ABB assembles subsea power parts to test stamina of data-rich system

Halfway through a five-year joint industry program to develop subsea power and control systems, technology developer ABB has started to build the subassemblies of components designed to provide decades of reliable service up to 3km below the surface, Jan Bugge, ABB's VP of Subsea technology and head of project, said.

Subsea systems must be strong and durable to justify deployment. (Image credit: allianoi)

In September 2013, Swiss-based technology group ABB entered into a joint industry program (JIP) with Norwegian operator Statoil to develop solutions for transmission, distribution and power conversion systems to power and control subsea pumps and gas compressors.

Statoil is leading the $100 million project on behalf of other participating operators, while ABB is developing the new technology, following subsea power studies executed in 2012.

“It's comprehensive and it’s massive. We want to be able to supply 100 MW over a step-out distance of 600km [between shore and factory], we want to cover any field in the world, so we need to go down to 3,000m, where the deepest production is in the Gulf of Mexico. These are all world firsts,” Bugge told Upstream Intelligence in an interview.

Once fully developed and operational, subsea pumping and gas compression is expected to provide greater recovery rates, reduce production costs and advance the development of deep water assets.

Statoil has estimated the systems could offer capital expenditure reductions of more than $500 million, taking an example of eight consuming sites and a distance of 200 kilometres from infrastructure.

Other technology companies developing subsea power solutions include Siemens, which is working on a subsea power grid in a separate JIP led by Chevron, France’s Schneider Electric and US giant General Electric (GE).

The extreme conditions associated with remote deepwater fields have necessitated the development of advanced equipment that can cope with high-pressure environments and function independently once installed.

"It’s like sending up a satellite. If these are Arctic conditions, you can’t fix anything,” Bugge noted.

Technology answers

ABB has been using the latest technology to maximise the integrity of the components. Sensors and computers running sophisticated diagnostic algorithms have been put in place, increasing the detail of monitoring.

“It has to be able to handle failures and it has to be able to reconfigure itself, even if everything goes black. You have to make it so that you could even work in a degraded mode so that it could continue until the next service interval, which could be next summer or whenever,” Bugge said.

High levels of redundancy have also been built in and computer control systems are designed to last.

“Here it’s reliability that is the real challenge because it's extremely complex – computers these days are powerful but you throw them out after two or three years. How do you have a control system that has to live for 30 years? You have to make them reliable enough to know exactly what’s going on in the equipment, and in a safe way you have to be able to reconfigure the drive if you need to, to enable it to last until the next service interval,” he said.

Other ways to manage faults are to duplicate components, so redundant systems can take over if the operational system fails. The degree of redundancy will be key to providing integrity, and also influence capital cost, Bugge noted. The extent of this work will be determined by the geophysics of the field and the operator's needs.

Variable speed drives are a key focus of the JIP, as well as the switchgear and the automation and control systems that operate them.

The design and specification of the variable speed drive units was a significant technical challenge.

“We're sure that the key components will eventually be good enough and we have selected the concept so we know how to build the drive. We are to now start to build subassemblies,” Bugge said.

The system has also been designed to limit the number of ordinary valve components exposed to extreme pressures, such as the wet mate connectors that link components of the subsea production system.

Backed by Industry

While oil price pressures have cut back overall spending on new production assets, demand for subsea technology has held firm, as forward-looking operators seek to optimise production and work on deepwater assets by installing the latest technology.
The collaboration with operators during the JIP has boosted the development of ABB's subsea power technology, allowing the firm to confirm previous studies conducted topside, Bugge noted.

“When we started this we knew how to do it topside and we knew what the key challenges were, but still it’s taken a lot of physical understanding of the properties and simulating 30 years of lifetime through accelerated tests,” he said.

Now over two years into the project, ABB has recently reached the key stage of moving from laboratory based work and bench tests to putting together the first sub-assemblies.

After this stage, system prototypes will be built and tested for 3,000 hours in a shallow-water offshore site, before final designs are produced in 2018.