Patent GB-1454699-A (GB)
IPC: E21B33/047
Filed: 1974-04-19
Abstract: 1454699 Wells BAKER OIL TOOLS Inc 19 April 1974 [1 June 1973 16 Nov 1973] 17235/74 Heading E1F A well safety valve assembly is adapted to be connected to an upper section of a production tubing string and lowered therewith into latching engagement with a downhole tubing hanger supporting the lower section of the production string, the assembly including a telescopic spacer which is operable to allow a hanger at the upper end of the upper section of the production string to be brought into engagement with a seat in a wellhead while the assembly is engaged with the downhole hanger. In the dual completion assembly shown, two safety valves V 1 , V 2  are in communication respectively with flow tubes 128, 129 which are received in bores 30 of the downhole hanger 22 which may be that disclosed in Specification 1416083, these tubes 128, 129 being threadedly engaged at 149 with a latch body 147 carrying a radial orienting key 150 guided into a vertical slot in the hanger 22. The valve V 2  is connected to tubing string T 4  via telescopic joint 143, 171, tubing 144a and safety joint 145, the latter including a plate 184 rotatably supporting a mandrel 185 connected to the tubing 144a, the plate 184 also being connected to the other upper tubing string T 3  by tubing 141a and to the valve V 1  by telescopic seal 200, 203 while the assembly is being run into the well, the joint 143, 171 is in an extended condition placing the head of coupling 144 in abutment with the underside of a plate 165 to which is secured the upper ends of a pair of control rods whose lower ends are connected to the cross-head 126 from which depend the latch fingers 152, each rod including upper and lower sections 160, 157 but only one such rod being visible in KG1c-f. Once the assembly has engaged the tubing hanger 22, the tubing string T 4  is rotated to the left to contract the joint 143, 171 and move the head of coupling 144 clear of plate 165 so that springs 166 can depress the control rods to set the latch, continued rotation of string T 4  then serving to further contract joint 143, 171, until a hanger at the upper end of string T 4  engages its seat in the wellhead, and to drive latch body 147 upwards to lock the latch fingers 152 in position. Due to its connection with string T 4  via plate 184, the string T 3  accompanies string T 4  in the downward movement thereof that accompanies the left-hand rotation of string T 4  and a hanger in string T 3  engages a seat in the wellhead at the same time that the hanger on string T 4  engages its seat, the downward movement of the string T 3  being accommodated by the seal 200, 203. Release of the latch to permit retrieval of the assembly is effected by right-hand rotation of the string T 4  to cause joint 143, 171 to jack up the strings and retract the latch, although if the joint 143, 171 seizes or the control rods fail then the right-hand rotation is continued to cause fracture of shear pins 163a connecting coupling 164 to plate 161, thus allowing mandrel 137 to be rotated by string T 4  and moves upwards due to threads 149 to raise the latch fingers relative to body 147. The valves are controlled via a conduit A 2  and are supplied with a lubricant or a balancing fluid via a conduit A 1 , these conduits incorporating telescopic seals 226, 227 and being connected to move with string T 3 . Upon failure of the safety joint 145, the strings T 3 , T 4  are retrievable leaving the mandrel 185 and seal cylinder 200 accessible for reconnection, the cylinder 200 carrying a guide 139 for facilitating the reconnection. In a modification, the weight of string T 3  is initially taken as above by plate 184 but the hanger on this string is arranged to engage its seat in the wellhead before the assembly lands in the downhole hanger and thus before the tubing spacing adjustment of string T 4  is made. In this case, the plate 184 is slidably keyed to an intermediate square-section portion of a further mandrel (184b) connected between the string T 3  and tubing 140. The control conduit A 2  in this case includes a telescopic seal assembly arranged to ensure that there is no change in volume in the control system as a result of tubing spacing adjustment and that control fluid pressure is removed from both valves before disengagement of strings T 3 , T 4 .