Abstract: System for producing de-watered oil from an underground formation to the surface, which system comprises a reception well having a substantially horizontal or inclined section for primary oil/water separation of the well fluid; a water discharge system having an upstream end that is capable of receiving during normal operation liquid from the lower region of the downstream part of the reception well; and a secondary underground oil/water separator having an upstream end that is capable of receiving during normal operation liquid from the upper region of the downstream part of the reception well, the secondary separator having an outlet for de-watered oil that is in fluid communication with the inlet of a production well and an outlet for a water-enriched component that is in fluid communication with the water discharge system.

Abstract: System for producing de-watered oil from an underground formation (2) to the surface (4), which system comprises a reception well (7) having a substantially horizontal or inclined section (10) for primary oil/water separation of the well fluid; a water discharge system (12) having an upstream end (13) that is capable of receiving during normal operation liquid from the lower region (14) of the downstream part (9) of the reception well (7); and a secondary underground oil/water separator (18) having an upstream end (19) that is capable of receiving during normal operation liquid from the upper region (20) of the downstream part (9) of the reception well (7), the secondary separator having an outlet (21) for de-watered oil that is in fluid communication with the inlet (5) of a production well and an outlet (22) for a water-enriched component that is in fluid communication with the water discharge system (12).