LONDON�Norwegian oil company Norsk Hydro AS's experiment in subsea water injection and separation�the Troll Pilot production unit in the Norwegian North Sea�has been sidelined for some 3 weeks, it emerged yesterday, due to a "small crack" in the insulation surrounding the power cable running between the system and the operator's Troll C field.
The electrical supply to the water injection pump was interrupted July 23, stated Troll C field unit oil project leader Knut Henrik Dalland, and would not return to operation before late September. Dalland stressed the unit's shutdown will not affect output from Troll C, where there was "ample" water handling capacity to continue production at a rate of 155,000 b/d.
Located in around 350 m of water, Troll Pilot�developed at a cost of 400 million kroner by ABB Offshore Systems AS�started operation in May. The first-ever subsea water injection and separation system, it was seen by Hydro at the time of its start-up as a test of "whether large, complex processing equipment on platforms and ships [would] be replaced by seabed solutions."
Until the shutdown, according to Hydro, the separator had been functioning "better than expected." The pump module was installed in June to boost injection capacity, but soon after, the malfunction was discovered and the pump removed.
Dalland suggested that setbacks should be expected in a pilot test. "If the technology were already in place, we wouldn't need the pilot," said Dalland.
"This technology, if successful, will allow [Hydro] to put more processing equipment on the seabed in the future," he stressed.
Production from Hydro's giant Troll West field, which contains estimated reserves of some 3.75 billion bbl�of which only 1.2 billion are presently within technological reach�started in 1995 via the Troll B platform.
Last November, the Troll C semisubmersible joined its sister installation, lifting output from 10 wells at the field toward expected plateau production of roughly 300,000 b/d�giving it grounds to claim the title of single most productive field on the Norwegian continental shelf.
