Tomographic inversion for 3-D complex near-surface model and static correction
Li luming
Key Laboratory of Gas Geology and De-velopment Engineering, Chengdu University of Science and Engineering, Chengdou City, Sichuan Province 610059, China
Abstract:In view of complex near-surface issue in 3-D seismic exploration,the paper presented a method for tomographic inversion by using 3-D first-break near-surface model and for static correction. Using 3-D seismic direct wave,bow tie,refracted wave and first break composed of above the three modes and 3-D tomographic inversion having advantage of 3-D spatially-varying velocity,the method can achieve tomographic inversion in 3-D complex near-surface model which the velocity can change arbitrarily;the.demand of the method on the first break is only detecting the break-time of first-arrived wave without interpretation of the wave mode;3-D network ray-tracing method based on Fermat's principle is adopted in the 3-D forward modeling;the damping least-square QR decomposition iterated algorithm is adopted in 3-D tomographic inversion. Adopted above-mentioned methods can both improve the reliability of tomographic inversion for near-surface velocity model,provide reasonable near-surface velocity model for tomographic static correction of 3-D seismic data and improve the computational efficiency,increasing the practicality of the method.