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The Late Cretaceous to Early Tertiary sediments of the Vøring and Møre basins are predominantly composed of fine-grained mudstones. Variations in the mineralogy and chemistry of these mudstones provide information regarding facies, provenance and burial history, and may also be used to predict rock properties. Over 300 cuttings’ samples from five wells were analysed by XRD. The results show significant changes in mineralogy as a function of burial depth, as well as important lateral variations throughout the basins. Eocene mudstones with up to 55% smectite probably represent a northern equivalent of the Balder Formation (North Sea). The underlying Late Cretaceous sequence probably had less primary smectite derived from volcanic ash, as indicated by the lower iron content. The distribution of smectite is also limited by its thermal stability, thus providing important constraints on the temperature history. These mudstone sequences may appear to be relatively homogeneous based on gamma-ray and shale volume calculations from wireline logs, but mineralogical and geochemical analyses from cuttings show that they vary significantly in composition. The smectite content is greatest in the south ( c . 55%) and decreases significantly northward ( c . 20%), indicating a marked regional control on velocity/porosity–depth curves. Mudstones containing high smectite content are characterized by lower velocities, lower densities and higher porosities when compared with published burial curves. Stratigraphic and regional variations in velocity and density are important for seismic interpretation and are significant for basin modelling.

This thesis entitled "Compaction of siliceous sediments-Implications for basin modeling and seismic interpretation" has been submitted to the Department of Geosciences at the University of Oslo in agreement with the requirements for the degree of Philosophiae Doctor (Ph.D.) The work presented in this study was completed as part of a large research project funded by The Research Council of Norway within the PETROMAKS program (Program for Optimal Management of Petroleum Resources) entitled "Petrophysical properties of mudstones and sandstones and their seismic response". The study is based on results from well log data in natural sediments from the Norwegian continental shelf. The derived compaction results have been integrated with results from experimental compaction studies performed within the same PETROMAKS project (Mondol, 2007). In addition, some of the work presented herein was completed in collaboration with a FORCE research project (Norwegian Sea Research Consortium) sponsored by ConocoPhillips, Gaz de France, Norsk Hydro and Statoil. The thesis comprise of an introduction together with six individual papers. A brief scientific introduction to the topic, the main objectives, summary of the papers enclosed, and finally some concluding remarks are given in the introduction. Three of the papers vi