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逆时偏移对速度模型有较强的依赖性,速度模型精度高低决定着偏移效果的好坏,速度模型越准确,偏移效果越好.因此,如何获取高精度的速度模型是实现有效逆时偏移的关键步骤.全波形反演方法利用叠前地震波场的运动学和动力学信息重建地下速度结构能够得到高精度的速度模型.为了验证全波形反演能否提高逆时偏移效果,本论文以OVERTHRUST速度模型为例,在频率域进行全波形反演,并实现了速度模型的更新.逐步缩小了初始速度模型与真实速度模型的残差,提高了速度模型的准确度.然后使用初始OVERTHRUST速度模型以及经过反演的速度模型分别进行逆时偏移,应用结果表明,使用经过全波形反演后的速度模型进行逆时偏移,其成像效果较好.因此,逆时偏移结合全波形反演可以有效的提高成像精度.
The inverse time migration has a strong dependence on the speed model, the accuracy of the speed model determines the offset effect, the more accurate the speed model, the better the offset effect. Therefore, how to obtain high-speed speed model is effective Inverse time migration.The full waveform inversion method can reconstruct the subsurface velocity structure using the kinematics and dynamics information of the prestack seismic wave field to get the high velocity model.To verify whether the full waveform inversion can improve the inverse time migration In this paper, the OVERTHRUST velocity model is taken as an example, the full waveform inversion is carried out in the frequency domain, and the velocity model is updated, the residuals of the initial velocity model and the true velocity model are gradually reduced, and the accuracy of the velocity model is improved. Then the inverse velocity migration is carried out using the initial velocity model and the inverted velocity model, respectively. The application results show that the inverse time migration using the velocity model after the full waveform inversion has good imaging effect. Therefore, Offset combined with full waveform inversion can effectively improve the imaging accuracy.