Reservoir modelling of bryozoan limestone, Fakse quarry, Denmark

A 3D reservoir model is constructed based on geological and geophysical data sets from the bryozoan limestone formation in the Fakse quarry, Southern Zealand. The model can be used as an analog to North Sea chalk deposits of Danian age. The collected data can be divided into 3 groups reflecting the hierarchical nature of the limestone formation: 1) Large scale structures, 2) Characterization of lithofacies, 3) Petrophysical properties.
The applied stochastic modelling software Heresim3D simulates the spatial distribution of matrix porosity and permeability by taking measured data into account and by using a dense grid of 2 mill. cells. Next, the reservoir grid density is reduced to upscale the reservoir model. Permeability measurements on limestone matrix cannot account for the large scale transmissivity controlled by fractures and the Heresim3D software is not designed to work with faulted reservoirs. As an alternative, thin high permeable layers representing observed fractures parallel to bedding are introduced to match pumping test data from the Fakse area.