Chapter List

14.1 Why do we need to process seismic data?

Raw seismic data bears no resemblance to features inside the earth. It is primarily an expression of the experimental details of how it was acquired. Seismic data processing draws on our full knowledge of wave propagation effects and acquisition geometry to create geologically meaningful images of the subsurface.

A bewildering array of processes are applied to seismic data. Most fall into one of four categories: wavelet, traveltime, amplitude, or noise.

• Wavelet adjustments. Vibroseis correlation, deconvolution, filtering, phase rotation.

• Traveltime corrections. Statics (elevation, weathering, residual), normal moveout (and velocity analysis), dip moveout, migration (and velocity analysis).

• Amplitude corrections. Geometric spreading, attenuation, various forms of gain (t ⁿ, e ^at, normalization, automatic gain control, etc.).

• Noise reduction. Vibroseis correlation, vertical stack, mute, CMP stack, filtering (frequency, f-k, radon, etc.), multiple suppression.

A popular free processing system, SeismicUn*x, contains about 250 individual programs developed from the late 1970s to the present. Allowing for many of these to be graphics and utilities, there are still more than 150 core seismic processing programs. The field of seismic data processing is enormous. Published contributions stretch back to the beginnings of reflection seismology in the 1920s and accelerate with the introduction of digital computers in the 1960s. Our treatment of...