Abstract: A downhole tool having selectively openable ports therein, the tool being actuable between a closed configuration in which the ports are closed, a primed configuration in which the ports are primed for opening, and an open configuration in which the ports are opened.

Abstract: A valve device for use downhole is described as comprising a body member and a channel through the body member through which fluid can flow. A moveable member is mounted within the body member, and comprises an obturating member for selectively obturating the channel. The moveable member is moveable between a first position in which the channel is not obturated and fluid flow through the channel is permitted, and a second position in which the channel is obturated and fluid flow through the channel is substantially prevented.A method of preventing the fluid flow downhole is also described as comprising the steps of inserting a downhole tool comprising a valve device according to the present invention downhole and moving the moveable member from the first to the second position such that the obturating member obturates the channel.