Well tool device comprising a housing having an axial through bore, where the well tool device is comprising: - a sleeve section axially displaceable relative to the housing, where the sleeve section comprises an axial through bore aligned with the axial through bore of the housing; - a fluid flow preventing disc; - an axial fluid passage bypassing the disc when the well tool device is in an initial state, thereby allowing a fluid flow between a first location axially above the disc and a second location axially below the disc; where the axial fluid passage is closed when the well tool device is in an intermediate state; - the fluid flow preventing disc is provided in the bore of the sleeve section in sealing engagement with the sleeve section; - the well tool device further comprises a disc supporting device for supporting the disc in relation to the sleeve section, where the disc supporting device is releasably connected to an inside of the sleeve section by means of a releasable connection device; - the well tool device further comprising a first actuation system for moving the sleeve section axially in relation to the housing from the initial state to an intermediate state; characterized in that: the fluid flow preventing device is a fluid flow preventing frangible disc; - the well tool device further comprises a disintegration device for disintegration of the frangible disc, where the well tool device is in a final state when the frangible disc has been disintegrated by means of the disintegration device; - the well tool device comprises a second actuating system for releasing the releasable connection device, thereby causing a release of the disc supporting device from the sleeve section. - a sleeve section axially displaceable relative to the housing, where the sleeve section comprises an axial through bore aligned with the axial through bore of the housing; - a fluid flow preventing disc; - an axial fluid passage bypassing the disc when the well tool device is in an initial state, thereby allowing a fluid flow between a first location axially above the disc and a second location axially below the disc; where the axial fluid passage is closed when the well tool device is in an intermediate state; - the fluid flow preventing disc is provided in the bore of the sleeve section in sealing engagement with the sleeve section; - the well tool device further comprises a disc supporting device for supporting the disc in relation to the sleeve section, where the disc supporting device is releasably connected to an inside of the sleeve section by means of a releasable connection device; - the well tool device further comprising a first actuation system for moving the sleeve section axially in relation to the housing from the initial state to an intermediate state; - the well tool device further comprises a disintegration device for disintegration of the frangible disc, where the well tool device is in a final state when the frangible disc has been disintegrated by means of the disintegration device; - the well tool device comprises a second actuating system for releasing the releasable connection device, thereby causing a release of the disc supporting device from the sleeve section.