DEVICE FOR WELL CLEANING Russian patent published in 1996 - IPC

FIELD: operation and completion of wells; applicable in cleaning wells, particular, bottom-hole formation zone from cuttings and colmatage sediments. SUBSTANCE: device for well cleaning has body connected with pipe string. Body has port closed by spring-loaded valve. Installed on body are packer and stem with perforations. Hollow rod being extension of pipe string is installed in body for limited axial motion and has section of hollow rod with perforations and isolated from body hollow. Lower part to close side hole. After landing of stem on the well bottom, packer isolates the bottom-hole formation zone. Then, hollow rod is extended and hollow of pipe string and body hollow are communicated, spring-loaded valve opens, and pipe string is filled with cuttings. Upon equalization of pressure, the spring- loaded valve closes. Device is lifted to the surface. Prior to lifting, side hole of pipe string may be opened, and the string itself may be washed with cleaning agent from the surface through pipe string- casing annulus. EFFECT: higher efficiency. 6 cl, 2 dwg