Initiating offshore output above the 62nd parallel (the northern limit of the North Sea), this milestone was passed on Draugen in the Halten Bank area, 145 kilometres north-west of Kristiansund.
It also marked the first time that Shell produced oil as an operator on the Norwegian continental shelf (NCS), and occurred on the northernmost platform operated by the company worldwide.
A lot of people were surprised when Draugen was discovered in 1984, because the field lies in a place where most geologists had not expected to find oil-bearing strata. Since oil from the Halten Bank has migrated eastwards and upwards, Draugen is shallower than other reservoirs in the area at a depth of 1 600 metres.
The field produces from two structures. Its main reservoir is the Rogn formation, formed of Late Jurassic sandstone. In the western part, production also comes from the Middle Jurassic sandstones in the Garn formation.
When Draugen was discovered, Shell estimated a recovery factor of about 17 per cent of resources in place – a conclusion which was realistic in the 1980s.
This proportion remained below 40 per cent when the field came on stream in 1993, but has more than doubled since then. Draugen now ranks among the Norwegian fields with the highest recovery factors, at around 70 per cent.
In other words, it has already produced far more oil than was originally thought possible and is positioned to become one of the world’s best offshore performers in terms of recovery factor.
Plans assumed an average output of about 90 000 barrels per day when the field was developed, but both reservoir and platform proved capable of producing more.
At peak, Draugen yielded roughly 225 000 barrels of oil per day. One well alone produced a daily maximum of 77 000 barrels.
The field originally had a calculated producing life of 17-20 years, but this has now been extended to 2027 and output – if all goes well – could continue beyond that date.