【摘要】 设计合适的空间离散网格是频率域地震波模拟和成像的关键步骤之一.以基于Padé近似的广义屏算子为例,根据照明分析、波场模拟和偏移结果考察了时间步长、道间距和空间网格间距之间的关系.数值试算表明,该频率域算子存在稳定性条件,计算网格须满足此条件,否则偏移结果会存在不可预知的噪音甚至假像.此外,当处理稀疏空间采样的地震数据时,常规的道间插值或使用较细的计算网格均不能明显改善偏移成像效果.因此,偏移时合理的做法是在检点之间的网格点上赋零值地震道.这为其他频率域算法的计算网格设计提供了重要参考.更多还原

【Abstract】 Defining an appropriate discrete grid is a crucial part of frequency-domain modelling and imaging.The results of the illumination analysis, modelling and migration were applied to investigate the relationship among time step,trace interval and spatial grid interval for the Padégeneralized screen propagator.Numerical tests indicate that the stability condition must be satisfied when defining grid discritization strategies,or the frequency-domain migration result could be mistakenly interpreted due to the existence of unexpected coherent noise.Besides,when migrating the insufficient spatial-sparsesampling data,the spatial grid doesn’t have to be too fine.And the regular interpolations among traces can hardly improve the migration result.Therefore it’s more reasonable to inject zero-value traces on grid points between adjacent receivers than using interpolation.This study provides an important reference for efficiently defining discrete grids for other frequency-domain methods.更多还原