Barents Sea Source Rocks

Malvin Bjorøy, Peter Barry Hall, and Ian L. Ferriday
Geolab Nor AS, Trondheim, Norway

The first well was drilled in the Barents Sea area in 1980. Since then over 60 Norwegian sector wells have been drilled. The main Norwegian discoveries are Snøhvit, Askeladden, Albatross (in combination yield 160 billion m3 gas and about 28 million m³ condensate and NGL) and Goliat (~50 million barrels oil). There are also a number of smaller oil and gas discoveries. In the Russian sector the most significant find is the Shtokman field (approximately 16 times the size of Snøhvit). There are several potential source rocks in the Norwegian sector, ranging in age from the Cretaceous to Carboniferous. The dominant source rocks are in the Mesozoic, Hekkingen, Snadd and Kobbe Formations and in the Permian, the Ørret Formation. Because of the significant uplift and subsequent erosion during the Tertiary, maturation of source rocks was halted or at least reduced in some areas. The oils and condensates in the Norwegian sector have a wide range of maturities from early oil window to condensate window maturity. The oils can be divided into at least two separate groups, being sourced by marine Upper Jurassic and/or Triassic source rocks. They also show evidence of reservoir alteration (waterwashing, migration contamination etc.).

Our data are based on analysis of 53 wells from the Norwegian sector and five from the Russian sector and analysis of 25 oils/condensates. The characteristics of the different source rocks will be discussed, together with the contribution of these in the different areas, especially over the Norwegian part of the Barents Sea.