Underwater wellhead with re-entry lubricator

Claim 1

A LUBRICATOR FOR A WELLHEAD STRUCTURE THROUGH WHICH COMMUNICATION WITH A WELL MAY BE OBTAINED IN ORDER TO CARRY OUT CERTAIN WELL OPERATIONS, SAID LUBRICATOR COMPRISING (A) A TUBULAR LUBRICATOR HOUSING SECURED TO THE TOP OF A PRODUCTION WELLHEAD ASSEMBLY WHICH IS POSITIONED AT A NORMALLY CLOSES TO TOP OF A WELL HAVING AT LEAST TWO STRINGS OF PIPE SUSPENDED THEREIN, SAID TUBULAR HOUSING HAVING A VERTICAL BORE THERETHROUGH IN COMMUNICATION AT ITS LOWER END WITH AT LEAST ONE PIPE STRING OF SAID WELL AND BEING OPEN AT ITS UPPER END, (B) AN OUTR SEALING SURFACE FORMED AS PART OF THE OUTER SURFACE OF SAID TUBULAR LUBRICATOR HOUSING, SAID SEALING SURFACE BEING ADAPTED TO RECEIVE THEREON ANNULAR SEALING MEANS, (C) VERTICAL BY-PASS CONDUIT MEANS IN SAID LUBRICATOR HOUSING IN COMMUNICATION THROUGH SAID HOUSING WITH THE SPACE OUTSIDE THEREOF ABOVE AND BELOW THE OUTER SEALING SURFACE THEREOF AND (D) INNER SEALING SURFACE MEANS FORMED ON THE INNER WALL OF SAID TUBULAR LUBRICATOR HOUSING FOR RECEIVING SEAL MEANS CARRIED BY A LUBRICATOR MANDREL.