- 26 July 2007 -

Subsea separation has environmental benefits

The world's first subsea separating system for oil, water and sand, created by a Dutch and Norwegian group, has been presented with this year's EUREKA Lillehammer Award for its environmental benefits. The technology, which was developed by Dutch project leader CDS Engineering in cooperation with partners Statoil and FMC Technologies, can ensure a better use of increasingly scarce resources and improve the economics of offshore oil and gas production.

"Using this technology, you can exploit an oilfield much deeper - so, for instance, you can recover five to 10% more from the original reserves, an enormous advantage," says Toine Hendriks, CDS Engineering's senior process engineer. "It is also expected that this technology will facilitate new oil field developments in deeper and more remote areas, an advantage for the future as most of the easy accessible oil has already been produced," he added.

In oil and gas production, the separation equipment splits the wellstream, which could comprise oil, gas, water and sand, into individual constituents. "By installing a full field subsea separation facility, Statoil expects to improve the Tordis field's recovery factor from 49% to 55%," explains Rune Mode Ramberg, Statoil's subsea processing discipline adviser. Along with other upgrades to the field, the separation system will allow Statoil to extract roughly 35 million extra barrels of oil from the Tordis field. This is achieved by reducing the back pressure towards the Tordis field, separating water and sand from the wellstream subsea, re-injecting water and sand in a separate well subsea, boosting the wellstream and reducing the receiving pressure at the topside production platform.

As well as this, less oil can be discharged into the sea - instead, up to 100,000 barrels of produced water with some residual small oil droplets will be re-injected into a separate subsea well. If these oil discharges could be avoided in more offshore oilfields, the benefits could be considerable, the company says.

www.cdsengineering.com