Ultrafiltration and Sulphate Removal - Seawater Treatment in Offshore Angola

VWS Westgarth, a subsidiary of Veolia Water Solutions & Technologies (France), has been awarded a multi-million dollar contract by Daewoo Shipbuilding & Marine Engineering Co. (DSME) for the design, supply and delivery of an Ultrafiltration system and a Sulphate Removal Package (SRP) system. The two treatment units, designed for DSME’s Floating Production Storage and Offloading vessel (FPSO), will be installed in the Cravo-Lirio-Orquidea-Violeta (CLOV) Fields, located Offshore Angola. The project completion is expected in January 2012.

The ultrafiltration and sulphate removal packages will be installed on the FPSO topsides to provide the necessary seawater treatment for subsea well injection. The ultrafiltration unit, which is the pre-treatment step to the SRP, will have a capacity of 66,208 m3/day (391,288 BWPD) and the sulphate removal package will treat 59,496 m3/day (374,230 BWPD).

The fine filtered seawater (nominally 0.01µm) from the ultrafiltration system provides the feed for the sulphate removal package. Ultrafiltration provides a significant weight/footprint reduction and improved water quality compared with multi-media seawater filtration technology.

The SRP removes sulphates and other divalent ions from injection water to enhance oil recovery using Dow Filmtec membranes. The removal of these ions reduces the tendency of barium sulphate and strontium sulphate scale to form in the reservoir, and enhances oil recovery.