Reflection/Refraction Seismology

Abstract

SynonymsControlled-source seismology; Multichannel reflection seismics; Wide-angle reflection/refraction profiling (WARRP) DefinitionsMethods to image and to physically parameterize the subsurface geologic structures and conditions by means of artificially generated shock waves that travel through the subsurface and return to the surface. OverviewControlled-source seismology comprises a variety of geophysical methods to image and to physically parameterize the subsurface geologic structures and conditions. All these methods base upon the principle that artificially generated shock waves travel through the subsurface and that the returned signal can be analyzed regarding the properties of the subsurface. During the last decades the discrepancies between marine seismic equipment as used by the academic marine research community and that used by the hydrocarbon (HC) exploration industry increased significantly, caused by different research targets and the simple fact that gear commonly used for HC exploration is much too costly. In this chapter we will focus on those systems which are typical for academic marine research.In principle, seismic data acquisition requires an energy source, a receiver, and a recording system. The two most important seismic methods are reflection and refraction seismology (Fig. 1).Reflection seismologists deal mainly with steep angle reflections, which means that the source to receiver distance is small compared to the target depth. This method utilizes the fact that a small part of the down-going energy is reflected on geological layer boundaries. The main fraction of the energy is transmitted and travels deeper where reflections occur at the next layer boundary and so on. This method results in a good vertical and horizontal structural resolution of the subsurface. Earth scientists benefit from the technical and methodical developments of the exploration industry which uses reflection seismology for the detection of oil and gas in depths of up to several kilometers below the seafloor.

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