Patent Application
20130319678
The invention pertains to multi-function (including openable and closeable) surge reduction tools for use in down-hole environments.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Referring to
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.
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.
As seen in
To open the tool 10 into the position shown in
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.
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.
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
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.
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.
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.
Referring to
Referring to
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.
