建立速度模型的层析成像方法研究

Study of tomographic inversion in the construction of velocity model

针对目前叠前深度偏移速度模型建立中 ,全局反演的层析成像方法存在稳定性和走时拾取困难 ,以及局部反演的偏移速度分析大多存在假设条件过于苛刻等问题 ,通过分析 ,提出了利用地震同相轴的多种信息进行层析反演 ,并在反演中加入富有地质含义的倾角信息以增加反演过程的稳定性和收敛速度 ,利用类似于叠加速度谱的斜率速度谱来拾取地震同相轴的斜率 ,抛开了层位反演要求拾取同一同相轴这一实际应用难度很大的条件 ,使拾取方便 ,算法稳定。通过理论试算 。

The tomographic inversion currently used in the construction of prestack migration velocity model suffers from instability, difficulty in picking traveltime, and rigorous conditions in the analysis of local migration velocity. This paper proposes a new method of tomographic inversion that can use the information of seismic events. The stability and convergence rate of inversion is improved by introducing information of dips. The difficulty in picking up the same events with the ones used in inversion is overcome by picking up the slopes of seismic events with slope velocity spectra. Tests with synthetic data show the proposed method is effective.