Downhole production and injection pump system

Abstract

A downhole pump, positionable in a fluid column that is substantially separated into an oil portion and a water portion, for selectively lifting the oil to a surface and injecting the water into an injection zone includes a housing having a top wall, and a bottom wall defining a cylinder; a plunger positioned within the cylinder reciprocable through an induction stroke and a production stroke; a piston moveably positioned between the plunger and the top wall separating an oil chamber from a water chamber; an oil intake assembly providing one-way fluid flow from the fluid column to the oil chamber, the oil intake assembly including means for selectively allowing induction of the oil and blocking induction of the water into the oil chamber; an oil exhaust providing one-way fluid flow from the oil chamber to the surface; a water intake providing one-way fluid flow from the fluid column to the water chamber; a flow restriction position in the water intake to substantially balance the pressure drop in the oil intake assembly; and a water discharge providing one-way fluid flow from the water chamber toward the injection zone. On the induction stroke the oil fluid is drawn into the oil chamber and the water is drawn into the water chamber at a pre-selected oil to water ratio, and on the production stroke the oil is produced to the surface and the water is injected into the injection zone if the injection zone pressure is overcome.