Time Domain Full Waveform Inversion Method Using Grid Acoustic Wavefield Simulation with Variable Step Size

Abstract

The invention relates to a time-domain seismic waveform inversion method by utilizing variable-step-length grid acoustic wave field simulation in the field of seismic data depth modeling. The method is characterized by carrying out subdivision by utilizing a variable-step-length grid in continuation depth direction; increasing calculating grid points on grid diagonals of a star convolution operator; obtaining an accurate relational expression of a wave field evolved with the time in a time-wave number domain; calculating convolution coefficients of the grid points according to wave field propagation speed of spatial points and time continuation step length to enable the error of wave number domain time evolution relationship corresponding to each point to be minimum; in the simulation space range, establishing speed indexes and calculating convolution operators corresponding to the speeds; and carrying out wave field forward simulation by utilizing the convolution operators and the speed indexes to enable error of a seismic wave field recorded in the field and a seismic wave field obtained through forward simulation to be reduced, and iteratively updating a speed model and finishing inversion. The method solves the problem of poor precision of time derivative approximate calculation caused by an existing algorithm and solves the problem of heavy wave field simulation calculation burden and low calculating efficiency.

Description

technical field [0001] The invention relates to oil exploration technology, and is a time-domain seismic waveform inversion method applied to seismic data depth modeling by using variable step size grid acoustic wave field simulation. Background technique [0002] One of the important purposes of seismic data processing is to obtain high-quality depth-domain images through depth migration. The quality of depth domain image depends on the quality of seismic velocity model, so modeling technology plays a pivotal role in the whole seismic data processing. Full Waveform Inversion (Full Waveform Inversion) is a data domain (DataDomain) seismic modeling technology. process until the difference between simulated and observed data is minimized. Compared with the traditional image domain (Image Domain)-based modeling methods (such as tomographic inversion), the advantages of the full waveform inversion method are (1) high resolution; (2) less manual intervention is required. [00...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a solution to the numerical dispersion phenomenon caused by insufficient simulation accuracy in the time direction in the realization of the full waveform inversion in the time domain, and greatly reduce the amount of calculation and improve the efficiency of the acoustic wave field simulation using the variable step size grid Time Domain Full Waveform Inversion Method

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