Bidirectional downhole isolation valve

1. An isolation valve for use in a wellbore, comprising:

a housing;

a piston longitudinally movable relative to the housing;

a flapper carried by the piston for operation between an open position and a closed position, the flapper operable to isolate an upper portion of a bore of the valve from a lower portion of the bore in the closed position;

an opener connected to the housing for opening the flapper; and

an abutment independently movable from the piston and configured to receive the flapper in the closed position, thereby retaining the flapper in the closed position.

2. The isolation valve of claim 1 , wherein:

the housing is tubular,

the housing has a coupling at each end thereof for assembly as part of a casing string,

the housing has a hydraulic chamber formed therein, and

the piston has a portion disposed in the hydraulic chamber.

3. The isolation valve of claim 1 , further comprising a hinge pivotally connecting the flapper to the piston.

4. The isolation valve of claim 1 , further comprising a slide hinge coupling the flapper to the piston.

5. The isolation valve of claim 1 , further comprising a spring biasing the flapper toward the closed position.

6. The isolation valve of claim 1 , wherein:

the opener is a flow sleeve, and

the piston is operable to move the flapper into engagement with the stationary flow sleeve,

the flapper is pushed to the open position by the engagement, and

the piston is further operable to move the flapper into a protective chamber formed between the flow sleeve and the housing.

7. The isolation valve of claim 6 , wherein:

the valve further comprises a hinge,

the flow sleeve has a tapered lower end, and

the flow sleeve is oriented relative to the flapper to engage a portion of the flapper adjacent the hinge.

8. The isolation valve of claim 1 , wherein:

the abutment is a shoulder of a lock sleeve operable to engage the housing, and

the isolation valve further comprises a linkage coupling the lock sleeve to the piston.

9. The isolation valve of claim 1 , wherein the abutment is a profile formed in the housing.

10. The isolation valve of claim 1 , wherein:

the flapper is curved, and

the abutment has a curvature complementary to a curvature of the flapper.

11. The isolation valve of claim 1 , further comprising one of:

a seat formed in a lower end of the piston; and

a cap connected to a lower end of the piston and having a seat formed therein,

wherein the flapper seals against the seat in the closed position.

12. The isolation valve of claim 11 , wherein the abutment has a port formed therethrough to prevent sealing between the flapper and the abutment.

13. The isolation valve of claim 1 , wherein:

the abutment is a shoulder of a lock sleeve operable to engage the housing, and

the isolation valve further comprises a latch fastening the lock sleeve to the housing.

14. The isolation valve of claim 1 , further comprising a latch operable to fasten the piston to the housing.

15. The isolation valve of claim 1 ,

further comprising a linear spring biasing the flapper toward the closed position,

wherein the abutment is further operable to kickoff the flapper.

16. The isolation valve of claim 15 , wherein the abutment is operable between an expanded position for kickoff of the flapper and a compressed position for receiving the closed flapper.

17. A system for use in drilling a wellbore, comprising:

the isolation valve of claim 1 ;

a hydraulic closer line connecting the isolation valve to a control station; and

the control station comprising a microcontroller (MCU) operable to calculate a differential pressure across the flapper.

18. The isolation valve of claim 1 , further comprising:

a lower wireless sensor sub having a proximity sensor for confirming closing of the flapper; and

an upper wireless sensor sub for receiving the confirmation and operable to transmit the confirmation to a wireless identification tag.

19. The isolation valve of claim 1 , further comprising a pressure relief device set at a design pressure of the flapper and operable to bypass the closed flapper.

20. An isolation assembly, comprising:

the isolation valve of claim 1 ; and

a power sub for opening and/or closing the isolation valve and comprising:

a tubular housing having a bore formed therethrough;

a tubular mandrel disposed in the power sub housing, movable relative thereto, and having a profile formed through a wall thereof for receiving a driver of a shifting tool; and

a piston operably coupled to the mandrel and operable to pump hydraulic fluid to the isolation valve piston.

21. A method of isolating a string in a wellbore, comprising:

deploying the string in the wellbore, the string having an isolation valve;

moving a piston of the isolation valve towards an abutment of the isolation valve;

moving the abutment independently of the piston;

closing a flapper of the isolation valve to isolate a bore of the valve; and

engaging the flapper with the abutment when the flapper is in the closed position.

22. The method of claim 21 , wherein the flapper seals against a seat of the isolation valve and does not seal against the abutment.

23. The method of claim 21 , wherein:

hydraulic fluid is supplied to move the piston via a hydraulic control line, and

the method further comprises:

shutting in the control line after closing the flapper; and

determining a differential pressure across the closed flapper by monitoring pressure in the shut in control line.

24. The method of claim 21 , wherein:

the casing string further has a power sub in fluid communication with the piston,

the drill string further has a shifting tool, and

hydraulic fluid is supplied to move the piston by driving the power sub with the shifting tool.

25. An isolation assembly for use in a wellbore, comprising:

an isolation valve, comprising:

a housing;

a piston longitudinally movable relative to the housing;

a flapper for operation between an open position and a closed position, the flapper operable to isolate an upper portion of a bore of the valve from a lower portion of the bore in the closed position;

a sleeve for opening the flapper; and

a pressure relief device set at a design pressure of the flapper and operable to bypass the closed flapper; and

a power sub for opening and/or closing the isolation valve and comprising:

a tubular housing having a bore formed therethrough;

a tubular mandrel disposed in the power sub housing, movable relative thereto, and having a profile formed through a wall thereof for receiving a driver of a shifting tool; and

a piston operably coupled to the mandrel and operable to pump hydraulic fluid to the isolation valve piston.