Seismic interpretation

In seismic exploration, an acoustic energy source radiates elastic waves into the earth from the surface; receivers on the surface detect acoustic energy reflected from geological interfaces within the earth. The recorded data are processed in ways which ease interpretation. Seismic interpretation is the interface between the exact mathematics of seismic data processing and inexact geological reasoning. Oil and gas occur in sedimentary rocks, where source rocks are present and a porous and permeable reservoir is sealed by an impermeable cap rock to form a trap. The principal use of seismic exploration is to find potential oil and gas traps primarily by mapping geological structure. Integration of exploration well data with seismic data can reduce the ambiguity of the interpretation. Because seismic measurements are affected only by the elastic properties of the earth, geological interpretation beyond structural mapping is difficult. Furthermore, resolution is limited by the bandwidth of the recorded data, which in turn is limited by frequency-dependent attenuation of elastic waves by the earth. However, in some circumstances we can detect gas occurrences directly. Recent developments include the use of seismic data in unraveling the geological history of an area; the use of amplitudes and other attributes of seismic recording; the use of transverse waves; and three-dimensional seismic exploration. In the future, interpretation will become more automated and more integrated with processing.