Numeric simulation in the relationship between low frequency shadow and reservoir characteristic
Numeric simulation in the relationship between low frequency shadow and reservoir characteristic
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发表时间：
2011
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通讯作者：
Zhong Wen-li
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作者：
Zhong Wen-li
为了研究不同储层厚度和不同储层下反射界面深度处低频阴影的出现和特征，提出了频率-波数域三维扩散粘性波动方程（DVWE）波场延拓算法，设计了5种不同含油气层地质模型，利用DVWE对模型的地震响应进行了模拟，并与常规波场延拓算法进行了对比。结果表明，当储层Q值较低、多孔介质中流体的扩散性和粘性较大时，LFS现象更为明显，且LFS现象出现在储层下不同深度处，在8-12 Hz时，储层能量是一个亮点，在储层下方显示出强LFS，即，当频率为16-60 Hz时，LFS逐渐衰减，直至阴影消失，而储层的光谱能量仍相对较强，即：“强储弱影”。
In order to explore the appearance and characteristics of low-frequency shadow(LFS) at different thickness of reservoir and different depth of reflection interface beneath reservoir,a wave-field extrapolation algorithm of a 3D diffusive and viscous wave equation(DVWE) in frequency-wavenumber domain was proposed.Five different geological models with hydrocarbon-bearing bed were designed and the seismic response of the models was simulated using DVWE,and the instantaneous spectral decomposition was performed using the generalized S transform.The seismic response and its reflection energy variation with the frequency of each model were comparatively analyzed.The results reveal that LFS become more apparent when low Q in reservoir,greater diffusiveness and viscousness properties of fluid in porous media.LFS appeared at different depth under reservoir.At 8-12 Hz,the reservoir energy was a bright spot,and a strong LFS was shown beneath the reservoir,i.e."strong reservoir and bright shadow".As the frequency was 16-60 Hz,LFS was gradually attenuated until the shadow gone,while spectral energy of the reservoir wasstill relatively strong,i.e."strong reservoir and weak shadow".