Patent ID: 8100189

Claim:
System for dynamic sealing around a drill stem ( 16 ) of a variable diameter in water carrying, drilling fluid carrying or hydrocarbon carrying wells, comprising a sealing arrangement ( 10 ) arranged for mounting to existing equipment on the well and for use with riserless systems, the sealing arrangement ( 10 ) comprises an elongated dynamic sealing unit ( 30 ) arranged to envelop the drill stem ( 16 ), and a receiver unit ( 40 ) mounted to said existing equipment on the well and which is arranged to receive the sealing unit ( 30 ), wherein internal pressure support is provided in the sealing arrangement ( 10 ), at least corresponding to the surrounding pressure, to provide a dynamic seal around the drill stem ( 16 ), by a pressure medium in defined annular spaces ( 32 , 34 ) between a number of sets of main seals ( 20 , 22 , 24 ), and said main seals ( 20 , 22 , 24 ) are arranged mutually spaced apart with a distance longer than the length of the pipe coupling in the drill stem ( 16 ), in the longitudinal direction of the sealing unit ( 30 ).