BRIDGE PLUG Russian patent published in 1996 - IPC

FIELD: well drilling. SUBSTANCE: device has a casing. The casing is made in the form of a cylinder with radial channel. The device has return valve, sealing member and switching device with radial channel. The device has a suspension in the form of pipes. Stepped piston is placed inside the switching device. The switching device shapes the form of the piston. Stepped piston and pipe form annular space between. The switching device has additional radial channel. It is provided for opening outer space to the annular cavity. The switching device is secured by smaller step in the casing. Stepped piston and the casing and smaller step of the pipe form a space under the piston. This space is filled with packaging liquid. EFFECT: high efficiency. 4 dwg