Dispersive Rayleigh wave attenuation using inverse-dispersion method

Abstract

Reflections provide the most valuable information about the stratigraphy in seismic exploration. On land reflections are always contaminated by surface waves, high amplitude, low frequency, and low velocity and also dispersive. All these characteristics enable surface wave to be separated from reflections. A particular complication is that surface waves are dispersive. Then, frequencies of surface waves and reflections are overlapped in the spectral domain, the same can be found in the f-k domain. Traditional processing from doing surgical muting may cause damage to the data such as waveform distortion and narrowing the spectral band of the signal, especially when the surface waves are strongly dispersive. In this paper, a new method named inversedispersion algorithm is presented to suppress surface waves that overlap with reflections in frequency. We use the linear Radon transform and Fourier transform to find the dispersion curve of surface wave. With the help of dispersion curve and offset information, phases of every trace are moved. The phase-moving step is named the inverse-dispersion method. After the inverse-dispersion step, surface waves with different frequencies are transformed to be nearly parallel and away from reflections, which are easily separated. As it should be, the phase is moved back after surface wave elimination. In this paper the method is tested on field data, showing a good result with excellent protection of the reflections.