(86d) De-Oxygenation Experience at World's Largest Seawater Treatment Plant for Oil Reservoir Injection

Nicos P. Isaias, Mohammed H. Al-Ghamdi, Ibrahim B. Din, Ahmad M. Hawsawi

Sea Water Injection Department, Saudi Aramco, P.O. Box 9000, Abqaiq,

Saudi Arabia

ABSTRACT

Seawater used for oil reservoir injection should be disinfected and should also be non-corrosive, non-scaling, and free of particulate matter to minimize oil reservoir damage.  A Saudi Aramco seawater treatment plant facility, (Plant #1), with a present design capacity of 14 million barrels per day, is the world’s largest seawater treatment plant for oil reservoir injection. The plant disinfects the seawater, for bacterial control, through the addition of sodium hypochlorite upstream of the deaeration process and by batch biocide addition, downstream. The suspended solids are removed through granular media filtration using the world’s largest horizontal deep bed pressure filters. The dissolved oxygen of the filtered seawater is removed by cascading it down the de-oxygenation tower, where the seawater splashes onto a series of trays, causing dissolved oxygen to be lost to a nitrogen stream, which is blown counter-currently. Sulfurous acid is added to scavenge the remaining oxygen to control corrosion and prevent aerobic bacterial growth. Nitrogen and sulfurous acid are both manufactured on-site. Residual sulfurous acid is maintained in the seawater transport pipelines to avoid seawater re-oxygenation.

The objective of this paper is to give an overview of the treatment plant process and, in particular, to describe in some detail, the de-oxygenation process, the improvements made to the system and the challenges encountered.