Locating oil-water separation and produced water treatment subsea is a crucial step for brownfields as, by removing water at the source, the high water cut is managed and the load on topside facilities is reduced, simultaneously increasing oil recovery and extending the life of existing infrastructure. Within the industry, this approach has been deployed once, but several issues encountered has inhered the pilot performance. Saipem and Veolia in collaboration with Oil&Gas operators have developed a two-stage solution for deepwater applications addressing these issues. The first stage is “SpoolSep”, a multipipe gravity separator, designed for ultra deep waters but suitable for shallow waters as well, which 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. Previous qualification programs have demonstrated the validity of the individual elements of this solution. The next qualification step has been outlined with TotalEnergies. It is a three-stage approach 1) reduced scale testing for sand removal, 2) large scale test of PWT system and 3) large scale testing of Spoolsep and PWT system combined. These testing steps have been planned in collaboration with the Federal University of Itajuba, considering their experimental facilities and identifying the adaptations needed to test at high separation pressure conditions. The presentation will outline the technology main features along with the JIP qualification program.