Abstract:
A ball release mechanism is mounted near the intended seat. The ball or balls are kept out of the circulating stream. High circulation rates followed by curtailment of circulation places an outlet port in position to allow the ball or balls to be pushed out by a spring. The spring or one of the balls prevents the return of an ejected ball back into the protected pocket. The ball is delivered to the seat without circulation.

Description:
FIELD OF THE INVENTION  
         [0001]    The field of the invention is a ball release device and more particularly a device that is mounted near the hole bottom with the stored ball or balls protected until release after circulation.  
         BACKGROUND OF THE INVENTION  
         [0002]    Most prior ball release devices store the ball in the fluid stream and use circulation to transport it to the seat. Several problems can occur with this design. The ball may not release because the carrier gets clogged with debris from the mud. The carrier can become worn resulting in premature release of the ball. The ball is released during high circulation. It can slam against a seat and create high pressure spikes that can damage other equipment. The high circulation rates around the ball can erode parts of it causing it to not hold pressure even if it lands on the ball seat. Some examples of prior designs that have the ball in the circulating path are U.S. Pat. Nos. 6,390,200; 6,220,360; and 5,960,881. U.S. Pat. No. 4,171,019 shows a cement float shoe with a ball in a side pocket such that it can be displaced against a ball seat if the flow direction reverses. Balls have been used to fix a range of motion of a sleeve valve member, as shown in U.S. Pat. No. 4,406,335.  
           [0003]    What the prior devices lacked is addressed by the present invention. The ball is retained near its intended seat near the bottom of the hole. It is retained out of the flowing stream. The ball discharge procedure is such that ball release occurs after circulation is stopped and not during circulation. Once the ball is released it is prevented from reentering its original storage location. These and other benefits of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the claims, which appear below.  
         SUMMARY OF THE INVENTION  
         [0004]    A ball release mechanism is mounted near the intended seat. The ball or balls are kept out of the circulating stream. High circulation rates followed by curtailment of circulation places an outlet port in position to allow the ball or balls to be pushed out by a spring. The spring or one of the balls prevents the return of an ejected ball back into the protected pocket. The ball is delivered to the seat without circulation. 
       
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a part section view of the tool during the run in;  
         [0006]    [0006]FIG. 2 is the view of FIG. 1 in the circulation position;  
         [0007]    [0007]FIG. 3 is the view of FIG. 2 with the ball released after circulation has ceased. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0008]    Referring to FIG. 1, a housing  10  is connected at thread  12  to a string and downhole equipment (not shown). Housing  10  comprises a primary ball seat  14  preferably mounted on ball carrier  16  or in another housing in fluid communication with housing  10 . As illustrated, ball seat  14  provides resistance to circulation to move the ball carrier  16 . However, that resistance can be from another constriction on ball carrier  16  with the ball seat in another housing in fluid communication with housing  10 . In the preferred embodiment, the balls  22  and  24  drop less than a meter to get to ball seat  14 . A shear pin  18  initially holds the ball carrier  16  to the housing  10 . In the run in position, an outlet port  20  is so positioned that balls  22  and  24  cannot escape. Balls  22  and  24  are biased toward tapered surface  26  on ball carrier  16  by spring  28 . Housing  10  further comprises a sleeve  30  biased by spring  32  toward ball carrier  16 . A seal  34  seals between ball carrier  16  and housing  10 . For run in, sleeve  30  holds in detent pin  36  against the bias of spring  38 .  
         [0009]    The operation of the tool will now be reviewed. Circulation is started through housing  10 . As a result a net force is applied to ball carrier  16  shifting it down against sleeve  30  and compressing spring  32 . While the restriction from ball seat  14  that causes ball carrier  16  to be displaced by circulation is shown at the lower end of the ball carrier  16 , the actual restriction that causes the ball carrier  16  to shift can be located elsewhere on ball carrier  16 , while the ball seat  14  can be in any other location below balls  22  and  24 . The shear pin  18  is broken by movement of ball carrier  16 . Balls  22  and  24  are held retained by tapered surface  26 . Circulation is then stopped. Spring  32  displaces sleeve  30  to position outlet port  20  in alignment to let balls  22  and  24  escape with a push from spring  28 . Ball  22  lands on primary ball seat  14 , which is less than a meter away, while ball  24  is optional. Ball  24  keeps ball  22  near seat  14  because the upper end  40  of ball carrier  16  as well as spring  28  in its extended position help to maintain ball  24  in the position shown in FIG. 3. Spring  38  has pushed out detent pin  36  to prevent needless cycling of ball carrier  16  at a later time when circulation is resumed for other purposes.  
         [0010]    A secondary ball seat  42  is provided to accept a ball dropped from the surface in a known manner, in the event ball  22  fails to seal or hold enough pressure against primary ball seat  14 .  
         [0011]    Those skilled in the art will appreciate that the present invention has many unique features. The ball or balls are stored out of the flowing path of mud and are less likely to be eroded or deformed by circulation. The balls are not released during circulation. Pressure spikes are eliminated as the balls are released from a location very close to the seat after circulation has stopped. There is no need to wait a long time for the ball to seat from the time of release, because the release point is so close to the ultimate seat location. This tool can be run below tools that would not be able to pass a ball. The tool is of particular advantage on a horizontal run. In the past, a ball dropped from the surface could land in many places short of the desired seat. This is particularly the case when running long lengths of screen to be expanded in a horizontal run. In the present invention, seating occurs almost immediately after release due to the close proximity between the release point and the seat. In the unlikely event of a failure of the tool, a secondary seat is provided to allow a backup ball to be dropped in the known manner. Alternatively, a plurality of balls of different sizes can be stored in the tool. Bigger balls can reuse Ball seat  14  after an initial ball expands the seat a given amount in a known manner. Alternatively, smaller balls can be subsequently released that will pass through seat  14  after the first ball is blown through it and land on another seat further down. While the preferred embodiment has been shown with two balls, one ball or more balls can be used. They can be released all at once or one at a time such as by using a ratchet device actuated by cycling the circulation on and off. To do this the detent pin  36  could be eliminated. No rotation is required to operate the tool making it useful in deviated wells.  
         [0012]    The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.