· · · Institutional Repository

Wintershall is operating a number of Buntsandstein fields in the Southern North Sea. It has proven a major exploration challenge in the area to predict the reservoir quality of these fields based on seismic data only. The effect of salt present in the area plugging the pore space leads at first sight to similar seismic responses on post-stack data as for gas filled reservoirs. This study aims to gain better insight into the (subtle) differences in seismic response induced by water-, gas- or salt-fill scenario. The approach adopted is by studying the seismic response at various existing wells in one of the fields and the corresponding seismic responses of the processed 3D seismic survey. First a thorough analysis of the log responses of 13 wells is made and the effect of a.o. depth trends, compaction, diagenesis and facies changes to the seismic response is qualitatively investigated. Then, a match between the log data and the poststack seismic data is established by creating synthetic seismic data. Finally by using fluid substitution and more recent solid substitution theory, subtle changes in seismic response, both pre-stack and post-stack, between the different porefills are predicted. Based on these modeled predictions recommendations are made concerning the type of data analysis that should be carried out to discern the different porefills on the seismic data. The results of this research should lead to an improved characterization of the Buntsandstein reservoirs and as a consequence, to a higher success rate in drilling (i.e. less “dry wells”).