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This capsule review is a condensation of an SEG Continuing Education short course that is designed to present recent advances in seismic exploration from viewpoints based upon (1) a linear filter model and (2) a geometric model, with statistical communication theory unifying these two viewpoints.
Convolution of the source pulse with the earth reflectivity gives the seismic signal in the linear filter model. Absorption introduces the time variance. Horizontally traveling noise and random noise are additive processes that complete the filter model. Analysis of signal and noise in f-k (frequency-wavenumber) space leads to methods of noise suppression based upon spacial filters in the field and velocity filters in processing. Distortion of the source pulse by ghosts and reverberations is overcome by deconvolution, where the unknown and spacial varying source pulse is replaced by one that has constant and more desirable properties, such as zero phase.
The geometric model overcomes the one-dimensional shortcoming of the filter model, and allows for refractions and diffractions. Horizontal stacking to suppress multiples and increase signal-to-noise ratio requires accurate knowledge of the stacking velocity which is derived by analysis of normal movement.
Utilization of optimal acquisition and processing to preserve the amplitude and frequency characteristics of the underlying reflectivity, along with velocity estimates from strictly surface measurements, significantly improves interpretation in terms of lithology, stratigraphy, and fluid content, and demonstrates that the seismic method is more than a structural mapping tool.
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