COUNTERFLOW PREVENTION SET FOR WELL FUND OPERATIONS

摘要

backflow prevention assemblies and methods for downhole systems having outer columns and inner columns include a housing defining a cavity and being part of the outer column, a flowtube disposed between the inner column and the axially movable outer column within the outer column and a backflow prevention structure having a flap and a sealing seat, the flap inclined toward a closed position and held in an open position by the flow tube. the flap is housed within the cavity when in the open position and the flap and sealing seat form a fluid seal to prevent fluid flow to or through the flow tube when in the closed position. When the flow tube is moved from a first position holding the flap in the open position to a second position, the backflow preventer structure operates to close the flap and seal the backflow preventer structure.