一维频率域中观尺度虚岩石物理方法

地震波在地下含流体孔隙介质中传播时，双相介质中观尺度非均质性产生的流体流动是引起地震波在地震频带内衰减和频散的主要因素。基于两种不同的含流体孔隙地震波传播方程，构建一维虚岩石物理模型，采用频率域有限差分方法模拟地震波衰减和频散，与周期性层状斑块饱和介质模型解析解对比验证了方法的有效性；通过数值计算不同数量特征单元模型叠置情况的地震波衰减和频散，进一步说明了特征单元表征模型衰减信息的唯一性；分析了在相同含气饱和度条件下不同非均匀尺度和结构的地震波衰减和频散；最后利用上述方法模拟了三相流体周期性层状介质的地震波衰减和频散结果及其模型的位移与应力在频率域的空间分布特征，结果表明不同流体之间的中观尺度相对流动是诱导地震波在地震频带衰减的主控因素。

A method of 1D mesoscopic digital rock physics in the frequency domain

The attenuation and dispersion of seismic wave in seismic frequency band are mostly induced by mesoscopic heterogeneity because of the fluid flow of different scales in the porous medium when the seismic wave propagates in saturated media.We build a 1D digital physical model with two kinds of the wave equations in porous medium,and calculate the attenuation and dispersion of the 1D physical model with the finite-difference method in the frequency domain.We test and verify the accuracy of the method presented in the context by the model of porous layers alternately saturated with water and gas.In this paper,the characteristic elements are shown to be effective by calculating models containing different amounts of characteristic elements.Then we analyze the results of different heterogeneous scales and combination cases of the layers saturated water and gas in the condition of the same gas saturation.Finally the results for the 1D porous media alternately saturating three kinds of fluid indicate that the wave-induced fluid flow in mesoscopic heterogeneities mostly causes the attenuation and dispersion in the seismic frequency band.