Browse by author
Lookup NU author(s): Professor Stephen Larter
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Troll field represents the largest petroleum discovery within the entire North Sea area in oil equivalents, with 74% of the accumulated petroleum present as dry gas and 26% as a heavy biodegraded oil leg. The field is divided into several provinces based on the distribution of gas and oil, and the gas and oil have been suggested to be cogenetic. The migration and filling model presented in this paper suggests that the oil and gas represent two different migration phases and that gas migration and filling predate oil emplacement. Two different oil populations have been characterized and mapped in Troll field applying conventional geochemical techniques. We suggest that the two oil populations migrated into the structure through two different migration systems. Oil and gas were subsequently biodegraded within the reservoir. The two oil populations have been found in neighboring oil and gas discoveries, and an oil-oil correlation with these discoveries has been used to determine the location of field filling points and regional migration routes. When oil biodegradation terminated, fresh oil continued to migrate into the reservoir and mixed with the residue of the biodegraded oil. The field was tilted downward to the west in the Neogene, and oil and gas remigrated within the field with a possible spillage of gas. Tilting resulted in a dominantly upward movement of the oil phase whereas gas migrated laterally. Residual oils in the water zone have been used to reconstruct the paleoconfiguration of the field that controlled the current distribution of oil populations within Troll field.
Author(s): Horstad I, Larter SR
Publication type: Article
Publication status: Published
Journal: American Association of Petroleum Geologists Bulletin
Year: 1997
Volume: 81
Issue: 2
Pages: 222-248
Print publication date: 01/02/1997
ISSN (print): 0149-1423
ISSN (electronic): 1558-9153
Publisher: American Association of Petroleum Geologists
