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[0001]     This application claims priority to Provisional Patent Application 60/695,828 filed on Jun. 30, 2005 and entitled, “Downhole Bypass Valve” the contents of which are incorporated herein by reference for all purposes. New matter has been added. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     A wellbore may be drilled in the earth for various purposes, such as hydrocarbon extraction, geothermal energy, or water. After a wellbore is drilled, the wellore is typically lined with casing. The casing preserves the shape of the wellore as well as provides a sealed conduit for fluid to be transported to the surface.  
         [0003]     In general, it is desirable to maintain a clean wellore to prevent possible complications that may occur from debris in the wellore. For example, accumulation of debris can prevent free movement of tools through the wellore during operations, as well as possibly interfere with production of hydrocarbons or damage tools. Potential debris includes cuttings produced from the drilling of the wellore, metallic debris from the various tools and components used in operations, and corrosion of the casing. Much of this debris may be removed by increasing the annular fluid velocity to bring larger particles to the surface of the wellbore.  
         [0004]     However, over time, the casing or liner within the wellbore becomes covered with hard deposits. These deposits must be periodically removed or they can build up to levels of thickness and hardness where they can adversely affect efficient operation of the oil well.  
         [0005]     Many tools operate continuously through a wellbore, for example scrapers and brushes. While it is useful to have such continuous use tools, it is often beneficial to have tools that are selectively operable when the tool has reached a preferred location in the wellbore.  
         [0006]     Cleaning involves spraying or jetting the inner wall of the casing with cleaning fluid at very high pressure to break up and dislodge the deposited material. A cleaning device having side jetting nozzles is lowered into the wellbore casing on the end of a drill string. Once a section of the wellbore casing has been jet cleaned, the cleaning device is withdrawn from the wellbore casing and removed from the end of the string. The drill string is then returned to the wellbore casing and cleaning fluid is run through the casing to a point below the section of the wellbore casing that was jet cleaned. The cleaning fluid circulates upward through the annulus between the wellbore casing and the drill string, carrying material dislodged during the jetting operation to the top of the wellbore casing. This operation of jetting and flushing is repeated as necessary to clean the wellbore casing of deposited material. Many cleaning and jetting tools use multiple balls to actuate and de-actuate the tool. It would be an improvement to have a cleaning tool that can be actuated and de-actuated without the need to use multiple balls.  
       SUMMARY  
       [0007]     In one aspect, the disclosed invention relates to an apparatus for cleaning a wellbore casing including an outer housing having an axial through passage between an inlet and a first outlet wherein the inlet and the first outlet are adapted for connection in a work string, the outer housing having a second outlet extending in a direction generally transversely of the through passage, an index mandrel slidably located within the outer housing and having an axial bore extending therethrough, the index mandrel being movable relative to the outer housing between a first position in which the second outlet is closed and a second position in which the second outlet is open, a ball seat located on an upper end of the index mandrel, a spring located within the outer housing and biasing the index mandrel toward the first position, a ball retainable on the ball seat to prevent flow from the inlet to the first outlet, and wherein application of a first pressure on the ball forces the index mandrel against the spring into the second position and reduction of said first pressure permits return of the index mandrel to the second position.  
         [0008]     In another disclosed embodiment of the invention, a method of cleaning an inner surface of a casing in a wellbore includes lowering a jetting tool on a work string into the wellbore to a desired location, wherein the jetting tool has an outer housing with an axial through passage between an inlet and a first outlet, the outer housing also having a second outlet substantially transverse to the axial through passage, and an index housing slidingly retained within the outer housing in a first position such that the second outlet is closed, the index housing having a ball seat on an upper end and being biased toward the first position, dropping a ball into the axial through passage to rest on the ball seat, thereby preventing fluid flow between the inlet and the first outlet of the axial through passage, causing fluid pressure to force the index housing to a second position wherein the second outlet is open, circulating fluid from the axial through passage and the second outlet at a fluid pressure sufficient to clean the casing, decreasing the fluid pressure to return the index housing to the first position, increasing the fluid pressure to move the index housing to a third position wherein the second outlet is closed, and wherein the increased fluid pressure is sufficient to shear the ball from the ball seat, thereby reducing the fluid pressure on the index housing causing it to return to the first position.  
         [0009]     In another embodiment of the disclosed invention, a method of opening and closing an outlet through a side of a cylindrical outer housing of a jetting tool in a wellbore includes biasing the index housing to an upward position within the outer housing in which the index housing is blocking the fluid outlet through the side of the outer housing, dropping a ball to seal against a ball seat located at the upper end of the index housing and block fluid flow through the jetting tool, forcing the index housing to a lower position inside the outer housing as a result of increased pressure behind the ball, wherein the fluid outlet through the side of the outer housing is open, reducing the fluid pressure on the ball to permit the biasing of the index housing towards the upward position, wherein the fluid outlet through the side of the outer housing is closed, and increasing the fluid pressure on the ball to a pressure sufficient to shear the ball through the ball seat, thereby permitting the index housing to return to the upward position.  
         [0010]     Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a cross-sectional view of an embodiment of a well cleaning tool.  
         [0012]      FIG. 2  is a front view of an embodiment of a well cleaning tool.  
         [0013]      FIG. 3  is a detail cross sectional view of an embodiment of a well cleaning tool.  
         [0014]      FIG. 4  is a layout of an embodiment of an indexing groove.  
         [0015]      FIG. 5  is a schematic of a well cleaning tool in a first, run-in-hole, position.  
         [0016]      FIG. 6  is a schematic of a well cleaning tool in a second, jetting, position.  
         [0017]      FIG. 7  is a schematic of a well cleaning tool in a third, intermediate, position.  
         [0018]      FIG. 8  is a schematic of a well cleaning tool in a fourth, ball shear, position.  
         [0019]      FIG. 9  is a partial cross sectional view of the downhole bypass valve in a first run in position.  
         [0020]      FIG. 10   a  is a partial cross sectional view of the indexing pin and surrounding components.  
         [0021]      FIG. 10   b  is a partial cross sectional view of a port and a bonded seal member.  
         [0022]      FIG. 10   c  is a partial cross sectional view of a collet assembly.  
         [0023]      FIG. 11  is a partial cross sectional view of the downhole bypass valve in the first position with the ball actuator.  
         [0024]      FIG. 12  is a partial cross sectional view of the downhole bypass valve in a second position.  
         [0025]      FIG. 13  is a partial cross sectional view of the downhole bypass valve in a third position.  
         [0026]      FIG. 14  is a partial cross sectional view of the downhole bypass valve in a fourth position.  
         [0027]      FIG. 15  is a layout of the indexing groove. 
     
    
     DETAILED DESCRIPTION  
       [0028]     Referring to  FIGS. 1 and 2 , a downhole jetting tool  100  that may be used to selectively divert fluid that is flowing down the drill string bore  102  to the annulus  104  between the drill string and the casing  106  of a wellbore  108 . The jetting tool  100  includes an outer housing  110  and a spring-loaded index mandrel  168  defining a tubular assembly having an inlet  206  and a first outlet  208 .  
         [0029]     The outer housing  110  defines an axial through passage  124  within which the index housing  168  is located. The outer housing  110  has a top sub  126  provided at a top end  112 , wherein the top sub  126  includes a threaded box  114  to couple to an upper drill string component (not shown). The top sub  126  has one or more radially extending ports  132  extending from the axial through passage  124  to the annulus  104 , collectively defining a second outlet  128 . The top sub  126  is coupled to a swivel housing  116  for the index housing  168  at a lower end  130 . The coupling of the swivel housing  134  and the top sub  126  provides an upper shoulder  138  at the lower end  136  of the top sub  126 . A lower shoulder  140 , formed in the swivel housing  116 , is spaced apart from the upper shoulder  136  to form an inner recess  142  within which a swivel ring  144  is retained. The swivel ring  144  includes at least one indexing pin  146  extending radially into the axial through passage  124  defined by the outer housing  110 . While the swivel ring  144  is axially retained by the upper and lower shoulders  138 ,  140 , the swivel ring  144  is not rotationally retained to the outer housing  110 . Thus, the swivel ring  144  may rotate within the confines of the upper and lower shoulders  138 ,  140 . Along a middle portion  150  of the swivel housing  116 , a spring housing  152  is coupled thereto. A lower portion  154  of the swivel housing  116  protrudes axially within a through bore  156  defined by the spring housing  152 . The lower portion  154  of the swivel housing  116  is spaced apart from the corresponding portion of the spring housing  152  such that a small gap  162  is created. Within this small gap  162 , a spring sleeve  162  is coupled to the spring housing  152 . As will be explained below, the spring sleeve  164  is included primarily to aid in the assembly and disassembly of the jetting tool  100 . The spring housing  152  is provided with external threads  120  at lower end  118  to coupled to a ball catcher  122  or another lower drill string component (not shown).  
         [0030]     As previously stated, the index housing  168  is located within the outer housing  110 . The index housing  168  includes an indexing mandrel  170  coupled at a lower end  172  to a collet blank  174  to define a mandrel through passage  176 . The through passage  176  has a mandrel bore radius  178 . The indexing mandrel  170  has a ball seat  148  sealingly coupled at a top end  158 . An o-ring  166  may be included to seal the interface between the ball seat  148  and the index mandrel  170 . Other sealing means known in the art may be used. The ball seat  148  includes a lower shoulder  186 , which rests against top end  158 . A frustroconical section  188  at the top of the ball seat  148  provides a guide to direct a ball  250  (the ball  250  and related features are shown in  FIGS. 5-8 ) through the center of the through passage. A landing section  190  projects generally inward at the bottom  194  of the ball seat  148 . The landing section  190  projects inward a sufficient distance and angle to seat the ball  250  as will be described. The radius  240  of the landing section  190  is thus smaller than the ball radius  252 . A seal member  180  is located above a shoulder formation  182  in the outer surface  184  of the indexing mandrel  170  and below the lower shoulder  186  of the ball seat  148 . Below the shoulder formation  182 , a recess  202  is formed in the outer surface  184  of the indexing mandrel  170 . An o-ring  204  or other sealing member seals the interface between the outer surface  184  of the indexing mandrel  170  and the inner surface  192  of the top sub  126  below the recess  202 .  
         [0031]     An indexing groove  200  is formed into the outer surface  184  of the indexing mandrel  170  between the o-ring  204  and a lower end  172  of the indexing mandrel  170 . The indexing pin  146 , coupled to the outer housing  110 , is positioned within the indexing groove  200 . The function of the indexing groove  200  and the indexing pin  146  is described in greater detail below.  
         [0032]     A spring assembly  210  includes the collet blank  174 , a spring follower  214  and a spring  216 . As was previously described, the collet blank  174  couples to the index mandrel  170 . The spring  216  is located within the through passage  156  defined by the spring housing  152 . A shoulder formation  218  in the inner surface  220  of the spring housing  152  near the lower end  118  provides support to a lower end  222  of the spring  216 . The spring follower  214  has a lower shoulder  224  that is seated atop an upper end  226  of the spring  216 . The collet blank  174  has a lower end  228  that is seated atop an inner shoulder  230  of the spring follower  214  such that the lower end  228  of the collet blank  174  is within the spring follower  214 .  
         [0033]     The ball  250  will be used to actuate the jetting tool  100 . The ball  250  will be dropped from the top of the work string and allowed to float downward through the fluid in the axial through passage  124  until it reaches the ball seat  148 . Thus, the ball  250  is formed from a material having a specific gravity greater than fluid though which it will be dropped. Further, the ball  250  must be made from a material that will not be degraded by the chemical composition of the fluid in axial though passage  102 . Also, when the jetting tool  100  no longer needs to be cycled, the ball  250  can be sheared through the ball seat  148  by increasing the fluid pressure through the axial through passage  102 . Thus, the ball  250  is also formed from a material that will deform under a predetermined minimum pressure. For example, in one embodiment, the ball is made from a thermoplastic polyester based on polyethylene terephthalate, such as ERTALYTE (™).  
         [0034]     When the jetting tool  100  is assembled, the spring  216  is lowered into the spring housing  152  and the spring follower  214  is placed atop the spring  216 . The swivel housing  116  couples to the spring housing  152 . However, the length of the spring  216  when loaded only with the spring follower  214  would extend beyond the lower end  160  of the lower portion  154  of the swivel housing  134  when the swivel housing  116  is coupled to the spring housing  152 . Instead of loading the spring  216  with the swivel housing  116  while coupling to the spring housing  152 , the spring sleeve  164  is coupled to the spring housing  152  to preload the spring  216 , through the spring follower  214 , against a lower shoulder  166 . The smaller size of the spring sleeve  164  makes it easier to couple to the spring housing  152  while simultaneously preloading the spring  216 . The larger swivel housing  134  may then be simply coupled to the spring housing  152 . When disassembling the jetting tool  100 , the spring sleeve  164  retains the spring  162  and spring follower  214  within the spring housing  152  while the swivel housing  116  is removed.  
         [0035]     In one embodiment a jetting housing  196  is provided around the bypass valve  100 . The jetting housing  196  displaces annular space when the bypass valve  100  is to be used in a bore, such as that of a riser, having a sufficiently large inner diameter that annular fluid velocity would be lost if the jetting tool  100  were used without the jetting housing  196 . By reducing the annular area, fluid velocity through the second outlet  132  into the annulus  104  may be maintained at a rate that is effective for removing debris or circulating fluid. Jetting housings  196  having different outer diameters may be available and the choice of size is typically based upon the diameter of the casing to be cleaned. Referring to  FIGS. 2 and 3 , the jetting housing  196  includes a plurality of jetting ports  198 . When the second outlet  128  is open, the jetting ports  198  focus a stream of fluid toward the casing  106  of the wellbore  108  in a direction substantially perpendicular to the axial through passage  124 . As the fluid exits the jetting ports  198 , the direction of the stream of fluid will be affected by fluid circulation in the annulus  104  fluid pressure in the annulus  104 , as well as the geometry of the jetting port exits. While the fluid is directed toward the casing  106 , it will be appreciated by a person of skill in the art that the fluid direction will not be precisely pointed at a point on the casing, but rather a general area of the casing  106 . In one embodiment, the jetting housing  196  includes a plurality of tangent jetting ports  212 , as can be seen in  FIG. 3 . Tangent jetting ports  212  direct fluid flow in a direction substantially tangent to the flow of fluid out of the jetting ports  198 . As with the jetting ports  198 , fluid flow out of the tangent jetting ports  212  is affected by a variety of factors including fluid circulation in the annulus  104  fluid pressure in the annulus  104 , as well as the geometry of the tangent jetting port exits. In one embodiment, the jetting housing  196  is rotationally retained on the outer housing  110 . In one embodiment, tangent jetting ports  212  rotate the jetting housing  196  about the outer housing  110 .  
         [0036]     When lowered downhole on the drill string, the jetting tool  100  is in a first position, as depicted in  FIGS. 1 and 5 . In this position, the recess  202  of the indexing mandrel  170  is positioned inside the second outlet  128 . As depicted in  FIG. 1 , the seal ring  180  is located above the second outlet  128  while the o-ring  204  is positioned below the second outlet  128  to prevent fluid communication between the through passage  176  and the annulus  104 . Returning to  FIGS. 1 and 5 , fluid may continue to flow through the through passage  176  defined by the index housing  168  and the through passage  156  defined by the spring housing  152 .  
         [0037]     Referring to  FIG. 6 , when it is desired to actuate the jetting tool  100 , a ball  250  is dropped through the drill string and circulated until it reaches the jetting tool  100 . The ball  250  has a ball radius  252 , which is less than the outer housing radius  232  and greater than the landing section radius  240 , thus permitting the ball  250  to continue to circulate through the jetting tool  100  until it comes to rest atop the landing section  190 . The ball  250  prevents further fluid flow through the bore  238 ,  156  of the index housing  168 , spring  216 , and spring housing  152 . As the fluid pressure is increased, the ball seat  148  and index housing  168  are pushed downward against the upward force of the spring  216 . The indexing groove  200  on the indexing mandrel  170  interfaces with the indexing pin  146  to direct the position of the indexing mandrel  170  within the outer housing  110 .  
         [0038]     The indexing groove path  262  is depicted in  FIG. 4 . When the jetting tool  100  is in the first position, the indexing pin  146  is located in a first groove location  260 . Referring to  FIG. 6 , after the ball  250  is seated on the ball seat  148 , fluid pressure is increased until the ball seat  148  and indexing mandrel  170  are driven downward against the force of the spring  216 . As the indexing mandrel  170  moves downward within the outer housing  110 , the indexing pin  146  follows the indexing groove path  262  until it has reached a first groove wall  264 . Upon contacting the first groove wall  264 , the indexing pin  146  continues a path parallel to the first groove wall  264  until it has shouldered against second groove location  266 . The outer housing  110  is rotationally fixed by the drill string. The swivel ring  144  is rotated within the outer housing  110  as the indexing pin  146  follows the indexing groove path  262 . When the indexing pin  146  is shouldered against the second groove location  266 , the jetting tool  100  is in a corresponding second position, shown in  FIG. 6 .  
         [0039]     In the second position, the ball  250  remains seated atop the landing section  190  of the ball seat  148 . The indexing mandrel  170  and ball seat  148  have moved a sufficient distance downward to open the second outlet  128 , providing fluid communication from the through passage  124  to the annulus  104 . So long as the fluid flow remains sufficient to provide pressure to the ball  250  and the index housing  168  to overcome the upward force of the spring  216 , the jetting tool  100  will remain in the second position.  
         [0040]     Referring to  FIGS. 6 and 7 , when the flow drops to below a predetermined flow rate corresponding to a predetermined fluid pressure, the spring  216  will push the index housing  168  upward. The indexing pin  146  continues to follow the indexing groove path  262  and contacts a second groove wall  268 . The indexing pin  146  follows the incline of the second groove wall  268  to position the indexing mandrel  170  within the outer housing  110 . The indexing mandrel  170  continues to move upward until the indexing pin  146  shoulders against a third groove location  270 . When the indexing pin  146  is in the third groove location  270 , the jetting tool  100  is in a corresponding third position, shown in  FIG. 7 .  
         [0041]     In the third position, the ball  250  remains seated atop the landing section  190  of the ball seat  148 . The second outlet  128  is closed, resulting in no fluid communication from the through passage  124  to the annulus  104  and no flow through the through passage  124  to the first outlet  208 .  
         [0042]     The fluid pressure may be increased to cycle the indexing mandrel  170  to a fourth position, in which the indexing pin  146  is shouldered against a fourth groove location  272  longitudinally located along the indexing mandrel  170  between the second groove location  266  and the third groove location  270 . So long as the fluid pressure does not exceed a predetermined pressure sufficient to deform the ball  250 , decreasing the fluid pressure again will return the indexing mandrel  168  to the third position, wherein the indexing pin  146  is shouldered against another third groove location  270 . Increasing pressure when the ball  250  is in the third position for the second time will return the indexing mandrel  170  to a second position in which the second outlet  128  is open. This cycle may be continued until the indexing pin  146  has traversed the indexing groove path  262  any number of times.  
         [0043]     When the jetting operation is completed, the jetting tool  100  is cycled by increasing and decreasing fluid pressure on the ball  250  until the indexing pin  146  is again in the fourth groove location  272 . The pressure may then be increased to a predetermined pressure sufficient to shear the ball  250  through the bottom  194  of the ball seat  148 , as shown in  FIG. 8 . The ball  250  is then forced downward through the through passage  238  of the index housing  168  and the through passage  156  of the spring housing  152 . The ball  250  is caught in a downstream ball catcher  122 . When the ball  250  is released from the ball seat  148 , the fluid pressure counteracting the spring force is relieved and the spring  216  pushes the index housing  168  and the ball seat  148  upward. The indexing groove  200  and pin  146  interact to reposition the indexing mandrel  170  in the first position in which the second outlet  128  is closed and from which the entire process may be performed again.  
         [0044]     Referring to  FIG. 1 , the ball catcher  122  includes a ball catcher sub  234  within which a ball catcher tube  236  is retained. A trap finger  238  is provided near the top end  242  of the ball catcher tube  236 . The top end  242  of the ball catcher tube  236  may be provided with slots  276 . The trap finger  238  is pivotally retained to the ball catcher tube  236  near the top end  242  along a pivot edge  244 . A torsion spring  246  biases the trap finger  238  toward a “closed” position. As shown in  FIG. 1 , a free edge  248  is rotatable within the ball catcher sub  234 . The trap finger  238  has a length  254  such that the trap finger  238  free edge  248  can travel through slot  276  and is caught on an edge of the slot  276  before opening in an upward position. A stopper  178  may be included near the free edge  248  to aid in catching the slot edge before over-traveling. When the ball  250  is discharged from the ball seat  148 , the ball  250  pushes the free edge  248  downward and enters the ball tube  236 . Once the ball  250  has cleared the trap finger  238 , the torsion spring  246  moves the trap finger  238  back to the closed position.  
         [0045]     The ball catcher tube  236  has an outer diameter less than the inner diameter of the ball catcher sub  234 , defining a ball catcher annulus  274 . The ball catcher tube  236  is also provided with a number of holes  258  though the wall of the tube  236  providing fluid communication from the though passage of the ball catcher tube  236  to the ball catcher annulus  274 . If reverse circulation is desired, the holes  258  and ball catcher annulus  274  allow fluid flow around any balls  250  retained in the ball catcher tube  236  and to the tools above the ball catcher  122 . Any balls  150  in the ball catcher tube  236  that are forced upward by the reverse circulation are retained by the trap finger  238 . Any force on the trap finger  238  by retained balls  250  will reinforce the force of the torsion spring  246  in pushing the free edge  248  against the slot edge of the ball catcher tube  236 , thereby preventing the loss of balls  250  from the ball catcher  122 . The ball catcher tube  236  may be sized to accommodate any number of balls  250 . For example, in one embodiment, the ball catcher tube  126  holds six balls  250 .  
         [0046]     The jetting tool  100  can be used to clean the inner surface of a casing and/or a blowout preventor (BOP). To perform a cleaning operation, the jetting tool  100  is assembled on a work string and lowered into the wellbore  108  to a location to be cleaned. The index housing  168  is in a first position relative to the outer housing  110 , as shown in  FIG. 5 , and the second outlet  128  through the outer housing  110  is closed off by the index housing  168 . The ball  250  is dropped into the axial through passage  102  of the work string and is circulated through the work string until the it reaches the ball seat  148  of the jetting tool  100 . When the ball  150  reaches the ball seat  128 , it is directed to a landing section  190  where it prevents fluid from flowing through the index housing  168  and spring housing  152  as well as the lower work string tools (not shown). Fluid continues to be pumped at a predetermined rate into the through passage  102  of the work string, thereby applying pressure to the ball  250 . This pressure works against the upward force of the spring  216 . As the pressure on the ball  250  increases, the index housing  168  is lowered relative to the outer housing  110  until the index housing  168  reaches a second position, shown in  FIG. 6 . When the index housing  168  is in the second position, the second outlet  128  through the outer housing  110  is open. The fluid that is being pumped into the axial through passage is then directed through the second outlet  128  and the jetting ports  198  at a pressure sufficient to clean the casing and/or BOP. The jetting tool  100  may be rotated by rotating the work string to direct fluid flow from the jetting ports  198  at a circumferential area of the casing or BOP. The jetting tool  100  may be raised and/or lowered by raising and/or lowering the work string to direct flow from the jetting ports  198  at a longitudinal area of the casing or BOP. As previously discussed, the jetting housing  196  may be rotationally retained on the outer housing  110  and tangential jetting ports  212  utilized to rotate the jetting housing  196  to clean a circumferential area of the casing and/or BOP.  
         [0047]     When a location of the casing and/or BOP has been cleaned, fluid pressure through the axial through passage  124  may be reduced. As the pressure is reduced to a pressure insufficient to overcome the spring force, the spring  216  pushes the index housing  168  upward relative to the outer housing  110  to a third position, shown in  FIG. 7 . The second outlet  128  through the outer housing  110  is closed when the index housing  168  is in the third position.  
         [0048]     The pressure may be increased again to a predetermined pressure that is sufficient to overcome the spring force but that is insufficient to deform the ball  250 . This drives the index housing  168  to a fourth position. From the fourth position, the fluid pressure may be decreased again so that the spring  216  forces the index housing  168  into another first position. Increasing the pressure from this third position will force the index housing  168  into another second position in which the second outlet  128  is again open and additional cleaning activities may be performed. If such additional cleaning activities are not desired, from the fourth position, the fluid pressure may be increased by an additional amount sufficient to shear the ball  250  from the ball seat  148 . When the ball  250  has been sheared from the ball seat  148 , the spring  216  will force the index housing  168  into another first position and the jetting tool may be re-actuated by dropping another ball  250 . The sheared ball  250  is circulated through the remainder of the jetting tool  100  and is caught by the ball catcher  122 . As previously discussed, if recirculation of the fluid is desired, the ball catcher  122  will retain any sheared balls  250  previously caught in the ball catcher  122 .  
         [0049]     Referring to  FIG. 9 , in another embodiment, a downhole bypass valve  300  is used to selectively divert fluid that is flowing down the drill string bore  302  to the annulus  304  between the drill string and the casing  306  of a wellbore  308 . The bypass valve  300  includes an outer housing  310 , a spring-loaded mandrel  368 , and a cantilever-type ball seat collet assembly  410  defining a tubular assembly having an inlet  406  and a first outlet  408 .  
         [0050]     The outer housing  310  defines an outer housing through bore  324  within which the spring-loaded mandrel  368  and the collet assembly  410  are located. The outer housing  310  has a top sub  326  provided at a top end  312 , wherein the top sub  326  includes a threaded box  314  to couple to an upper drill string component  316 . The top sub  326  is coupled to a ported seal housing  328  at a lower end  330 . The ported seal housing  328  has one or more radially extending ports  332  extending from the outer housing through bore  324  to the annulus  304 , defining a second outlet. A swivel housing  334  is coupled to a lower end  336  of the ported seal housing  328 . As shown more clearly in  FIG. 10   a , the coupling of the swivel housing  334  and the ported seal housing  328  provides an upper shoulder  338  at the lower end  336  of the ported seal housing  328 . A lower shoulder  340 , formed in the swivel housing  334 , is spaced apart from the upper shoulder  336  to form an inner recess  342  within which a swivel ring  344  is retained. The swivel ring  344  includes at least one indexing pin  346  extending radially into the through bore  324  defined by the outer housing  310 . While the swivel ring  344  is axially retained by the upper and lower shoulders  338 ,  340 , the swivel ring  344  is not rotationally retained to the outer housing  310 . Thus, the swivel ring  344  may rotate within the confines of the upper and lower shoulders  338 ,  340 . Returning to  FIG. 9 , along a middle portion  350  of the swivel housing  334 , a spring housing  352  is coupled thereto. As shown more clearly in  FIG. 10   c , a lower portion  354  of the swivel housing  334  protrudes axially within a through bore  356  defined by the spring housing  352  and has a recess formation  358  in an inner surface  359  at its lower end  360 . The lower portion  354  of the swivel housing  334  is spaced apart from the corresponding portion of the spring housing  352  such that a small gap  362  is created. Within this small gap  362 , a spring sleeve  362  is coupled to the spring housing  352 . As will be explained below, the spring sleeve  364  is included primarily to aid in the assembly and disassembly of the bypass valve  300 . Returning again to  FIG. 9 , the spring housing  352  is provided with external threads  320  at lower end  318  to couple to a lower drill string component  322 .  
         [0051]     As previously stated, the spring-loaded mandrel  368  is located within the outer housing  310 . The spring-loaded mandrel  368  includes an indexing mandrel  370  coupled at a lower end  372  to a shoulder sub  374  to define a mandrel through bore  376 . As shown in  FIG. 10   b , the through bore  376  has a mandrel bore radius  378 . A bonded seal member  380  is located above a shoulder formation  382  in the outer surface  384  of the indexing mandrel  370 . A retaining ring  386  may be secured to the indexing mandrel  370  such that it is spaced apart from the shoulder formation  382  to maintain the bonded seal member  380  in a position near the upper end  387  of the indexing mandrel  370 . The bonded seal member  380  includes a pair of resilient outer seals  388 ,  390 , which seal the interface between the inner surface  392  of the ported seal housing  328  and the outer surface  394  of the bonded seal member  380 . An o-ring  396  seals the interface between an inner surface  398  of the bonded seal member  380  and the outer surface  384  of the indexing mandrel  370 . Below the shoulder formation  382 , a recess  402  is formed in the outer surface  384  of the indexing mandrel  370 . An o-ring  404  seals the interface between the outer surface  384  of the indexing mandrel  370  and the inner surface  392  of the ported seal housing  328  below the recess  402 . Returning to  FIG. 9 , an indexing groove  400  is formed into the outer surface  384  of the indexing mandrel  370  between the o-ring  404  and a lower end  372  of the indexing mandrel  370 . The indexing pin  346 , coupled to the outer housing  310 , is positioned within the indexing groove  400 . The function of the indexing groove  400  and the indexing pin  346  is described in greater detail below.  
         [0052]     The ball seat collet assembly  410  includes a collet member  412 , a spring follower  414  and a spring  416 . As will be described, the collet assembly  410  has limited axial mobility within the through bore  324  of the outer housing  310 . The spring  416  is located within the through bore  356  defined by the spring housing  352 . A shoulder formation  418  in the inner surface  420  of the spring housing  352  near the lower end  318  provides support to a lower end  422  of the spring  416 . As can be seen more clearly in  FIG. 10   c , the spring follower  414  has a lower shoulder  424  that is seated atop an upper end  426  of the spring  416 . The collet member  412  has a lower end  428  that is seated atop an upper shoulder  430  of the spring follower  414 . From the collet member lower end  428 , several cantilevered collet arms  432  extend upward. A collet head  434  is located at an upper end  436  of each collet arm  432 . In the position shown in  FIG. 9 , each collet head  434  is biased outward by the corresponding cantilevered collet arm  432  to contact the inner surface  359  of the lower portion  354  of the swivel housing  334 . The collet heads  434  form a collet through bore  438  having a collet inner radius  440 .  
         [0053]     When the bypass valve  300  is assembled, the spring  416  is lowered into the spring housing  352  and the spring follower  414  is placed atop the spring  416 . The swivel housing  334  couples to the spring housing  352 . However, the length of the spring  416  when loaded only with the spring follower  414  would extend beyond the lower end  360  of the lower portion  354  of the swivel housing  334  when the swivel housing  334  is coupled to the spring housing  352 . Instead of loading the spring  416  with the swivel housing  334  while coupling to the spring housing  352 , the spring sleeve  364  is coupled to the spring housing  352  to preload the spring  416 , through the spring follower  414 , against a lower shoulder  366 . The smaller size of the spring sleeve  364  makes it easier to couple to the spring housing  352  while simultaneously preloading the spring  416 . The larger swivel housing  334  may then be simply coupled to the spring housing  352 . When disassembling the bypass valve  300 , the spring sleeve  364  retains the spring  362  and spring follower  414  within the spring housing  352  while the swivel housing  334  is removed.  
         [0054]     In an alternative embodiment a jetting housing (not shown) may be provided around the bypass valve  300 . The jetting housing displaces annular space when the bypass valve  300  is to be used in a bore, such as that of a riser, having a sufficiently large inner diameter that annular fluid velocity would be lost if the bypass valve  300  were used alone. By reducing the annular area, fluid velocity through the ports  332  into the annulus  304  may be maintained at a rate that is effective for removing debris or circulating fluid.  
         [0055]     When lowered downhole on the drill string, the bypass valve  300  is in a first position, as depicted in  FIG. 9 . In this position, the recess  402  of the indexing mandrel  370  is positioned inside the ports  332 . As depicted in  FIG. 10   c , the outer seals  388 ,  390  of the bonded seal ring  380  are located above the ports  332  while the o-ring  404  is positioned below the ports  332  to prevent fluid communication between the through bore  376  and the annulus  304 . Returning to  FIG. 9 , fluid may continue to flow through the through bore  376  defined by the spring loaded mandrel  368  and the through bore  356  defined by the spring housing  352 . In the first position, the collet inner radius  440  is slightly smaller than the mandrel radius  378  (shown in  FIGS. 10   c  and  10   b , respectfully).  
         [0056]     Referring to  FIG. 11 , when it is desired to actuate the bypass valve  300 , a ball  450  is dropped through the drill string and circulated until it reaches the bypass valve  300 . The ball  450  has a ball radius  452 , which is less than the mandrel bore radius  378  and greater than the collet inner radius  440 , thus permitting the ball  450  to continue to circulate through the bypass valve  300  until it comes to rest atop the collet heads  434  of the collet assembly  410 . The ball  450  prevents further fluid flow through the bore  438 ,  456  of the collet assembly  410 , spring  416 , and spring housing  352 . As the fluid pressure is increased, the collet assembly  410  is pushed downward against the upward force of the spring  416 . The increased fluid pressure within the axial through bore  376  and the lower pressure outside of the mandrel  368  causes the spring loaded mandrel  368  to move downward as well. The indexing groove  400  on the indexing mandrel  370  interfaces with the indexing pin  346  to direct the position of the spring loaded mandrel  368  within the outer housing  310 .  
         [0057]     The indexing groove path  462  is depicted in  FIG. 15 . When the bypass valve  300  is in the first position, the indexing pin  346  is located in a first groove location  460 . Referring to  FIGS. 12 and 15 , after the ball  450  is seated on the collet heads  434 , fluid pressure is increased until the collet assembly  410  is driven downward against the force of the spring  416 . The spring loaded mandrel  368  is also pushed downward by the increased fluid pressure within the axial bore  376 . As the spring loaded mandrel  368  moves downward within the outer housing  310 , the indexing pin  346  follows the indexing groove path  462  until it has reached a first groove wall  464 . Upon contacting the first groove wall  464 , the indexing pin  346  continues a path parallel to the first groove wall  464  until it has shouldered against second groove location  466 . The outer housing  310  is rotationally fixed by the drill string. The spring loaded mandrel  368  is rotated within the outer housing  310  as the indexing pin  346  follows the indexing groove path  462 . When the indexing pin  346  is shouldered against the second groove location  466 , the bypass valve  300  is in a corresponding second position, shown in  FIG. 12 .  
         [0058]     In the second position, the ball  450  remains seated atop the collet heads  434 . The spring loaded mandrel  368  has moved a sufficient distance downward to open the ports  332 , providing fluid communication from the through bore  324  to the annulus  304 . So long as the fluid flow remains sufficient to provide pressure to the ball  450  and the collet assembly  410  to overcome the upward force of the spring  416 , the bypass valve  300  will remain in the second position.  
         [0059]     Referring to  FIGS. 13 and 15 , when the flow drops to below a predetermined flow rate corresponding to a predetermined fluid pressure, the spring  416  will push the collet assembly  410  upward. The collet assembly  410  in turn pushes the spring loaded mandrel  368  upward. The indexing pin  346  continues to follow the indexing groove path  462  and contacts a second groove wall  468 . The indexing pin  346  follows the incline of the second groove wall  468  to rotate the spring loaded mandrel  368  within the outer housing  310  as it continues to move upward until the indexing pin  346  shoulders against a third groove location  470 . When the indexing pin  346  is in the third groove location  470 , the bypass valve  300  is in a corresponding third position, shown in  FIG. 13 .  
         [0060]     In the third position, the ball  450  remains seated atop the collet heads  434 . The ports  332  remain open, providing fluid communication from the through bore  324  to the annulus  304 . In this position, the fluid can be reverse circulated at any desired rate. Circulation can be maintained up to a predetermined rate at which the fluid pressure would overcome the spring force once again. In the third position, multiple batches of various fluids can be circulated, depending upon the viscosity and density of the fluids, so long as the predetermined rate is not exceeded.  
         [0061]     The fluid pressure may be increased to cycle the spring loaded mandrel  368  to the second position, in which the indexing pin  346  is shouldered against another second groove location  466 . Decreasing the fluid pressure again will return the spring loaded mandrel  368  to the third position, wherein the indexing pin  346  is shouldered against another third groove location  470 . This cycle may be continued until the indexing pin  346  has traversed the indexing groove path  462  to shoulder against a final third groove location  470 , corresponding to the third position.  
         [0062]     Referring to  FIGS. 14 and 15 , to close the bypass valve  300 , the fluid pressure may be increased when the indexing pin  346  is shouldered against the final third groove location  470 . As previously described, as the fluid pressure is increased, the collet assembly  410  and mandrel  368  are driven downward against the force of the spring  416 . This time, however, the indexing pin  346  is directed along the indexing groove path  462  until it shoulders against a final groove location  472 . The final groove location  472  corresponds to a fourth position of the spring loaded mandrel  368  that is farther downhole, relative to the outer housing  310 , than in the first, second, or third positions. In the fourth position, the collet assembly  410  is driven downward against the force of the spring  416  until the collet heads  434  are received into corresponding recess formations  358  in the lower portion  354  of the swivel housing  334 . Once the collet heads  434  spring outward into the recess formations  358 , the collet inner radius  440  is enlarged such that it is larger than the ball radius  452 . The ball  450  is then forced downward through the bore  438  of the collet assembly  310  and the bore  356  of the spring housing  352 . The ball  450  will be caught in a downstream ball catcher (not shown). When the ball  450  is released from the collet heads  434 , the fluid pressure counteracting the spring force is relieved and the spring  416  pushes the collet assembly  410  upward. The collet assembly  410  in turn pushes the spring loaded mandrel  368  upward. The indexing groove  400  and pin  346  interact to reposition the spring-loaded mandrel  368  in the first position in which the ports  332  are closed and from which the entire process may be performed again.  
         [0063]     While the claimed subject matter has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the claimed subject matter as disclosed herein. Accordingly, the scope of the claimed subject matter should be limited only by the attached claims.

Summary:
An apparatus for cleaning a wellbore casing includes an outer housing having an axial through passage between an inlet and a first outlet wherein the inlet and the first outlet are adapted for connection in a work string, the outer housing having a second outlet extending in a direction generally transversely of the through passage, an index mandrel slidably located within the outer housing and having an axial bore extending therethrough, the index mandrel being movable relative to the outer housing between a first position in which the second outlet is closed and a second position in which the second outlet is open, a ball seat located on an upper end of the index mandrel, a spring located within the outer housing and biasing the index mandrel toward the first position, a ball retainable on the ball seat to prevent flow from the inlet to the first outlet, and wherein application of a first pressure on the ball forces the index mandrel against the spring into the second position and reduction of said first pressure permits return of the index mandrel to the second position.