Abstract: The surface and subsurface structural patterns in the region in front of the southwest foothill area of the Tarim Basin are highly complex, with diverse lithological and structural features. This area is a typical case of “dual complexity” in both surface and subsurface geology, leading to complex seismic wavefields and significant challenges in data processing and imaging accuracy. To clarify the seismic wavefield propagation characteristics in this region and provide a theoretical basis for subsequent data processing, this study constructs a dual-complexity velocity model representative of the area's geological features, based on field seismic data, well logging data, and near-surface outcrop information, and conducts seismic wavefield simulation analysis. During the modeling process, a near-surface velocity model was first developed using near-surface tomography data and elevation information. Then, a structurally complex model was constructed and refined based on seismic interpretation results. These models were subsequently integrated to form the final velocity structure model. To accurately characterize the Q value distribution within the target area, this study proposes a method for constructing a Q model based on sparse well data. Seismic wavefield forward modeling was conducted using the developed velocity and Q models to analyze the effects of surface elevation variation and near-surface velocity distribution on the subsurface wavefield. The findings are expected to provide a theoretical basis for optimizing seismic acquisition system parameters and improving seismic imaging quality in the study area.

Key words: 3D geological modeling, rolling surface, numerical simulation, numerical dispersion, visco-acoustic wave modeling