The Stratigraphic Method Applied to History Matching of the Norne Field

Abstract

History matching is the process of improving a reservoir simulation model by modifying its parameters until simulations reproduce the observed data. This thesis presents a history match of the North Sea oil field, Norne. The Norne oil field data is available through the IO Center, via the owner Statoil and partners ENI and Petoro. The history matching approach is manual, and performed with the stratigraphic method. This method and the history matching results are evaluated and discussed.The stratigraphic method is a structural and well-organized approach to manual history matching. The logic of the method is to reduce complex three-dimensional systems, such as the Norne simulation model, to a series of simpler two-dimensional systems. Then history-matching adjustments can be applied at four hierarchical levels until validation of each level. The adjustment levels are (1) global, (2) layer group or zonal, (3) individual layers and (4) individual wells. Vertical transmissibility, fault zonation and fault transmissibility are the key history matching parameters. The fault zonation and transmissibility control the flow of fluids within the reservoir. The vertical transmissibility through the field-wide stratigraphic barriers controls the water rise. Bottomhole pressures at all wells are matched at each adjustment level. At the individual layer level, there is matching of the water rise as well.Key faults in the study were C_08_S, C_20, C_23, C_26, DE_1, E_01_F3 and E_01. Both water rise and bottomhole pressures were sensitive to modifications of these. Additionally, the local transmissibilities of layer 15 were very sensitive to changes. Most changes were conducted in layer 10. The final simulation model obtained three percent closer matches in most wells, acceptably matched production rates and a water rise similar to the original model.Recommendations following the study are (1) to utilize computer-assisted parameter optimization in the history-matching process for higher efficiency, and (2) to study the geological model in higher detail to find unaccounted faults or high-permeability flow channels.