| 摘要: |
| 地震波有限差分数值模拟中，使用优化的差分系数可以有效地减少数值频散（相速度误差）。为了同时压制空间频散与时间频散，提出种时空优化的等效交错网格有效差分正演模拟方法。采用以减少给定波数范围内所有传播方向的相对频散误差为目标函数，并借助牛顿法快速获取优化的差分系数。频散分析表明等效交错网格正演在低速介质中容易出现空间频散，在高速介质中高波数分量容易出现时间频散，数值模拟显示该方法既能有效地压制空间频散，也可以减少时间频散。Marmousi模型测试表明该方法适用于复杂地质模型的地震波场正演模拟。相比传统差分方法，该时空优化差分方法在不增加计算量的前提下，可以有效地提高数值模拟精度。 |
| 关键词: 数值频散 时空优化差分系数 等效交错网格 地震波 正演模拟 牛顿法 |
| DOI：10.3969/j.issn.1673-5005.2017.06.008 |
| 分类号: |
| 基金项目:山东省重大创新工程（2017CXGC1608，2017CXGC1602）；中国科学院战略性先导科技专项（XDA14010303）；国际合作重点项目（41720104006）；国家油气重大专项课题（2016ZX05006-004，2016ZX05014001，2016ZX05002）；中央高校基本科研业务费专项（R1701023A） |
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| Forward modeling by optimized equivalent staggered-grid finite-difference method for time-space domain |
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YONG Peng, HUANG Jianping, LI Zhenchun, LI Qingyang, LIU Peijun, YANG Mingwei, YUAN Shuangqi, REN Yingjun
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School of Geosciences in China University of Petroleum, Qingdao 266580, China
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| Abstract: |
| Optimized finite-difference (FD) coefficients can effectively suppress numerical dispersion errors (phase velocity errors) in seismic wave modeling. Most optimized FD schemes used to solve seismic wave equation suppress only spatial but not temporal dispersion errors. In this paper, we develop an optimized FD scheme with high spatial and temporal accuracy for numerical scalar-wave modeling based on equivalent staggered grids. The final aim of optimized FD coefficients is to reduce phase velocity errors. We design an objective function for minimizing relative temporal and spatial dispersion errors of waves propagating in all directions. In addition, Newton method is applied to quickly solve this nonlinear problem. Dispersion analysis has demonstrated that space dispersion easily appear in the low-velocity media, while time dispersion has more probability to occur in the high-velocity media. Modeling tests indicate that the proposed method ensures high accuracy not only in the time domain but also in the space domain. Compared with the traditional methods, the proposed method can improve numerical accuracy without sacrificing computation efficiency. |
| Key words: numerical dispersion time-space domain optimized finite-difference operators equivalent staggered grid finite-difference seismic wave forward modeling Newton method |
