Calibrated Fluid Flow and Charge Modelling Using a Geological and Geochemical Integrated Approach

Daniel Stoddart¹, Olav Lauvrak¹, Balazs Badics¹, Arne Steen¹, Susanne Sperrevik¹, Michael Erdmann¹, Marian Vaage¹, Øyvind Sylta², and Ane Lothe^2
1 Norsk Hydro, Bergen, Norway
² SINTEF Petroleum Research, Trondheim, Norway

The mapping of oil/gas migration in the subsurface through time is notoriously complex and demands that all data types must be considered to piece together a geologically viable migration history. The Greater Oseberg area, Norwegian North Sea, is surrounded by several petroleum generating grabens, all contributing oil and gas to the Horda Platform and the flanks of the North Viking Graven, giving rise to several large accumulations, most notably Oseberg Field, Troll West Oil Province, and Brage Field.

We will showcase how the integration of molecular geochemistry, PVT data, reservoir geochemistry, fluid inclusion analyses, detailed fluid contact information, knowledge of expelled petroleum volumes through time, and fluid flow modelling can be used to establish a charge history model. Briefly, four main oil and gas migration routes have been confirmed, 1.) Oseberg Main – C-Structure – Brage – Troll West Oil Province, 2.) Tune - Oseberg South, 3.) Vestlefrikk – Oseberg East – Brage Horst, 4.) Southern Brage fault spill sequence. Specific petroleum families have been determined based on geochemical information for different boiling range fractions, each population representing both variations in source type and maturity. The capability of multi-component kinetic models to recreate petroleum phase as a function of maturation and corresponding charge timing into the structures was tested. The finalised model tries to honour uncertainties of the input parameters and the large number of input variables that lead to non-unique solutions. The results can help to improve risking of yet undrilled compartments and satellite prospects in the area.

Summarising, this integrated approach lends credence to fluid flow models used in infrastructure exploration.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005