GB1199086A - Retrivable Well Packer - Google Patents

Abstract

1,199,086. Well packers. SCHLUMBERGER TECHNOLOGY CORP. 29 Oct., 1968, No. 51206/68. Heading E1F. A well packer comprises a mandrel 11, a hollow tubular body 23 slidably positioned on the mandrel, packing means 28, anchor means (36) below the packing means, fluid by-pass passage 72 extending along the mandrel and communicating with the well bore above, at 74, and below the packing means, valve means 79 on the mandrel and engageable with a valve seat 75 on the body 23 to close the passage, a piston 109 connected to the mandrel and operative in response to the tubing pressure - i.e. the pressure below the packing means - exceeding the annulus pressure - i.e. the pressure above the packing means -to exert a force on the mandrel to oppose the force thereon of this pressure difference, and a piston 112 operative in response to the annulus pressure exceeding the tubing pressure to exert force on the mandrel to counterbalance the force thereon exerted by the pressure difference. The piston 109 is slidable within the body 23 and has the annulus pressure applied to the bottom surface through openings 74 in the body, and the tubing pressure applied to the top surface thereof through bypass passage 72, passageway 101 and bore 116. The piston 112 has the annulus pressure applied to the top surface thereof and the tubing pressure applied to the bottom surface. Accordingly when the annulus pressure exceeds the tubing pressure, piston 112 bears against piston 109 or as shown, or alternatively against a shoulder on the mandrel with the effective difference D in area between the two pistons being chosen to be equal to .the effective horizontal cross-sectional area of the mandrel on which the annulus pressure acts so that there is no net force on the mandrel. Above piston 112 slips are provided and are moved outwardly to engage the casing P by another double piston when the tubing pressure through passageway 101 exceeds the annulus pressure. Beneath the packer the tubular body 23 is jayed to the mandrel and has drag blocks which on un-jaying prevents the bottom portion moving downwardly with the mandrel so that the anchor means (36) can be set, and the tubing string weight applied to the packing means to set the packer.