The shales of the Kimmeridge Clay formation cover an extensive area of the North Sea and act as both seal and source rock for many reservoirs. The properties of the Kimmeridge Clay are often ignored, with the focus being on the hydrocarbon bearing sand reservoirs. However, much of the Kimmeridge Clay of the Moray Firth area can be seen to lie off the Greenberg-Castagna (1992) Vp-Vs trend for shales.

Here we will document the Kimmeridge Clay trend for the Moray Firth area using a database of some forty wells, creating a suggested empirical trend for the Kimmeridge Clay shales in this area. Also, some ideas will be put forward to suggest the causes for the change in shale trend.

These findings have implications for seismic interpretation and rock physics in areas where Kimmeridge Clay is present – in both developed fields and new prospects. It also highlights the importance of regional context and also of an integrated approach to projects in exploration, appraisal and development stages.