sleeve  118  preventing its expansion. Therefore, the c-ring has expanded to its relaxed state since it is now positioned above the inner sleeve. However, the inner diameter of the c-ring  110  remains smaller than the outer diameter of the sub  106 , and the outer diameter of the c-ring  110  is now larger than the inner diameter of the inner sleeve  118 . Thus, a portion of the top of the preformed profile  138  within the sub  106  contacts a portion of the top of the c-ring  110  and a section of the bottom of the c-ring  110  contacts a section of the top of the inner sleeve  118 . The “X”  300  visible in  FIG. 3A  represents the convergence of the first fluid flow pathway  122 , the fluid flow pathway two  128 , and the fluid flow pathway three  130 . 
   In  FIG. 4A , the inner sleeve  118  has been moved axially downwards in relation to the outer member  120  in order to place the tool in its open position. Movement of the inner sleeve in relation to the outer member occurred by mechanical axially downward movement of the work string  108  from the surface. Axial movement of the work string also moved the attached sub  106  axially. The uncompressed c-ring  110  contacted with the sub  106  and inner sleeve  118  to transfer the sub&#39;s axial movement to the inner sleeve  118 . Therefore, the work string  108 , sub  106 , c-ring  110 , and inner sleeve  118  moved axially in unison through the outer member  120 . The inner sleeve continued sliding through the outer member until the plurality of outwardly biased collet fingers  140  located on the top of the inner sleeve expanded into a preformed profile  142  on the outer member. Outward expansion of the collet fingers increased the inner diameter of the top portion of the inner sleeve. Therefore, the enlarged inner diameter of the inner sleeve is larger than the outer diameter of the uncompressed c-ring  110 . Sliding the inner sleeve  118  from its run in position to the open position in  FIG. 4  rotated the multiposition valve  114  approximately ninety degrees. The rotation positioned the ball  200  and ball seat  116  from being aligned in the axial fluid delivery bore  202  to a position adjacent to the axial fluid delivery bore. In the open position, fluid flow pathway two  128  and fluid flow pathway three  130  are apertures in the multiposition valve  114  that are aligned with the axial fluid delivery bore  202  to provide a substantially open passage through the multiposition valve. Initially, the ball  200  stays seated on the ball seat  116  during the rotation of the multiposition valve due to frictional contact between the ball  200  and ball seat  116 .  FIG. 4B  depicts a view of the gear  136  on the multiposition valve  114  after the inner sleeve  118  has been lowered and the multiposition valve  114  has been subsequently rotated as shown in FIG.  4 A and FIG.  4 C. While the foregoing describes sliding the inner sleeve  118  with axial movement of the workstring, known methods of utilizing rotational movement of the workstring may be used to accomplish the same axial movement of the inner sleeve. 
     FIG. 5A  illustrates the final position of the embodiment shown in  FIG. 1A  with the telescoping sleeve  104  inserted into the multiposition valve  114 . Movement of the telescoping sleeve  104  into fluid flow pathway three  130  on the multiposition valve occurred by continued mechanical axially downward movement of the work string  108  from the surface. Due to the lack of contact between the c-ring  110  and the top of the inner sleeve  118 , the work string  108  and sub  106  passed inside the inner sleeve  118  that was held in position on the outer member  120  by collet fingers  140  engaging the outer member  120 . A lower portion of the telescoping sleeve  104  contacts a surface adjacent the fluid flow pathway two  128  on the multiposition valve. Therefore, the telescoping sleeve  104  traps the ball  200  within the multiposition valve thereby blocking the ball  200  from entering the axial fluid delivery bore  202  and closes other apertures on the multiposition valve in order to guide subsequent equipment (not shown) through the multiposition valve. 
     FIG. 6  illustrates an embodiment of the invention shown in  FIG. 1A  wherein the ball  200  (which could be a different size than the ball supposed to land in ball seat  116 ) is carried within the multiposition valve  114  in flow pathway two  128  or three  130  in the run in position of the tool. Upon operation of the tool resulting in flow pathway two  128  and flow pathway three  130  to be aligned with the main bore of the tool, the ball will be released in order to sealably land on a ball seat further downhole. In addition, one skilled in the art may envision a rotatable valve similar to the one described herein that possesses a closed portion in the place of the ball seat. One skilled in the art could also foresee a multiposition valve like the one described in  FIGS. 1-6  that rotates to more than two positions. 
   Additionally, rather than rotating a valve to an open position, a valve could be utilized having at least one additional flow pathway with an axis therethrough that is parallel to the axis of a flow pathway having a ball seat therein. By shifting the valve components laterally, a second, substantially unobstructed flow pathway could be provided through the valve. 
     FIG. 7  represents another embodiment of the present invention. It shows a ball  700 , a ball seat  702 , a ball seat support member  704  annularly disposed around the ball seat in the position of  FIG. 7 , a sleeve  706  which is slidable and fixed to the ball seat with a lateral opening  708  therethrough and a stab  710  which is lockable to the sleeve and is mechanically fixed to the work string  712  which includes a lateral aperture  714  therethrough. The run in position for the tool would be the same as shown in  FIG. 7  except that the ball  700  would not be present.  FIG. 7  shows the device as it would appear in a wellbore after the ball  700  has been seated on the ball seat  702 . The ball was dropped or pumped through the tubular from the surface after the tool was in position and at a predetermined time. The ball cannot pass beyond the ball seat since the inner diameter of the ball seat is smaller than the outer diameter of the ball. In this position, the ball sealably obstructs fluid flow in the axial fluid delivery bore  716 . An o-ring  718  on the outside of the sleeve prevents fluid flow between the sleeve and outer member. Similarly, an o-ring  720  above the lateral port on the sleeve and an o-ring  722  below the lateral port  708  on the sleeve prevents fluid flow between the stab and the sleeve. Therefore, a fluid seal above the ball and ball seat allows this section of tubular to be pressurized in order to operate a hydraulic device such as a liner hanger. A lateral opening  714  located in the work string  712  provides a fluid path for pressurized fluid to travel to the hydraulic device (not shown). Once the hydraulic tool has completed its function, the increased pressure above the ball and ball seat can be relieved. 
     FIG. 8  shows the device of  FIG. 7  with the stab  710  having been moved up in relation to the sleeve  706  in order to expose the lateral opening  708  in the sleeve to fluid pressure. Therefore, a fluid path between areas above and below the ball and ball seat has been created, and the pressure above and below the ball and ball seat has been equalized. Axial movement of the work string  712  (shown in  FIG. 7 ) can be performed from the surface of the well. Thus, upward axial movement of the work string provided the movement of the attached stab relative to the sleeve. A portion of the stab with a decreased outer diameter forms an outwardly facing shoulder  724 . Similarly, a plurality of collet fingers  726  on an upper portion of the inner sleeve  706  have a section of increased inner diameter that forms an inward facing shoulder  728 . Also shown in the  FIG. 8 , the stab  710  has been raised until the outwardly facing shoulder  724  on the stab contacts the inwardly facing shoulder  728  on the inner sleeve  706 . 
     FIG. 9  illustrates the next step in operation of the device in  FIG. 7  whereby the stab  710 , the sleeve  706 , and the ball seat  702  have been raised in relation to the outer member  730  and the ball seat support member  704 . Further upward movement of the work string placed the stab upward relative to the outer member. Upward movement of the sleeve in relation to the outer member is made possible by the contact between the outward shoulder on the stab contacting the inward shoulder on the sleeve. In  FIG. 9 , the sleeve has been raised until the outwardly biased collet fingers  726  on the sleeve contact a preformed profile  732  formed in the outer member  730 . Similarly, one skilled in the art could envision using an outwardly biased c-ring instead of the collet fingers for engaging the outer member.  FIG. 10  illustrates the device in a subsequent position showing the sleeve  706  fixed to the outer member  730  and stab  710  raised from its position in FIG.  9 . At this point, checking the weight on the work string verifies that the liner is properly hung off since the work string should be free of the load created by the liner. 
     FIG. 11  shows the tool in  FIG. 7  in its open position after the actual release of the ball downhole. Downward axial movement of the work string  712  (shown in  FIG. 7 ) has moved the stab  710  axially downwards in relation to the sleeve  706  and the ball seat  702  which are secured to the outer member  730  by the expanded collet fingers  726  engaging the preformed profile  732  on the outer member. A lower portion of the stab comprises a ball seat engaging end  734  that has increased an inside diameter of the ball seat  702 , permitting the ball  700  to fall free. The stab covers the inside of the expanded ball seat when the tool is in its open position. This creates a substantially open axial fluid delivery bore and protects subsequent equipment that passes through the tool. Further, one skilled in the art could envision a segmented lower portion of the stab with an initial inner diameter larger than the outer diameter of the ball. When this segmented lower portion of the stab engages the ball support it is collapsed down to an inner diameter smaller than the outer diameter of the ball in order to engage the ball and push it through the ball seat. 
     FIG. 12  illustrates another embodiment of the present invention. This figure shows a ball  1200 , a ball support member  1202  with a ball seat  1204  positioned at a lower end, a ball seat support member  1206  with a ball seat support surface  1208  annularly disposed around the ball seat, a stab  1210 , and a slidable sleeve  1212  secured to a top sub  1213  by a shear screw  1216 . The top sub  1213  is connected to the upper outer member  1215  which is connected to the lower outer member  1214  to form the entire outer portion of the tool. A plurality of collet fingers  1218  on an upper portion of the stab  1210  are held within a preformed profile  1220  on the upper outer member  1215  due to the outer surface of the inner sleeve  1212  contacting the collet fingers and preventing them from moving out of the preformed profile. This secures the stab to the upper outer member. An upper portion  1222  of the ball support member  1202  possesses an increased outer diameter that engages an area of increased inner diameter of the lower outer member  1214 . The ball seat support member  1206  extends upward from the ball seat support surface  1208  between the ball support member  1202  and the lower outer member  1214 . Additionally, three longitudinally elongated apertures  1224  in the ball support member allow three keys  1226  to connect the ball seat support member  1206  to the stab  1210 .  FIG. 13  shows a cross section view of the tool across the area where the keys  1226  connect the ball seat support member  1206  to the stab  1210 . The piston chamber  1228  is defined by a portion of the sleeve  1212  with a decreased outer diameter that passes inside a portion of the stab  1210  with an increased inner diameter. A lateral opening  1230  in the stab provides a fluid path for pressurized fluid to enter the piston chamber. Additionally, an o-ring  1232  circumscribing the stab and an o-ring  1234  circumscribing the sleeve seal the piston chamber. The o-ring  1234  around the sleeve separates fluid pressure between the piston chamber  1228  and the bore pressure chamber  1236 . A second o-ring  1238  circumscribing the sleeve on the opposite end of the bore pressure chamber seals the bore pressure chamber from the rest of the tool. A portion of the upper outer member  1215  with a larger inner diameter than a portion of the sleeve  1212  with a decreased outer diameter and a lower portion of the top sub  1213  define the bore pressure chamber  1236 . A lateral opening  1240  in the upper outer member adjoining the bore pressure chamber allows pressure equalization between the bore pressure chamber and the annular bore. The atmospheric, ATM, chamber  1242  is created between the stab  1210  and the upper outer member  1215  due to a cavity between an outwardly biased shoulder  1244  of the stab and the inward facing shoulder  1246  of the upper outer member. Since the ATM chamber is sealed prior to lowering the tool in the well, the gas within the ATM chamber remains at atmospheric pressure. An o-ring  1232  circumscribing the stab above the ATM chamber and an o-ring  1248  circumscribing the stab below the ATM chamber further seals the gas in the ATM chamber from the rest of the tool. 
   The run in position of this embodiment would be the tool as shown in  FIG. 12  without the ball  1200 . In the run in position, the ball seat  1204  has a smaller inner diameter than the outer diameter of the ball  1200 . At a predetermined time once the tool is in position a ball was dropped or pumped through the bore in order to seal the axial fluid delivery bore  1256  by landing the ball on the ball seat. An o-ring  1250  circumscribing the ball support member adjacent to the ball seat provides a fluid seal between the ball support member  1202  and the ball seat support member  1206 . Another o-ring  1252  circumscribing the ball seat support member  1206  prevents fluid passage between the ball seat support member and the lower outer member  1214 . Therefore, fluid above the ball and ball seat can be pressurized to operate a hydraulic tool such as a liner hanger located above the ball and ball seat. 
     FIG. 14  shows the sleeve  1212  raised with respect to the upper outer member  1215  in the first step in opening the axial fluid delivery bore. The movement of the sleeve was accomplished when fluid pressure above the ball and ball seat was increased beyond the pressure required to actuate the hydraulic tool. The increased fluid pressure within the axial fluid delivery bore acted in an upward force on the sleeve  1212  due to the increased pressure in the piston chamber  1228  relative to the bore pressure chamber  1236 . This increased pressure sheared the shear screw  1216  that attached the sleeve to the top sub and pushed the sleeve upward with respect to the top sub. The portion of the sleeve  1212  with an increased outer diameter that previously contacted the collet fingers  1218  has been moved past the collet fingers and thereby allowed the collet fingers to move inward and out of the performed profile  1220 . 
   In  FIG. 15 , the stab  1210  and the ball seat support member  1206  have been moved axially downwards in relation to the ball support member  1202  and the lower outer member  1214 . Under the increased pressure surrounding the ATM chamber  1242  while downhole, the ATM chamber volume collapsed once the collet fingers  1218  on the stab were liberated from the upper outer member and the stab was free to move. As a result, the stab moved downward until the shoulder  1244  of the stab that forms the top of the ATM chamber was proximate the shoulder  1246  of the upper outer member that forms the bottom of the ATM chamber. Since the ball seat support member  1206  is connected to the stab  1210  with three keys  1226 , it traveled downward respectively with the stab. Therefore, the downward movement of the stab caused a lower portion of the stab comprising a ball seat engaging end  1254  to increase an inside diameter of the ball seat permitting the ball  1200  to fall free. In addition, one skilled in the art could envision a segmented stab with an initial inner diameter larger than the outer diameter of the ball, that when it engages the ball support it collapses down to an inner diameter smaller than the outer diameter of the ball in order to push the ball through the ball seat. 
     FIG. 16  illustrates another embodiment of the present invention. This figure shows a ball  1600 , a ball support member  1602  with a ball seat  1604  at a lower portion thereof, a retaining member  1606 , and an outer member  1608 . Run in position for the tool would be the tool as shown in  FIG. 16  without the ball  1600 . A plurality of collet fingers  1610  on an upper portion of the ball support member  1602  engage a shoulder  1612  that is formed by a portion of the outer member  1608  with an increased inner diameter. The outer diameter of the retaining member  1606  contacts the inner diameter of the collet fingers and prevents their release from the shoulder  1612  on the outer member. Therefore, a securing assembly comprising the collet fingers  1610  and retaining member  1606  maintain the ball seat  1604  and ball support member  1602  in the run in position. At a predetermined time once the tool was in position a ball was dropped or pumped through the bore in order to seal the axial fluid delivery bore  1614  by landing the ball  1600  on the ball seat  1604 . An o-ring  1616  circumscribing the inner diameter of the outer member prevents fluid flow between the ball support member and the outer member. 
     FIG. 17  shows the retaining member  1606  axially raised with respect to the outer member  1608  and ball support member  1602 . Movement of the retaining member that is attached to the work string (not shown) was accomplished by axial movement of the work string from the surface. Since the retaining member  1606  has been moved out of contact with the collet fingers  1610 , the collet fingers can move inward and out of the shoulder  1612  on the outer member. Fluid pressure above the ball  1600  and ball support member  1602 , gravity, or a biasing member acting on the ball support member has moved the ball and ball support member axially with respect to the outer member  1608  as shown in FIG.  18 . This movement continues until the ball and ball seat drop down the borehole creating an open axial fluid delivery bore  1614 . 
     FIG. 19  shows another embodiment of the present invention. This figure shows a ball  1900 , a ball support member  1902  with a ball seat  1904  at a lower portion thereof, a retaining member  1906 , and an outer member  1908 . Run in position for the tool would be the tool as shown in  FIG. 19  without the ball  1900 . A plurality of dogs  1910  on an upper portion of the ball support member  1902  engage a preformed profile  1912  that is formed by a portion of the outer member  1908  with an increased inner diameter. The outer diameter of the retaining member  1906  contacts the inner surface of the dogs  1910  and prevents their release from the preformed profile  1912  on the outer member. Therefore, a securing assembly comprising the dogs  1910  and retaining member  1906  maintain the ball seat  1904  and ball support member  1902  in the run in position. At a predetermined time once the tool was in position a ball was dropped or pumped through the bore in order to seal the axial fluid delivery bore  1914  by landing the ball  1900  on the ball seat  1904 . An o-ring  1916  circumscribing the inner diameter of the outer member prevents fluid flow between the ball support member and the outer member. 
     FIG. 20  shows the retaining member  1906  axially raised with respect to the outer member  1908  and ball support member  1902 . Movement of the retaining member that is attached to the work string (not shown) was accomplished by axial movement of the work string from the surface. Since the retaining member  1906  has been moved out of contact with the dogs  1910 , the dogs can move inward and out of the preformed profile  1912  on the outer member. Fluid pressure above the ball  1900  and ball support member  1902 , gravity, or a biasing member acting on the ball support member has moved the ball and ball support member axially with respect to the outer member  1908  as shown in FIG.  21 . This movement continues until the ball and ball seat drop down the borehole producing an open axial fluid delivery bore  1914 . 
     FIG. 22  shows another embodiment of the present invention. This figure shows a ball  2200 , a ball support member  2202  with a segmented ball seat  2204  at an upper portion thereof, a support member  2206 , and an outer member  2208 . Run in position for the tool would be the tool as shown in  FIG. 22  without the ball  2200 . An inner diameter of the support member  2206  contacts an outer diameter of the ball seat  2204  and prevents radial outward expansion of the ball seat that would thereby increase the inner diameter of the ball seat. At a predetermined time once the tool was in position a ball was dropped or pumped through the bore in order to seal the axial fluid delivery bore  2210  by landing the ball  2200  on the ball seat  2204 . An o-ring  2212  circumscribing the inner diameter of the outer member prevents fluid flow between the ball support member and the outer member. 
     FIG. 23  shows the support member  2206  axially raised with respect to the outer member  2208  and ball support member  2202 . Movement of the support member that is attached to the work string (not shown) was accomplished by axial movement of the work string from the surface. Since the inner diameter of the support member  2206  has been moved out of contact with the outer diameter of the ball seat  2204 , the ball seat segments are free to open up in the radial direction. Radial expansion of the ball seat increases the inner diameter of the ball seat  2204  until the ball  2200  is permitted to fall down hole as seen in FIG.  24 . 
     FIG. 25  illustrates another embodiment of the present invention. This figure shows a ball  2500 , a ball support member  2502  with a ball seat  2504  at a lower portion thereof, a retaining member  2506 , and an outer member  2508 . Run in position for the tool would be the tool as shown in  FIG. 25  without the ball  2500 . A plurality of dogs  2510  positioned at a lower end of the retaining member  2506  engage a preformed profile  2512  on the outside diameter of the ball support member  2502  and prevent axial movement of the ball seat and ball support member relative to the retaining member. The inside diameter of the outer member  2508  contacts the outside surface of the dogs  2510  and prevents their release from the preformed profile  2512  on the ball support member. Therefore, a securing assembly comprising the dogs  2510  and retaining member  2506  maintain the ball seat  2504  and ball support member  2502  in the run in position. An o-ring  2516  circumscribing the outer diameter of the ball support member prevents fluid flow between the ball support member and the outer member.  FIG. 26  shows the retaining member  2506  axially moved to a position adjacent a section  2518  of the outer member  2508  with an increased inside diameter, thereby permitting the dogs  2510  to move outward and out of the preformed profile  2512  on the ball support member  2502 . Therefore, fluid pressure above the ball and ball support member, gravity, or a biasing member acting on the ball support member can move the ball and ball support member axially as shown in FIG.  27 . This axial movement continues until the ball and ball seat drop down the borehole creating an open axial fluid delivery bore  2514 . 
     FIG. 28  illustrates another embodiment of the present invention. This figure shows a ball  2800 , a ball support member  2802  with a ball seat  2804  at a lower portion thereof, a retaining member  2806 , and an outer member  2808 . Run in position for the tool would be the tool as shown in  FIG. 28  without the ball  2800 . A plurality of collet fingers  2810  positioned at a lower end of the retaining member  2806  engage a preformed profile  2812  on the outside diameter of the ball support member  2802  and prevent axial movement of the ball seat and ball support member relative to the retaining member. The inside diameter of the outer member  2808  contacts the outside diameter of the collet fingers  2810  and prevents their release from the preformed profile  2812  on the ball support member. Therefore, a securing assembly comprising the collet fingers  2810  and retaining member  2806  maintain the ball seat  2804  and ball support member  2802  in the run in position. An o-ring  2816  circumscribing the outer diameter of the ball support member prevents fluid flow between the ball support member and the outer member.  FIG. 29  shows the retaining member  2806  axially moved to a position adjacent a section  2818  of the outer member  2808  with an increased inside diameter. This permits the collet fingers  2810  to expand outward and out of the preformed profile  2812  on the ball support member  2802 . Therefore, fluid pressure above the ball and ball support member, gravity, or a biasing member acting on the ball support member can move the ball and ball support member axially as shown in FIG.  30 . This axial movement continues until the ball and ball seat drop down the borehole creating an open axial fluid delivery bore  2814 . 
   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.

Summary:
A method and apparatus for obstructing the passage of fluid within a fluid flow conduit and subsequently reconfiguring the tool to allow substantially full-bore passage therethrough. Pressure developed upstream of the obstruction can be utilized to operate pressure actuated tools such as liner hangers. Equipment used in subsequent wellbore operations such as drill pipe darts can pass undamaged through the opened port. In an embodiment, the flow through a tubular is obstructed by placing a ball on an expandable ball seat, developing a pressure differential across the ball seat, equalizing the pressure after the hydraulically actuated tool completes its function, and mechanically manipulating the drill string to open the expandable ball seat and allow the ball to pass through.