--> Abstract: Oil Migration And Filling History Of The Beryl And Adjacent Fields In The South Viking Graben, North Sea, by C. C. Walters, H. M. Chung, S. P. Buch, and G. G. Bingham; #90928 (1999).

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WALTERS, CLIFFORD C.1, H. MOSES CHUNG1, STEVEN P. BUCH2, and GAIL G. BINGHAM2
1Mobil Technology Company, MEPTEC, Dallas, TX
2Mobil North Sea Limited, Aberdeen, UK

Abstract: Oil Migration and Filling History of the Beryl and Adjacent Fields in the South Viking Graben, North Sea

Since its discovery in 1972, Mobil has collected and analyzed more than a hundred oil samples from the Beryl Complex and adjacent fields. This historic program provides Mobil an opportunity to examine the area as a Petroleum System; that is, to study the relationships of petroleum fluid flow from the source(s) to the reservoir. Excellent linear relationships are observed when examining compounds of similar molecular weight. Generally poor correlations exist in the molecular and isotopic compositions of volatile and non-volatile hydrocarbons indicating that most Beryl Field oils are mixtures of hydrocarbons originating from different sources. A multiple source model can explain the chemistry of the Beryl Complex oils and gases. This hypothesis is based on general modeling concepts of hydrocarbon generation and expulsion from Kimmeridge Clay/Heather source system. The Kimmeridge Clay Formation is an organic-rich source containing Type II, or Type IIS kerogen. Early expulsion of oil may occur at temperatures as low as ~90°C, with peak expulsion occurring at ~120°C. The Heather Formation has lower generative potential and contains a mixed Type II/III kerogen. Consequently, hydrocarbon expulsion from the Heather Formation requires higher temperatures than the Kimmeridge Clay. Initial expulsion occurs at ~120°C with peak at ~140-150°C. Lower Jurassic coals also may play a role in gas/condensate generation. The distribution of oil and gas in the complex structures of the Beryl field is attributed to multiple migration pathways of hydrocarbons from different source kitchens.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas