Apparatus and method for the downhole gravity separation of water and oil using a single submersible pump and an inline separator containing a control valve

A downhole gravity oil and water separation system comprising:

• a. a casing having one or more production perforations, said casing extending from a ground surface downwardly such that said production perforations communicate with a production zone so that produced liquid hydrocarbons and produced water enter said casing through said production perforations;
• b. a low-volume submersible pump disposed in said casing;
• c. a pump inlet means for permitting the produced liquid hydrocarbons and produced water to enter said pump;
• d. a pump outlet means for permitting the produced liquid hydrocarbons and produced water to exit the pump;
• e. a gravity oil and water separator defined by the casing, an upper downhole packer and a lower downhole packer, said downhole packer sealing tightly to the casing to form a pressure tight seal, said separator enclosing a mixture of oil and water in a variable volume defined by the position of the packers;
• f. a flexible electrical cable frictionally engaged to the pump and extending between said pump and the ground surface, said cable providing electric power to said pump and being sufficiently thin and flexible to pass through the separator if necessary without interfering with the operation of said separator;
• g. a single standpipe conduit extending between the separator and the pump outlet means, said standpipe conduit discharging near the center of the separator and allowing the separator to be pressurized to the output pressure of the pump;
• h. an oil discharge means connecting the oil side of the separator to the ground surface, said discharge means terminating near the top of the separator;
• i. a control valve system capable of regulating the flow of oil and water from the separator;
• and
• j. a water discharge means connecting the water side of the separator to a water disposal system, said water discharge means terminating near the bottom of the separator.