Seismic slope tomography method based on depth weighting

Abstract

The invention relates to a depth-weighted seismic slope tomographic imaging method, which belongs to the technical field of velocity modeling for seismic data processing. It solves the problem of poor deep velocity modeling effect due to weak deep reflection events and few effective signals in complex structural areas, and improves the inversion accuracy of deep formation velocity while ensuring the accuracy of shallow velocity. The invention includes the following steps: preprocessing the seismic data; picking up the travel time and slope of the reflected wave to form observation data; establishing an initial velocity model and initial ray segment parameters to form a model space; joint inversion of ray segment parameters and velocity models; Quality control is performed on the inversion results. If the inversion results do not converge, the inversion iterations are continued. If the inversion results are converged, the velocity model and ray segment parameters are output.

Description

technical field [0001] The invention relates to a depth-weighted seismic slope tomographic imaging method, which belongs to the technical field of velocity modeling for seismic data processing. Background technique [0002] Seismic slope tomography was proposed by Frédéric Billette in 1998. This method combines the travel time of reflected waves and the slope information of local coherent events to establish a subsurface velocity model and estimate the position of reflection points. Compared with reflection wave traveltime tomography, slope tomography introduces slope information to constrain the ray propagation path, which helps to reduce inversion ambiguity; at the same time, this method does not need to establish a one-to-one correspondence between continuous reflection events and subsurface interfaces relationship, only the traveltime and slope of the local coherent event need to be picked up, which is more suitable for low signal-to-noise ratio data processing in comple...

AI Technical Summary

Problems solved by technology

[0003] For the actual seismic data, on the one hand, due to the spherical diffusion of seismic waves and the absorption and attenuation of the medium, the energy of seismic waves from deep formations is weak; on the other hand, the information of deep seismic data from areas with complex and diverse geological structures and large velocity changes The noise ratio is often relatively low, such as the concealed buried hill under the control of multiple stages of Mesozoic-Paleozoic tectonic movements, and the event axis inside the buried hill is not clear and very messy

Therefore, the travel time and slope data of deep effective reflected waves that can be picked up are often less, resulting in insufficient ray coverage in deep formations and poor inversion speed effect

For seismic data with less effective deep reflection data, the current slope tomography method cannot establish an accurate deep velocity field, especially when the difference between the initial velocity and the real velocity is large, the accuracy of the established depth velocity field is very low, and cannot meet the velocity requirements. mold requirements

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