Traditionally, the offshore oil and gas industry has used fixed or floating facilities to support processing systems. As developments move into deeper water, the cost of these fixed or floating facilities increases significantly, providing an incentive to develop seabed or even downhole processing systems.

While moving processing systems closer to the reservoir generally improves ultimate recovery and processing efficiency, the cost of subsea maintenance and repair and the associated risk of lost production has made the industry reluctant to adopt such processing systems.

Last Wednesday, a Society for Underwater Technology seminar at the Melbourne Hotel in Perth discussed these issues.

Sponsored by Aker Kvaerner Subsea, the ‘Subsea Processing – how close is the horizon?’ event attracted more than 100 people, many working on projects that would benefit from this particular area of technology. Operators, vendors and service companies were all well represented.

BHP Billiton Stybarrow subsea manager Martyn Witton outlined the long history of subsea separation and pointed to several key success projects while comparing the culture of oil and gas equipment development with that of the military when aiming for high reliability.

Using information provided by Aker Kvaerner Subsea, Woodside Energy principal subsea engineer Chris Lawlor compared the time frames for oil and gas equipment development with the medical, information systems and general consumer products sectors. This showed that the time to develop and prototype new products in oil and gas could be as long as 30 years – two to three times the time required in other industries such as information systems.

Graham Bonner of Chevron showed that with surface facilities needed to support a typical deep water compression platform costing in the order of US$600m to put in place and US$40m to operate each year, the prize for reliable subsea compression was enormous.

Aker Kvaerner Subsea has been actively involved in the development of various subsea processing solutions over the last two decades. Greg Ross presented one of these developments nearing full qualification and finding commercialisation in the form of a subsea booster unit, which has been developed to cover a wide range of operating conditions where higher gas-to-oil ratios make conventional centrifugal pumps inoperable or inefficient.

This particular pump design suits low-pressure fields with variable oil and gas flows or fields nearing the end of economic life where direct pressure boosting could gain significant production increases. Ross cited a recent project in the Gulf of Mexico where use of the Aker Kvaerner Subsea Booster pump has been justified on pure commercial grounds, promising to boost oil recovery by US$1 billion for an investment of some US$30 million.

Martin Sorensen of FMC Technologies discussed the subsea separation and gas compression technology being developed and supplied by FMC for the Tordis and Ormen Lange developments in Norway, both of which have their own unique and challenging requirements. The development builds on considerable experience now centred in Norway. An investment of US$230 million could lead to the recovery of an additional US$2 billion of oil from Tordis.

Tordis is tied back to Statoil's Gullfaks C platform, and the improved oil recovery project is expected to boost its recovery factor from 49 to 55%, corresponding to about 35 million barrels of oil in addition to associated gas.

Tordis IOR comprises two phases. The first covers necessary platform modifications on Gullfaks C to convert to low-pressure production. Planned to come onstream in October next year, this stage should improve recovery by about 16 million barrels.

Phase two entails adding separation station and pumps with support systems for the platform. This is expected to recover roughly 19 million barrels of additional oil from October 2007.

The Perth branch of the SUT will hold its AGM next month at the Maritime Museum. Details will be posted on the SUT website www.sut.org.au