METHOD FOR ISOLATION OF LOST-CIRCULATION FORMATIONS IN WELLS AND DEVICE FOR ITS REALIZATION Russian patent published in 1994 - IPC

FIELD: well drilling. SUBSTANCE: prior to lowering plugging device, supporting pipe is connected to its lower part so that clearance between pipe and well walls is within 8-60 mm. Plugging device with supporting pipe is lowered to depth below the foot of lost-circulation formation. This depth is determined from expression given in invention description. Then, grouting mortar is injected by piston manner in annular space of supporting pipe. Device includes container accommodating piston which separates container into above-piston and working hollows. Working hollow is filled with grouting mortar. Installed above container is pulser with inlet and outlet channels. Outlet channel is hydraulically communicated with above-piston hollow. Rigidly connected to container bottom part is supporting pipe whose diameter is smaller than container diameter. Upper part of supporting pipe has overflow ports. Made above overflow ports is upper head installed for axial motion. Landing seat is made below overflow ports to receive upper head. Lower part of supporting pipe has lower head. Landing seat has hole. In addition, device is provided with hydraulic packer installed between container and pulser. Hollow of hydraulic packer is hydraulically communicated with pulser inlet channel. EFFECT: reduced accident rate in isolation work and high reliability of isolation of lost-circulation formations distant from well bottom. 5 cl, 1 dwg