Method and apparatus for restricting fluid flow in a downhole tool

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.

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.