SHELL has run into a new problem as it tries to work out an acceptable way of disposing of its giant Brent Spar oil storage buoy.
A study on the 14,500 tonne structure by engineering consultants, W.S. Atkins, has shown that the Spar would buckle and break if the cheapest and easiest technique to bring it ashore was used.
Ever since a successful Greenpeace campaign halted Shell's attempts to sink the Spar in the north east Atlantic just over a year ago, the giant oil company has been working on different disposal options, which include bringing it ashore and breaking it up for scrap.
In the meantime, the structure, essentially a vast, cylindrical, crude oil storage tank over 400ft tall, has been anchored in a deep Norwegian fjord.
Shell had been considering simply reversing the method it used to put the Spar into use in its Brent field, half way between Shetland and Norway, back in the early 1970s.
This involved gradually letting sea water into its storage tanks in a controlled sequence, which turned it from floating on its side with a shallow draught (once it had been taken out of dry dock where it was built) into floating on its end.
The new study, which used advanced computer techniques not available when the Spar was designed, has shown that the buoy would almost certainly rupture its one inch thick walls if this sequence was reversed. So, if it is to be brought ashore, another method will have to be found.
At a press conference yesterday, Shell UK said that 21 leading contractors from eight different nations had now received firm invitations to set out their options for disposal of the Brent Spar. They will have to offer the best combination of minimising environmental damage, risks to disposal workers health and safety and costs.
Mr Eric Faulds, Shell's decommissioning manager, said the 21 contractors had not yet told Shell what they had in mind, but they had been selected on the basis of their reputation, previous experience and financial viability.
"When we get down to a shortlist of half a dozen schemes we want a spread of options," he said. "We don't want them all to involve bringing it ashore and breaking it up.
"I would hope we would get some fairly imaginative proposals which involve re use of a large part of the structure intact, for example in a breakwater or a harbour." He said that Shell had not ruled out the deep sea disposal option which attracted such controversy a year ago, because that might yet prove to be the best practical environmental choice.
Mr Heinz Rothermund, Shell's exploration and production managing director, promised more dialogue with pressure groups and the public in selecting an option. "We have acknowledged that we originally set out to dispose of the Spar without explaining what we were doing early enough or widely enough." Shell has placed a Brent Spar site on the Internet.
The Spar, although emptied after 20 years of use, still contains several dozen tonnes of oily sludge, much smaller quantities of toxic metals and some mildly radioactive salts which have built up on its pipework and tank linings. There is a scientific consensus that these would pose only an extremely small threat if the structure was dumped at a depth of 7,000 feet in the Atlantic, as was originally planned.
One of the many ideas suggested to the company has been to use the Spar as a fish ranch in a Norwegian fjord. Proposed by a businessman in the fish farming equipment business, this would involve feeding fish guts and offal from fish farms to crabs, lobsters and fish, which would congregate in huge numbers around the sunken structure.