Patent ID: 7909089

Claim:
A downhole jet pump for positioning in a well from a tubular string to pump formation fluid from the well, the jet pump comprising: an exterior pump housing defining an elongate housing passageway therein having a central axis and extending from an upper portion to a lower portion of the pump housing; a power fluid jet nozzle having an exterior sealed to the pump housing, the jet nozzle having a jet passageway therein for increasing fluid velocity of power fluid transmitted through the jet nozzle; a mixing tube fluidly downstream from the jet nozzle and having an elongate mixing tube passageway receiving fluid from the jet nozzle; a plurality of venturi ports for drawing formation fluids from within the housing radially through the venturi ports and into the mixing tube; a nose piece within the housing fluidly downstream from the mixing tube, the nose piece having a nose piece passageway in fluid communication with the mixing tube passageway, the nose piece passageway substantially aligned with the central axis of the pump housing; and a diffuser fluidly downstream from the nose piece and having a curved flow path therein, the lower end of the nose piece sealing within a bore in an upper end of the diffuser, a lower end of the diffuser passing through a side port in the pump housing for discharging a mixture of power fluid and formation fluids to the annulus surrounding the pump housing, a discharge end of the curved flow path of the diffuser angled with respect to the central axis of the pump housing, the diffuser having a rigid body from the upper end of the diffuser to the side port in the pump housing, an interior surface of the rigid body being clad with a metal coating; an inlet valve positioned below the diffuser for controlling the passage of formation fluid into a flow path within the pump housing radially external of the diffuser, then through the venturi ports, and then into the mixing tube, the inlet valve including a ball cage including a seating surface for seating with a ball when in the closed position, the ball cage having a ball positioning surface above the seating surface for engaging the ball when the inlet valve is opened, the ball positioning surface having a radius substantially equal to or greater than the radius of the ball, and the ball cage having radially extending through passageways axially between the seating surface and the ball positioning surface to pass fluid to the flow path in the pump housing.