PREVENTER Russian patent published in 2005 - IPC

FIELD: bottomhole equipment used for underground oil and gas well repair, for sealing well head in emergency and during long operation interruption.

SUBSTANCE: preventer has body with axial channel, pipe rams for sealing pipes to be lowered in well through above axial channel, blind rams for sealing axial channel in the absence of pipes in the well. Composite, namely hydraulic and manual ram drive is made as hydraulic cylinder with high-pressure and low-pressure compartments and piston with screw rod. Piston has channel to establish communication between high-pressure and low-pressure compartments. The channel is provided with bypass valve made as a slide spring-loaded from both sides. Value of spring power and width of gap between slide and seat orifice of the piston are chosen to provide free working liquid flow from one compartment into another one in "manual drive" mode. In "hydraulic drive" mode slider may move in one of its extreme positions under the action of dynamic head in liquid at hydraulic cylinder inlet so that slider closes above channel in the piston.

EFFECT: increased ability of manual ram driving.

9 dwg