Patent GB-788637-A (GB)
Title: Retrievable double holding subsurface well tool
IPC: E21B33/129
Filed: 1956-04-04
Abstract: 788,637. Well tools. BAKER OIL TOOLS, Inc. April 4, 1956 [Sept. 26, 1955], No. 10319/56. Class 85 A well tool comprises a body 10 adapted to be moved. longitudinally within the casing B, upper and lower expanders 11, 18 on the body, slips 17, 19 slidable longitudinally of the body to coact with the expanders, and releasable locking means 21 between the body and the slips preventing longitudinal movement of the slipsrelative to the body. The expanders 11, 19 are respectively fixed to and slidable on the body. The slips 17 are mounted in slots in a slip ring 23 slidable on the body and pivot about a ring 32, the slips being normally biased by springs 29 so that their gripping portions 24 are retracted. The slip ring is fixed to a ring 37 of the locking means. The locking means comprises upper rings 37, 54, lower rings 62, 52, a sleeve 65 connecting the upper rings to the lower rings and permiting relative rotation of the lower rings relative to the upper rings, a locking segment 56 urged by a spring in the direction of the body to coact with a groove 57 in the body, and a stop segment 73 fixed to the ring 54 and co-operating with a key 75 on the body. The groove 57 extends partly around the body, its ends being bridged by a body portion 58 of normal section. The slips 19 are similar to the slips 17, the lower slip ring 46 being fixed to the ring 52. Counter clockwise rotation of the body moves the groove 57 into longitudinal alignment with the lock segment so that when the lock segment is brought into the plane of the groove, the segment enters the groove to lock the slips against longitudinal movement relative to the body. Rotation of the body in the clockwise direction places the portion 58 in longitudinal alignment with the locking segment so that the slips are longitudinally movable with respect to the body. The lower expander 18 has a shoulder 80 co-acting with a flange 81 on the body to limit longitudinal movement of the expander relative the body ,and is operatively connected to a packer 20. The packer consists of elastic rings 83, 84 mounted on a sleeve 82 fixed to the expander 18, and a compression ring 86. The compression ring is carried by a sleeve 38 fixed to a guide member 14 in turn fixed to the body by a left hand screw connection' 12, 13. Longitudinal movement of the sleeve 82 relative to the body is limited hy a flange 87, and relative rotation between the sleeves 82, 88 is prevented by a key 90. The tool, set so that the segment 56 engages the groove 57 to lock the slips against longitudinal movement along the body, is fixed to a tubing string C, and lowered into the casing B (Fig. 1). Further tubing may be supported by the guide member if required. When the desired tool position is reached the string and body are rotated clockwise to permit raising of - the string and body with the expanders whilst the slips remain stationary under the action of their drag portions 28, 43. Raising of the string and body causes the expander 18 to pivot the slips 19 so chat their gripping portions 39 engage the casing, further raising of the body expanding the packer so that the tool is anchored in a packed-off condition against upward movement (Fig. 2). Downward pressure on the packer causes the string to stretch, the resultant lowering of the expander 18 freeing the slips 19, but the lowering of the expander 11 causing the gripping portions 24 of the slips 17 to engage the casing so, that further downward movement of the tool is prevented. On release of 'he downward pressure the tool returns to the position shown in Fig. 2. The string and body are moved downwardly and turned anti-clockwise to release the slips and lock them to the body so that the tool may be removed from the casing. In the event of the tool becoming stuck in the casing, the string and body are raised and rotated clockwise to unthread the connection 12, 13 to raise the slips 19 and lower the expander 18. If, when the connection is completely undone. the slips 19 are still jammed the string is hoisted to shear a ring 92 so that the body, expander 11, slips 17, 19, and the locking means may be withdrawn from the casing. In a modification (Figs. 11-13, not shown) the packer is at the top of the tool which is usually used for anchoring against downward movement. In a further modification (Figs. 14-16, not shown) the packer is omitted and both expanders are fixed to the body. This tool is used to hold a tubing string in tension. Should the string fracture the upper slips operate to support the fractured end of the string.