GB759889A - Method and apparatus for pressuring well bores - Google Patents

Abstract

759,889. Well tool and method for pressurizing well bores. BAKER OIL TOOLS, Inc. Sept. 13, 1954 [Oct. 12, 1953], No. 26459/54. Class 85 A well tool comprises an. upper packer connected at the top to a tubular string and at the bottom to releasable coupling means by which a lower packer is coupled so that the tool may be lowered in a well. casing, the lower packer set below perforations in the well casing, the coupling means released and the upper packer raised and set above the perforations when positive or negative pressures may be applied to the locations surrounding the casing perforations by means of fluid in the tubular string and afterwards the upper packer released, lowered and recoupled to the lower packer which is released and the whole tool moved longitudinally in the well casing. The lower packer anchors against both upward and downward displacement. The upper packer C may be of any suitable retrievable type. The releasable coupling D comprises an outer cylinder 120 secured to tubing 122a extending from the upper packer C by a cup 121 to which an inner cylinder 129 is also secured; between the cylinders slides an annular piston 128 urged downwards by a spring 134 and having latches 127 attached to its lower end. The latches are forced inwards by tapered surfaces 141, 143 to grip below the shoulder 125 of a head 124 on a rod 78, forming part of the lower packer E, for upward movement of the packer E'. For downward movement of the packer E a tapered surface 146 of the outer cylinder 120 engages ribs 145 on the rod 78. To release the coupling pressure is applied to the fluid in the string B, 122a, the small annular orifice between the rod 78 and the bottom of the cylinder 120 throttling the fluid so causing sufficient back pressure to raise the piston 128 which moves the latches outwards when. they can be drawn upwards past the head 124. Fig. 4a is a continuation of Fig. 4 showing the lower packer having a central tubular member 26 through which passes the rod 78 which has shoulders 104. 105 adapted to cooperate with spring-pressed valves 88, 96 closing the ends of the tubular member 26 so that during downward motion the lower valve 96 is raised off its seat by the shoulder 105 to allow fluid to pass through the packer, the fluid pressure raising the upper valve off its seat and vice versa for upward movement. Secured to the tubular member 26 are upper and lower rubber packing cups 36. 46 held in place by collars 35, 45 with expanders 32, 43. Slidable en the tubular member 26 is a sleeve 52 which has spring-pressed friction drag blocks 50 and upper and lower sets of slips 28, 39. The upper slips 28 co-operate with the expander 32 automatically during downward dislacement to anchor the packer and the lower slips anchoring during upward displacement. Extending through the rod 78 is a flat cross-piece 74 the ends of which extend through diametrically opposite slots in the tubular member 26 and engage grooves 73 in the sleeve 52. When the rod 78 is pushed downwards by the coupling D the cross-piece 74 engages the lower ends of the slots and the grooves 73 and holds the sleeve 52 in a central neutral position in which retainer rings 63, 61, Similarly during upward movement when suspended from the expanders 32, 43 by rods 64, 69, hold the slips 28, 39 inwards. the rod 78 is pulled upwards the sleeve 52 is held in the neutral position by the crosspiece engaging the top of the slots and grooves. When, the coupling D is released the spring-pressed valves 88, 96 cause the rod to take up a position in which the crosspiece is in the middle of the slots and grooves 73 so that the sleeve 52 is free for relative movement to anchor the packer.