Downhole safety valve having flapper and protected opening procedure

A downhole valve has a closure device (e.g., one or more flappers) for closing off the valve. A no-go actuation mechanism protects the flappers from damage. When the flappers are closed, the mechanism prevents a tool from passing into the valve and causing damage to the flappers. Yet, the mechanism may open the valve's flappers when the tool string is forced into the valve. When the valve has successfully opened, then the mechanism moves out of the way of the toolstring so it can pass through the valve. For the mechanically operated valves, operators use a shifting profile in the valve only in the upward direction to return the valve to the closed position. For hydraulic actuated valves, hydraulic pressure may be used or exhausted, depending on the design, to allow the flappers to go closed. Once the flappers have closed, the no-go mechanism is once again realized.

BACKGROUND

Operators perform completion operations during the life of a well to access hydrocarbon reservoirs at various elevations. Completion operations may include pressure testing the tubing, setting a packer, activating safety valves, or manipulating sliding sleeves. In certain operations, it may be desirable to isolate one portion of the completion from another. Typically, an isolation valve having an internal ball valve is disposed in the completion to isolate portions of the well. One example of such an isolation valve is the completion isolation valve (CIV) from Weatherford.

FIG. 1Ashows a completion isolation valve10in an opened condition with the ball valve20allowing flow through the valve's bore12. When running a tool string through the open valve10, operators insert a profiled stinger30on the end of the tool string into the valve10as shown inFIG. 1B. The stinger30engages dogs16in the valve10. Downward movement of the stinger30engaged by the dogs16then moves a shifting mechanism14to lock the internal ball valve20open. Once the valve10is opened, a tool string can be passed through the valve10to work on the lower completion. To remove the tool string, operators lift the profiled stinger30at the end of the string back into the valve10. As shown inFIG. 1C, the stinger30raised in the upward direction closes the internal ball valve20by engaging the dogs16as the stinger30passes up through the valve10.

Although effective in isolating portions of a completion, valves using internal ball valves have several drawbacks. For example, ball valves require a large wall thickness to house it. The increased wall thickness required by a ball mechanism makes it have either a smaller ID or a larger OD than the flapper designs. To overcome such drawbacks, isolation valves have been developed that use flappers to isolate portions of a completion. One example of such a valve having dual flappers is the Optibarrier available from Weatherford and disclosed in U.S. patent application Ser. No. 11/761,229, entitled “Dual Flapper Barrier Valve,” which is incorporated herein by reference in its entirety.

In many valves used downhole, operators use shifting sleeve profiles to mechanically actuate the valve open and closed. Unfortunately, operators deploying a tool downhole to mechanically actuate the valve may inadvertently miss engaging the profile during run in. In such a circumstance, the tool string may slip through and run into the closed valve, damaging the closure device and rendering the valve inoperable. To avoid this, operators must pay careful attention while running a tool in the hole so as not to damage any downhole valves.

SUMMARY

A downhole valve has one or more flappers for closing off the valve, and a no-go actuation mechanism protects the one or more flappers from damage. When the one or more flappers of the valve are closed, the no-go mechanism prevents a tool from passing into the valve and causing damage to the one or more flappers. Yet, the passable no-go mechanism is used to open the valve's one or more flappers when the tool string is forced into the valve. When the valve has been successfully opened, then the no-go mechanism is moved out of the way of the tool string so the tool string can pass through the valve. Operators use a shifting profile in the valve only in the upward direction to mechanically return the valve to the closed position.

In one implementation, the protected valve has a bore with a closure disposed therein. The closure can include one flapper, or the closure can include dual flappers (i.e., upper and lower flappers) disposed in the bore. For the dual flapper arrangement, the flappers are rotatable in opposing directions between opened and closed positions in the bore.

When the valve deploys downhole, a tool may be deployed into the valve either intentionally or unintentionally. For example, the tool may be a stinger on the end of a tool string intended to reach a portion of the wellbore below the valve. Alternatively, the deployed tool can be any arbitrary tool inadvertently deployed by operators into the closed valve. In either case, the tool engages against at least one dog extendable into the valve's bore as the tool moves downhole into the valve while closed. The tool engaged against the dog shifts a sleeve while the tool moves downhole. The closure is automatically actuated with the sleeve from the closed condition to the opened condition before the tool moves downhole to the closure. For the closure having dual flappers, for example, the flappers rotate open before the tool moves downhole to the flappers, and the lower flapper preferably rotates open before the upper flapper.

For hydraulic actuated downhole valves, hydraulic pressure may be used or exhausted, depending on the design, to allow the one or more flappers to go closed. Once the flapper has closure, the no-go mechanism is once again realized. For the mechanically operated downhole valves, however, operators use a shifting profile in the valve only in the upward direction to mechanically return the valve to the closed position. If the tool is a stinger intentionally deployed into the valve, for example, then the stinger can be used to close the valve as the stinger is pulled uphole through the valve. In particular, a shoulder on the stinger engages against a profile in the sleeve as the stinger moves uphole through the open valve. The sleeve with the stinger engaged against the profile shifts uphole and automatically closes the closure. For example, the flappers rotate closed with the shifting of the sleeve with the upper flapper preferably closing before the lower flapper.

DETAILED DESCRIPTION

A downhole valve100inFIG. 2forms part of a completion assembly (not shown) with the tool's upper sub102connected to an upper completion and the tool's lower sub108connected to a lower completion. In use, the valve100isolates the upper and lower completions from one another using a closure device, shown here as including a first (upper) flapper150and a second (lower) flapper160. The upper flapper150controls pressure from below the valve100when closed and opens downwards into the tool's bore104, while the lower flapper160controls pressure from above the valve100when closed and opens upwards into the tool's bore104.

The flappers150/160are shown in open positions inFIGS. 2 and 3and are shown in closed positions inFIG. 4. The actual opening and closing of the flappers150/160uses a predetermined sequence that considers the impact that debris in the well may have on the valves' operation. Upper and lower flow tubes140/180, an actuating sleeve110, and a shift and lock mechanism130open and close the flappers150/160according to the predetermined sequence. A similar procedure for opening and closing the flappers150/160is described in detail in incorporated application Ser. No. 11/761,229.

In operation, the upper flapper150is closed first to protect the lower flapper160from debris that may be dropped in the wellbore from above to the valve100. To close the upper flapper150, operators deploy a stinger or shifting tool200as shown inFIG. 3into the valve100. The stinger200has a plurality of fingers202that mate with actuating sleeve110's profile112so the sleeve110can be pulled toward the upper sub102. In moving upward, flexible ribs117on the actuating sleeve110push past a surrounding lower rim107defined in the tool's bore104. As the sleeve110then moves further upward, the shift and lock mechanism130unlocks the flappers150/160and moves the upper flow tube140away from the lower flow tube180. Once the upper flow tube140passes the upper flapper150, the newly freed upper flapper150rotates by a spring (not shown) around a pivot point and seals against a valve seat155to isolate pressure below the flapper150as shown inFIG. 4.

As the shifting tool200urges the sleeve110further toward the upper sub102, a latch152can be activated to secure the upper flapper150in the closed position but may allow the upper flapper150to crack open if necessary. After the upper flapper150is closed, upward movement of the shifting tool200continues to urge the actuating sleeve110toward the upper sub102. The upper flapper150and its seat155connect by a cage170to the lower flapper160and its seat165. With the continued urging of the sleeve110, the lower flapper160and seat165also move upward. At the same time, the lower flapper160moves away from its flow tube180, thereby allowing a spring (not shown) to pivot the flapper160against its seat165to seal pressure from above.

Thereafter, the actuating sleeve110being urged closer to the upper sub102causes the flappers150/160to lock in place by actuating the shift and lock mechanism130. As shown inFIG. 4, the shift and lock mechanism130has a series of intermediate sleeves132/134, dogs136, and slots for locking in position as the actuating sleeve110shifts the mechanism130. As shown, the actuating sleeve110interacts via dogs and slots with an inner intermediate sleeve134that couples to the upper flow tube140. This inner intermediated sleeve134is biased by a spring120and interacts via dogs and slots with an outer intermediate sleeve132that couples to the upper flapper's seat155. In this way, shifting and locking of the mechanism130using the actuating sleeve110moves the flow tube140relative to the upper seat155and moves the cage170relative to the lower flow tube180so that the upper and lower flappers150/160can be opened and closed.

Once the flappers150/160are closed as shown inFIG. 4, it is desirable to protect them from damage by downhole tools being inadvertently or intentionally passed through the valve100while in the closed condition. For this reason, the valve100has a passable no-go mechanism to protect the flappers150/160once closed. As shown inFIG. 5A, an arbitrary downhole tool210that is inadvertently or intentionally passed into the valve100will engage a series of dogs115disposed in the upper sleeve110before reaching the closed flappers150/160. With the valve100closed as shown inFIG. 5A, these dogs115have moved away from corresponding recesses105defined in the surrounding housing102. Thus, the dogs115extend into the valve's bore104and can engage the downhole tool210passing through the closed valve100from above.

When the tool210engages the dogs115, the tool210may be initially prevented from passing further into the closed valve100, thereby preventing inadvertent damage to the closed flappers150/160. In particular, downward movement of the tool210against the extended dogs115must push the ribs117on the sleeve110past an upper rim109near the dog's slots105. This initial catch of the ribs117on the rim109may indicate to operators that the valve100is closed and that passage of the tool210could be harmful.

In any event, continued force of the downhole tool210against the dogs115may eventually move the ribs117past rim109. In this instance, the engaged dogs115force the tool210to move the sleeve110, manipulate the shift and lock mechanism (130;FIG. 2), and open the flappers150/160before the tool210can reach the closed flappers150/160and cause damage. This form of opening may occur, for example, when operators inadvertently force the arbitrary downhole tool210through the closed valve100without realizing the valve100is closed. Alternatively, operators may intentionally be opening the valve100to reach the lower completion below the valve100, in which case the tool210may actually be a stinger or the like that is purposefully used to open the valve100.

Regardless of why the tool210is passed through the closed valve100, the lower flapper150opens first in the opening sequence. Initially, the downhole tool210pushes the upper sleeve110downward in the tool100by engaging the dogs115and forces the ribs117on the sleeve110past the upper rim109as discussed above. As a result, the shift and lock mechanism130unlocks the flappers150/160. Next as shown inFIG. 5A, pressure on both sides of the lower flapper160equalizes when ports167on the lower seat165align with slots182formed in the flow tube180as the sleeve110moves downward. (See alsoFIG. 4). Thereafter, further movement of the sleeve110downward causes the lower flapper160to meet its flow tube180, and further movement downward subsequently causes the lower flapper160to open and fit in the annulus between the flow tube180and the surrounding housing106.

After the lower flapper160opens, the upper flow tube140moves toward the upper flapper150as the shift and lock mechanism130is manipulated by the downward moving tool210. Before the flow tube140contacts the upper flapper150, pressure on both sides of the flapper150may be equalized. Thereafter, the flow tube140meets the upper flapper150and pivots it to the open position. Subsequently, the flappers150/160are locked in place by further manipulation of the shift and lock mechanism130.

Once opened as shown inFIG. 5B, the downhole tool210can pass through the valve100while the flappers150/160remain open. In this way, the flappers150/160can be opened to prevent damage when operators either intentionally or accidentally pass the tool210into the valve100. Advantageously, the valve100has an internal bore104that is larger than available with a ball valve, because the disclosed valve100uses the dual flappers150/160.

Closing the flappers150/160uses the procedure outlined previously. As shown inFIG. 5C, for example, fingers222on a stinger or other tool220can engage the upper sleeve's profile112so that the sleeve110can be pulled upward in the valve100to initiate the closing procedure for the valve100outlined previously for the mechanically operated downhole valve100. For a hydraulic actuated downhole valve, hydraulic pressure may be used or exhausted, depending on the design, to allow the flappers150/160to go closed. Once the flappers150/160have closed, the no-go mechanism is once again realized.

Although the actuating sleeve110, profile112, dogs115, slot105, etc. of the present disclosure have been discussed in connection with the valve100having dual flappers150/160, it will be appreciated with the benefit of the present disclosure that these features can be used for a valve having a single flapper. In addition, the teachings of the present disclosure can be used in a fail-safe type of safety valve (as represented by the disclosed valve100) and can be used in a hydraulic type of safety valve.

For example, a suitable example of a fail-safe type of safety valve having a single flapper that can use the disclosed features is the SSSV (Subsurface Safety Valve) available from Weatherford—the Assignee of the present disclosure. The SSSV has a single flapper and uses a hydraulic opening piston and a spring closure mechanism. As another example, a suitable example of a hydraulic type of safety valve having a single flapper that can use the disclosed features is the DDV™ (Downhole Deployment Valve) available from Weatherford—the Assignee of the present disclosure. The DDV has a single flapper and uses a hydraulic opening piston and a hydraulic closing piston. In either case, the protected opening of the flapper can use the same components and procedures outlined above with reference to the dual flapper valve, although without the added complexity of having to open the second flapper.

The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.