叠前地震衰减各向异性的裂缝预测方法及应用（英文）
|
摘要
储层的裂缝分析在油气勘探中已变得愈来愈重要。品质因子Q值是表征地下介质对地震波吸收衰减特性的一个重要参数,不仅能够反映介质内部的本质特征,同时也可用于裂缝识别。在储层地震属性和反演中,地震叠前资料比叠后资料包含更加丰富的储层信息,因此,利用叠前地震道集进行吸收衰减参数提取能够进一步提高衰减系数估算的准确性。本文提出了一种在改进S变换基础上利用叠前地震CMP道集资料提取品质因子Q的方法。改进的叠前Q提取方法,首先是利用时频分辨率可调的改进S变换对叠前CMP道集进行时频分析,推导了利用改进S变换的频谱比法计算公式,其次采用能谱密度比替代传统的振幅比来逐道求取估算Q值的频谱比的斜率;然后建立谱比斜率与炮检距之间的关系式,采用多道拟合的方法消除炮检距影响,从叠前地震道集资料中提取准确的品质因子Q。最后本文把该叠前Q值计算方法引入到前进潜山储层裂缝预测中,纵波吸收衰减的各向异性具有好的实际应用效果。
The analysis of fractured reservoirs is very important to hydrocarbon exploration.The quality factor Q is a parameter used to characterize the attenuation of seismic waves in subsurface media.Q not only reflects the inherent properties of the medium but also is used to make predictions regarding reservoir fractures.Compared with poststack seismic data,prestack seismic data contain detailed stratigraphic information of seismic attributes and data inversion in reservoirs.The extraction of absorption parameters from prestack data improves the accuracy of attenuation estimates.In this study,I present a new method for calculating Q based on the modified S transform(MST) using common midpoint(CMP)preprocessed gathers.First,I use the MST with adjustable time-frequency resolution to carry out a high-precision time-frequency analysis of prestack CMP gathers and derive the calculation formula for the improved S transform-based frequency spectrum ratio method.Then,I use the energy density ratio to calculate the slope of the frequency spectrum ratio instead of the conventional amplitude ratio.Thus,I establish the relation between the slope of the spectrum ratio and offset as well as eliminate the offset effect by multichannel linear fitting,obtaining accurate Q values from seismic prestack data.Finally,I use the proposed prestack Q extraction method to study the fractured reservoir in Qianjin burried hill and P-wave absorption and attenuation anisotropy with good results in the fracture characterization.
The analysis of fractured reservoirs is very important to hydrocarbon exploration.The quality factor Q is a parameter used to characterize the attenuation of seismic waves in subsurface media.Q not only reflects the inherent properties of the medium but also is used to make predictions regarding reservoir fractures.Compared with poststack seismic data,prestack seismic data contain detailed stratigraphic information of seismic attributes and data inversion in reservoirs.The extraction of absorption parameters from prestack data improves the accuracy of attenuation estimates.In this study,I present a new method for calculating Q based on the modified S transform(MST) using common midpoint(CMP)preprocessed gathers.First,I use the MST with adjustable time-frequency resolution to carry out a high-precision time-frequency analysis of prestack CMP gathers and derive the calculation formula for the improved S transform-based frequency spectrum ratio method.Then,I use the energy density ratio to calculate the slope of the frequency spectrum ratio instead of the conventional amplitude ratio.Thus,I establish the relation between the slope of the spectrum ratio and offset as well as eliminate the offset effect by multichannel linear fitting,obtaining accurate Q values from seismic prestack data.Finally,I use the proposed prestack Q extraction method to study the fractured reservoir in Qianjin burried hill and P-wave absorption and attenuation anisotropy with good results in the fracture characterization.
引文
Al-Marzoug,A.,Neves,F.A.,Kim,J.J.,and Nebrija,E.,2006,P-wave anisotropy from azimuthal AVO and velocity estimates using 3D seismic data from Saudi Arabia:Geophysics,71(2),E7-E11.
Askari,R.,and Hejazi,S.H.,2014,Estimation of surfacewave group velocity using slant stack in the generalized S-transform domain:Geophysics,80(4),EN83-EN92.
Bath,M.,1974,Spectral analysis in geophysics:Developments in solid Earth geophysics,vol.7:Elsevier.
Behura,J.,Tsvankin,I.,Jenner,E.,and Calvert,A.,2012,Estimation of interval velocity and attenuation anisotropy from reflection data at Coronation Field:The Leading Edge,31(5),580-587.
Clark,R.A.,Benson,R M.,Carter,A.J.,and Moreno,C.A.G.,2009,Anisotropic P-wave attenuation measured from a multi-azimuth surface seismic reflection survey:Geophysical Prospecting,57,835-845.
Dasgupta,R.,and Clark,R.A.,1998,Estimation of Q from surface seismic reflection data:Geophysics,63(6),2120-2128.
Ekanem,A.M.,Wei,J.,Wang,S.,Di,B.,Li,X.,and Chapman,M.,2009,Fracture detection using 2-D P-wave seismic data:A seismic physical modelling study:79th SEG Annual Meeting,Expanded Abstracts,2647-2651,Houston,USA.
Engelhard,L.,1996,Determination of the seismic wave attenuation by complex trace analysis:Geophysical Journal International,125(2),608-622.
Futterman,W.I.,1962,Dispersive body waves:Journal of Geophysical Research,67(13),5279-5291.
Li,D.,and Castagna,J.,2013,Modified S-transform in time-frequency analysis of seismic data:83rd Ann.Internat.Mtg.,Soc.Explor.Geophys.,Expanded Abstracts,4629-4634.
Liu,E.,Maultzsch,S.,Chapman,M.,Li,X.,Queen,J.,and Zhang,Z.,2003,Frequency-dependent seismic anisotropy and its implication for estimating fracture size in low porosity reservoirs,The Leading Edge,22(7),662-665.
Qu,S.L.,Ji,Y.X.,Wang,X.,Wang,X.L.,Chen,X.R.,and Shen,G.Q.,2007,Fracture detection by using full azimuth P wave attributes:Applied Geophysics,4(3),238-243.
Quan,Y.L.,and Harrisy,J.M.,1997,Seismic attenuation tomography using the frequency shift method:Geophysics,62(3),895-905.
Reine,C.M.,van der Baan,and Clark,R.,2009,The robustness of seismic attenuation measurements using fixed-and variable-window timefrequency transforms:Geophysics,74(2),WA123-WA135.
Ruger,A.,1998,Variation of P-wave reflectivity with offset and azimuth in anisotropic media:Geophysics,63(3),935-947.
Schoenberg,M.A.,Dean,S.,and Sayers,C.M.,1999,Azimuth dependent turning of seismic waves reflected from fractured reservoirs:Geophysics,64(4),1160-1171.
Shen,F.,Sierra,J.,Burns,D.R.,and Toksoz,M.N.,2002,Azimuthal offsetdependent attributes applied to fracture detection in a carbonate reservoir:Geophysics,67(2),355-364.
Shekar,B.,and Tsvankin,I.,2012,Anisotropic attenuation analysis of crosshole data generated during hydraulic fracturing:The Leading Edge,31(5),588-593.
Stockwell,R.G.,Mansinha,L.,and Lowe,R.P.,1996,Localization of the complex spectrum:The Stransform:IEEE Transactions on Signal Processing,44(4),998-1001
Wang,Z.J.,Cao,S.Y,Zhang,H.R.,Qu,Y M.,Yuan,D.,Yang,J.H.,and Shao,G.M.,2015,Estimation of quality factors by energy ratio method:Applied Geophysics,12(1),86-92.
White,R.E.,1992,The accuracy of estimating Q from seismic data:Geophysics,57(1),1508-1511.
Willis,M.E.,Burns,D.R.,Rao,R.,Minsley,B.,Toksoz,M.N.,and Vetri,L.,2006,Spatial orientation and distribution of reservoir fractures from scattered seismic energy:Geophysics,71(5),043-051.
Zhang,C.,and Ulrych,T.J.,2002,Estimation of quality factor from CMP records:Geophysics,67(5),1542-1547.
Zheng,Y.,Fang,X.,Fehler,M.C.,and Burns,D.R.,2013.Seismic characterization of fractured reservoirs by focusing Gaussian beams:Geophysics,78(4),A23-28.
Askari,R.,and Hejazi,S.H.,2014,Estimation of surfacewave group velocity using slant stack in the generalized S-transform domain:Geophysics,80(4),EN83-EN92.
Bath,M.,1974,Spectral analysis in geophysics:Developments in solid Earth geophysics,vol.7:Elsevier.
Behura,J.,Tsvankin,I.,Jenner,E.,and Calvert,A.,2012,Estimation of interval velocity and attenuation anisotropy from reflection data at Coronation Field:The Leading Edge,31(5),580-587.
Clark,R.A.,Benson,R M.,Carter,A.J.,and Moreno,C.A.G.,2009,Anisotropic P-wave attenuation measured from a multi-azimuth surface seismic reflection survey:Geophysical Prospecting,57,835-845.
Dasgupta,R.,and Clark,R.A.,1998,Estimation of Q from surface seismic reflection data:Geophysics,63(6),2120-2128.
Ekanem,A.M.,Wei,J.,Wang,S.,Di,B.,Li,X.,and Chapman,M.,2009,Fracture detection using 2-D P-wave seismic data:A seismic physical modelling study:79th SEG Annual Meeting,Expanded Abstracts,2647-2651,Houston,USA.
Engelhard,L.,1996,Determination of the seismic wave attenuation by complex trace analysis:Geophysical Journal International,125(2),608-622.
Futterman,W.I.,1962,Dispersive body waves:Journal of Geophysical Research,67(13),5279-5291.
Li,D.,and Castagna,J.,2013,Modified S-transform in time-frequency analysis of seismic data:83rd Ann.Internat.Mtg.,Soc.Explor.Geophys.,Expanded Abstracts,4629-4634.
Liu,E.,Maultzsch,S.,Chapman,M.,Li,X.,Queen,J.,and Zhang,Z.,2003,Frequency-dependent seismic anisotropy and its implication for estimating fracture size in low porosity reservoirs,The Leading Edge,22(7),662-665.
Qu,S.L.,Ji,Y.X.,Wang,X.,Wang,X.L.,Chen,X.R.,and Shen,G.Q.,2007,Fracture detection by using full azimuth P wave attributes:Applied Geophysics,4(3),238-243.
Quan,Y.L.,and Harrisy,J.M.,1997,Seismic attenuation tomography using the frequency shift method:Geophysics,62(3),895-905.
Reine,C.M.,van der Baan,and Clark,R.,2009,The robustness of seismic attenuation measurements using fixed-and variable-window timefrequency transforms:Geophysics,74(2),WA123-WA135.
Ruger,A.,1998,Variation of P-wave reflectivity with offset and azimuth in anisotropic media:Geophysics,63(3),935-947.
Schoenberg,M.A.,Dean,S.,and Sayers,C.M.,1999,Azimuth dependent turning of seismic waves reflected from fractured reservoirs:Geophysics,64(4),1160-1171.
Shen,F.,Sierra,J.,Burns,D.R.,and Toksoz,M.N.,2002,Azimuthal offsetdependent attributes applied to fracture detection in a carbonate reservoir:Geophysics,67(2),355-364.
Shekar,B.,and Tsvankin,I.,2012,Anisotropic attenuation analysis of crosshole data generated during hydraulic fracturing:The Leading Edge,31(5),588-593.
Stockwell,R.G.,Mansinha,L.,and Lowe,R.P.,1996,Localization of the complex spectrum:The Stransform:IEEE Transactions on Signal Processing,44(4),998-1001
Wang,Z.J.,Cao,S.Y,Zhang,H.R.,Qu,Y M.,Yuan,D.,Yang,J.H.,and Shao,G.M.,2015,Estimation of quality factors by energy ratio method:Applied Geophysics,12(1),86-92.
White,R.E.,1992,The accuracy of estimating Q from seismic data:Geophysics,57(1),1508-1511.
Willis,M.E.,Burns,D.R.,Rao,R.,Minsley,B.,Toksoz,M.N.,and Vetri,L.,2006,Spatial orientation and distribution of reservoir fractures from scattered seismic energy:Geophysics,71(5),043-051.
Zhang,C.,and Ulrych,T.J.,2002,Estimation of quality factor from CMP records:Geophysics,67(5),1542-1547.
Zheng,Y.,Fang,X.,Fehler,M.C.,and Burns,D.R.,2013.Seismic characterization of fractured reservoirs by focusing Gaussian beams:Geophysics,78(4),A23-28.