Wellhead cementing assembly with by-pass

Claim 1

APPARATUS FOR DRILLING AND CEMENTING AN UNDERWATER WELL FROM AN OPERATIONAL BASE POSITIONED ABOVE THE SURFACE OF A BODY OF WATER, SAID APPARATUS COMPRISING (A) A WELLHEAD ASSEMBLY FIXEDLY POSITIONED BELOW THE SURFACE OF A BODY OF WATER, (B) SAID WELLHEAD ASSEMBLY INCLUDING A CASINGHEAD HAVING LANDING SURFACE MEANS FOR SUSPENDING THEREFROM A PAIR OF CONCENTRIC PIPE STRINGS WITH THE UPPER ENDS IN AXIAL SPACED RELATIONSHIP, (C) A DRILLING ASSEMBLY HAVING A VERTICAL BORE THERETHROUGH IN COMMUNICATION BETWEEN SAID OPERATIONAL BASE AND THE INTERIOR OF SAID WELLHEAD ASSEMBLY THE LOWER END OF SAID DRILLING ASSEMBLY BEING FIXEDLY SECURED TO THE UPPER END OF SAID WELLHEAD ASSEMBLY IN A FLUIDTIGHT MANNER, AND (D) FLUID BYPASS CONDUIT MEANS OUTSIDE AND CONNECTED BETWEEN SAID DRILLING ASSEMBLY AND SAID WELLHEAD ASSEMBLY AND IN COMMUNICATION THROUGH THE WALLS THEREOF WITH THE VERTICAL BORE OF SAID DRILLING ASSEM BLY AND THE INTERIOR OF SAID CASINGHEAD AT A POINT INTERMEDIATE THE LANDING SURFACE MEANS IN SAID CASINGHEAD FOR SAID PAIR OF PIPE STRINGS.