Study on Formation Rule of Seismic Wavelet in Kelvin Medium

Abstract

Seismic wavelet plays an important role in the processing and interpretation of seismic data. And wavelet is also the premise of forward modeling and inversion of seismic wave. So it is important to study the formation process and formation rule of seismic wavelet. The viscoelastic properties of geologic body can be represented using Kelvin medium. The formation rule of seismic wavelet was analyzed using the mathematical model of propagation process of rectangle pulse in Kelvin medium. The experimental results have shown that characteristic frequency and band width were major frequency spectrum parameters causing the variation of waveform. The characteristic frequency and band width decreased with the increase of propagation distance. The characteristic frequency decreased in negative exponential law and became stable finally. The change of characteristic frequency and band width was related to the mechanical parameters of medium. With the increase of propagation distance, characteristic frequency decreased more slowly as elastic modulus increased than as viscous coefficient increased. The correlation coefficient increased with the increase of propagation distance, i.e., waveform became stable at last. Ratio of stability distance to characteristic wave length increased with the increase of elastic modulus and the decrease of viscous coefficient, then tended to become stable.