Compaction model for quartzose sandstones application to the Garn Formation, Haltenbanken, Mid-Norwegian Continental Shelf

Abstract

The compaction of quartzose sandstones is described by a macroscopical visco–elasto–plastic model, derived from microscopical considerations. This model considers that the reduction of total porosity (the relative pore volume) is related to the changes in the relative cemented volume and the relative intergrain volume. Furthermore, we consider that the variations of these two petrophysical parameters result from two physical mechanisms, mechanical compaction and closed system chemical compaction.The model has been calibrated for the Middle Jurassic Garn Formation from the Haltenbanken area of the Mid-Norwegian Continental Shelf. Around 300 data points from 17 wells have been used in this study. The viscous parameters have been optimised against the present day data. With total porosity data the best fit is obtained for an activation energy between 14 and 16kJ/mole and a macroscopical viscosity at 15°C between 39 and 46GpaMa (1.21024–1.41024Pa.s). If quartz cement data are used, the best fit is obtained for an activation energy between 16 and 18kJ/mole and a macroscopical viscosity at 15°C between 47 and 56GpaMa (1.51024–17.1024Pa.s).The visco–elasto–plastic compaction model has been tested in the Haltenbanken area of Mid Norway, with the result that observed porosity trends and pore pressures can be modelled. Using multiple 2-D basin modelling simulations the results of this model and its implications for fluid flow and petroleum systems analysis can be seen. The compaction method has significant impact on the simulated fluid flow and petroleum migration pattern.