Год издания: 2022

Land seismic challenges are usually attributed to superimposed near-surface noise. We suggest that small- scale near-surface scattering distorts the reflections themselves via a mechanism we refer to as "seismic speckle," similar to speckle noise in optics and acoustics. We describe a simple mathematical model of multiplicative seismic noise that captures the main features of such distortions seen on the field data. The first type of multiplicative noise with random phase perturbations explains the severe coherency loss and a substantial amplitude reduction after stacking. Residual statics is another type of multiplicative noise leading to progressive loss of higher frequencies. Both mechanisms combined quantitatively explain amplitude transformation observed while locally stacking field data. We present field observations confirming seismic speckle and also numerically demonstrate how local stacking can recover the accurate phase of the undistorted signal on synthetic data.