The world's first full-scale seabed facility for separating water and sand from a wellstream is now functioning on the Tordis field we operate in the North Sea. This technology represents a breakthrough for a new generation of subsea solutions.
New subsea installation improves recovery
Subsea separation on Tordis is part of a project to improve the recovery factor for this field from 49% to 55%, corresponding to about 35 million barrels in extra oil plus associated gas.
Located in block 34/7 in the Tampen area of the northern North Sea, Tordis came on stream as a subsea development tied back to Gullfaks C in 1994.
Opportunities
"The technology we've installed on Tordis opens new opportunities for other fields we operate, both on the NCS and internationally," says Arne Sigve Nylund, senior vice president for operations west in Exploration & Production Norway (UPN).
Subsea separation makes it possible to improve recovery and accelerate oil and gas production, which increases utilisation of the installed facilities on Gullfaks C.
"The technology provides additional oil recovery in cases where production is restricted by pressure and capacity in the processing system," explains Monika Bertheussen, head of our corporate initiative for improved oil recovery (IOR).
This solution is particularly suitable for developments in ultradeep water or far from land, and in areas where natural conditions make subsea installations the best option.
Process
The normal procedure in underwater production has been to conduct the wellstream up to a surface installation where oil, water and gas can be separated in a process facility.
In contrast, the new seabed facility on Tordis separates out sand and water before the oil and gas are pumped on to Gullfaks C.
Separated water and sand are injected directly from the subsea installation into an underground saline aquifer (brine-filled structure) called the Utsira formation and stored there.
This solution avoids the need to transport large volumes of water brought up from the reservoir over the 10 kilometres to Gullfaks C and up onto the platform.
"That saves energy," observes Jan Kyllo, our project manager for Tordis.
Better
We are one of the leading companies operating in the deepwater parts of the Gulf of Mexico, and experience from Tordis could contribute to better development solutions there.
Knowledge gained from this project could also be beneficial for our participation in the Shtokman development in the Russian sector of the Barents Sea.
"We see that the technology can be utilised in many parts of the world," affirms Mr Kyllo.
Quickly
The decision to install the equipment was taken in 2005, and the project was completed very quickly.
"Two years for a groundbreaking job like this is fast," observes Mr Kyllo. "We've received good support from our partners in the licence, both in the decision-making projects and during execution of the project. They've been important collaborators for us as operator."
FMC Technologies has been responsible for delivering the subsea installations in collaboration with Framo Engineering. Fabrication and assembly were handled by Grenland Group in Tønsberg south of Oslo, with Acergy, Saipem and Fabricom doing field installation.
