VTI介质长偏移距非双曲动校正公式优化
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摘要
常规Alkhalifah动校正公式精度低,不能精确描述各向异性介质长偏移距地震反射同相轴的时距关系.本文以提高VTI介质长偏移距地震资料动校正公式的精度为目标,在分析VTI介质常规动校正方程的基础上,根据误差最小原理建立优化校正系数图版,实现对常规动校正公式大偏移距误差的修正,建立最优化校正Alkhalifah动校正方程,实现了对VTI介质长偏移距地震资料常规动校正方程的改进.之后由Fomel群速度公式导出高精度VTI模型长偏移距时距函数,提出了高精度VTI介质长偏移距地震资料动校正方程.将以上的动校正方程用于各向异性参数反演,模型计算表明最优化校正Alkhalifah动校正方程的反演精度是常规长偏移距动校正方程反演精度的2~4倍,高精度动校正方程的反演精度是常规动校正方程反演精度的2~8倍.
The conventional Alkhalifah moveout correction equation is characterized by low precision,and even worse it may fail to describe relation of traveltime-offset of long-offset seismic data in VTI media.Aiming at improving accuracy of the moveout correction equation of long-offset seismic data in VTI media,we analyze the Alkhalifah's NMO equation at first.Then based on the least-error principle,chart of optimal correction coefficients are calculated to compensate errors resulted from long offset cases using the conventional moveout correction equation.Therefore,the optimal Alkhalifah moveout correction equation is proposed here to improve the conventional moveout correction equation.Subsequently,we derive the travetime-offset function with a high precision model from the Fomel's group velocity equation for VTI.The moveout correction equation with high precision is put forward.Above moveout correction equations are applied to inversion calculation of anisotropic parameters from long-offset seismic data.Numerical results show that the accuracy of inversion using optimal Alkhalifah moveout equation is twice that of inversion using the conventional moveout equation,and the inversion method using the high precision moveout correction equation is the most accurate.
The conventional Alkhalifah moveout correction equation is characterized by low precision,and even worse it may fail to describe relation of traveltime-offset of long-offset seismic data in VTI media.Aiming at improving accuracy of the moveout correction equation of long-offset seismic data in VTI media,we analyze the Alkhalifah's NMO equation at first.Then based on the least-error principle,chart of optimal correction coefficients are calculated to compensate errors resulted from long offset cases using the conventional moveout correction equation.Therefore,the optimal Alkhalifah moveout correction equation is proposed here to improve the conventional moveout correction equation.Subsequently,we derive the travetime-offset function with a high precision model from the Fomel's group velocity equation for VTI.The moveout correction equation with high precision is put forward.Above moveout correction equations are applied to inversion calculation of anisotropic parameters from long-offset seismic data.Numerical results show that the accuracy of inversion using optimal Alkhalifah moveout equation is twice that of inversion using the conventional moveout equation,and the inversion method using the high precision moveout correction equation is the most accurate.
引文
[1]Tariq Alkhalifah.Acoustic approximations for processing intransversely isotropic media.Geophysics,2000,65(4):1239~1250
[2]Anderson J,Alkhalifah T,Tsvankin Fowler.DMO and timemigration for transversely isotropic media.Geophysics,1995,60:835~845
[3]Chang X,Liu Y K,Wang H.3-D tomographic static correction.Geophysics,2001,66(4):1275~1285
[4]刘伊克,常旭,王辉.三维复杂地形近地表速度估算及地震层析静校正.地球物理学报,2001,44(2):272~278Liu Y K,Chang X,Wang H.Estimation of near-surface velocity for3-D complicated tomography and seismic tomographic staticscorrections.Chinese J.Geophys.(in Chinese),2001,44(2):272~278
[5]Alkhalifah Tariq,Tsvankin IIya.Velocity analysis for transverselyisotropic media.Geophysics,1995,60(5):1550~1566
[6]Tariq Alkhalifah.Velocity analysis using nonhyperbolic moveout intransversely isotropic media.Geophysics,1997,62(6):1839~1854
[7]Vladimir Grechka,Tsvankin IIya.Feasibility of nonhyperbolicmoveout inversion in transversely isotropic media.Geophysics,1998,63(3):957~969
[8]Tsvankin,Thomsen.Nonhyperbolic reflection moveout in anisotropicmedia.Geophysics,1994,59(8):1290~1304
[9]Leon Thomsen.Weak elastic anisotropic.Geophysics,1986,51(10):1954~1966
[10]Zhang F,Uren N.Approximate explicit ray velocity functions andtravel times for P-wave in TI media.71st SEG meeting,SanAntonio,Texas,USA,Expanded Abstract,2001.106~109
[11]Fomel Sergey.On anelliptic approximations for qP velocities in VTImedia.Geophys Prosp.,2004,52:247~259
[12]Taner M T,Koehler F.Velocity spectra-digital computer derivationand applications of velocity functions.Geophysics,1969,34(6):859~881
[13]Grechka V,Tsvankin.3-D description of normal moveout inanisotropic media.66thAnn Internat.Mtg.,Soc.Expl.Geophys,Expanded Abstracts,1996.1487~1490
[2]Anderson J,Alkhalifah T,Tsvankin Fowler.DMO and timemigration for transversely isotropic media.Geophysics,1995,60:835~845
[3]Chang X,Liu Y K,Wang H.3-D tomographic static correction.Geophysics,2001,66(4):1275~1285
[4]刘伊克,常旭,王辉.三维复杂地形近地表速度估算及地震层析静校正.地球物理学报,2001,44(2):272~278Liu Y K,Chang X,Wang H.Estimation of near-surface velocity for3-D complicated tomography and seismic tomographic staticscorrections.Chinese J.Geophys.(in Chinese),2001,44(2):272~278
[5]Alkhalifah Tariq,Tsvankin IIya.Velocity analysis for transverselyisotropic media.Geophysics,1995,60(5):1550~1566
[6]Tariq Alkhalifah.Velocity analysis using nonhyperbolic moveout intransversely isotropic media.Geophysics,1997,62(6):1839~1854
[7]Vladimir Grechka,Tsvankin IIya.Feasibility of nonhyperbolicmoveout inversion in transversely isotropic media.Geophysics,1998,63(3):957~969
[8]Tsvankin,Thomsen.Nonhyperbolic reflection moveout in anisotropicmedia.Geophysics,1994,59(8):1290~1304
[9]Leon Thomsen.Weak elastic anisotropic.Geophysics,1986,51(10):1954~1966
[10]Zhang F,Uren N.Approximate explicit ray velocity functions andtravel times for P-wave in TI media.71st SEG meeting,SanAntonio,Texas,USA,Expanded Abstract,2001.106~109
[11]Fomel Sergey.On anelliptic approximations for qP velocities in VTImedia.Geophys Prosp.,2004,52:247~259
[12]Taner M T,Koehler F.Velocity spectra-digital computer derivationand applications of velocity functions.Geophysics,1969,34(6):859~881
[13]Grechka V,Tsvankin.3-D description of normal moveout inanisotropic media.66thAnn Internat.Mtg.,Soc.Expl.Geophys,Expanded Abstracts,1996.1487~1490
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