Abstract: Two types of isolation tools are disclosed for installation between the upward end of the LMRP and the lower end of a riser string in the drilling of a subsea well using dual gradient techniques, one of which is especially adapted for rotation about a rotating drill sling. Each type includes insert packer adapted to be closed about the drill string to divert drilling fluid in the annulus between the drill string and the subsea wellhead into lines extending along the side of the riser to the surface. The insert is selectively removable to permit conventional drilling.

Abstract: Two types of isolation tools are disclosed for installation between the upward end of the LMRP and the lower end of a riser string in the drilling of a subsea well using dual gradient techniques, one of which is especially adapted for rotation about a rotating drill sling. Each type includes insert packer adapted to be closed about the drill string to divert drilling fluid in the annulus between the drill string and the subsea wellhead into lines extending along the side of the riser to the surface. The insert is selectively removable to permit conventional drilling.

Abstract: There are disclosed two types of valves connectible in a subsea drilling riser to permit the opening and closing of side ports therein. One such valve is automatically opened when the hydrostatic subsea pressure is greater by a predetermined amount than that of drilling mud in the riser. The other valve is installed in the lower end of the riser and is adapted to be opened to discharge drilling fluid therefrom.

Abstract: A riser string for a subsea well uses the outer conduit or air can members to support the weight of the riser string. The outer conduits have flanges on their ends which are bolted together. The outer conduits have ports to admit sea water, and a gas injection system to displace some of the sea water for providing buoyancy. Mounting plates are located at each end of the outer conduits. Inner conduits for conveying well and production fluids are mounted between these mounting plates. The mounting plates are intrinsically curved in vertical cross-section, such that when the conduit flanges are bolted together, the mounting plates flatten to provide a compressive force across the faces. Metal seals are located in the holes provided in the mounting plates for the inner conduits. The inner conduits are supported along their lengths by one or more lateral supports.

Abstract: A metal seal for sealing the male end of a tube into the female end of another tube, particularly in a subsea well installation. An annular metal lip is located on the exterior of the male end of the tube. The lip has a free end with a radially protruding metal band. The band has an outer diameter greater than the inner diameter of the female tube bore, providing an interference fit. An annular recess is located inward from the lip, allowing the lip to deflect and exposing the inner portions of the lip to pressure in the bore to act outwardly on the lip.

Abstract: A marine conductor coupling is shown in use in a subsea well installation for connecting a blowout preventer stack to the subsea well head with the coupling including a one piece body of annular configuration having a mandrel receiving vertical bore aligned to a vertical through bore, a plurality of latching dogs received in a mating plurality of horizontally disposed dog receiving slots extending through the annular side wall of the body normal to and intersecting the mandrel receiving bore, mounting studs for connecting the body directly to the associated blowout preventer stack component, whereby forces tending to separate the connector body from the well head mandrel are transmitted directly through the one piece body of the connector, an actuating ring disposed about the inclined rear faces of the latching dogs for urging the dogs into latching engagement with the mandrel, a knock-out ring having a lost motion connection to and being suspended below the actuating ring to be raised by dog releasing motion

Abstract: A subsea well assembly has features that allow a riser string leading to the surface to be purged of well fluids prior to pulling the riser string. The well assembly includes a riser connector that seats on a Christmas tree. The Christmas tree and connector have coaxial bores, the ends of which are separated from each by a chamber. A stinger interconnects the bores and extends through the chamber. The stinger has upper and lower pressure shoulders. Hydraulic fluid pressure applied to the lower shoulder causes the stinger to retract from the Christmas tree bore. This allows communication of the connector bore with an annulus passage also located in the connector bore. Fluid can then be pumped down the annulus passage to flow through the chamber and return up the connector bore, purging the riser of well fluid.

Abstract: A subsea marine conductor bending tool for bending lower portions of the marine conductor when in the sea adjacent a subsea wellhead to align the conductor and its coupling member to a subsea wellhead has a plurality of individual bending beam assemblies and means for connecting them together in an articulated vertical array, a running tool for running the array of beam assemblies down within the conductor from an overhead platform to lower portions within the conductor adjacent a subsea location to which the conductor is to be aligned and hydraulically operated means on each of the bending beam assemblies operable from the overhead platform for applying bending forces against adjacent interior portions of the conductor to bend the same as required to align the conductor and its end connector to the wellhead.

Abstract: An electrical circuit between a floating vessel and electrical apparatus located at a remote subsea location associated with a subsea well is provided with as first electrical conduit connected to a mandrel member run from the vessel, a second electrical conduit run from the remote electrical apparatus to a mandrel receiving socket member associated with the subsea well equipment and a slip fit connect-disconnect electrical connection means provided on the mandrel and socket member with a first contact member on the mandrel and a concentric second contact ring member in the socket member whereby landing and removal, respectively, of the mandrel relative the socket member automatically completes and interrupts, respectively, the electrical circuit between the vessel and the remote electrical apparatus.

Abstract: A flexible supportive joint is provided between a buoyancy chamber of flotation means and a sub-sea well riser conduit upon which the flotation means is mounted. In a preferred exemplary embodiment, such flexible supportive joint comprises an assembly of coaxial, telescopically oriented pipe sections with a cylindrical elastomeric member bonded therebetween to flexibly join the two sections in load bearing relation, one section being connected to the riser conduit with the other section being connected to the flotation means buoyancy chamber. In a first alternative exemplary embodiment, the flexible supportive joint is provided by a ball and socket-like connection while in a second alternative construction, the flexible supportive joint is provided by a combination of an elastomeric member in load bearing relation with coaxial conduit sections and a ball and socket-like joint between the sections.