Frequency extension and robust full-waveform inversion based on n th power operation

Acta Geophysica

article

Zhang, Pan¹  Han, Liguo¹  Gao, Rui³  Zhang, Fengjiao¹  Xing, Zhenzhen¹ 

[1] College of Geo-exploration Science and Technology, Jilin University;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources, Institute of Geology, Chinese Academy of Geological Sciences;School of Earth Science and Geological Engineering, Sun Yat-sen University

关键词: Full-waveform inversion;    Low frequency;    Frequency extension;    Source independent;   

DOI  :  10.1007/s11600-020-00465-6

学科分类：地球科学(综合)

来源: Polska Akademia Nauk * Instytut Geofizyki

【 摘 要 】

The conventional full-waveform inversion (FWI) often minimizes the objective function using some local optimization algorithms. As a result, when the initial model is not good enough, the inversion process will drop into a local minimum. The low-frequency components contained in seismic data are of vital importance for reducing the initial model dependence and mitigating the cycle-skipping phenomenon of FWI. In this research, a frequency extension method using the nth power operation is proposed, which compresses the seismic data in time domain and extends their frequency band. Based on this, we construct a new objective function using the nth power wavefield and derive the corresponding gradient formula. The new objective function shows better property to overcome local minimum than the conventional one. When conduct inversion, we can invert from high-order to low-order successively, which is a new multiscale strategy. Since seismic data is more sensitive to source wavelet errors after high-order operation, we make the method more robust by proposing a source-independent method to mitigate the effects of source wavelet inaccuracy. After that, we extend the proposed method to encoded multisource waveform inversion. The numerical examples on the Marmousi model demonstrate that the proposed method can effectively mitigate the cycle-skipping of FWI, and it also has good anti-noise property.

【 授权许可】

Unknown