Practical Seismic Data Analysis

Seismic resolution and fidelity are two important measures of the quality of seismic records and seismic images. Seismic resolution quantifies the level of precision, such as the finest size of subsurface objects detectable by the seismic data. Several definitions of seismic resolution are introduced in this chapter. Seismic fidelity quantifies the truthfulness, such as the genuineness of the data or the level to which the imaged target position matches its true subsurface position. Since seismic data are band-limited, seismic resolution is proportional to the frequency bandwidth of the data or the resulting images. If the bandwidth is too narrow, the resolution will be poor because a single subsurface reflector may produce a number of indistinguishable wiggles on the seismic traces. For multiple datasets with the same bandwidth, it is easier in practice to recognize or resolve events with the zero phase wavelet rather than the minimum phase or mixed phase wavelets. Seismic fidelity is about global resolution, the resolution in the big picture.

In principle, the highest-quality seismic imagery requires the highest level of seismic resolution and fidelity. However, in real cases the seismic resolution and fidelity are always limited because of limited seismic illumination, producing various types of seismic artifacts. It is therefore important to assess the level of seismic resolution and fidelity in each seismic processing project, as illustrated by examples in this chapter. One of the physical reduction factors for seismic resolution is seismic attenuation, the loss of energy of the seismic signal with the increase of traversing distance. Hence the final topic discussed here is on the estimation and correction for seismic attenuation in processing seismic data.