The Study On 3D Scalar Wave Full Waveform Inversion Algorithm

Full waveform inversion based on the full wave field numerical simulation of wave equation is a typical local optimization problem of nonlinear iterative inversion.Full waveform inversion attempted to find an earth model that minimized the difference between the synthetic data computed by performing modeling using this earth model and the observed wave field,including the seismic traveltime information,amplitude and phase information,with the highest resolution features.This paper carried out the study on 3D scalar wave full waveform inversion algorithm.The main view of the article is the efficiency,accuracy of 3D full waveform inversion.We summarized the advantage of the full waveform inversion,and pointed out the difficulties of 3D full waveform inversion and where is the solution.The application of 3D land actual data was carried on the preliminary exploration.The first part is the basic theory.Based on the forward modeling of the 3D scalar wave equation,we deduced the 3D wave equation in time domain and used the high order finite difference method for numerical simulation with analyzing the influence of numerical finite difference problem such as stability,numerical dispersion and boundary conditions.In view of the nonlinear problem of the full waveform inversion,we analyzed the advantages and disadvantages of different local optimization algorithm and selected the improved L-BFGS quasi-newton algorithm for iterative inversion.The second part is the algorithm and strategy section.Computationally intensive problems for three-dimensional scalar wave time domain full waveform inversion,we designed CPU+GPU three heterogeneous parallel computing strategies to improve efficiency and improved the source wave field reconstruction algorithm to reduce the tremendous I/O consumption significantly.In terms of precision,we proposed different gradient pretreatment methods to improve the accuracy of the gradient operator and gave some idea of the wavelet extraction.Finally,we applied the scalar wave full waveform inversion algorithm to some model testing and used it in practical applications of onshore data preliminaries.We tested the effect of full waveform inversion with block complex model,classic Marmousi model and three-dimensional SEG/EAGE overthrust model,highlighting the abilities of the full waveform inversion to describe configuration details.And we tested the efficiency of the three-dimensional full wave form inversion to indicate the feasibility.Furthermore,we applied the three-dimensional scalar wave full waveform inversion to actual data for the land preliminarily.We analyzed the main problems that exist in real data applications,and demonstrated the practical application of three-dimensional full waveform inversion effect.