Complex Seismic Trace, Bandwidth and Vertical Resolution

Resolution is the ability to distinguish separate features. Improving resolution is the key problem to see thinner stratigraphic units, for instance. Horizontal resolution is connected to the size of the Interface Fresnel Zone. Vertical resolution is usually considered as being enhanced by both high frequencies and broadband signals. This common belief is true for zero-phase signals, such as Ricker wavelets, but is incorrect for mixed-phase signals (i.e., non zero-phase signals). For this type of signals, the complex trace, and more specifically the envelope, is a fundamental tool for the analysis of seismic resolution. We propose a criterion based on the separation of two envelopes as a new key element. This criterion is connected to the bandwidth that is consequently the key parameter for enhancing vertical resolution.