关键词: 海上油田, 井下, 油水分离, 管柱, 实时监测, 参数调控

Abstract: When an offshore oilfield enters into its later high water-cut period, it is more and more difficult to lift, store and treat the produced water with the cost on the rise, causing a great pressure on the offshore oil field in the energy saving and pollution-reducing areas. In addition, part of platform facilities cannot satisfy the demand for treatment. CNOOC has developed a new-type downhole oil-water separator and designed the pipe string for the process, thus creating a set of suspending downhole oil-water separation and re-injection process suitable for offshore oilfields. The maximum outer diameter of the new-type oil-water separator is 130mm and the handling capacity reaches 1200 cubic meters per day. The whole process system adopts the suspending three-pass joint device to establish the flow path, ensuring that a large flow channel is established in the wellbore. The downhole parameters monitoring and adjusting facilities can make realtime inspection and adjustment of the entrance pressure of the oil-water separator on the surface to ensure the separation efficiency of the system. With a large handling capacity, this system is compact in structure. The process is similar to the process of the production pipe string of electric submersible pump currently used in offshore oilfields, significantly lowering the risks for operation and service.

Key words: offshore oilfield, downhole, oil-water separation, pipe string, real-time inspection, parameters adjustment