Angle-Weighted Reverse Time Migration With Wavefield Decomposition Based on the Optical Flow Vector

Frontiers in Earth Science

卷:9

Chuang Xie¹  Shaowen Wang¹  Jun Tan²  Peng Song²  Bo Zhao²  Xishuang Li⁴ 

[1] College of Marine Geo-Sciences, Ocean University of China, Qingdao, China;

[2] Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of Education, Qingdao, China;

[3] Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology, Qingdao, China;

[4] The First Institute of Oceanography, Ministry of National Resources, Qingdao, China;

关键词: reverse time migration;    low-wavenumber noise;    wavefield decomposition;    optical flow vector;    angle weighting;   

DOI  :  10.3389/feart.2021.732123

来源: DOAJ

【 摘 要 】

Reverse time migration (RTM) is based on the two-way wave equation, so its imaging results obtained by conventional zero-lag cross-correlation imaging conditions contain a lot of low-wavenumber noises. So far, the wavefield decomposition method based on the Poynting vector has been developed to suppress these noises; however, this method also has some problems, such as unstable calculation of the Poynting vector, low accuracy of wavefield decomposition, and poor effect of large-angle migration artifacts suppression. This article introduces the optical flow vector method to RTM to realize high-precision wavefield decomposition for both the source and receiver wavefields and obtains four directions of wavefields: up-, down-, left-, and right-going. Then, the cross-correlation imaging sections of one-way propagation components of forward- and back-propagated wavefields are optimized and stacked. On this basis, the reflection angle of each imaging point is calculated based on the optical flow vector, and an attenuation factor related to the reflection angle is introduced as the weight to generate the optimal stack images. The tests of theoretical model and field marine seismic data illustrate that compared with the conventional RTM with wavefield decomposition based on the Poynting vector, the angle-weighted RTM with wavefield decomposition based on the optical flow vector proposed in this article can achieve wavefield decomposition for both the source and receiver wavefields and calculate the reflection angle of each imaging point more accurately and stably. Moreover, the proposed method adopts angle weighting processing, which can further eliminate large-angle migration artifacts and effectively improve the imaging accuracy of RTM.

【 授权许可】

Unknown