Patent ID: 8201632

Claim:
A downhole valve assembly comprising: a generally tubular body defining a fluid flow path therethrough; a ball valve mounted within the body, the valve movable between an open position and a closed position for thereby controlling the flow of fluid along the fluid flow path; a valve actuation mechanism mounted within the body, the actuation mechanism located in a position which is, in use, downhole of the valve; and a fluid communication arrangement for communicating wellbore fluid pressure to the valve actuation mechanism to facilitate operation of the valve actuation mechanism and thereby operation of the valve, the fluid communication arrangement comprising a fluid inlet port which is, in use, located uphole of the valve; wherein the valve actuation mechanism takes the form of a primary valve actuation mechanism, and the assembly further comprises a secondary valve actuation mechanism, wherein the secondary actuation mechanism comprises a fluid actuated override member, which takes the form of an override piston, wherein the override member is adapted to exert a force on a coupling member of the primary actuation mechanism, to move the valve, wherein the secondary actuation mechanism further comprises an operating member taking the form of a sliding sleeve located, in use, uphole of the valve and which is fluidly coupled to the override member and controls movement of the override member, wherein the sleeve is mounted for movement within the body and whereby movement of the sleeve pumps fluid to the override member such that the valve is moved.