Inversion of 3D velocity and anisotropy of near surfaces based on an azimuth-dependent dispersion curve inversion method
Jiang Ning-Bo 1, Liang Chun-Tao♦1,2, and Peng Wen 3
1. Key Laboratory of Earth Exploration and Information Technology of Ministry of Education, Chengdu University of Technology, Chengdu 610059, China.
2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China.
3. BGP, CNPC, Chengdu 610213, China.
Abstract In petroleum seismic exploration, dense seismic ray coverage is often guaranteed through dense seismic sources and geophones. Dense ray coverage facilitates the highresolution 3D velocity structure imaging of near surfaces using surface waves. In this study,the 3D velocity and anisotropy structure of a petroleum exploration area are obtained using the azimuth-dependent dispersion curve inversion (ADDCI) method. Imaging results show that low-velocity zones correspond to a river channel. The fast propagation direction (FPD) of S-waves along this channel is basically consistent with the direction of the channel. The eastern part of the study area has a surface sediment layer with a thickness of less than 20 m, which corresponds to the sand and gravel deposits formed by the river alluvial deposition near the surface. In addition, a relatively thick sedimentary layer is formed on the southern side of the study area. The anisotropy shows that the FPD is positively correlated with the direction of alluvial flow and that the magnitude of anisotropy in the deep part is greater than that in the shallow part. Inversion results are basically consistent with the geological data and suggest that the obtained model can truly reflect the 3D velocity structure and anisotropy of the nearsurface area. This study shows that the ADDCI method can maximize the high-energy surface waves in exploration data to obtain near-surface velocity structures, which provide a highly accurate model for near-surface static correction.
This work was supported by the National Key Research and Development Program of China (No. 2017YFC0601206), the Science and Technology Innovation (Seedling Project) Cultivation Program of Sichuan Province in 2020 (No. 2020127), and the National Natural Science Foundation of China (Nos. 41674059, 41340009).
. Inversion of 3D velocity and anisotropy of near surfaces based on an azimuth-dependent dispersion curve inversion method[J]. APPLIED GEOPHYSICS, 2021, 18(2): 213-225.
2021, Vol. 18 
