复杂介质的层析建模及模型反演

Tomography modeling for complex media and tests on models

针对地震反射走时层析成像方法在复杂介质速度建模时面临数据拾取困难的问题,本文从理论上对其形成的原因进行了分析,认为是模型描述中反射层的引入导致了数据拾取的困难。本文采用了新的模型描述方法和反演目标函数,利用地震波的传播方向和传播时间作为反演的数据,并利用拾取的地震波传播方向约束射线路径,保证射线路径的惟一性,从而在模型上无需定义地震反射层位。为检验该方法的有效性,利用Mar-mousi模型进行了试验计算,计算结果表明该方法在一定程度上可有效解决复杂介质的速度建模问题。

Regarding the data picking-up difficulty when using seismic reflection travel-time tomography in velocity modeling for complex media,the theoretical analysis of the cause for the difficulty is conducted in this paper.The author believes that the introduction of the reflection horizon in modeling description caused the difficulty.In order to overcome the difficulty the new modeling description method and inversion object function were applied in this paper,seismic wave propagation direction and travel time were taken as the input for the inversion,the picked-up seismic wave propagation direction was used to constrain the ray path,so the uniqueness of the ray path was assured,at last it was not needed to define the seismic reflection horizon for the model.In order to validate the effectiveness of the new method,test calculation was carried out with Marmousi model,the test results show that the new method can in a certain extent overcome the difficulty which is often encountered in velocity modeling in complex media.