Cementing the sandstone foundation: a field-scale reconstruction from depositional fabric to diagenetic framework in the Rotliegend of the Groningen gas field
Understanding sandstone reservoir heterogeneity at grain scale is important for predicting its geomechanical response and for subsurface applications such as geothermal energy and carbon storage. Yet understanding the origin of this heterogeneity and predicting reservoir properties remains challenging.
The Upper Rotliegend sandstone reservoir of the Groningen gas field, Europe’s largest gas reservoir, provides an opportunity to investigate this heterogeneity from grains to field scale. More than 300 thin sections from 15 wells reveal how depositional and burial processes control present properties.
The results show that much of the reservoir’s heterogeneity was established when the sand was deposited. Differences in depositional environment, grain size, sorting and composition created a framework that controlled how the sandstone changed during burial. The distribution of minerals formed after deposition can be explained by this inherited framework and local processes, revealing regional patterns in clay minerals across the field. These findings show that large-scale external fluid flow is not needed to explain the mineralogical variability.
The study also reveals that compaction cannot be explained by depth alone. Early minerals such as dolomite and clay coatings could either reduce pore space or protect the original grain framework, while later burial processes amplified rather than erased these differences. In particular, early dolomite cement locally stabilized the grain framework, preserving intergranular volume, while reducing porosity.
Together, these findings show how geological processes operating at grain scale can shape reservoir behaviour at field scale, providing a framework relevant to other arid continental sandstone reservoirs.