Patent ID: 6904973

Claim:
A downhole pump comprising: a pump barrel defining a pumping chamber having a first end and a second end; a first one-way valve positioned at said first end of said pumping chamber, said first one-way valve operable to permit a flow of fluid out of said first end of said pumping chamber; a second one-way valve positioned at said second end of said pumping chamber, said second one-way valve operable to permit a flow of fluid out of said second end of said pumping chamber; and a plunger movably disposed in said pumping chamber and having first and second ends facing said first and second ends of said pumping chamber respectively; wherein said pumping chamber has an inlet adapted to be in flow communication with a production zone and wherein said plunger is movable in said pumping chamber between at least a first position and a second position, wherein said second end of said plunger is positioned on a first side of said inlet when said plunger is in said first position such that said inlet is in flow communication with said second end of said pumping chamber, and wherein said first end of said plunger is positioned on a second side of said inlet when said plunger is in said second position such that said inlet is in flow communication with said first end of said pumping chamber.