Patent GB-1166590-A (GB)
Title: Underwater Wellhead Flowline Connection
IPC: E21B43/013
Filed: 1968-08-06
Abstract: 1,166,590. Wells &c. ROCKWELL MFG. CO. 6 Aug., 1968 [1 Nov., 1967], No. 37458/ 68. Heading E1F. [Also in Division F2] Flow connection loops 25 of an underwater wellhead assembly are connected to delivery flowlines 35 by means of socketted hubs 31, 32 and connector 33 which are located into a cradle 30 and interconnected .by remote control from the surface. The wellhead conductor casing 2 projecting from the ocean floor carries a support base 3 on which the cradle is mounted and having vertical guide columns 4 with guide cables 5 reaching to the surface. The production tree 10 is lowered into position and connected to the wellhead conductor by remotely controlled connector 20. The cradle 30 (Fig. 2, not shown) is provided with end sections into which the hubs 31, 32 are lowered and latched in place, and a central section to receive the connector 33 as it is also lowered into position. Hub 31 is lowered into position with the tree. The flowline 35 is lowered into position with hub 32 Fig. 7, to which it is connected. Each hub 32 is provided with two flow bores 90 and two hydraulic fluid passages 91 (only one of each being visible in. the section shown in Fig. 7), each hub being a minor image of the other. Flowline hub 32 requires a special guide frame 100, Fig. 9a, for its installation in the cradle. This consists of a pair of guide, tubes 102 which follow down the guide cables 5 and are located on vertical guide tubes attached to the tree, and a running string connection cylinder 106 carrying the mounting and dismounting tool 120. The hub 32 rests on yoke-pieces 53 of the cradle. Bolted to the upper surface of the hub 32 is an upstanding pin 122 (Figs. 10 and 11, not shown) having lateral ears under which locking pins are moved by the movement of a hydraulic piston (130) when pressure is supplied through running string 107. The latches holding the hub may be disengaged for removal of the hub by retractors (141) which are fitted when required. Hydraulic pressure is applied to the other side of the locking piston (130) by rotation of the running string 107. This shears a set-screw (158) in joint 110 and places a feed port into communication with an alternative duct connected to the reverse side of the piston (see Fig. 12, not shown). The connector 33 is now lowered into position in the cradle 30 to connect the pipe-hubs together. This is achieved by the same guide frame 100 but with the locating tool in a different position (in box 104, not shown) appropriate to the position of the connector between the hubs, the same hydraulic running string 107 being employed and the connector being held by a vertical pin (303) in a similar manner to hub 32. When the connector is seated in the cradle yoke-pieces 61, 65, Fig. 15A, hydraulic pressure is applied into area 260 to force pistons 233 and rams 230 outwardly at each side towards the hubs 31, 32. This carries flow and hydraulic tubes 226 and 227 (227, not visible) into connecting sockets 94, 95 of the hubs (Fig. 7). Simultaneously, further movement of latch cylinder 225 and latches 224, compresses springs 255a until a latch lip 251 catches over locking flange 98 on the hub. Still further movement of cylinder 225 causes it to embrace the latches and lock them in position. To retract the connection pressure is applied in the area behind piston 242 (265, Fig. 15C, not shown). A drawing tool connector for applying pressure selectively to regions the connector is also described (Fig 16, not shown). Flexible but non-rotatable joints, Fig. 9B, are interposed into the flowlines 35 to reduce the strain on it. These joints, consist of a ball 190 working in sockets 185, 195 which are screwed together and sealed to the ball by 0- rings 194, 194b. Rotation is prevented by inter meshing dogs 188a on the end of the ball and in each socket 185. The joint is lubricated at 195a.