The next phase for the National Oilwell Varco (NOV) subsea oil storage technology is a joint industry project due to start later this year for large-scale testing of the system in realistic operating conditions, writes Beate Schjolberg.

The plan is to find a suitable dock, probably in Norway, and submerge a subsea storage unit (SSU) of between 250 and 500 cubic metres, considerably larger than the 3 cubic-metre tanks used to test various membrane qualities and the oil-ventilation system in a trial that is now drawing to a close.

The project will aim to test the entire system using oil from a North Sea field to make it as realistic as possible, said Birte Johannessen, senior project manager at NOV.

The upcoming 15-month verification JIP is expected to be supported financially by Norwegian operator Equinor as well as the UK Oil & Gas Technology Centre (OGTC), which is keen to see the technology verified because of the large number of small UK discoveries that require cost-effective solutions to be developed.

The OGTC last year launched its “Facility of the Future” initiative, aiming to halve development and operating costs to unlock 3.5 billion barrels of oil stranded in more than 360 small discoveries of 50 million barrels or less across the UK continental shelf.

NOV also hopes to get one or two more sponsors for the project, which has a total price tag of about Nkr67 million ($7.7 million).

When the verification project is completed in the second half of next year, the system is ready for an operator to take it further into front-end engineering and design studies and eventually offshore deployment, Johannessen said.

One hurdle to be overcome before then is to qualify a reliable and accurate metering system for subsea use, an essential element for offloading from underwater tanks, said Marius Bjorn, department manager at NOV’s process and control division in Norway.

Though the SSU solution could be used for any number of fields, Equinor is a potential first mover, having worked closely on the product development with Kongsberg Oil & Gas and later NOV since the beginning.

The Norwegian operator previously considered the subsea storage technology for its Njord field, which is currently under redevelopment, but the technology was not sufficiently matured when the investment decision was taken in 2017.

Njord is due back on stream late next year, using an upgraded FSO for oil storage.

Weekly

Joint industry project to aid SSU progress