低频阴影与储层特征关系的数值模拟  

Numeric simulation in the relationship between low frequency shadow and reservoir characteristic

作　　者：陈学华[1,2] 贺振华[1,2] 钟文丽[3] 

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059 [2]成都理工大学地球物理学院,四川成都610059 [3]成都理工大学地球科学学院,四川成都610059

出　　处：《中国矿业大学学报》2011年第4期584-591,共8页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(41004054);高等学校博士学科点专项科研基金项目(20105122120002);四川省教育厅自然科学重点项目(092A011)

摘　　要：为了研究在不同储层厚度、储层下部地层反射界面不同深度情况下低频阴影的出现规律及特征，推导了一种三维弥散黏滞型波动方程的频率波数域波场延拓算法，设计了5个不同的含油气地质模型，对各个模型的地震响应进行了数值模拟，再利用广义S变换对模拟的剖面进行瞬时谱分解，分析了各模型的地震响应以及反射能量随频率的变化等．结果表明：储层低Q时、孔隙介质中流体的黏滞性和弥散性等物理性质明显，且油气层达到一定厚度时低频阴影更明显，它可出现在油气层下部的不同深度位置．在8～12Hz时，油气层为强能量亮点，其下部显示有强能量的低频阴影，即“上强下强”特征，随着频率增高至16～60Hz时，低频阴影逐渐减弱直至消失，而油气层的谱能量仍相对较强，即表现为“上强下弱”特征．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 hydrocarbonbearing bed were designed and the seismic response of the models was simulated using DVWE, and the instantaneous spectral cecomposition 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 res- ervoir, 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 weakshadow＂.

关 键 词：低频阴影 数值模拟 储层特征 油气识别 瞬时谱分解 

分 类 号：P631[天文地球—地质矿产勘探]