The present invention relates to circulation tools of a type used downhole in a well for transferring fluid through ports from a bore within the tool to an annulus surrounding the tool and for subsequently closing the ports to pass fluid through the tool. The circulation tools of the present invention are sometimes referred to as surge tools or surge reduction tools.
Downhole circulation tools have been used for decades to selectively flow fluid from the interior of a tubing string or work string to the annulus surrounding the tool. Some tools have the ability to selectively close off circulation ports to subsequently pass fluid down the tubing string or work string. Many of these tools, however, make it difficult or unreliable to pass a cementing plug through the work string after the circulation ports are closed without damaging the plug. Other tools require that the work string be placed on bottom or engage some type of restriction in the well to cycle the tool. Various types of circulation tools have thus been devised for circulating fluid within a tubular string to an annulus, and for subsequently moving a sleeve to close the annulus so that fluid can be passed through the tool.
Prior art circulation tools for selectively closing off flow through a side port in the tool and for subsequently passing cement and cement plugs through the tool include tools with a deformable or expandable seat to allow the ball to pass through the seat and thus through the tool once the sleeve has shifted to close off flow ports in the tool. This type of tool significantly restricts the size of the cement plug which may be reliably passed through the tool, and the deformable seats may damage the plug wiper seals or rubber wafers while passing through the deformable seat. As a consequence, cementing operations are adversely affected since an unknown quantity of cement may pass by the wiper plug after the wiper plug has passed through the tool. Other types of tools employ a flangible disc within the bore of the tool. Pressure builds up on top of the disc to shift a sleeve to close off the circulation ports. A subsequent increase in pressure breaks the flangible disc. Fragments from the disc can be very damaging, however, to a cementing plug which is subsequently passed through the tool. Disc fragments may cut or tear at the wiper plug, thereby damaging the wiper plug.
Another type of tool utilizes a J-type mechanism for moving the sleeve between the open and closed positions. This type of tool or a tubular extending downward from the tool conventionally sits on the bottom of the well so that weight can be applied to manipulate the J-type mechanism.
Other types of surge tools do not provide substantially a full bore opening through the tool, and the restriction in the ID of the tool is thus a significant detriment to the use of the tool.
U.S. Pat. No. 6,275,929 discloses a circulation tool with axially moveable sleeves. Similar tools are disclosed in U.S. Pat. Nos. 6,571,875 and 5,176,208. U.S. Pat. No. 5,402,850 discloses a tool for reverse circulation of fluid in the wellbore. A circulation tool with wash ports is disclosed in U.S. Pat. No. 4,987,841. Another type of circulation tool is disclosed in U.S. Pat. No. 4,657,092. A downhole tool with a combination ball valve and sliding sleeve is disclosed in U.S. Pat. No. 5,335,731.
The disadvantages of the prior art are overcome by the present invention. An improved downhole circulation tool which may be reliably used with cementing operations is subsequently disclosed.
In one embodiment, a circulation tool for use downhole in a well is suspended in a well from a tubular string. The tool includes a tubular housing including one or more bypass ports for circulation between a bore within the housing and an annulus surrounding the housing. A sleeve is axially movable within the housing and supports axially spaced seals. A rotatable ball has a small diameter flow port therein and a seat surrounding the small diameter flow port for seating engagement with a ball or other plug. The ball is rotatable to an open position such that a large diameter through port in the ball has an axis generally aligned with the axis of the tubular housing.
In one embodiment, the large diameter port has a diameter of at least 90 percent of an innermost diameter of the axially movable sleeve. Cam members interconnected with the ball are movable within slots in the sleeve to rotate the ball to the open position.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
Referring now to
Pusher 59 movably interconnects the lower end of sleeve 46 with sleeve 44, which has a slot 88 therein, as shown in
During operation of the circulation tool, fluid conventionally travels upward through the full diameter bore and passes outward through one or more of the circulation port 16 to the annulus surrounding the tool. Some fluid may also flow upward through the small diameter port 55 in the ball 52. When it is desired to close off the ports 16, e.g., for a cementing operation, multiple size or multiple diameter balls may be dropped to the seat of the surface 54 of the ball, thereby raising the pressure above the ball 52. This creates a downward force which acts on the assembly, shearing the pins 28 and moving the sleeves 30, 44, and 68 downward, thereby closing off the port 16. Shoulder 31 on sleeve 30 passes under the lock ring 38, thereby locking the tool in the circulation port closed position. After the sleeve 56 has closed off the ports 16, shear pins 64 shear during the final movement, lowering the ball 52 as it rotates to the full bore open position. With the sleeve 68 in the fully closed position and the ball 52 rotated to the full open position, a full bore is provided through the circulation tool.
The circulation tool of the present invention is particularly well suited for operations involving the run in of the liner in a well, and the subsequent cementing of the liner by pumping through the work string. When the liner is run in a well, a check valve at the bottom of the liner is conventionally opened so that well fluid enters and passes upward through the liner. The work string or drill pipe at the upper end of the liner thus begins to fill with fluid, and desirably most of that fluid passes through the circulation tool to the annulus rather than continuing up the drill string or work string. Once the liner is at bottom and positioned for cementing in place, a ball is dropped from the surface and lands on the ball 52, closing off the port 55 through the ball and creating a downward force to move the sleeve 68 to the closed position. As previously explained, the ball rotates after the sleeve 68 moves to the closed position to provide a full bore flow path through the circulation tool, at which time the dropped ball may be released to either be caught by a conventional ball catcher or passed to the bottom of the string. Plugs or darts may then be passed through the drill string or work string to cement the liner in place, with the darts or plugs passing through the open bore 13 in the circulation tool, which is not restricted and has no sharp edges to damage the plug or wiper.
For the embodiment depicted, the seals between the sleeve 68 and the housing 12 are provided on the sleeve. In other embodiments, the seals could be provided on the housing. In a preferred embodiment, a ball is provided with a hole therein, so that when the ball is closed some fluid can pass from below to above the ball. This construction allows fluid to drain from above to below the ball in the event the operator needs to pick up on the tubular string before setting the liner in place. Although various types of plugs may be used for seating with the flapper, a preferred plug is a ball. The seat on the ball is also configured for seating with balls of various sealing diameters, thereby increasing the versatility of the tool.
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.
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5383520 | Tucker et al. | Jan 1995 | A |
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Number | Date | Country | |
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20060272825 A1 | Dec 2006 | US |