N'goma (formally Xikomba)

Client: SBM Offshore

Process: Sulphate Removal

Country: Angola

Contract Description: Supply of Sulphate Removal System and Wash Water System

Contract Date:  June 2011

Contract Completion Date: June 2012

SRP Capacity: 117,455 BPD (18,672 m3/day)

Sea Water Conversion: 75%

Sea Water Feed Quality: 35,177 (tds)

Product Water Output Quality: <20mg/l sulphate


Project Description:

The award is for the design, procurement and supply of equipment and provision of construction technical assistance for a single lift module seawater sulphate reduction package (SRP) system sized for 117,455 BPD (18,672 m3/day) and an integrated seawater reverse osmosis (SWRO) system with a capacity of 12,075 BPD (1,920 m3/day). FPSO Xikomba was previously operating in Block 15 offshore Angola and is planned for relocation to new moorings in an adjacent area of that block (Block 15/06 - West Hub).

Project Scope:

The project scope consists of equipment for a single lift module arrangement comprising: Cartridge Filters, SRP & SWRO HP Feed Pumps, Sulphate Removal and SWRO Trains, CIP System & Chemical Dosing Systems.

Process Description:

Inlet feed is treated by a set of cartridge filters to provide fine filtration down to 5µm prior to the membrane trains. The set of cartridge filters supplies feed water for two (2) trains.

The conditioned water, boosted to the required feed pressure, enters the Sulphate removal trains. Each membrane train is fitted with pressure vessels containing SR90HR-440i high rejection nanofiltration elements in order to meet the stringent sulphate permeate level. A recovery of 75% is achieved by a 2:1 brine staged configuration. Brine reject from the process is discharged overboard, while the low Sulphate permeate is routed to a vacuum type deaerator package (existing equipment and located off the module), where oxygen is removed by mechanical and chemical means. A dedicated clean in place (CIP) package, consisting of cleaning tank, heater, pump and cartridge filter vessel is provided for membrane cleaning purposes. A SWRO package plant is provided to supply wash water for the main process plant. Chemical Dosing systems for the SRP & SWRO systems are also provided.