Patent GB-872704-A (GB)
Title: Improvements in well packers
Inventor: HALL JESSE E
IPC: E21B33/12
Filed: 1960-01-08
Abstract: 872,704. Oil wells. ABASTECEDORA JEFE S. A. Jan. 8, 1960, No. 781/60. Class 85. In a well packer in which a resilient body is expanded radially against the well casing, extrusion of the body towards the region of lower fluid pressure is prevented by a resilient metallic barrier ring which holds the body against its tendency to flow. The resilient body 34 is compressed axially to effect radial expansion, and seats in a bowl 35 having a taper 35b surrounded by a helical coil 36, the taper being thrust into the coil to expand it to present its upper convolution to the casing 21 immediately beneath the body 34 which is thereby prevented from extruding downwardly. The coil is of square section wire, the wire being twisted to present flat surfaces to the taper, and to have line contact of the top convolution with the casing 21. The packer is connected to a tubing string 20 for positioning in the well, a coupling 23 having a valve face 24 connecting the string with a mandrel 25 having a sleeve 29 which abuts on a ring 30 and locates packing rings 28. As shown, two resilient bodies 34 and an interposed collar 34a are slidable on a sleeve 32 secured to a thimble 31 having a recess 31a to receive the rings 28 and the valve face 24, the ring 30 being retained by an inward flange 31b. A sleeve 38 having an inward flange 38a lying between an abutment ring 37 for the coil 36 and an outward flange 32a on the sleeve 32, is secured at 40 to a tapered slip member 39, the slips 41 being connected by links 42 to a cylinder 43 having friction springs 44. The cylinder 43 rests upon shoulders 45a on a sleeve 45 resting on a coupling 26 screwed to the mandrel 25, and holding the slip member 39 against downward movement on the mandrel. When the packer is lowered into the well, movement of the parts slidable on the mandrel is prevented by an assembly ring 46, and by pins 27 which engage open slots 43a in locking heads 43c at the bottom of the cylinder 43. When the packer is at the desired depth, the mandrel is turned to release the pins 27 from the slots, the springs 44 holding the cylinder 43 stationary whilst the mandrel descends, with the slip body 39 to engage the slips 41 with the casing 21. Further descent of the mandrel effects entry of the rings 28 and the valve face 24 into the thimble 31 which is then depressed to cause radial expansion of the bodies 34. The packer is released by reverse operations. The packer described above may be used as the lower of two packers between which is isolated a high pressure zone, e.g. as used in fracturing operations. The upper packer is connected to the string 20 by a coupling 52 and comprises a mandrel 51, a cup-shaped resilient body 50, a bowl 54 having an outward flange 54a and a recess slidably engaging a member 56 screwed on to the mandrel. The body 50 is backed up against extrusion by a coil spring 55, the square sections of the coiled material becoming progressively less wide to conform with a slightly tapered face on the member 56. A bell member 57 wholly envelops the said tapered face when the packer is run into the well. The coil 55 is eventually forced over the tapered face, to be expanded against the casing 21, by fluid pressure forcing the body 50 upwardly. Assuming that the lower packer has been installed, and the upper packer correctly positioned, the string 20 is rotated, the bell 57 is held by friction springs 58a and, because of a screw connection 59 with the mandrel, is moved upwardly to withdraw from the coil 55. When the upper packer is being run into the casing, pressure on both sides of the body 50 are equalized by apertures in the walls of the string between the upper and lower packers, and by ports 63 in the mandrel which are registered with ports 62 in the bell 57 when it is in its lower position on the mandrel. When the bell screws up on the mandrel, the ports 63, 62 are out of register, and pumped pressure in the space below the body 50 forces it up. The member 55 is disengaged from the casing by raising the tubing string and the packer may thus be removed. In a modification, the slips are formed on pistons moved radially outwards by hydraulic pressure, the resilient packer body is compressed axially by hydraulic means, and the backing-up, anti-extrusion means comprises a cylindrical split spring sleeve which tends to contract radially, but is forced to expand radially by cam means forced into operation by the compression of the resilient body, the cam means supplementing the backing up action of the split sleeve.