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从反射地震学的角度来看,可以将层析成像定义为用实测的旅行时资料来确定岩石的速度。作者提出一种层析反演法,它不仅使用在震源与检波点间实测的反射波的旅行时,而且也使用了射线参数。这种射线参数(其实质是波的传播角度)是在震源点和检波点上实测的。这种方法的重大意义在于,只需假定反射面(层位)是局部连续的,且在层速度反演过程中无需确定界面的位置。借助于迭代射线跟踪技术计算拾取到的资料,以求出使非线性最小平方目标函数减至最小的层速度模型。这种目标函数是基于地面上实测的射线路径(由拾取到的资料确定)与根据速度模型计算出的射线路径之间的不吻合程度而确定的。为了消除速度模型中明显的变化,在目标函数中包含了补偿项。该层析反演法应用于合成资料及海上反射地震勘探资料时,都得出了很好的结果。
From a reflection seismological point of view, tomography can be defined as using measured travel time data to determine rock velocity. The authors propose a tomographic inversion method that uses not only the travel of the actually measured reflected wave between the source and the detection point but also the ray parameters. This ray parameters (the essence of the wave propagation angle) is measured at the source point and the detection point. The significance of this method is that it is only necessary to assume that the reflecting surface (horizon) is locally continuous and there is no need to determine the position of the interface during the inversion of the layer velocity. The collected data are calculated by means of iterative ray tracing techniques to find a layer velocity model that minimizes the nonlinear least squares objective function. This objective function is determined based on the degree of mismatch between the measured ray path on the ground (determined from the picked-up data) and the ray path calculated from the velocity model. In order to eliminate the obvious changes in the velocity model, the compensation function is included in the objective function. The tomographic inversion method has been applied to synthetic data and seismic reflection seismic data at sea, have obtained very good results.