Demonstration of an Integrated Subsea Separation and Produced Water Treatment

Oil-water separation and treating produced water subsea is an interesting option for handling the increased water cuts typically observed on brownfields, where additional investments on an aging floating infrastructure are rarely economically justified. By removing treated water at the seabed, the high-water cut is managed, and the load on topside facilities is reduced. A concurrent increase of oil recovery and an extension of the existing infrastructure life are also obtained, leading to a much better business case. Within the industry, this approach has been deployed in the past, but several issues were encountered that hindered the pilot performance. A new two-stage solution for deepwater applications that address these issues has been developed by Saipem and Veolia in collaboration with Oil&Gas operators. The first stage is "SpoolSep", a horizontal multipipe gravity separator, designed for ultra deep waters but suitable for shallow waters as well. It provides advantages on performance, weight and fabricability when compared to a single separator vessel. The second stage is the produced water treatment (PWT) system which treats the water recovered by the first stage, to achieve the required water quality for re-injection into the reservoir or disposal to sea.