The Delft Sandstone in the West Netherlands Basin

Abstract

The Delft Sandstone Member (Late Valanginian, Early Cretaceous) is part of the Delfland Subgroup that is deposited in the West Netherlands Basin, in the southwestern part of the Netherlands. It is the target sandstone for the Delft Aardwarmte Project, that is planning to produce hot water from this sandstone. A detailed reservoir-geological model is an important step in assessing the spatial distribution of lithofacies- and fault-related heterogeneities in this sandstone, because these are of influence on the fluid flow properties of the sandstone. The Delft Sandstone Member consists of fluvial deposits in a syn-rift tectonic setting. The thickness, stacking, and lateral connectivity of the fluvial sandstones determine the overall reservoir communication. The present study comprises an analysis of available literature about the West Netherlands Basin and the Delft Sandstone Member in particular. Furthermore the core of the Moerkapelle 11 (MKP 11) well is described and compared to the logs of the Delft 03 (Del 03) well, with the aim to get a better understanding of the Delft Sandstone Member and make a comparison between the two Delft Sandstone Member packages. The Delft Sandstone Member is approximately twice as thick in the Delft area compared to the Moerkapelle area, probably because of the location of the MKP 11 near the boundary of the basin, where the Del 03 is located near the middle of the graben where more subsidence has resulted in more accommodation space. Both packages show loosely stacked sandstone bodies in the bottom of the Member and thicker stacked sandstone bodies in the top. The vertical connectivity is best in the stacked sandstones in the top of the Member, the lateral connectivity is difficult to establish only on the basis of correlation of wide-spaced well logs. Due to extensive faulting in the West Netherlands Basin, thickness modelling of the Delft Sandstone Member is almost impossible.