SPRINGS~R: Subsea Sulphate Removal for Water Injection-Subsea Tests from FPU Alima

摘要

SPRINGS~R (Subsea PRocess and INjection Gear for Seawater) is a subsea technology for the treatment of seawater prior to injection into wells. The prime capability required of the system is to remove sulphates from the seawater injection stream before it reaches the reservoir. Otherwise, severe scaling is likely to occur if sulphates mix with barium or calcium, often present in high concentrations in the reservoir. The technology is the product of a collaboration between Total, Saipem and Veolia (VWS Westgarth) that started in 2007 to create robust solutions featuring the use of membranes to treat seawater on the deep offshore seabed. The final qualification step for the technology is a six month offshore test campaign started in the second quarter of 2014 from FPU Alima in the Moho Bilondo field offshore Congo. The test campaign employs a purpose-built Subsea Test Unit (STU): a small-scale subsea module which is suspended by an umbilical from the production unit. The STU replicates the pre-treatment and operating conditions of the SPRINGS design and is used to investigate nanofiltration membrane performance and fouling when operated under in situ subsea conditions. This paper provides information on the design of the STU, a first report on the challenges and successes of the test campaign, and discussion on the future for the STU and the SPRINGS technology.