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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 72 (1988)

Issue: 12. (December)

First Page: 1522

Last Page: 1522

Title: Generation, Migration, and Entrapment of Hydrocarbons on Southern Norwegian Shelf: ABSTRACT

Author(s): Raymond C. Leonard

Article Type: Meeting abstract


The Southern Norwegian Shelf (56°-58°30^primeN) has proved to be one of the most prolific hydrocarbon provinces in Europe. Recoverable reserves of about 4.8 billion bbl of oil plus oil equivalent are found predominantly in Upper Cretaceous and Danian-age chalk and Jurassic sandstones. The excellent quality of seismic data, moderate to dense well control, and the detailed geochemical evaluations of the Kimmeridge Clay, the principal source rock, make the Southern Norwegian Shelf an ideal area for hydrocarbon generation studies.

A geochemical analysis of the area contained five basic steps: (1) construction of a nine-layered three-dimensional grid summarizing the burial history of the sediments by using well control and seismic data, (2) calculation of geothermal gradients, (3) source rock analysis to investigate variations in thickness and richness of the Kimmeridge Clay study area, (4) maturation study based on the results of the three initial steps, and (5) volumetric analysis and prospect evaluation.

Major factors affecting hydrocarbon accumulations in the structural and stratigraphic closures of the study area include the amount of oil generated within the catchment areas of the various closures and, particularly in the case of the chalk fields, the level of hydrocarbon generation of the Kimmeridge Clay directly under the crest of the structure and presence of faults to act as conduits for vertical migration of hydrocarbons from the Upper Jurassic Kimmeridge Clay to the Upper Cretaceous Danian chalk. The expulsion and migration efficiency (hydrocarbons in place/hydrocarbons generated within the catchment area of individual closures) for tested closures average approximately 8% for the study area, with individual culminations having values as high as 40% or as low as 0%, based in art on the previously mentioned factors.

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Copyright 1997 American Association of Petroleum Geologists