Abstract: A method and apparatus is provided for diverting a ground water supply source located in a stratum that is hydraulically separated from a hydrocarbon-containing reservoir formation for injection into the reservoir proximate the oil-water interface to enhance the flow rate and production of the hydrocarbons through one or more well bores without pumping the injection water to the earth's surface. A submersible electric pump (ESP) and Y-tool assembly is positioned in the well bore at the level of the ground water supply and water is pumped down the well casing for injection into the formation, e.g., below the hydrocarbon-containing reservoir rock. Suitable seals, packers and cement plugs are provided to isolate the high pressure injection water from the ground water drawn into the first upper portion of the casing.