DOWNHOLE VALVE DEVICE Russian patent published in 1994 - IPC

FIELD: oil producing industry. SUBSTANCE: downhole valve device has a body with upper and lower valves. Lover valve 11 prevents fluid drainage through axial channel 10. Upper valve 3 is fixed in its initial position in seat 4 by springy split ring 5. When pressure exceeding the maximal rated pressure for split ring 5 is applied into the drill string-casing annulus, back-pressure valve 3 is pressed through the ring and opens channel 8 which connects chamber 9 to the casing string-borehole annulus. The valve device ensures: tubing pressure testing by lowering the electrically-driven centrifugal pump; maintaining fluid column in the tubing with electrically- driven centrifugal pump shut off; draining fluid from tubing the pump is withdrawn from the well; direct and reversed fluid circulation in the well. EFFECT: increased efficiency of operation. 2 cl, 1 dwg