Patent Application
20180230773
The field of the invention is the provision of a mechanical closure in a tubular string. This could be a single closure for drilling applications or act as a second barrier when opening the borehole at the surface to meet regulatory criteria for well safety.
Occasions arise when a wellhead needs to be removed, a well put on suspension prior to nippling down the tree or tools advanced into the borehole that are too long for a lubricator and have to be assembled with the top of the borehole open. In such instances regulations in many countries require dual closures in series for safety reasons. There are numerous criteria when designing such systems. One predominant one is cost and another is a need to avoid intervention to operate the barriers. There have been dual valve arrangements in the past that stack two ball valves as shown in U.S. Pat. No. 8,752,653 FIG. 4. This is an expensive solution that further presents issued of complex mechanisms to rotate the balls when needed. Other arrangements involve two barriers but only one is a tubing valve to the formation below and the other valve blocks annulus access to the tubing string above a formation isolation valve that is typically a ball valve. This is shown in U.S. Pat. No. 4,440,221 FIG. 6 and U.S. Pat. No. 4,566,478 FIG. 2B. Dual isolators around a pipe in a blowout preventer are shown as C1 in FIG. 9 of U.S. Pat. No. 9,376,870. Dual isolators in a side pocket mandrel but not in a main tubular passage are illustrated in U.S. Pat. No. 8,714,264.
Another design uses pressure responsive sliding sleeves to sequentially open access to different parts of a formation for injection as tubing pressure increases. The increase in tubing pressure separates an inline valve member from an associated seat located on a pressure responsive sleeve. When flow is provided the inline valve opens first and the sliding sleeves leading to the formation open sequentially as the tubing pressure increases. Reduced pressure from the surface allows the sliding sleeve valves to close as well as the inline valve. This design is discussed on US 2016/0305228. A downside of this design is that the inline valve member 47 always remains in the tubing flow passage to obstruct it and would need intervention for removal to allow other tools to pass.
US 2015/0361763 is similar to the previous reference but in this case the isolation devices are in series in the tubing passage and flow separates a seat from an inline valve member and interacts with a flow tube to open a flapper. Removing the flow lets springs push the sleeves back to a run in position where the seat moves to the upper barrier that blocks the flow passage while below the spring raises the flow tube to allow the flapper to swing shut against a seat to prevent flow out of the borehole at two spaced locations. Again the upper valve member 520 obstructs the passage to prevent passage of any tools unless there is an intervention to remove it.
The present invention seeks an economical solution to a second barrier that need not obstruct the tubing flow path and is responsive to built up pressure rather than flow. The second barrier is run in open and released to close when the dual barriers are needed. Thereafter the second barrier is rotated out of the tubing passage and locked in the open position. Objects landed on seats for pressure buildup will degrade and move out of the way or push past after the sleeve shifts. The seats can also degrade, drop into the hole by shearing out a support, or snap out up out of the bore hole. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims.
A second barrier is provided in a tubular string to meet regulations requiring dual barriers for safety when opening up the top of the well or single barriers that are mechanically actuated for other applications. A first object lands on the seat to force the sleeve away from the flapper to allow the flapper to close to serve as a barrier. After the top of the well is reclosed after being open a second object engages a seat on a second sleeve to push the flapper back to open and to lock the flapper in the open position. The objects degrade or are blown through the seats leaving the tubular passage open for the passage of tools or production.
Referring to the Figure, a tubular string could have (but is not required) an isolation valve such as a flow tube operated flapper or a ball valve 10 that is operated remotely with control line, lines or other means. Such an isolation valve is typically provided in a tubular string 12 that extends to a surface location that is not shown. Item 10 can be located above or below the Interventionless Closure Operable with a Full Bore Tubular String Isolation Valve
The closure for passage 14 is provided in the form of a flapper 16 that is mounted with a pivot spring to a pin 18 for 90 rotation. A seat 20 is engaged by the flapper 16 when the flapper 16 is allowed to rotate by virtue of moving sleeve 22 that initially holds the flapper 16 open for running in. This allows circulation or reverse circulation when running in. After the desired location is achieved, a first ball 24 is landed on seat or collet 26 to block the opening 29 and passage 28 so that pressure buildup or flow moves sleeve 22. This can be done with shearing a pin, compressing a collet or otherwise overcoming resistance to build up pressure so that sleeve 22 can move. A ratchet feature or recess 30 for a collet to expend into can be used to lock sleeve 22 after its upper end 32 clears the lower end 34 of flapper 16. The bias at pin 18 or flow uphole will move the flapper 16 to rotate 90 degrees to contact seat 20. When that happens there can be two closures, isolation valve 10 (if present) can be remotely closed through a control line or through other means that are not shown and flapper 16 against seat 20. It should be noted that other isolation valves are preferably kept open as the ball 24 makes its way to seat 26 so that flow can be used to speed the ball 24 to seat 26. Alternatively the travel of ball 24 can be assisted by gravity in more vertical installations. As another alternative to moving and locking sleeve 22 the sleeve 22 with the ball 24 can be simply blown to the bottom of the hole. In another alternative the ball 24 can be made of a disintegrating material such as CEM (controlled electrolytic material) that is commercially available and disintegrates over time with exposure to fluids in or added to the well or thermal inputs to pass through seat 26 to reopen passage 28 for later passing of tools or production flow. As another option the seat 26 itself can be made of a degrading material or even the sleeve 22 itself so that after time long enough to achieve the proper borehole positioning the sleeve 22 can be used for its intended purpose and then removed in totality from passage 28.
Once the flapper 16 is operational the top of the hole is sealed from the reservoir or bore hole. The top of the hole could also be open while meeting the requirements of regulations for dual closures if a second isolation valve 10 was closed. After the top of the hole is again closed off it is necessary to allow production by reopening or removing flapper 16. One way to do this is to land an object 36 on seat 38 of sleeve 40 to close off opening 41 and build pressure or increase flow. At some point a retaining device such as a shear member that is not shown will break or collet finger will shift and the lower end of sleeve 40 will pass through seat 20 and push the flapper 16 away from seat 20 and on the outside of sleeve 40 effectively holding the flapper 16 open with sleeve 40 whose shifted position can be secured with a ratcheting device or collet 42. The object 36 can be from a degradable material such as CEM (controlled electrolytic material) so that it will degrade and pass through seat 38 after shifting sleeve 40. In another option the object 36 which can be a ball or a dart can just be blown through seat 38 with sufficient applied pressure.
Those skilled in the art will appreciate that the closure represented by flapper 16 can be run in open to speed up the running in with no need to circulate or reverse circulate when running in. No well intervention, control line or other actuation mechanism is needed to activate the flapper 16 for use or to subsequently lock it open. Passage 14 is reopened after the flapper is placed in the locked open position. The balls 24 or 36 can be blown through their respective seats or can be made of a degrading material to allow passage through the respective seats without forcing the objects through the seats. The mechanism is economical to fabricate and works reliably due to its simplicity. Optionally, sleeve 40 can be fished out by overcoming the ratchet mechanism 42 to close the valve again for future use. A fishing neck or latch groove can be provided in the bore of sleeve 40 for this purpose.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
