Abstract: The Yantai Depression in the South Yellow Sea Basin is an important potential area for geological carbon dioxide sequestration in China’s offshore regions. Multiple sets of high-quality reservoir–seal assemblages have been developed in the Cenozoic strata. Due to the use of towed-streamer seismic acquisition, the raw data suffer from ghost reflections, narrowed wavelet frequency bands, and missing high- and low-frequency energy, making it difficult to meet the high-resolution requirements for thin interbed characterization, small-scale fault identification, and caprock integrity assessment in carbon sequestration site selection. In this study, a combination of a small-volume, shallow-submergence air gun and a shallow-towed streamer was used for acquisition. Spectrum analysis confirms that there is no ghost notching effect within the dominant frequency band, eliminating the need for ghost suppression. Accordingly, a high-resolution multi-channel seismic processing technical system is established, with two core techniques: HHT spectral-shaping regularized inverse Q filtering and broadband quasi-zero-phase deconvolution. This approach transforms the HHT (Hilbert–Huang transform) spectral whitening into a spectral-shaping regularization operator, which is embedded into the inverse Q filtering inversion workflow, achieving simultaneous formation attenuation compensation and time–frequency domain spectral equalization. Combined with broadband quasi-zero-phase deconvolution, it compresses the seismic wavelet, broadens the effective frequency band, and maintains phase stability, significantly improving both vertical and lateral resolution. Practical application shows that after processing, the high- and low-frequency components of the seismic data are effectively restored, vertical resolution is significantly enhanced, and deep reflection structures are clearly imaged. This allows accurate characterization of the reservoir body, faults, and their contact relationships with caprocks, providing reliable high-precision data support for carbon sequestration site selection evaluation in the Yantai Depression, and serving as a technical reference for broadband processing of shallow marine seismic data in similar offshore areas.