Patent GB-1500936-A (GB)
Title: Seal assembly for a well
IPC: E21B33/02
Filed: 1975-02-26
Abstract: 1500936 Wells &c S W PUTCH and N A NELSON 26 Feb 1975 [11 March 1974] 8005/75 Heading E1F A seal assembly 20 for sealing between a wellhead 10 and a easing hanger 14, one of which includes a locking notch 22, comprises a locking dog 48 for locking in the notch 22, a locking sleeve 50 which can be moved down behind the locking dog 48 to move it into the notch 22, a first member 40 connected to the locking sleeve 50 by a limited lost motion connection, and a second member 70 connected to the first member 40 by a screw thread whereby right hand rotation of the first member 40 moves the second member 70 downwardly to compress a seal 72 into contact with the wellhead 10. The assembly also includes a third member 80. In a first embodiment (Fig. 4) the locking notch 22 is formed in the wellhead 10. The first member 40 is connected to the locking sleeve 50 by a limited lost motion connection consisting of ring 64 and grooves 60, 62 and is temporarily fixed to the locking sleeve 50 by shear pin 58. The first member 40 is also connected to the third member 80 by a limited lost motion connection consisting of ring 90 and slots 86, 88 and is temporarily fixed by shear pin 84. The second member 70 is connected to the first member 40 by left hand thread 66 and is connected to the third member 80 by pins 78. The third member 80 is prevented from rotating by spring loaded pins 74 engaging between the flutes of the casing hanger 14. The seal assembly is installed using a running tool 24 (Figs. 4, 11) consisting of an upper part 26 connected to a lower part 28 by a lost motion connection consisting of ring 38 and grooves 34, 36. The assembly is lowered into the well by the running tool which has lugs 30 on the lower part 28 engaging J-slots 32 on the first member 40. When the third member 80 has engaged the top of the casing hanger 14 setting down on the running tool 24 causes a shoulder 46 on the upper part 26 to depress the locking sleeve 50 thereby shearing pin 58 and moving the locking dog 48 into the locking notch 22. The running tool 24 is then given a righthand rotation which is transmitted to the first part 40 by dogs 42 on the upper part 28 engaging recesses at the tops of the J- slots on the first part 40 thereby shearing pin 84 and moving the second member 70 downwardly to compress the seal 72. The running tool 24 can also be used to test the seal. Since the running tool 24 engages the third member 80 which, in turn, engages the casing hanger 14, the seal 72 is not stressed by the running tool 24 during the testing operation. After testing and removal of the running tool a bowl protector (not shown) may be landed over the seal assembly. The seal assembly can be removed by a retrieving tool (not shown) which engages a downwardly facing shoulder 52 on the locking sleeve 50, an upward pull on the sleeve 50 releasing the locking dog 48 and allowing the first and second members 40, 70 to move upwardly. to relax the seal 72.  In a second embodiment (not shown) the locking notch 22 is provided in the casing hanger 14, and either the second member 70 or the first member 40 abuts the bottom of the locking dog 48, a right hand thread being provided between the members 40 and 70 in the latter case. In a modification (not shown) the third member 80 is omitted and the seal 72 contacts both the casing hanger 14 and wellhead 10.