Efficient Wavefield Reconstruction Inversion using Plane-wave in Frequency Domain

Abstract:

Wavefield reconstruction inversion (WRI) can alleviate cycle-skipping by matching wavefields to both observed data and the solution of the Helmholtz equation. Usually, WRI has been implemented with common shot gathers. However, if immense numbers of common shot gathers are used, WRI can encounter huge computational burden from the many over-determined linear systems that require to be solved. For mitigating this computational problem, we propose an efficient WRI strategy with plane-wave transformation (WRI-PW) in frequency domain. Generally, plane-wave transformation can significantly reduce the number of datasets. For this reason, this transformation is widely applied in many seismic data processing (e.g. reverse time migration, least-squares reverse time migration, waveform inversion, etc). Firstly, we implemented a simple numerical experiment, and confirmed that WRI-PW also could generate the scattering wavefield in a constant velocity model. After that, we checked the computational efficiency with modified Marmousi-2 velocity model. Computational efficiency and the accuracy of inversion results are depending on the plane-wave angle. Accordingly, the sufficient plane-wave angle is used for WRI-PW, satisfactory inversion result can be obtained with reduced computational costs. Furthermore, we verified the robustness on random noise of WRI-PW through the numerical experiment by using dataset contaminated with random noise. Lastly, we compare WRI-PW and conventional full waveform inversion (FWI) with modified SEG/EAGE salt velocity model. This example indicates that WRI-PW has less dependency on accuracy on starting velocity model on waveform inversion than conventional FWI.

ACKNOWLEDGMENTS

This research was supported by the Basic Research Project (20-3313) of the Korea Institute of Geoscience and Mineral Resources(KIGAM) funded by the Ministry of Science, ICT and Future Planning of Korea, and the Korea Institute of Energy Technology Evaluation and Planning (KETEP) with a grant funded by the Ministry of Trade, Industry and Energy, Republic of Korea (No. 20182510102470).