Evaluation of Source Rocks in the Mid-Norway Area

Ian L. Ferriday, Malvin Bjorøy, and Peter B. Hall
Geolab Nor AS, 7437 Trondheim, Norway

Since the first discovery in 1981, the Mid-Norway area has become one of the most important oil and gas provinces offshore Norway. Many gas and oil fields have been discovered in the years since 1981 and, as new deep water blocks have been opened to exploration, further discoveries have been made (e.g. Ellida and Ormen Lange).
It is generally believed that the Upper Jurassic Spekk Formation is the main source rock for the oil in the area. Other potential source rocks range from the Tertiary to Permian in age. There is considerable disagreement as to the extent to which potential source rocks other than the Spekk Fm. may have contributed. In the Vøring Basin, there is doubt as to whether the Spekk Fm. will be an effective source rock due to being overmature. The oil shows found in this area may be early remnants or possibly from another, younger source rock. Another problem is regarding the contribution by the coals/shales of the Åre Formation.
The analytical results discussed here are based mainly on our own database of oils and source rocks. This data is derived from a total of approximately 100 oils and from about 100 wells.
Evidence from a range of petroleum geochemistry analyses confirms the Spekk Formation possibly involving different facies developments as the main source rock. However, in some cases there have probably been contributions from other source rocks than the Spekk Formation. Another factor considered in our evaluation is the problem of interpretation caused by oil-based drilling muds.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece