Designing nonlinear sweep signal to improve the resolution of vibroseis acquisition

ABSTRACT The widespread usage of vibroseis in seismic acquisition offers several advantages, including environmental sustainability and precisely controllable excitation. However, challenges persist, such as low acquisition efficiency and suboptimal data quality. Expanding the frequency bandwidth of linear sweep signals can potentially enhance the resolution of seismic exploration. However, its effectiveness is limited by subsurface absorption and attenuation effects. Recent advancements have introduced nonlinear sweep signals, providing broader frequency bandwidth and improved resolution. Nevertheless, the combination of waveform and frequency range in these methods remains suboptimal, which indicates that there is room for further improvement in data quality. To address these limitations, we develop a nonlinear sweep signal design method based on a derived equation. Unlike traditional approaches, this method eliminates the need for inverse transformation processes, reducing uncertainty in signal design. The nonlinear function is guided by reflection characteristics, enabling the creation of a tailored encoding window for each time sampling interval. This tailored design ensures a better match with seismic data, leading to improved resolution. In addition, time window segmentation yields more refined frequency domain information, enhancing the adaptability of the sweep signal to field conditions. Overall, this method broadens the frequency bandwidth of acquired seismic data, mitigates subsurface absorption and attenuation effects, and improves resolution, thereby providing a theoretical framework for designing nonlinear sweep signals.