Prediction Method for Water-Layer-Related Multiple of Rugged Seabed Based on Born Simulation Using Phase Shift Operator

Water-layer-related multiple (WLRM) is a critical type of surface-related multiple. The model-based multiple prediction method has proven effective for predicting WLRMs while requiring less data acquisition compared to data-driven method. The model-based WLRMs prediction process is described as the convolution of recorded data and the seabed primary response. According to the ray theory, the primary response is typically approximated using the first-arrival travel times of seabed primary reflection. However, in rugged seabed case, this ray-theory-based method may reduce the accuracy of WLRMs prediction. This article proposes a WLRMs prediction method based on Born simulation. The proposed method can characterize the multiple diffractions and multiarrival reflections generated by rugged seabed, resulting in a more accurate WLRMs prediction result. The prediction process consists of two main steps, namely downward extrapolating the sea surface recorded data to the seabed, and upward extrapolating the multiple scattered wavefield generated by the seabed back to the surface. We efficiently implement the wavefield extrapolation in the water-layer using phase shift operators. The synthetic data validate the accuracy of the proposed method in predicting WLRMs from rugged seabed. Then we successfully applied this method to attenuate WLRMs in 3-D field data. The demultiple results demonstrate that the WLRMs in the synthetic and field data are effectively suppressed, thus verifying the effectiveness of the proposed method.