Patent GB-934216-A (GB)
Title: Improvements relating to oil-well equipment
IPC: E21B33/035
Filed: 1960-07-28
Abstract: 934,216. Wells. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. July 28, 1960 [July 30, 1959], No. 26291/60. Class 85. A subaqueous wellhead assembly, having conduits 33, 34, and a removable conductor 100 (Fig. 4), extending to above the surface, is closed by closing the conduits at points below the top of the assembly, inserting grease through the conductor into voids in the assembly, sealing the top of the assembly with a plug 71 (Fig. 2), and removing the conductor. The assembly is coupled to a well casing 12 (Fig. 1), and comprises a container 23 housing electro-hydraulic power units 21, 22, power actuated components such as flow line valves 13 . . . 16, and power actuated swabbing valves 17, 18. The assembly is closed by apparatus 26 having a member 30 containing the conduits 33, 34. The conduits have shoulders or recesses 35 . . . 48 for positioning tools or valves, and are connected at their lower ends to side conduits 51, 52 which may be shut-off by slide valves 53, 54 and lead to the power actuated components. The member 30 is closed by the plug 71 which has dogs 72 engaging recesses 73. The member has grease ports 75, 76 extending from the conduits 33, 34, and channels 79, 80, 154, 155. The conduits 33, 34 may also be shut by tubing plugs such as plug 83. The member 30 is protected from corrosion by a retractable spring-loaded bellows sleeve 90, 91, to the inner surface of which grease is supplied by the ports and channels. To enter the wellhead the conductor 100 is lowered from a drilling barge and locked to the member 30 by a head 101 which collapses the bellows. The head is locked to the member 30 by dogs 106, 107 which are forced inward to engage a groove 74 by movement of a piston 112. The plug 71 is removed and separate strings 97, 98 are run into conduits 33, 34 and locked on to pins 95, 96. Sleeve valves 53, 54 are moved by wire-line tools to connect the side conduits to the conduits 33, 34 so that fluid may be pumped to actuate the pressure actuated components of the wellhead assembly. Both conduits may be used to supply the pressure or one conduit may be used for supply, and the other may be used for return of the fluid. When required to close the wellhead assembly the strings 97, 98 are withdrawn and plug 71 is run down the conductor to close the top of member 30. Grease is inserted into the conductor ahead of the plug 71 so that as the plug is forced into place grease is forced through the ports and channels to fill all voids including the space between the bellows and the member 30. The head 101 is unlatched and the head and pipe 100 are removed the bellows extending to cover the member 30. Conduits 115, 116 which end near the bottom of the member 30 each have two side conduits (Fig. 5, not shown), leading to the power actuated components and which may be opened or closed by longitudinal movement of strings extending through the conductor and engaging spring-loaded valves. In a modification (Fig. 8, not shown), the plug 71 is replaced by a cap-type plug which is provided with guide arms, and check valves for the supply of grease.