Patent GB-1532256-A (GB)
Title: Well tools
IPC: E21B33/043
Filed: 1975-12-19
Abstract: 1532256 Wells &c FMC CORP 19 Dec 1975 [2 May 1975] 52002/75 Heading E1F A well tool 30 for running and actuating a well device such as a packoff assembly 118 (Fig. 1B) shown landed on a casing hanger 134 in a wellhead 136, comprises an annular body 32, means such as an upper end element 34 threaded at 36, 40 for connecting the body 32 to a well pipe 38 for running the tool 30 into a well, a piston 60 disposed for linear movement in the body 32 in response to fluid pressure entering the body, means connected to the piston 60 to convert the linear movement into torque, these means comprising e.g. a ball nut 76 and screw 78 assembly (see also Figs. 11A, 11B, not shown), an acme nut and screw assembly (Figs. 12A, 12B, 15-18), or a helical spline system, and means to transmit the torque to a well device or packoff 118 when the tool 30 and device 118 are interconnected, these means comprising e.g. a sun gear 100 in mesh with planetary gears 104 which themselves mesh with an annulus gear 110 that can interconnect with the device 118, or a single annular drive element (Figs. 11B, 12B, 15, 19). The arrangement is such that the well device 118 can be run into a well on the well pipe 38 and then actuated by hydraulic fluid conducted to the tool 30, without rotation of the well pipe. In operation, the packoff 118 is installed on the tool 30 by aligning lugs 172, 176 on the annulus gear 110 with axial slots 180 in a rotatable body element 116 of the packoff 118, and moving the packoff onto the tool until the lower lugs 172 register with an annular groove 174 in the element 116. The packoff is then rotated to move the lugs 172, 176 out of alignment with the slots 180 to jay the packoff on the tool, and in this position the combination is run into the well on the well pipe 38 until the packoff lands on the shoulder 158 of the casing hanger 134. Hydraulic fluid passed down the pipe 38 has its flow checked by a wireline retrievable ball check valve 182 so that fluid passes through a port 182b and a radial passage 186 in the element 34 to the chamber 58 of the piston 60 which is thus moved downwards against the force of a coil spring 188. Any fluid present in the annulus. 192 below the piston exits to the well bore 194 above the tool through a radial passage 196, axial passages 198 and check valves 200. The initial downward movement of the piston 60 rotates the tool until reaction dogs 210, .212 are aligned with slots 214, 216 in the inner surface of the wellhead 136. This stops further rotation of the tool 30, and also the piston 60 and ball nut 76 since the tool body 32 carries cam followers 64 which extend into longitudinal grooves 62 in the piston 60. Further downward movement of the piston 60 causes rotation of the ball screw 78 and the gears 100, 104, 110. When the lugs 172, 176 on the gear 110 come into alignment with the slots 180, the tool 30 drops so that the lugs move down into the slots and the element 116 now turns with the annular gear 110. During this drop, a slip ring 224, secured to the lower end of the tool body 32 by shear pins 226, forces a setting mandrel 164 downwards behind a setting ring 160 to force the latter into an opposing groove 170 in the wellhead 136 to lock the packoff in the wellhead. Further rotation of the gear 110 breaks a shear pin 146 connected between the element 116 and a lower body element 142 which is prevented from rotation by lugs 148 that engage lugs 150 on the hanger 134. The element 116 now rotates and also moves upward through left hand threads 144 so that the setting ring 160 rests against the top of its groove 170 and the element 142 is pressed downwards to force seal elements 152, 154 into contact with the wellhead 136 and hanger 134. The fluid pressure is increased to set the pressure-holding capability of the packoff as desired. For pressure testing of the packoff, blowout preventers are closed around the pipe 38 and pressure is applied to the bore 194 through a choke and/or kill line 230. If the difference between the outside diameter of the pipe 38 and the inside diameter of the hanger 134 is sufficient, the shear pins 226 break and the tool drops with respect to the slip ring 224 until a surface 232 of the tool comes to rest on an upper surface 234 of the hanger 134, thus transferring all the axial load from the packoff to the hanger. Test pressure is then applied through the line 230. After testing, the valve 182 is removed and the tool 30 lifted straight up on the pipe 38, the spring 188 returning the piston 60 to its starting position after disengagement of the lugs 172. Amongst other variations described, the tool 30 may be used in conjunction with a wireline retrievable piston resetting tool (Fig. 18) for returning the piston 60 to its starting position, and the bearing assemblies of the tool may be spring-mounted.