染色算法在三维复杂介质微弱地震信号模拟和成像中的应用

发布时间：2018-01-19 13:28

本文关键词： 染色算法模拟成像信噪比内存高效微弱信号　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：在二维地震偏移成像中,染色算法被证实可以有效地提高弱照明区域的信噪比。染色算法应用于逆时偏移过程中,与目标成像区域相关的染色波场和常规的震源波场同步正向传播。分别将染色波场和震源波场与反向传播的检波点波场进行互相关运算,我们可以获得两个成像结果:仅包含目标结构的成像结果,以及传统的逆时偏移成像结果。该成像过程需要消耗巨大的计算机内存用以存储波场,尤其是在大尺度三维地质模型中。为了使染色算法适用于三维逆时偏移,在交错网格有限差分机制下,我们提出一种将染色算法应用于三维声波模拟的方法,该方法适应于有限差分算子的空间精度。同时在染色算法应用于弹性波,电磁波等波动方程有限差分模拟问题中,该方法同样适用。考虑到内存消耗问题,在检波点波场反向传播的过程,我们采取随机边界条件(RBC)。利用保存的最后一步的检波点波场,我们可以重建所有时刻的检波点波场。同时,在染色波场和震源波场正向同步传播的过程中,我们采取拟最佳匹配层(NPML)边界条件。复杂地质模型上的数值实验表明RBC-NPML联合策略不仅可以最大程度地减少内存消耗,同时可以保证高质量的成像结果。通过该策略,我们将染色算法应用于三维逆时偏移成像。数值实验表明染色算法可以给出目标结构高信噪比的成像结果。
[Abstract]:In two-dimensional seismic migration imaging, dyeing algorithm has been proved to be effective in improving signal-to-noise ratio of weak illumination region, and it is applied to inverse time migration process. The dyed wave field related to the target imaging region and the conventional source wave field are propagated synchronously in the forward direction. The coloring wave field and the source wave field and the detection point wave field propagating in the reverse direction are respectively correlated with each other. We can obtain two imaging results: only the imaging results of the target structure and the traditional inverse time migration imaging results, which require huge computer memory to store the wave field. Especially in the large-scale 3D geological model, in order to make the coloring algorithm suitable for 3D inverse time migration, under the staggered grid finite difference mechanism, we propose a method to apply the coloring algorithm to 3D acoustic wave simulation. This method is suitable for the spatial accuracy of finite difference operator, and it is also applicable to the finite difference simulation of wave equations such as elastic wave and electromagnetic wave using coloring algorithm, taking into account the problem of memory consumption. In the process of backward propagation of the detection point field, we adopt random boundary conditions. Using the last step of the preserved detection point field, we can reconstruct the detection point field at all times. At the same time. In the process of positive synchronous propagation of dyed wave field and source wave field. The numerical experiments on complex geological models show that the combined RBC-NPML strategy can not only reduce the memory consumption to the maximum extent. At the same time, the high quality imaging results can be guaranteed. Through this strategy, we apply the coloring algorithm to 3D inverse time migration imaging. Numerical experiments show that the algorithm can give the imaging results with high signal-to-noise ratio of the target structure.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.4

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