Abstract

Correlation noise is a serious problem in many areas with vibroseis system due to dynamic range of more than 60db between the strong first arrival and weak reflection events arriving at several seconds later. A simple and easily implemented method of reducing correlation noise is amplitude tapering (Edepman 1966), but unfortunately tapering induces an increase in main peak width (Berkhout 1984), which is an undesirable effect. Application of tapering minimizes high frequencies caused by the vertical ends; and with deconvolution it can some extent control this noise but cannot cope up always with such a large dynamic range in the presence of noise. So far, Non-linear, Linear sweeps have been employed with varied success for many years. With the approach of Varisweep technique with Non-linear sweep, Vibroseis source spectra were modeled as an objective to broaden /whiten the effective signal bandwidth as received at the geophone, while reducing the ground roll generation at seismic source and correlation