PACKER FOR DOUBLE-STAGE CEMENTATION OF CASING STRING Russian patent published in 1999 - IPC

FIELD: oil and gas production industry. SUBSTANCE: device has body with row of radial holes, cementation openings, overflow valves. End of lower bush is made with protrusion and slot. Interacting with protrusion is middle movable bush. Upper differential bush is located in head. Plugs close through-passage in packer. Corresponding holes through slots in bush are aligned. Working fluid is injected under flexible collar. No packing of well is performed. Cementation is carried out through openings which are open. Closing of openings is realized by means of upper differential bush. Application of aforesaid embodiment of packer excludes failure of seals. Flow area of packer is increased, reliability of packing is improved. EFFECT: higher efficiency. 2 cl, 1 dwg