Patent GB-891359-A (GB)
Title: Retrievable double grip well packer
Inventor: CONRAD MARTIN BARCLEY
IPC: E21B33/129
Filed: 1959-03-31
Abstract: 891,359. Well packers. BAKER OIL TOOLS Inc. March 31, 1959, No. 10872/59. Class 85. A well packer comprising two sets of slips to lock the packer against movement in either direction relative to the well-casing, and having a sealing device between the two sets of slips is characterized in that means are provided to prevent the upper set of slips being expanded into engagement with the well casing until the lower set of slips have gripped the casing. The packer consists of a mandrel 10 connected to a string of drill-pipe C and in which, at the lower end of the mandrel there is a set of slips 21 housed in inclined T-slots 23 in a lower expander 24. The lower ends of the slips are also T-shaped and fit into similar grooves 35 in a slip ring 29 which is part of the drag-body 30 of a drag device 31 which encircles the mandrel. The body 30 is fitted with spring loaded pads 37 which press against the well casing B. The body 30 can be locked to the mandrel 10 by a clutch 45 to prevent relative movement between the slips and the mandrel. The lower expander is linked to the slip ring 29 by a sleeve 65 which has flanges 67 and 69 at the top and bottom respectively, and the upper portion 24a of the lower expander is linked to a lower abutment 71 for a packing structure 72 which is expanded to seal against the well casing. A sleeve 73 connects the lower abutment 71 to an upper abutment 78 and is also connected by a tie ring 104 to a retaining member 92 which has upwardly projecting arms 95 which engage an inwardly directed flange 103 on the skirt portion of an hydraulic cylinder 100. The cylinder slides on the mandrel 10 and is connected to an upper expander 124 which operates an upper set of slips 115 which are connected to the expander by T-slots and also to a retainer ring 118 by similar slots in the same manner as the lower slips. The expander 124 and retainer ring 118 are normally pushed apart by a plurality of coil springs 130 The annulus between the mandrel 10 and the cylinder 100 forms an hydraulic working cylinder which is connected to the bore of the mandrel by ports 138, and is sealed at its lower end by a sleeve 135 which carries a latch by which the sleeve 135 can be coupled to the cylinder 100 after the slips 115 have been expanded into contact with the well casing so that forces acting on the body 10 from below the packer will be transmitted directly from the mandrel to the slips. To achieve this the sleeve 135 has upwardly extending arms 150 with an enlarged head 152 which has a sloping surface 153 which engages a fixed surface 154 on the mandrel 10 so that as the sleeve 135 moves downwards, the arms move outwards and teeth 156 on the arms engage similar teeth 157 on the inside wall of the cylinder 100. In use the apparatus is lowered into the well with the parts disposed as shown in Figs. 1 and 1a in which the clutch 45 is engaged to lock the lower expander to the mandrel. At the desired position the clutch 45 is released and further downward movement of the drill string causes the slips 21 which are prevented from moving down by the drag device 31, to ride up the expander, engage the well casing and lock the lower abutment 71 against downward movement. As the mandrel continues to move down, the upper abutment 78 bears on the packing structure 72 and expands it against the well casing. Fluid pressure is then created in the drill string and will move the cylinder 100 and expander 124 upwards to lock the slips 115 against the well casing. Subsequently the sleeve 135 moves downwards and locks the body to the slips as described above.