Wu Xiao, Liu Yang, Wang Yong, Xu Shi-Gang, and Jia Wan-Li
1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing 102249,China.
2. Faculty of Petroleum, Karamay Campus of China University of Petroleum (Beijing), Karamay, Xinjiang 834000, China.
3. CNPC Key Laboratory of Geophysical Prospecting, China University of Petroleum (Beijing), Beijing 102249, China.
4. Sinopec Geophysical Exploration Institute of Jiangsu Oilfield, Jiangsu, 210046, China.
Abstract The conventional fast converted-wave imaging method directly uses backward Pand converted S-wavefield to produce joint images. However, this image is accompanied by strong background noises, because the wavefields in all propagation directions contribute to it. Given this issue, we improve the conventional imaging method in the two aspects. First, the amplitude-preserved P- and S-wavefield are obtained by using an improved space-domain wavefield separation scheme to decouple the original elastic wavefield. Second, a convertedwave imaging condition is constructed based on the directional-wavefield separation and only the wavefields propagating in the same directions used for cross-correlation imaging, resulting in effectively eliminating the imaging artifacts of the wavefields with different directions; Complex-wavefield extrapolation is adopted to decompose the decoupled P- and S-wavefield into directional-wavefields during backward propagation, this improves the efficiency of the directional-wavefield separation. Experiments on synthetic data show that the improved method generates more accurate converted-wave images than the conventional one. Moreover, the improved method has application potential in micro-seismic and passive-source exploration due to its source-independent characteristic.
*This research is supported by the National Science and Technology Major Project of China (No.2017ZX05018-005) and National Natural Science Foundation of China (No. 41474110)
Corresponding Authors: Liu Yang (Email: wliuyang@vip.sina.com)
E-mail: Email: wliuyang@vip.sina.com
About author: Xiao Wu, graduated from the College of Geophysics and Information Engineering, China University of Petroleum (Beijing) in 2011 with a degree in exploration technology and engineer ing . In 2014, he obtained a master’s degree in geophysical prospecting and information technology from the College of Geophysics and Information Engineering, China University of Petroleum (Beijing). Now he is a Ph.D. student in China University of Petroleum (Beijing). His interests are forward modeling
Cite this article:
. An improved fast converted-wave imaging method[J]. APPLIED GEOPHYSICS, 2019, 16(2): 173-194.
2019, Vol. 16 
