基于Wigne-Ville分布和短时傅立叶变换时频分布计算地震波衰减梯度
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摘要
地震波在储集层中传播时,伴有能量的剧烈衰减,且频率越高能量衰减越快,因此,通过地震波高频端能量衰减梯度能够灵敏地检测地层中是否有烃类流体存在。短时傅里叶变换的时频分辨率不及Wigne-Ville分布,而Wigne-Ville分布虽有高的时频分辨率但存在交叉项的干扰。应用Wigne-Ville分布和短时傅里叶变换相结合的方法来计算地震信号的时频分布,然后利用高频成分能量分布与对应频率的拟线性关系估算出地震波能量衰减梯度。实际资料表明,基于短时傅立叶变换联合Wigner-Ville分布的能量衰减梯度在储集层预测中有较高的应用价值。
Seismic wave propagation in oil-gas reservoirs accompanies intense energy attenuation,and the higher the frequency,the faster the energy attenuation.So the energy attenuation gradient can be applied to detecting if hydrocarbons exist in reservoirs.The time-frequency resolution of short-time Fourier transform(STFT) is affected by window size,while Wigner-Ville distribution(WVD) is affected by cross part.This paper computes the time-frequency distribution of seismic signals based on WVD and STFT,and then estimates the seismic wave energy attenuation gradient using the quasi-linear relationship between the high frequency component energy distribution and the corresponding frequency.The case study indicates that this method has a higher value of application in reservoir prediction.
Seismic wave propagation in oil-gas reservoirs accompanies intense energy attenuation,and the higher the frequency,the faster the energy attenuation.So the energy attenuation gradient can be applied to detecting if hydrocarbons exist in reservoirs.The time-frequency resolution of short-time Fourier transform(STFT) is affected by window size,while Wigner-Ville distribution(WVD) is affected by cross part.This paper computes the time-frequency distribution of seismic signals based on WVD and STFT,and then estimates the seismic wave energy attenuation gradient using the quasi-linear relationship between the high frequency component energy distribution and the corresponding frequency.The case study indicates that this method has a higher value of application in reservoir prediction.
引文
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[13]刘希强.高斯线调频连续小波变换的时频能量衰减因子方法及其应用[J].中国地震,2003,19(3):225-235.
[2]Toksoz M N,Johnston G H,Timur A.Attenuation of seismic waves in dry and saturated rocks,laboratory measurements[J].Geophysics,1979,44(4):681-690.
[3]Best A I,McCann C,Sothcott J.The relationships between the velocities,attentions and petrophysical properties of res ervoir sedimentary rocks[J].Geophysical Prospecting,1994,42(2):151-178.
[4]Li Yandong,Zheng Xiaodong.Wigner Ville distribution and its application in seismic attenuation estimation[J].Applied Geophysics,2007,4(4):245-254.
[5]张贤达.现代信号处理[M].北京:清华大学出版社,2007:467-472.
[6]李小平,石光明.二次时频表示中核函数的优化设计[J].电波科学学报,2003,18(2):208-211.
[7]Farook Sattar,Goran Salomonsson.The use of a Filter bank and the Wigner Ville distribution for time frequency repre sentation[J].IEEE Trans Signal Processing,1999,47(6):1776-1783.
[8]Auger F,Flandrin P.Improving the readability of time frequency and time scale representations by the reassign ment method[J].IEEE Trans Signal Processing,1995,43(5):1068-1089.
[9]Tian Guangming.Product of two time frequency representat ions[C].The Eighth International Conference on Electronic Measurement&Instruments,2007:566-570.
[10]刘立峰.地震波吸收衰减技术在缝洞型碳酸盐岩储层预测中的应用[J].石油地球物理勘探,2009,44(1):121-124.
[11]唐向宏.时频分析与小波变换[M].北京:科学出版社,2008:110-113.
[12]程发斌,汤宝平,钟佑明.利用ASTFT谱有效抑制WVD交叉项的方法[J].电子与信息学报,2008,30(10):2299-2302.
[13]刘希强.高斯线调频连续小波变换的时频能量衰减因子方法及其应用[J].中国地震,2003,19(3):225-235.
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