Patent GB-712208-A (GB)
Title: Retrievable well packer
Inventor: BAKER REUBEN CARLTON
IPC: E21B33/129
Filed: 1952-01-22
Abstract: 712,208. Well packers. BAKER OIL TOOLS, Inc. Jan. 22, 1952, No. 1774/52. Class 85 A retrievable well packer comprises a tubular mandrel 10a, 10b, 10c connected to a string of drill pipe C and having secured at its lower end a guide shoe 16 connected by a rubber sleeve 19 to a slip ring 22 pivotally connected by links 25 to lower slip elements 23. The lower expander comprises two elements 32, 35, the element 32 being joined, so as to permit of radial movement, to a valve housing 52, the valve 66 being secured to the mandrel. The valve housing 52 is secured to the lower abutment 83 of the packer 82 and to the circulation sleeve 73 which slidably extends through the upper abutment 81. The upper abutment 81 is connected to the upper slip expander 79 with the tapered surfaces of which co-act slips 89 pivotally connected by links 93. with a swivel assembly which can be locked to the mandrel 10 by a spring actuated clutch 126. To this swivel assembly is connected a drag spring unit 116 and to said drag spring unit a further drag spring unit 161. The packer is lowered into the bore with the slips retracted and the clutch 126 engaging the teeth on the mandrel, so securing the parts of the packer against movement. A fluid by-pass is formed around the packer through ports 60 in the valve housing, past the open valve 64, passage 74 and ports 84. To set the packer, the clutch 126 is released and the mandrel, with attached parts, is drawn upwards with respect to the other parts of the packer which are restrained from upward movement by the drag spring units. This upward movement of the mandrel causes upward and outward movement of the lower slips 23, first due to the connection to the shoe 16, and then as a result of the outward movement of the expander element 32 as the element 35 is contacted and urged upwards by the stop 135 on the mandrel. At the same time the by-pass is closed as the valve 64 enters the passage 73 to abut against seat 72 and move packer 82, sleeve 73, connecting member 78 and expander 79 to set slips 89. Further upward movement results in the setting of the packer 82. The division of the lower expander into two elements 32, 35, the co-engaging surfaces of which taper in the opposite longitudinal direction towards the axis of the mandrel to the co-engaging surfaces of the element 35 and slips 23, prevents the retraction of the lower slips 23 when the mandrel and drilling string are slightly elongated due to any load set upon them. To withdraw the packer, the mandrel is forced downwards causing the slips 23 to be withdrawn radially by the links 25 or, if that is insufficient, by the valve head engaging the element 35 and forcing said element down to permit inward radial movement of element 32 or 35. This freeing of the lower slips permits downward axial movement of sleeve 73, the opening of the by-pass passage and release of packer and, when the sleeve engages the upper abutment, the freeing of the upper slips. Alternatively, to free the lower slips the mandrel can be rotated to withdraw the upper portion 10a in the socket 10c and cause positive downward movement of the lower portion 10b of the mandrel.