低频阴影与储层特征关系的数值模拟
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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8~12 Hz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16~60 Hz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 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".
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".
引文
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[13]GOLOSHUBIN G M,BAKULIN A V.Seismic re-flectivity of a thin porous fluid saturated layer versusfrequency[C]//SEG Technical Program ExpandedAbstracts.New Orleans:Society of ExplorationGeophysicists,1998:976-979.
[14]GOLOSHUBIN G M,KORNEEV V A.Seismiclow-frequency effects from fluid saturated reservoir[C]//SEG Technical Program Expanded Ab-stracts.Calgary:Society of Exploration Geophysi-cists,2000:1671-1674.
[15]LIU Y.Seismic“low frequency shadows”for gassand reflection[C]//SEG Technical Program Ex-panded Abstracts.Denver:Society of ExplorationGeophysicists,2004:1563-1566.
[16]陈颙,黄庭芳.岩石物理学[M].北京:北京大学出版社,2001:55-62.
[17]CHAPMAN M,LIU E,LI X.The influence of ab-normally high reservoir attenuation on the AVO sig-nature[J].The Leading Edge,2005,24(11):1120-1125.
[18]REN H,GOLOSHUBIN G,HILTERMAN F J.Poroelastic analysis of amplitude-versus-frequencyvariations[J].Geophysics,2009,74(6):41-48.
[19]FUTTERMAN W I.Dispersive body waves[J].Geophysics Research,1962,67:5729-5291.
[20]陈学华,贺振华,黄德济.广义S变换及其时频滤波[J].信号处理,2008,24(1):28-31.CHEN Xue-hua,HE Zhen-hua,HUANG De-ji.Generalized S transform and its time-frequency filte-ring[J].Signal Processing,2008,24(1):28-31.
[2]TANER M T,KOEHLER F,SHERIFF R E.Com-plex seismic trace analysis[J].Geophysics,1979,44(6):1041-1063.
[3]SUN S,CASTAGNA J P,SIEGFRIED R W.Ex-amples of enhanced spectral processing in direct hy-drocarbon detection[C]//SEG Technical ProgramExpanded Abstracts.Salt Lake City:Society of Ex-ploration Geophysicists,2002:457-460.
[4]CASTAGNA J P,SUN S,SIEGFRIED R W.In-stantaneous spectral analysis:Detection of low-fre-quency shadows associated with hydrocarbons[J].The Leading Edge,2003,22(2):120-127.
[5]KORNEEV V A,GOLOSHUBIN G M,DALEY TM,et al.Seismic low frequency effects in monitoringfluid-saturated reservoirs[J].Geophysics,2004,69(2):522-532.
[6]SINHA S,ROUTH P S,ANNO P D,CASTAGNAJ P.Spectral decomposition of seismic data with con-tinuous-wavelet transform[J].Geophysics,2005,70(6):P19-P25.
[7]GOLOSHUBIN G M,CONNIE V A,KORNEEV VA,et al.Reservoir imaging using low frequencies ofseismic reflections[J].The Leading Edge,2006,25(5):527-531.
[8]ODEBEATU E,ZHANG J,CHAPMAN M.Appli-cation of spectral decomposition to detection of dis-persion anomalies associated with gas saturation[J].The Leading Edge,2006,25(2):206-210.
[9]LIU J,MARFURT K J.Instantaneous spectral at-tributes to detect channel[J].Geophysics,2007,72(2):23-31.
[10]陈学华,贺振华,黄德济,等.时频域油气储层低频阴影检测[J].地球物理学报,2009,52(1):215-221.CHEN Xue-hua,HE Zhen-hua,HUANG De-ji,etal.Low frequency shadow detection of gas reser-voirs in time-frequency domain[J].Chinese Journalof Geophysics,2009,52(1):215-221.
[11]陈学华,贺振华,文晓涛,等.低频阴影的数值模拟与检测[J].石油地球物理勘探,2009,44(3):298-303.CHEN Xue-hua,HE Zhen-hua,WEN Xiao-tao,etal.Numeric simulation and detection of low fre-quency shadow[J].Oil Geophysical Prospecting,2009,44(3):298-303.
[12]EBROM D.The low-frequency gas shadow on seis-mic sections[J].The Leading Edge,2004,23(8):772.
[13]GOLOSHUBIN G M,BAKULIN A V.Seismic re-flectivity of a thin porous fluid saturated layer versusfrequency[C]//SEG Technical Program ExpandedAbstracts.New Orleans:Society of ExplorationGeophysicists,1998:976-979.
[14]GOLOSHUBIN G M,KORNEEV V A.Seismiclow-frequency effects from fluid saturated reservoir[C]//SEG Technical Program Expanded Ab-stracts.Calgary:Society of Exploration Geophysi-cists,2000:1671-1674.
[15]LIU Y.Seismic“low frequency shadows”for gassand reflection[C]//SEG Technical Program Ex-panded Abstracts.Denver:Society of ExplorationGeophysicists,2004:1563-1566.
[16]陈颙,黄庭芳.岩石物理学[M].北京:北京大学出版社,2001:55-62.
[17]CHAPMAN M,LIU E,LI X.The influence of ab-normally high reservoir attenuation on the AVO sig-nature[J].The Leading Edge,2005,24(11):1120-1125.
[18]REN H,GOLOSHUBIN G,HILTERMAN F J.Poroelastic analysis of amplitude-versus-frequencyvariations[J].Geophysics,2009,74(6):41-48.
[19]FUTTERMAN W I.Dispersive body waves[J].Geophysics Research,1962,67:5729-5291.
[20]陈学华,贺振华,黄德济.广义S变换及其时频滤波[J].信号处理,2008,24(1):28-31.CHEN Xue-hua,HE Zhen-hua,HUANG De-ji.Generalized S transform and its time-frequency filte-ring[J].Signal Processing,2008,24(1):28-31.
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