Common Focus Point Technology

Dit proefschrift is goedgekeurd door de promotor: 'Alles komt voort uit de chaos', wordt er in de Griekse Anthologie gezegd. En in-derdaad, alles komt voort uit de chaos. Buiten de wiskunde, die enkel met dode getallen en loze formules te maken heeft en derhalve volmaakt logisch kan zijn, is de wetenschap niet meer dan een kinderspel in de schemering, het willen vangen van vogelschaduwen en het willen tegenhouden van de schaduw van gras dat waait in de wind. Preface In January 1991 I finished my MSc project, which was supervised by professor Fokkema and professor Van Den Berg, at the department of applied Earth Sciences. During the MSc project professor Fokkema showed me the good things of seismic research. At the end of the academic year, August 1991, professor Fokkema introduced me to the group of professor Berkhout where I could begin a PhD study within the DELPHI project. Research in the Geophysical context was something I started to like a lot and working in a team was also an important reason for starting my PhD project in the group of professor Berkhout. The subject of my PhD project was initially set up to investigate the combination of elastic wavefield decomposition and weathered layer influences. In the first year it became clear that correct estimation of the propagation properties of the weathered layer is very important for the decomposition and all the further processing steps. Therefore the subject of my research changed to weathered layer estimation, using the areal shot record technology. An important side-off project of these first years was an optimization technique I used to construct the decomposition operators. This technique is also very successful for the optimization of extrapolation operators. During my work with areal shot records the areal shot record designed for one point in the sub-surface turned out to be a very useful intermediate step for imaging and velocity analysis. So finally the subject changed for the last time to Common Focus Point technology the main subject of this thesis. The last 2 years I have been working intensively on this subject and the results can be found back in this thesis. Note that although it seems that I have been doing a lot of other things besides the main subject of this thesis, all the things I have done before helped me to understand the main geophysical problems and gave me a broad overview. …