FIELD OF THE INVENTION 
       [0001]    The invention pertains to multi-function (including openable and closeable) surge reduction tools for use in down-hole environments. 
       BACKGROUND OF THE INVENTION 
       [0002]    Casing is used in oil and gas well construction. In certain applications a string of casing may be deployed using a work string, for example, drill pipe, so that the casing string does not extend all of the way back to the drilling rig. These scenarios can include a liner and a sub-sea casing longstring. 
         [0003]    A longstring is a string of casing whose upper end extends up to the wellhead. So a longstring used on a sub-sea well is one that does not extend up to the drilling rig once installed but whose top resides in the sub-sea wellhead which sits on the sea floor. A liner is a string of casing whose top end resides within the length of a previously installed casing string. The top end of a liner does not reside at surface or within a wellhead. 
         [0004]    Both of these scenarios utilize drill pipe in order to deploy the casing string. It is known in the industry that the deployment a casing string may exert excessive pressure on an open formation. The excessive pressure may overcome the strength of the formation and thus cause the formation to break down and cause a cement job. Surge reduction tools exists that when used in conjunction with auto-fill float equipment allow the fluid that is being displaced from the well bore to move up the inside of the casing and deployment string, thus reducing the surge pressure. Specifically, the surge reduction tools divert fluid flow from the inside of the deployment string to the annular space above the casing string. Once it is determined that casing string must be washed down and or cemented then surge tool is closed so that the fluid flow is no longer diverted to the annular space above the casing. Reliable closing of the flow diversion is critical for ensuring successful cementing operations. 
         [0005]    With the onset of dual gradient drilling methods a need exists which will require that a surge reduction tool begin in the closed position until it is deployed below the sea floor, then be allowed to open to allow fluid diversion from the inside to the annulus, and then be closed again to allow wash down or cementing operations. 
         [0006]    It is possible that other applications may exist for this type of tool. It is also possible that applications exist requiring a tool to be opened and closed multiple times. 
         [0007]    The present invention incorporates multiple shifting sleeves controlled by pressure enabled by sealing balls or plugging devices that land on seats and which shift the tool into an open or closed position. The seats then allow the ball or plugging device to be released through the tool. Proper sizing of the seats for balls or other plugging devices allows selective opening and closing of the tool, as well as allowing for a multi-stage tool that may be opened and closed repeatedly. 
         [0008]    Additionally, the invention may incorporate a test sub that allows the work string to be pressure tested after the tool is closed, providing a positive indication to the surface that successful closure and sealing has occurred, and that further operations may proceed. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention provides a multiple-sleeve tool, in which each sleeve is provided with a respective landing device, or seat, for a plugging tool. (Plugging tools, such as darts or balls, are typically dropped from the surface and either fall or are pumped downhole.) As the tool is run downhole, it is in a closed position, preventing fluid communication between its exterior and its interior. 
         [0010]    When the tool is in the desired position, it is opened by sending a first plugging device downhole to engage a landing seat. Because the tool provides multiple landing seats, the plugging device will be sized to pass through any up hole landing seats it may encounter until it reaches the desired one. Once the plugging device is sealingly engaged with the desired landing seat, pressure is used to release the sleeve associated with that landing seat, such as by shearable pins, screws, or rings, or other such pressure-releasable devices, thus shifting the sleeve downward. 
         [0011]    In a preferred embodiment, the first such shifting action shifts a first sleeve into position so that holes in the sleeve body align with holes in the tool body, opening fluid communication between the exterior and interior of the tool. 
         [0012]    In a similar manner, when it is desirable to again close and seal the tool, a second plugging device engages a second seat associated with a second sleeve. Upon increasing the work string fluid pressure, a second set of holding devices, such as shear screws, releases and allows the second sleeve to shift downward, closing off and sealing the fluid communication that was created by the shift of the first sleeve. 
         [0013]    As those of skill in the art will recognize, multiple stages, each providing two such sleeves, can be “stacked” along a work string, either together or with desired separations between them, so that fluid diverter operations may be repeatedly opened and closed without the need to withdraw the work string from the wellbore. 
         [0014]    Additionally, the invention provides for an optional test device comprising a yieldable seat, which yieldable seat can be sized to capture one or more of the plugging devices after they are released from the second sleeve seat(s). This test device allows the work string to be pressurized after the closing operation is completed, to test and insure that the closure occurred properly and that the device is sealed. After such testing, additional pressure may be used to release the plugging device and resume normal opeations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1A  is a sectional view of one embodiment of a tool of the present invention in the run-in position. 
           [0016]      FIG. 1B  is a sectional view of one embodiment of a tool of the present invention in the open position. 
           [0017]      FIG. 1C  is a sectional view of one embodiment of a tool of the present invention in the closed position. 
           [0018]      FIG. 2A  is a sectional view of an alternative embodiment of a tool of the present invention in the run-in position. 
           [0019]      FIG. 2B  is a sectional view of an alternative embodiment of a tool of the present invention in the open position. 
           [0020]      FIG. 2C  is a sectional view of an alternative embodiment of a tool of the present invention in the closed position. 
           [0021]      FIG. 3  is a perspective view showing the locking dogs of  FIG. 2  in greater detail. 
           [0022]      FIG. 4  is a sectional view of a test device mountable below a multi-function diverter tool of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Referring to  FIG. 1A , one embodiment of a tool of the present invention is shown in the run-in position. Multi-function diverter tool  10  comprises body  12 , upper sub  14 , lower sub  20 , ports  66 , and internal assemblies as described below. Upper sub  14  comprises upper threaded attachment  16  for connection to a work string, and upper body seal  18 . Lower sub  20  comprises lower threaded attachment  22  for connection to a work string, and lower body seal  24 . 
         [0024]    Internal assemblies include upper slider assembly  26  and lower slider assembly  44 . Upper slider assembly  26  comprises upper guide  28  connected to upper ball seat  30 , and also connected to upper slider  32  by upper slider connector  34 . Lower slider assembly  44  comprises lower guide  46  connected to lower ball seat  48 , and also connected to lower slider  50  by lower slider connector  52 . In a preferred embodiment, upper ball seat  30  is a larger diameter seat than lower ball seat  48 . 
         [0025]    In one embodiment of the invention, disassembly sleeve  62  is positioned above lower sub  20  and a sealing relationship with tool body  12  is provided by disassembly sleeve seals  64 . Alternatively, disassembly sleeve  62  may be omitted and tool body  12  may be formed to provide the same shape as if disassembly sleeve  62  were in place. However, the addition of disassembly sleeve  62  provides greater ease in disassembly after recovery of the mult-function diverter tool  10 , because it allows the internal portions of the tool  10  to slide out the bottom after removal of lower sub  20 . 
         [0026]    As seen in  FIG. 1A , in the run-in position ports  66  are sealed away from the inner bore  84  by the sealing relationship provided by first upper slider seals  80 , first lower slider seals  68 , second lower slider seals  70 , and disassembly sleeve seals  64 . Once the tool  10  is in the desired position downhole, it may be opened to allow diversion of fluid from the inner bore  84  to the exterior of the tool  10 . 
         [0027]    To open the tool  10  into the position shown in  FIG. 1B  a first ball (not shown) is dropped from the surface, and falls or is pumped downhole. The first ball is preferably of insufficient diameter to engage the upper ball seat  30 , but of sufficient diameter to engage lower ball seat  48 . Those of skill in the art will recognize that the first ball may engage upper ball seat  30  if it can be pumped through upper ball seat  30  at a pressure insufficient to shear upper shear screws  36 . 
         [0028]    Once the first ball is engaged on lower ball seat  48 , pressure in the inner bore  84  is increased until lower shear screws  54  shear. Lower slider assembly  44  will then shift downward until lower slider  50  lands on landing  61 . Lower latch ring  56  rides in lower latch ring groove  58  in lower slider  50 . As lower slider  50  lands on landing  61 , lower latch ring  56  reaches lower latch  60  and expands outward, thus engaging both lower latch ring groove  58  and lower latch  60 . This action locks lower slider  50  relative to disassembly sleeve  62  (or tool body  12 ), and prevents upward motion of lower slider assembly  44 . 
         [0029]    In the open position, ports  66  are aligned with lower slider windows  74 . Once the first ball is pumped clear, the exterior of tool  10  is in fluid communication with inner bore  84 , and the sides of the fluid pathway so provided are sealed by first upper slider seals  80 , second lower slider seals  70 , third lower slider seals  72 , and disassembly sleeve seals  64 . 
         [0030]    To close the tool  10 , for example to allow wash down and cementing operations, a second ball (not shown) is dropped from the surface, and falls or is pumped downhole. The second ball is of sufficient diameter to engage upper ball seat  30 . Once the second ball is in position on upper ball seat  30 , fluid pressure is increased to shear upper shear screws  36 , allowing the upper slider assembly to shift downward until it reaches the position shown in  FIG. 1C . Upper latch ring  38  rides in upper latch ring groove  40  until it reaches upper latch  42 . At this point, upper latch ring  38  expands outward so that it engages both upper latch ring groove  40  and upper latch  42 , preventing any upward shifting of upper slider assembly  26 . 
         [0031]    As upper slider assembly  26  shifts downward, any fluid trapped in outer annulus  78  is vented to the inner bore  84  via vents  76 , preventing hydraulic locking of the tool. 
         [0032]    In the closed position, ports  66  are isolated from the inner bore  84  by the sealing relationship between first upper slider seals  80 , second upper slider seals  82 , and tool body  12 . 
         [0033]    As those of skill in the art will recognize, it is possible to stack multiple stages of this invention by sizing upper and lower ball seats in each stage so that the ball seat diameter progressively increases going up the work string. In this way, the opening and closing operations can be repeated, stage by stage, as many times as desired or as space in the affected section of the wellbore allows. 
         [0034]    Referring to  FIG. 2 , an alternative embodiment of the present invention is shown. Upper slider  32  is radially penetrated by one or more locking dogs  86 . Locking dogs  86  engages groove  88  in locking sleeve  90 . In the run-in position ( FIG. 2A ), locking dogs  86  are prevented from inward movement because their inner surfaces engage lower slider  50 . (A more detailed view of one embodiment of the locking dogs  86  is seen in  FIG. 3 , in which locking dogs  86  are shown extended through the body of upper slider  32 .) The presence of locking dogs  86  serves to lock upper slider  32  in position, preventing any loading of upper shear screws  36  until lower slider  50  has been shifted into the open position. ( FIG. 2B ). With lower slider  50  in the open position, locking dogs  86  are free to move inward, disengaging from locking sleeve  90  and allowing loading of upper shear screws  36 . Upper shear screws  36  may then be sheared to move upper slider  32  and place the tool into the closed position. ( FIG. 2C ). 
         [0035]    Referring to  FIG. 4 , in an additional embodiment of the invention, test sub  92  may be installed in the work string somewhere below a multi-function diverter tool  10  of the present invention. Yieldable ball seat  94  is sized to catch a ball (not shown) released from upper ball seat  30 , which was used to shift the multi-function diverter tool  10  into the closed position. With the ball so caught, the work string may be pressure-tested to ensure that the ulti-function diverter tool  10  has properly closed and is sealed. As those of skill in the art will recognize, when multiple multi-function diverter tools  10  are present in the work string, one or more test subs  92  may be used, depending on the sizing of the yieldable ball seat  94  and the operational requirements for the work string. 
         [0036]    Those of skill in the art will recognize that the above descriptions are by way of example only, and do not serve to limit the scope of the invention as claimed below.
A multi-function diverter tool is disclosed that allows positive-indication opening and closing of the tool in a downhole environment.