Patent GB-1482125-A (GB)
Title: Well suspension system
IPC: E21B33/00
Filed: 1974-09-18
Abstract: 1482125 Well completion S W PUTCH and N A NELSON 18 Sept 1974 [27 Sept 1973] 40643/74 Heading E1F A subsea well casing hanger 16 is run into position through a conductor 10 using a running string to which it is connected by a wash tool 18 having a resilient locking ring 36 for reception in a groove 30 in the hanger, when the tool is telescoped over the hanger, the tool including a body 19 and a nut 32 which engages the hanger in a manner precluding rotation of the nut whereby the tool is releasable from the hanger by rotating the body to back it upwards to a position in which the locking ring can expand into a groove 34. The body 19 includes wash ports 42 which can be placed clear of the upper end of the hanger without disconnecting the tool from the hanger. Following due extension of the wellbore, a further casing string 46 (Fig. 5) is run into position with a hanger 50 which is connected to the running string by a tool 51 equivalent to tool 18 but having no wash ports. Hanger 50 includes a locking ring 52 which engages in a groove 54 in hanger 16, a variety of designs for ring 52 being disclosed one of which requires the ring to be connected to the hanger body by a shear pin or the equivalent so that once the ring has become engaged in the groove 54 the body can move down to land on the ring and lock it in its expanded condition. The ring 52 in each case includes depending guide keys also intended for reception in a groove in hanger 16, the keys in alternative embodiments of the ring forming part of a lower portion of the ring which is secured to an upper portion by a frangible connection, the arrangement is such latter cases being that once the upper portion has become engaged in groove 54 the hanger body 50 can move down, together with the lower portion of the ring, to land on the upper portion and lock it in its expanded condition. The hanger 50 may receive a further hanger (not shown) and is provided with a groove 56, which corresponds to groove 54, for that purpose. Upon removal of tool 51 a mechanically-set packoff assembly may be installed in the annulus between hangers 16, 50, this assembly either being carried at the lower end of a tool similar to tools 18, 51 (see Fig. 11, not shown) or being adapted to be latched into engagement with hanger 50 as shown in Figs. 15A, B where the assembly 110a is seen to include a body 121, a latch ring 132, a nut 130 engageable with lugs on the hanger 50 and a seal unit 116a, 126a. Also disclosed are two alternative forms of tool engageable with the top of hanger 50, one such tool 136 (Figs. 15A, B) including a hydraulically-actuated piston 144, 146 controlling extension, and retraction of the latching ring 140, the tool body carrying a seal ring 154 engageable with the top of the hanger 50. The other tool disclosed (Fig. 18) has a latching ring 172 which is engaged in the hanger groove 30 as the tool is telescoped over the hanger and is retained in the groove by picking up the tool to engage land 178 behind the ring. This tool is released by letting it down so that nut 164 becomes keyed to packoff assembly 110a at 167 168 and then rotating tool body 162 to align groove 170 with the ring 172.