Abstract:
A ball launcher for dispatching balls into a wellbore that includes a manifold for selective attachment to a wellhead assembly and a magazine mounted on the manifold in which the balls are stored for distribution to the manifold. Chambers are provided in a cylinder in the magazine, so that by rotating the cylinder the chambers register with a bore in the manifold, through which the balls are delivered to the wellbore. Flowing a flushing fluid into the bore in the manifold urges the balls downward. An auxiliary line through the manifold provides a conduit for the flushing fluid into the bore.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates in general to operations in oil and gas wells, and in particular to completion operations with a ball launcher for successively launching an indefinite number balls into a wellbore while mounted on a wellhead assembly. 
         [0003]    2. Description of Related Art 
         [0004]    Balls are sometimes launched into a wellbore promote oil and gas flow from a hydrocarbon producing wellbore. Reasons for injecting the balls including using a ball as a sealing member by having the ball land on a seat formed on an end of a tubular, where the inner diameter of the tubular is less than the outer diameter of the ball. In other applications, balls may be forced with pressure through a tubular for cleaning the tubular (similar to a pigging operation) or otherwise removing debris or obstructions within the tubular. Balls may be mixed with a treating fluid that is injected into an adjoining formation that produces oil and gas. Additional examples include landing the ball in a segment of casing to divert a flow of cement during staging operations. Balls dropped within a wellbore are also used to activate tools downhole, such as by shearing a pin or directly contacting a switch or other device for activating a tool. From time to time the ball may be used to operate as a safety valve. Typically, as the wellbore is generally at a pressure greater than ambient pressure at the surface, the balls are held for a period of time within a pressurized environment prior to being dropped into the wellbore. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Disclosed herein are example embodiments of a ball launcher for delivering balls into a wellbore. In an example embodiment a ball launcher includes a manifold body that has an axial bore in communication with the wellbore. A magazine is included that mounts on an end of the manifold body, where a cylinder is included with the magazine. A chamber extends axially through the cylinder; thus the cylinder can be rotated to align the chamber with the axial bore and a ball in the chamber can be launched into the axial bore for delivery to the wellbore. In an example embodiment, the ball launcher includes a launch system above the magazine. The launch system has a reciprocating launch rod for pushing the ball downward in the axial bore. In an example embodiment, the ball launcher includes a collet assembly and seal on a lower end of the rod for coupling with a profile in an outer circumference of the axial bore. In an example embodiment, the ball launcher includes an auxiliary line in the manifold body having an end in fluid communication with a flushing fluid and an end in fluid communication with the axial bore. In an example embodiment, the ball launcher includes a valve in the axial bore, so that when the valve is closed a pressure barrier is formed in the axial bore across the valve. In an example embodiment, the ball launcher includes another valve in the axial bore spaced axially away from the valve, so that when the another valve is closed a pressure barrier is formed in the axial bore across the another valve. In an example embodiment, the ball launcher includes a chamber with a ball disposed therein. In an example embodiment, wherein the end of the manifold body distal from the magazine is mounted on a wellhead assembly. In an example embodiment, the ball launcher includes notches on an outer periphery of the cylinder profiled for engagement by a ratcheting actuator for rotating the cylinder. 
         [0006]    Also disclosed herein is an example of a wellhead assembly on a wellbore. In an example embodiment, the wellhead assembly includes a production tree mounted on a wellhead housing. A main bore projects through the production tree and wellhead housing and into communication with the wellbore. A manifold body is included on the production tree, where the body has an axial bore that is open to the main bore. A ball chamber is included that is in a cylinder, where the cylinder rotates into a position with the ball chamber offset from the axial bore and also rotates into a position with the ball chamber in registration with the axial bore. In an example embodiment, the wellhead assembly includes a rod insertable into the axial bore to form a pressure seal in the axial bore. In an example embodiment, the wellhead assembly includes valves spaced axially apart in the manifold body and selectively and independently closed to each form a pressure barrier across the axial bore. In an example embodiment, the wellhead assembly includes a flush line intersecting the axial bore between the valves for providing a flushing fluid to urge a ball down into the wellbore. In an example embodiment, the wellhead assembly includes a plurality of ball chambers formed through the cylinder along a circular path and oriented substantially parallel with the axial bore. In an example embodiment, the wellhead assembly includes a ratcheting device for selectively rotating the cylinder so the ball chambers register with the axial bore. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0007]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0008]      FIG. 1  is a side partial sectional view of an example embodiment of a ball launcher in accordance with the present invention. 
           [0009]      FIGS. 2 and 3  are side partial sectional views of the ball launcher of  FIG. 1  in an example of use. 
           [0010]      FIG. 4  is a side partial sectional view of an example embodiment of a ball launcher in accordance with the present invention. 
           [0011]      FIGS. 5 and 6  are side partial sectional views of the ball launcher of  FIG. 4  in an example of use. 
           [0012]      FIG. 7  is a plan view of a magazine portion of a ball launcher in accordance with the present invention. 
       
    
    
       [0013]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    The apparatus and method of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. This subject of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. For the convenience in referring to the accompanying figures, directional terms are used for reference and illustration only. For example, the directional terms such as “upper”, “lower”, “above”, “below”, and the like are being used to illustrate a relational location. 
         [0015]    It is to be understood that the subject of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the subject disclosure and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the subject disclosure is therefore to be limited only by the scope of the appended claims. 
         [0016]    Shown in partial side sectional view in  FIG. 1 , is an example embodiment of a ball launcher  20  mounted on a wellhead assembly  22 . In the example of  FIG. 1 , the ball launcher  20  includes a manifold body  24  having an axial bore  26  formed therethrough. The upper end of the wellhead assembly  22  includes a production tree  27  on which the manifold body  24  is mounted. A main bore  28  is shown axially formed in the production tree  27  and registering with the axial bore  26  and the manifold body  24 . The main bore  28  also extends downward and within a wellhead housing  29 , on which the production tree  27  mounts, and into communication with a wellbore  30  that projects into a formation  32  below the wellhead assembly  22 . The manifold body  24  of  FIG. 1  further includes auxiliary lines  34 ,  36  that intersect and project radially outward from the axial bore  26 . Wing valves  28 ,  40  are set within the auxiliary lines  34 ,  36  that selectively open and close to regulate flow through the auxiliary lines  34 ,  36 . Passages  42 ,  44  are also shown formed laterally through the manifold body  24  that intersect with the axial bore  26 . In the embodiment of  FIG. 1 , the passages  42 ,  44  are substantially parallel with auxiliary line  36  and disposed respectively above and below the auxiliary line  36 . Valve assemblies are provided within the passage  42  that is made up of a gate  46  mounted on an end of a valve stem  47 . 
         [0017]    The gate  46  is shown extending within the axial bore  26  and when set in a closed position provides a pressure seal in the axial bore  26 . Similarly, a gate  48  with attached valve stem  49  is set within the passage  44 . The gate  48  also provides a pressure barrier within the axial bore  26  when set in its closed position. Actuators  50 ,  52  are provided with each of the valve assemblies for selectively reciprocating the valve gates  46 ,  48  and valve stems  47 ,  49  within the passages  42 ,  44  to set or remove a pressure seal within the axial bore  26 . 
         [0018]    Further illustrated in the example embodiment of  FIG. 1  is a generally planar magazine assembly  54  shown set on an upper end of the manifold body  24  and opposite where the manifold body  24  mounts to the production tree  27 . The magazine assembly  54  of  FIG. 1  includes a planar base  56  that extends substantially over the upper end of the manifold body  24  and having a portion thereof that may optionally extend past the outer periphery of the manifold body  24 . Set on the upper surface of the base  56  is a cylinder  58  whose outer radial periphery extends at least from a lateral end of the base  56  and projects past where the base  56  is intersected by an axis A X  of the axial bore  26 . The cylinder  58  of  FIG. 1  has an axis A C  that is laterally offset from and generally parallel with axis A X . The cylinder  58  has a diameter exceeding its thickness/height. The cylinder  58  is provided with chambers  60   1 - 60   n  ( FIG. 7 ) that each define an open passage through the cylinder  58  and in a direction substantially parallel with the axis A X . Balls  62   1 - 62   i  are shown set within each of the chambers  60   1 - 60   i ; each ball  62   1 - 62   i  may have the same or a different shape and/or diameter than any other ball  62   1 - 62   i . Optionally, more than one ball  62   1 - 62   i  may be provided within one or more of the chambers  60   1 - 60   i . The base  56  also includes an opening  64  that is formed therethrough and in a direction generally parallel with the axis A X . In the embodiment of  FIG. 1 , the opening  64  registers with the axial bore  26  thereby allowing access to within a portion of the axial bore  26  through the magazine assembly  54 . 
         [0019]    Shown in  FIG. 2 , the ball  60   1  within the chamber  62   1  registered with the opening  64  in  FIG. 1  is shown having fallen through the opening  64  and dropping within the axial bore  26 . Valve gate  46  has been retracted within the passage  42  by the actuator  50  to open the axial bore  26  and allow ball  62   1  travel downward past the passage  42  to the lower valve gate  48 . Referring now to  FIG. 3 , valve gate  46  is reinserted into the axial bore  26  by the actuator  50  to reform the pressure seal in the axial bore  26 . Conversely, valve gate  48  is shown pulled from within the axial bore  26  and out of the path of the ball  62   1  so it can continue to travel downward into the production tree  27 . A swab valve  65  in the production tree  27  is selectively put into an open position so the ball  62   1  may enter the main bore  28  on its way downward into the wellbore  30  below. 
         [0020]    An alternate embodiment of the ball launcher  20 A is provided in a side partial sectional view in  FIG. 4  in which a launch system  66  is included. In the example embodiment of  FIG. 4 , the launch system  66  mounts on an upper surface of the base  56  and includes an elongated support  68  having an end that bolts onto the base  56 . The support  68  extends generally axially away from the magazine assembly  54  and curves up to where it attaches to a launch assembly  70 ; which is shown suspended above the magazine assembly  54  on the support  68 . The launch assembly  70  reciprocates a launch rod  72 , which is shown extending partially within the launch assembly  70 . In one example embodiment, the launch assembly  70  may be hydraulically driven and include a piston  74  that attaches to the launch rod  72  and axially reciprocates within a cylindrical housing  76 . The end of the launch rod  72  facing the magazine assembly  54  includes a tip  78  and locking plug  80  depending from the lower end of the tip  78 . The locking plug  80  is provided with a shaped profile  82  on its outer periphery and configured for engagement with a profile  84  shown formed within the manifold body  24  along the outer circumference of the main bore  26 . The embodiment of the launch assembly  20 A of  FIG. 4  is shown having a single valve gate  48  disposed in passage  44 . Also, an optional protective screen  86  is illustrated provided in the entrance to auxiliary line  36  from the axial bore  26 . 
         [0021]    Referring now to  FIG. 5 , launcher  20 A is shown in a configuration wherein the launch assembly  70  urges the launch rod  72  and launch rod tip  78  through the chamber  60   1 , through the opening  64 , and into the axial bore  26 . Urging the launch rod  72  a designated amount into the axial bore  26  allows engagement between the profiles  82  of the launch assembly  70  and the profiles  84  in the manifold body  24 . In an example embodiment, a pressure seal is formed within the axial bore  26  where the locking plug  80  with its profiles  82  engage the profiles  84 . The ball  62   1  is shown within the axial bore  26  and on the valve gate  48 , where either gravity or the launch rod  72  may urge the ball  62  downward into the axial bore  26  past the passage  42  and to rest on the gate  48 . In environments where the wellhead assembly  22  is subjected to freezing conditions, fluids in the axial bore  26  may thicken and/or freeze to impede travel of the ball  62   1 , thus the launch assembly  70  may be required to force the ball  62   1  downward past any such obstacles. As noted above, the passage  44  is set below the auxiliary lines  34 ,  36  and at a distance so that the upper end of the ball  62   1  remains below the auxiliary lines  34 ,  36 . 
         [0022]    As illustrated in a partial side sectional view in  FIG. 6 , the gate  48  is drawn into the passage  44  from the axial bore  26  thereby opening the axial bore  26  to communication in the space from the auxiliary lines  34 ,  36  into the main bore  28  of the production tree  27 . As the engagement of the locking plug  80  with the axial bore  26  forms a pressure seal isolating the axial bore  26  from ambient, a flushing fluid may be introduced through one or both of the auxiliary lines  34 ,  36  and into the axial bore  26  below the profiles  84 . The flow of the fluid, coupled with pressure in the fluid, can be used for urging the ball  62   1  downward past the lower end of the axial bore  26 , through swab valve  65 , and into the wellbore  30 . 
         [0023]    A plan view of the magazine assembly  54  is provided in  FIG. 7 . In this example it can be seen that the cylinder  58  is provided with a plurality of chambers  60   1-n  shown formed in a generally circular path along the outer periphery of the cylinder  58 . In the example of  FIG. 7 , each of the chambers  60   1-n  is provided with a corresponding ball  62   1-n . Embodiments exist wherein one more chambers  60   1-n  may be empty, or include more than one ball. Further provided in the example embodiment of  FIG. 7  are notches  92  provided on the outer periphery of the cylinder  58 . In the example embodiment of  FIG. 7 , the notches  92  have a generally triangular shaped outline and extend the entire height or thickness of the cylinder  58 . Alternate embodiments exist wherein the notches  92  have rectangular, and/or curved shapes, and may extend along only a portion of the thickness of the cylinder  58 . Optionally, profiled surfaces, such as depressions along an upper or lower surface may be provided on the cylinder  58  in lieu of the notches  92 . 
         [0024]    Also shown set on the upper surface of the base  56  is a spring loaded pawl  94  having a tip profiled to engage the notches  92  and to limit rotation of the cylinder  58  to a single direction, i.e. clockwise or counterclockwise. Rotating the cylinder  58  can be accomplished by a ratcheting actuator  96 , also shown set on the base  56  and having an arm that reciprocates away from its body with a profile tip to engage the notches  92  thereby rotating the cylinder  58 . A spindle  98  may be included that is shown at approximately the center of the cylinder  58  that can extend into the base  56  thereby allowing rotation of the cylinder  58  with respect to the base  56 . 
         [0025]    In an example of operation of the ball launcher  20 , a ball  62   1  or balls  62   1-n  may be set within a chamber  60   1  or chambers  60   1-n  and the cylinder  58  rotated by the actuator  96  so that a designated chamber  60   1  may be aligned with the opening  64  of the magazine assembly  54  so the ball  62   1  drops into the axial bore  26 . Moving the valve gates  46 ,  48 , in conjunction with a flushing fluid provided through the auxiliary lines  34 ,  36 , moves the ball  62   1  into the wellbore  30 . Optionally, one of the auxiliary lines  34 ,  36  can be used to vent pressure from the axial bore  26  to allow the ball  62   1  to drop from the chamber  60   1  into the axial bore  26 . The actuator  96  may be reactivated to rotate the cylinder  58  thereby aligning another chamber  60  with the opening  64  and repeating the process for delivering additional balls  62  into the wellbore  30 . One or both of the auxiliary lines  34 ,  36  may be used as a blow down line to relieve pressure trapped in the axial bore between the valve gates  46 ,  48 . Thus prior to reopening valve gate  46  one or both of the wing valves  38 ,  40  can be opening to vent pressure in the axial bore  26 . 
         [0026]    An example use of the embodiment of  FIGS. 4-6 , the ball  62   1  within the aligned chamber  60   1  may be urged into the axial bore  26  using the launch assembly  70 . After the launch rod  72  is drawn out of the axial bore  26  by the launch assembly  70  the magazine assembly  54  may be rotated as described above for alignment of another chamber  60   i  for delivery of another ball  62   k . 
         [0027]    An advantage of the device described herein is that an indefinite number of balls  62  can be delivered into the wellbore  30  merely by placing a ball  62  within any chamber  60 . It should be pointed out that continuous operation can occur without the need for removing the magazine assembly  54  from the rest of the ball launcher  20 . 
         [0028]    While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.