【摘要】 高阶有限差分正演模拟将时间和空间离散,以差分代替微分,其求解精度受子波主频、网格大小以及有限差分精度的影响,不当的话会引起数值频散。海上勘探采用的气枪震源子波频带较宽,主频高,波长短,数值频散现象严重,而减小空间网格大小和提高有限差分精度需要较大的计算量和较长的计算时间。针对这一特点,采用通量校正传输(FCT)技术与有限差分相结合的方法来减少数值频散。在分析气枪震源子波的特征及该子波在粘弹介质中传播频谱特征的基础上,采用FCT有限差分模拟对粘弹介质盐丘模型进行了正演模拟。结果表明,FCT有限差分能够有效地压制数值频散,可以提高模拟的精度和运算效率。更多还原

【Abstract】 High-order finite difference forward modeling method dispersed time and space through difference instead of differential.Its accuracy was influenced by dominant frequency,grid size and the accuracy of finite difference,which would cause numerical dispersion if they were improperly processed.The air gun wavelet with large frequency bandwidth,high key frequency and short wavelet length used in exploration in offshore oilfield would cause serious numerical dispersion.However,reducing the space grid size and improving the accuracy of the finite difference needed longer computing time.In consideration of the above situation,finite difference method with the FCT(flux correction transport) was used to reduce numerical dispersion.On the basis of analyzing the characteristics of the air gun wavelet and the frequency characteristics that propagated in the visco-elastic media,the method was used for the forward modeling in the salt dome model.The result shows that FCT can effectively suppress numerical dispersion,improve the precision of simulation and operation efficiency.更多还原