Parameter optimization of the observation system for the South Yellow Sea strong shielding layer based on seismic illumination analysis

The seismic data of the Laoshan Uplift in the South Yellow Sea Basin reveal a low signal-to-noise ratio and low reflection signal energy in the deep Mesozoic–Paleozoic strata. The main reason is that the Mesozoic-Paleozoic marine carbonate rock strata are directly covered by the Cenozoic terrestrial clastic rock strata, which form a strong shielding layer. To obtain the reflection signals of the strata below the strong shielding layer, a one-way wave equation bidirectional illumination analysis of the main observation system parameters was conducted by analyzing the mechanism of the strong shielding layer. Low-frequency seismic sources are assumed to have a high illumination intensity on the reflection layer below the strong shielding layer. Accordingly, optimized acquisition parameter suggestions were proposed, and reacquisition was performed at the existing survey line locations in the Laoshan Uplift area. The imaging of the newly acquired data in the middle and deep layers was drastically improved. It revealed the unconformity between the Sinian and Cambrian under the strong shielding layer. The study yielded new insights into the tectonic and sedimentary evolution of the Lower Paleozoic in the South Yellow Sea.