The opening of the Qiongzhou Strait during the Holocene was a significant geological event in the Beibu Gulf, profoundly influencing sediment provenance and ocean circulation systems. Due to the scarcity of geological records documenting this event, the understanding of regional Holocene sedimentary evolution has been constrained. To investigate the impact of this event on sediment provenance and ocean currents in the Beibu Gulf, geochemical analyses were conducted on sediment core SO-31 retrieved from the South China Sea. The sediments in core SO-31 were stratigraphically divided into three units based on vertical geochemical profiles, reflecting changes in sea level and shifts in sediment provenance within the study area. The Th/Cr vs. Th/Sc scatter plot for core SO-31 indicate that sedimentary materials primarily originated from the Red River during 11,400–7700 a BP, and a significant change in provenance occurred in the study region around 7700 a BP, characterized by increased contributions from the Qiongzhou Strait and decreased contributions from the Red River. This suggests that the opening of the Qiongzhou Strait significantly influenced the sediment supply to the central Beibu Gulf around 7700 a BP. These findings provide critical geochemical evidence for studying the Qiongzhou Strait opening event and enhance our understanding of Holocene sedimentary evolution and “source–sink” transitions in the Beibu Gulf.

The presence of shallow gas or overlying gas reservoirs often degrades the imaging accuracy of underlying structural formations. To address the “pull-down” effect of deep structural reflectors caused by low-velocity shallow gas anomalies, this study takes the X Gas Field in the Pearl River Mouth Basin as an example. By using spectral attenuation attributes, we finely characterize the planar distribution and temporal thickness of the shallow gas. On this basis, a shallow gas anomaly thickness correction method is established. This approach integrates the temporal thickness of shallow gas (derived from spectral attenuation), characteristics of the seismic velocity field, and velocity differences calibrated by well logs to compute specific depth correction values. Application results, validated through blind well tests, show that the accuracy of the structural map can be improved to within 5 m. This multi-data integration strategy, which combines lateral velocity variation with vertical correction, offers a valuable reference for the detailed characterization of hydrocarbon reservoirs under similar geological conditions.

As the exploration and development of the basin continue to advance, the proportion of hydrocarbon reservoirs characterized by small scale, low structural relief, and complex faulting has been increasing year by year. Fine mapping of low-relief structures is a key technical challenge in the evaluation of such reservoirs, and its accuracy is primarily constrained by the precision of seismic data processing and velocity analysis. Taking X Oilfield in the Pearl River Mouth Basin as an example, this study proposes an integrated time–depth conversion method that combines seismic and well-log velocity data. Through steps such as horizon-guided velocity picking, average velocity field establishment, macroscopic trend correction, and spatial residual factor correction between wells and seismic data, a high-precision average velocity model is constructed. Practical applications demonstrate that this method can control the depth error of the target horizon structural map within 3 m, effectively supporting the fine characterization of low-relief structures and reservoir evaluation. The velocity analysis workflow established in this study can provide reliable technical reference for time–depth conversion of low-relief structures under similar geological conditions.