Optimization of data acquisition parameters for deep seismic reflection surveys in complex terrain

Fujian, located in the orogen region of the coastal areas of southeast China, exhibits well-developed structures and complex surface conditions, which make deep seismic reflection surveys challenging. In response to the diversity and complexity of seismogeological conditions in Fujian, this study optimized the seismic excitation means based on previous deep seismic surveys. Specifically, the combination of large, medium, and small guns was transitioned into the layout of normal guns (spacing of shot points:600 m) and large shots (spacing of shot points:15 km), leading to enhanced folds of large shots. Through simulation analysis, this study calculated the spacing of combined boreholes, aiming to concentrate the excitation energy and generate seismic elastic waves with the maximum efficiency. It optimized the dominant frequency of the nodal seismometers for data acquisition, reducing it from 10 Hz to 5 Hz to improve the resolution of data on the middle-deep crust in seismic records. Furthermore, this study increased the number of receiving channels from 1 200 to 2 400, achieving a maximum offset of 36 km. This value exceeds the depth of the Moho in Fujian, allowing for the acquisition of the reflection signals of deeper parts. After the optimization of the seismic acquisition parameters, the obtained original single-shot seismic records and initially stacked time sections featured high signalto-noise ratios. The optimization also contributed to clear reflected waves of the middle-deep crust and the Moho, as well as high imaging accuracy of the crustal structure. As a result, the expected geological survey effects were achieved. The newly obtained data parameters can provide a reference for deep seismic reflection surveys in similar areas.