A Novel EM Driven Approach to Frontier Exploration in the Barents Sea

The Barents Sea is a vast offshore area in northern Norway. Spanning from the Russian border to the deep ocean margin, it comprises a wide range of geologic settings, from Tertiary plays in the west, to Triassic in north-east, and Paleozoic in the south-east. Large parts of the area are still virtually unexplored.

Exploration started in the early 80’s and led to several promising discoveries, including Snohvit (Norway), discovered in 1984 and Stokman (Russia) discovered in 1988. However, after these discoveries, there was a row of disappointing wells, dry or with shows until there was a total stop in exploration drilling from 1994 until 2000, when the Goliat Discovery was made. Again this led to new optimism in the area, but until 2011, this was the last commercial discovery. From the wells drilled prior to 2011, a number of lessons have been learned:

- There is a working hydrocarbon system in the area

- Late uplift and erosion change the pressure regime, affecting reservoir and seal properties

- There is a challenge to find proper reservoir quality and volume to hold commercial amounts of hydrocarbons

- Seismic as standalone tool has proven inefficient in detecting these volumes

Since 2003, EMGS has acquired a large amount of CSEM data, covering all the different geologic provinces. In 2008 and 2010, two extensive multi-client programs were carried out prior to the 20th and 21st license rounds on the NCS, covering a total of 16 000 km2.

In 2011, two new major discoveries were made in 20th round licenses, both properly imaged by EM. Other EM surveys on earlier discoveries also demonstrate that the major hydrocarbon accumulations, such as Snohvit and Goliat, are seen on EM data, while minor, non-commercial discoveries do not exhibit any significant EM responses. This proves that CSEM data can provide a valuable addition to the exploration database, since EM is sensitive to saturation and volume, and therefore can indicate where the economic accumulations are. A substantial number of interesting observations are yet to be drilled in order to increase the understanding of EM measurements in the area.

Earlier this year, an agreement with Russia concerning the so-called ‘Grey Zone’ has opened a totally new area for exploration, which among experts is regarded as very promising. We believe that the use of EM data can significantly increase the success rate in future exploration.
 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California