UNDERGROUND RESERVOIR WELL SHUTOFF DEVICE Russian patent published in 1996 - IPC

FIELD: underground storage of oil products. SUBSTANCE: known shutoff device has controlled gates in string casing which are connected by pipeline with high-pressure sources on the ground. Novelty is that inner flow string has additional central string with shoe provided with clack valve. Shutoff gates are made in form of sets, valves installed for overlapping the seats at emergency pressure drops across wellhead and control chambers fastened stationary on working strings. Each valve is made in form of housing accommodating spring connected with pressure nut-piston. Control chambers communicate with working string annular space to place the latter is communication with high pressure source. Central string clack valve is made for overlapping the string when gate valve lowers to its seat. EFFECT: prevention of outbursts of gaseous and liquid hydrocarbons at wellhead failures. 1 dwg