WELL PLUGGING DEVICE Russian patent published in 1996 - IPC

FIELD: well drilling. SUBSTANCE: plugging device has container with piston separating the container into above-piston cavity and working cavity. Working cavity is filled with bridging material. Installed above container is jet pulser with inlet and outlet channels. Outlet channel is hydraulically communicated with above-piston cavity. Device signalling the end of piston stroke in form of hydraulic back-pressure valve is connected with piston by flexible member. Installed in above-piston cavity coaxially for rotation relative to the container is coil with axial channel. Flexible member is wound on coil. Made on the external surface of the coil on the area for winding the flexible member is longitudinal slot for flexible member. Lower part of flexible member is engageable with lock. Removable handle is installed in lower part of coil in through radial hole. Flexible member is connected with hooks secured to hydraulic back-pressure valve and piston for axial rotation. Device is lowered into well and rotation is started, and mud pump is engaged. Pressure built up by the pulser is transmitted to above-piston cavity, and it acts on bridging mortar through piston. Bridging mortar is forced from the working cavity through hole to well. When piston moves down, flexible member comes from under lock and unwinds from coil. In lower position of piston, flexible member moves hydraulic back-pressure valve downward and mud flows into the well. Pressure in the inlet channel drops. After stopping the rotation and mud supply, device is lifted to the surface. EFFECT: higher operate reliability, simplified operation and installation, and excluded twisting of flexible member. 3 cl, 4 dwg