Downhole production and injection pump system

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, the pump comprising:

• 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;
• wherein 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.

A method of producing an oil portion of a fluid column in a well to the surface and injecting the water in the fluid column into an injection zone without lifting the water to the surface, the method comprising the steps of:

• positioning a pump in the fluid column, the pump having a plunger reciprocating through an induction stroke and a production stroke, and a sliding sleeve separating an oil chamber from a water chamber;
• on the induction stroke, drawing the oil into the oil chamber and water into the water chamber;
• and
• on the production stroke, producing the oil in the oil chamber to the surface and injecting the water from the water chamber into the injection zone if an injection pressure of the injection zone is overcome.