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Gullfaks yields more

July 8, 2003, 11:30 CEST

Gullfaks has so far yielded 570 million barrels of oil more than forecast in the original plan for development and operation of this North Sea field operated by Statoil.

The additional volume corresponds to estimated recoverable reserves from the group’s Norne development in the Norwegian Sea.

And Gullfaks is expected to produce considerably more in coming years, even though it is approaching the tail production phase.

Oil output from the main field is currently passing a level of about 1,880 million barrels.

In the longer term, the ambition is to recover a further 250-380 million barrels, reports Arild Hesjedal, manager for resource utilisation in the Gullfaks organisation.

The good results on this field have primarily been achieved through reservoir mapping with the aid of four-dimensional seismic surveying, and by advanced drilling and well technology.

Other Statoil-operated developments have also yielded more than originally forecast, primarily because the group has been committed to improved recovery since it was founded in 1972.

A recovery factor of more than 60 per cent has been achieved on Statfjord, for instance, and the target there is to produce as much as 68 per cent of the stock tank oil originally in place.

Statoil’s latest studies show that some 300 million barrels of oil over and above the level specified in existing plans could be recovered from the Tampen area. That would raise total recovery from 2.5 billion barrels to 2.8 billion.

Embracing Statfjord, Gullfaks and several other fields, this region is not the only part of the Norwegian continental shelf where Statoil has boosted recovery above the original estimate.

Forecasts have been upgraded by 47 per cent for Glitne in the North Sea and 42 and 24 per cent respectively for Heidrun and Norne in the Norwegian Sea.

A common factor on these fields is that the improvement in recovery can be attributed to enhanced reservoir description and monitoring.

Optimising drainage strategies and well solutions, applying four-dimensional seismic surveying and implementing new well targets have also been highly significant.