The Influence of Basalt Layers on Seismic Wave Propagation

Abstract

Large areas of the Earth are covered by intrusive and extrusive lavas, forming high velocity basalts, which are often opaque to cinventional seismicreflection surveys. On the North East Atlantic margin these basalts cover sediments in whose lateral extension away from the basalt cover proven hydrocarbon reservoirs and source rocks exist. To reveal the comparable structures that are expected to exist beneath the basalt cover novel seismic methods are required. <p> The primary objectives of this thesis are to examine the effects of basalts on seismic wave propagation and the concequent implications for imaging sedimentary structures beneath them. From studies of basalt propertiesand borehole data in connection with foreward modelling and real data, I show that new acquisition methods, like low frequency set-ups and far-offset recordings, have to be used to image beneath basalt sequences.