Method and apparatus for restricting fluid flow in a downhole tool

1. An apparatus for restricting fluid flow through a downhole tubular member, the apparatus comprising:

an annular housing configured for use in a wellbore;

an annular sleeve configured to be received within the housing, the annular sleeve having an inner surface defining a first section of a first diameter and a second section of a second, smaller, diameter; and

a resilient split-ring baffle at least partially received within the sleeve, the baffle comprising a longitudinal seam forming two separate circumferential ends in the baffle, the baffle being longitudinally moveable between a first position in the first section and a second position in the second section of the sleeve, wherein an outer surface of the baffle is configured to engage the inner surface of the sleeve to cause the baffle, when in the first position to be relatively radially expanded, and, when moved to the second position in the sleeve, to radially contract,

wherein the sleeve is configured to move longitudinally from a first position toward a second position within the housing in response to an applied force, and

wherein the housing comprises a plurality of apertures, which are covered when the sleeve is in the first position and uncovered when the sleeve is in the second position within the housing.

2. The apparatus of claim 1 , wherein the two circumferential ends of the baffle are offset from one another when the baffle is expanded and abut one another when the baffle is contracted.

3. The apparatus of claim 1 , wherein the two circumferential ends of the baffle are offset from one another by a first distance when the baffle is expanded and are offset from one another by a second distance that is less than the first distance when the baffle is contracted.

4. The apparatus of claim 1 , wherein:

a first longitudinal end of the sleeve comprises the inner surface, the inner surface comprising a tapered profile that defines a transition between the first section of the first diameter and the second section of the second, smaller, diameter;

at least a portion of a first longitudinal end of the baffle is received within the first longitudinal end of the sleeve; and

the first longitudinal end of the baffle comprises an outer surface comprising a tapered profile configured to engage the tapered profile of the first longitudinal end of the sleeve to cause the baffle, when moved to the first position in the first section of the sleeve, to radially expand, and, when moved to the second position in the second section of the sleeve, to radially contract.

5. The apparatus of claim 4 , further comprising a piston configured to be received within the housing, wherein the piston is configured to move longitudinally within the housing to engage the baffle to move the baffle from the first position in the first section of the sleeve to the second position in the second section of the sleeve.

6. The apparatus of claim 5 , wherein:

the movement of the piston within the housing to engage the baffle to move the baffle from the first position in the first section of the sleeve to the second position in the second section of the sleeve causes the apertures in the housing to be uncovered.

7. The apparatus of claim 4 , wherein:

the outer surface of the first longitudinal end of the baffle comprises a tapered surface and at least one tab protruding radially outward from the outer surface;

the inner surface of the first longitudinal end of the sleeve comprises a groove around the circumference of the inner surface; and

the at least one tab configured to be received in and engage the groove.

8. The apparatus of claim 6 , wherein the at least one tab comprises a plurality of tabs protruding radially outward from and distributed around the circumference of the outer surface of the first longitudinal end of the baffle.

9. The apparatus of claim 6 , wherein the at least one tab comprises an outer tapered surface defining at least a portion of the tapered profile of the outer surface of the first longitudinal end of the baffle, and wherein the groove comprises an inner tapered surface defining at least a portion of the tapered profile of the inner surface of the first longitudinal end of the sleeve.

10. An apparatus for communicating a fracturing fluid to one or more layers of a formation surrounding a subterranean wellbore, the apparatus comprising:

a tool string comprising a plurality of annular housings defining a central conduit of the tool string through which the fracturing fluid is communicated;

an annular sleeve configured to be received within one housing of the tool string, the annular sleeve having an inner surface defining a first section of a first diameter and a second section of a second, smaller diameter; and

a resilient split-ring baffle at least partially received within the sleeve, the baffle comprising a longitudinal seam forming two separate circumferential ends in the baffle, the baffle being longitudinally moveable between a first position in the first section and a second position in the second section of the sleeve, wherein an outer surface of the baffle is configured to engage the inner surface of the sleeve to cause the baffle, when in the first position to be relatively radially expanded, and, when moved to the second position in the sleeve, to radially contract,

wherein the sleeve is configured to move longitudinally from a first position toward a second position within the one housing in response to an applied force, and

wherein the one housing comprises a plurality of apertures, which are covered when the sleeve is in the first position and uncovered when the sleeve is in the second position within the one housing.

11. The apparatus of claim 10 , wherein the two circumferential ends of the baffle are offset from one another when the baffle is expanded and abut one another when the baffle is contracted.

12. The apparatus of claim 10 , wherein the two circumferential ends of the baffle are offset from one another by a first distance when the baffle is expanded and are offset from one another by a second distance that is less than the first distance when the baffle is contracted.

13. The apparatus of claim 10 , wherein:

a first longitudinal end of the sleeve comprises the inner surface, the inner surface comprising a tapered profile that defines a transition between the first section of the first diameter and the second section of the second, smaller, diameter;

at least a portion of a first longitudinal end of the baffle is received within the first longitudinal end of the sleeve; and

the first longitudinal end of the baffle comprises an outer surface comprising a tapered profile configured to engage the tapered profile of the first longitudinal end of the sleeve to cause the baffle, when moved to the first position in the first section of the sleeve, to radially expand, and, when moved to the second position in the second section of the sleeve, to radially contract.

14. The apparatus of claim 13 , further comprising a piston at least partially received within the one housing of the tool string within which the annular sleeve is received, wherein the piston is configured to selectively move longitudinally within the one housing to engage the baffle to move the baffle from the first position in the first section of the sleeve to the second position in the second section of the sleeve.

15. The apparatus of claim 14 , wherein:

the movement of the piston within the housing to engage the baffle to move the baffle from the first position in the first section of the sleeve to the second position in the second section of the sleeve causes the apertures in the housing to be uncovered.

16. The apparatus of claim 14 , further comprising an electro-hydraulic valve that is configured to be actuated to selectively move the piston longitudinally within the one housing.

17. The apparatus of claim 14 , wherein:

the outer surface of the first longitudinal end of the baffle comprises a tapered surface and at least one tab protruding radially outward from the outer surface;

the inner surface of the first longitudinal end of the sleeve comprises a groove around the circumference of the inner surface; and

the at least one tab configured to be received in and engage the groove.

18. The apparatus of claim 17 , wherein the at least one tab comprises an outer tapered surface defining at least a portion of the tapered profile of the outer surface of the first longitudinal end of the baffle, and wherein the groove comprises an inner tapered surface defining at least a portion of the tapered profile of the inner surface of the first longitudinal end of the sleeve.

19. A method of actuating an apparatus for restricting fluid flow through a downhole tubular member, the method comprising:

moving a split-ring baffle from a first position within a first section of an annular sleeve to a second position within a second section of the sleeve to cause the baffle to radially contract, wherein the sleeve comprises an inner surface defining the first section of a first diameter and the second section of a second, smaller, diameter, wherein the baffle comprises a longitudinal seam forming two separate circumferential ends in the baffle, and wherein an outer surface of the baffle is configured to engage the inner surface of the sleeve to cause the baffle, when in the first position to be relatively radially expanded, and, when moved to the second position in the sleeve, to radially contract; and

dropping a plug into the baffle when the baffle is in the second position and relatively radially contracted, wherein the plug is configured to lodge in the baffle to restrict fluid flow through the baffle when the baffle is contracted; and

moving the sleeve longitudinally from a first position toward a second position within the downhole tubular member,

wherein the downhole tubular member comprises a apertures which are covered when the sleeve is in the first position and uncovered when the sleeve is in the second position within the downhole tubular member.