三维超广角单程波传播算子及其在地震波模拟和成像中的应用

发布时间：2018-05-28 18:20

本文选题：超广角 + 单程波算子　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：在过去的几十年里,基于单程波波动方程的传统单程波算子广泛应用在理论研究和实际生产中。与双程波算子相比,单程波算子效率更高,需要的计算资源更少。在解决大型三维问题时,单程波算子的这两个优势显得尤其重要。然而由于与生俱来的广角限制,传统单程波算子不能模拟传播角度接近或超过90°的地震波。由于单程波算子只能沿着特定的方向传播(一般是深度方向),所以模拟回转波和反射波的问题超出了单程波算子的能力范围。我们发展了三维超广角单程波传播算子来克服传统单程波算子的这种广角限制,并且在带有大角度结构的复杂模型中使用超广角算子来模拟传播角度为超广角(即大于90°)的回转波,以此解决模拟和成像问题。具体实现中,通过特定的叠加格式,将下行波场和水平传播的波场叠加起来,保留优势方向上的正确波场,使得波场计算更加准确。为了将不同方向的波场进行叠加,设计了依赖于传播角度的权函数,并讨论了权函数的性质。由于三维问题计算的复杂性,在GPU上进行并行计算,以提高效率。为此,设计了一套适用于GPU架构的工作流程。数值算例表明,超广角单程波算子比传统单程波算子具有更高的计算精度,在含有竖直结构的成像中有更好的表现。事实上,超广角单程波传播算子可以基于任何单程波方法,提高地震波模拟和成像的效果。虽然超广角算子的计算效率和内存消耗比单程波算子差,但是优于双程波方法,实际中也是可以接受的。
[Abstract]:In the past few decades, the traditional one-way wave operators based on the one-pass wave equation have been widely used in theoretical research and practical production. Compared with two-pass wave operator, one-way wave operator is more efficient and requires less computing resources. In solving large-scale three-dimensional problems, these two advantages of one-way wave operator are particularly important. However, due to the inherent wide angle limitation, the traditional one-way wave operator can not simulate the seismic waves with propagation angles close to or greater than 90 掳. Because the one-way wave operator can only propagate along a specific direction (usually the depth direction), the problem of simulating the rotational wave and the reflected wave is beyond the capability of the one-way wave operator. In order to overcome the limitation of traditional one-pass wave operator, we developed a three-dimensional ultra-wide-angle one-way wave propagator. In order to solve the problem of simulation and imaging, a complex model with large angle structure is used to simulate the wave propagation with an ultra-wide angle (that is, more than 90 掳) by using the extended angle operator. In the concrete realization, the downlink wave field and the horizontal propagation wave field are superimposed by a specific superposition format, and the correct wave field in the dominant direction is retained, which makes the wave field calculation more accurate. In order to superposition the wave fields in different directions, the weight function which depends on the propagation angle is designed, and the properties of the weight function are discussed. Due to the complexity of 3D problem computation, parallel computation is carried out on GPU to improve the efficiency. Therefore, a set of workflow suitable for GPU architecture is designed. Numerical examples show that the ultra-wide-angle one-way wave operator has higher computational accuracy than the traditional single-pass wave operator and has better performance in imaging with vertical structure. In fact, the ultra-wide-angle one-way wave propagator can improve the effect of seismic wave simulation and imaging based on any one-way wave method. Although the computational efficiency and memory consumption of the ultra-wide-angle operator are worse than that of the single-pass wave operator, they are superior to the two-pass wave method and are acceptable in practice.
【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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