Integrating Basin Modeling and Organic Geochemistry for the Reconstruction of the Hydrocarbon-Filling History of a Haltenbanken Oil Field, Mid-Norway

Ondrak, Robert V.¹; Haberer, Raingard M.²; Vieth, Andera ¹; di Primio, Rolando ¹; Wilkes, Heinz ¹; Leith, Leslie ³; Horsfield, Brian ¹
(1)Organic Geochemistry, GFZ German Research Centre for Geosciences, Potsdam, Germany. (2) IGI Ltd, Bideford, United Kingdom. (3) Statoil ASA, Trondheim, Norway.

We present an integrated organic geochemistry and basin modeling study for the detailed reconstruction of the hydrocarbon-filling history of a Haltenbanken oil field, specifically the identification of the spatial and temporal maturity and generation history of different kitchen areas as well as the migration pathways into the reservoir. We studied hydrocarbon generation and migration in the northern Haltenbanken area using a 3D basin model constructed from seismic horizons of the main stratigraphic units and well-tops of about 100 exploration wells. We calibrated the model with vitrinite reflectance, temperature and pressure data.

The organic geochemical study comprised 24 crude oil samples and some 70 extracts from selected reservoir rock samples from the oil field supplemented by 23 oil samples from surrounding oil fields. Crude oil and condensate samples as well as extracts of core samples were investigated for their aliphatic and aromatic hydrocarbon composition using whole-oil-GC and GC-MS-analysis. Stable carbon and hydrogen isotopic compositions of individual hydrocarbons in Haltenbanken oils were studied to decipher primary and secondary processes in the oil fields. The geochemical part of the study indicates a strongly biodegraded eastern part of the oil field which did not receive a significant second charge while in the western part biodegraded oils of the initial charges have been mixed with a fresh oil charge. This was confirmed by the stable isotopes study. The geochemical study also revealed the spatial relations and similarities of the different fields which could be constrained in the basin modeling study.

Large differences in burial of the upper Jurassic Spekk Formation which is considered to be the main source rock in the study area led to the maturation of different kitchen areas throughout basin evolution. Source rock tracers assigned to the various kitchen areas based on structural elements and burial history allowed unraveling the timing of hydrocarbon generation and migration pathways in the study area. The study provides important understanding for the filling history of this Haltenbanken oil field. We can quantify the amounts to which the different kitchen areas contribute to the charge of the reservoir as well as the dominant migration pathways into the reservoir structure.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.