Abstract: The W Sag in the western South China Sea has been extensively explored. Consequently, most oilfields in the sag have transitioned into the medium to high water cut stage, facing challenges in tapping potential reserves and maintaining stable production. In this context, both hydrocarbon exploration in complex concealed reservoirs in the Paleogene strata and paleo-buried hills and fine-scale potential tapping in mature oilfields have become primary targets for reserve growth and production addition. However, under complex geological conditions, seismic exploration faces multiple issues, including complex seismic wavefields, weak seismic signals, low resolution, and strong anisotropy. To address the challenges encountered in the exploration and exploitation of complex reservoirs in the western South China Sea, this study investigated key technologies in terms of ghost wave suppression, multiple suppression, and high-precision velocity modeling. To this end, the characteristics of the acquired wide-azimuth ocean bottom cable (OBC) seismic data were considered, and the approach to broadening frequencies and preserving amplitude was followed. Consequently, a set of key technologies for processing the OBC seismic data of structurally complex areas was established, effectively improving the signal-to-noise ratio and imaging quality of seismic data. Application to actual data demonstrates that the technologies established in this study substantially enhanced seismic data quality, laying a solid foundation for the fine-scale geophysical characterization of complex reservoirs.