Optimization method for seismic data velocity spectrum based on empirical mode decomposition
LIU Yuping1,2, ZHANG Heng1,2, ZHANG Baojin1,2, GU Yuan1,2
1. Key Laboratory of Marine Mineral Resoures, Ministry of Natural Resources, Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou, Guangdong 511458, China; 2. National Engineering Research Center for Gas Hydrate Exploration and Development, Guangzhou, Guangdong 511458, China
Abstract：The propagation velocity of seismic waves in geological formations can indirectly reflect the subsurface lithology and geological structural features. The extraction and analysis of velocity greatly influence the entire process of seismic data processing and interpretation. Currently, the low resolution of velocity spectra leads to inaccurate velocity picking, and the accuracy of constructed velocity models often fails to meet the requirements for imaging complex geological structures. To address this issue, an optimization method for seismic data velocity spectrum based on Empirical Mode Decomposition （EMD） is proposed. This method is a frequency shift processing technique that effectively improves the signal-to-noise ratio of low-frequency energy in seismic data. Firstly, the instantaneous amplitude of seismic data is obtained based on Hilbert transform. Se-condly, the instantaneous amplitude is decomposed using EMD. Then, the intrinsic mode functions （IMFs） obtained from the decomposition are screened, and the ones containing useful information of velocity spectrum are selected. Finally, a new velocity spectrum is constructed. The optimized seismic data spectrum has a higher resolution and the effective frequency band is shifted towards the low-frequency end. Experimental tests and practical data processing results show that the proposed method effectively expands the optimized interval for velocity spectrum picking, improves the accuracy of velocity analysis, and enhances the imaging quality of seismic data. This method has wide application value in seismic data processing and velocity spectrum optimization.
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