For North Sea chalk fields, finite element models are used to evaluate the reservoir compaction and the associated seafloor subsidence. The present paper addresses aspects of the calibration of the stress strain laws to be used for the chalk and the overburden. Results of laboratory tests do not reflect the large scale deformation behaviour. The calibration is therefore mainly based on the back analysis of measured formation movements. Another topic is the coupling with reservoir simulation models, which provide the reservoir pressure. This coupling should be improved, if a local compaction cannot be derived from a simultaneous change in reservoir pressure at that location.