A method of pumping upper production fluid from an upper level of an
underground pool of production fluid and pumping lower production fluid
having a higher concentration of sand from a lower level during a single
pump cycle comprises providing a dual action reciprocating piston pump
comprising a pump barrel and a reciprocating piston dividing the pump
barrel into a lower and upper chambers. On a downstroke upper production
fluid is drawn from the upper level into the upper chamber through an
upper intake, and lower production fluid present in the lower chamber is
forced up a tube toward ground surface. On an upstroke lower production
fluid is drawn from the lower level into the lower chamber through a
lower intake, and upper production fluid in the upper chamber is forced
up the tube toward ground surface.