of use in the riser where, upon release from the drill pipe, it is actuated into a sealing state against the riser. In this embodiment, the body, also in the first state when run through the drill pipe, may be in sealing abutment against the interior of the drill pipe and thus form a barrier between fluids.
In one embodiment, a scraping means is attached to the conveying means and/or the installation device which, upon introduction of the body to the point of use, performs a cleaning of the riser wall. Thus, the riser is cleaned before the body, which in its active state is sealing against the riser, is to be run into the riser whilst it has a sealing function between two fluids in the riser.
According toone embodiment of the method, fluid is pumped into the riser through one or more pipes connected to the riser immediately above the wellhead, said fluid thus displacing the body upwards in the longitudinal direction of the riser.
The invention also relates to a device for use to separate fluids in a riser of the type used in offshore petroleum production, where the riser constitutes a connection between the wellhead on or above the seabed and a drilling vessel. According to the invention, the device comprises a body which has a first state in which it is conveyed to a point of use in the riser and a second state in which it has a sealing function against the riser, wherein it is sealingly in abutment against the riser