On the Nature of Scattering from Isolated Perturbations in Elastic Media and the Consequences for Processing of Seismic Data
The nature of seismic scattering was investigated by elastic scattering theory and numerical experiment. Seismic scattering situations can be classified by analyzing the amplitude versus scattering angle behavior of the scattered seismic wave field. The shape of large objects has significant impact on the dynamics of the scattered wave field. Gather oriented as well as prestack methods capable of enhancing the scattering response and assisting in classification were developed. A new 3D migration technique based on diffraction stack migration was introduced. The method uses either coherency (DCM) or polarization (DPM) information to enhance the image of scatterers. Multichannel seismic surveying using boomer sources was tested, as a first step towards a high resolution 3D marine seismic acquisition technique. A 2.5D seismic survey was conducted in northern Kiel Bay. A Pleistocene fluvial channel system was revealed beneath the sea floor. DCM efficiently enhanced the image of marine scatterers. Crustal VSP data was acquired within the scope of the DSI program which is aimed towards detecting massive volcanogenic ore deposits in the crystalline crust. DCM and DPM were applied to VSP data acquired in Matagami, Canada. DPM reduced imaging ambiguity and a scattering center in vicinity to the orebody was found. DCM was also applied to a VSP data set acquired at the Sudbury impact structure, Canada. Correlation with regional geology is aggravated by the imaging ambiguity imprint on the migration result.