DEVICE FOR INSTALLATION OF METAL PATCH IN CASING STRING Russian patent published in 1994 - IPC

FIELD: technology of major repair of oil and gas wells. SUBSTANCE: device has bypass unit installed above anchor and made in form of hollow branch pipe with radial channels and seat. Located concentrically in branch pipe seat for axial motion is hollow shutoff bushing with seat on its inner surface and valve spring-loaded relative to shutoff bushing. Shutoff bushing is installed for closing radial channels of branch pipe in extreme low position and communicating body hollow through branch pipe hollow and its radial channels with well space behind body in its extreme upper position. Valve is installed for closing shutoff bushing hollow in initial position of device. EFFECT: higher reliability of operation on viscous fluid by provision of hydraulic communication of intertube and tube inner spaces when pistons of hydraulic jacks are checked. 4 dwg