A new filtration unit to remove naturally-occurring sulphate from injection seawater was lifted onto Statoil’s Heidrun platform in the Norwegian Sea today, 23 July.
Standing 27 metres high and weighing 970 tonnes, this modular plant will ensure that piping and sub-surface formations do not become plugged.
It arrived on the field last night after being lifted aboard one of the world’s largest crane barges, Saipem 7000, in the Åmøy Fjord outside Stavanger.
The sulphate needs to be removed because of a high concentration of barium, a metallic element, in the Heidrun reservoir. These two substances react easily together to produce deposits and coatings inside tubing and rock formations.
The filtration unit represents a pioneering project, reports construction supervisor Kjell Himle. No similar sulphate treatment plant exists on the Norwegian continental shelf today.
“We expect installation work to go well,” says Mr Himle. “This facility has been constructed as a single unit.”
The plant is the second of two large modules being installed on Heidrun as part of its water injection project, with the first holding three large pumps.
Injecting produced water and sulphate-free seawater into the field will boost its reservoir pressure and thereby improve recovery.
Such injection also provides an environmental gain by eliminating harmful discharges to the sea.
Work on the project, costed at roughly NOK 1.5 billion, is due to be completed during November. Fabricom and Sørco are the main contractors.
The filtration unit itself was fabricated by Leirvik Module Technology at Stord between Stavanger and Bergen. A