复杂地表地震资料叠前深度偏移成像
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摘要
分析了复杂地表地区复杂地震波场的形成原因,探讨了基于高角度时空域单程波动方程适用于起伏地表之下构造成像的逆时叠前深度偏移方法。从声波方程有限差分法合成起伏地表上的炮集记录知,当激发点位于低速层中,共炮点道集中低速层表面和高速层表面接收到的信号强度相差较大:低速层表面的信号很强,而高速层表面的信号很弱,低速层中产生了较强的槽波。将该逆时叠前深度偏移方法应用于起伏地表地震波场的偏移处理。虽然在偏移成像前既没有压制与低速层有关的槽波,又没有压制随机噪声,但偏移剖面上界面清晰、位置正确,断层面也得到了很好的聚焦。
We analyzes the cause of formation of complicated wave field on rugged surface,and proposes a reverse-time prestack depth migration method based on a time-space domain one-way wave equation with high dip angle for imaging subsurface geological structures below the rugged surface.From synthetic shot gathers of a complicated structure with rugged surface simulated by solving acoustic wave equations using the finite-difference method,it is known that if the shot is in the low velocity layer,the energy received on the low velocity layer is much stronger than that received on the high velocity layer,and a strong guided wave is created in the low velocity layer.The proposed prestack migration method is applied to the synthetic shot gathers.Although neither the guided wave related to the low velocity media,nor the random noise is suppressed before migration,the interfaces are clear and their positions are correct,and the planes of fault are well focused too.
We analyzes the cause of formation of complicated wave field on rugged surface,and proposes a reverse-time prestack depth migration method based on a time-space domain one-way wave equation with high dip angle for imaging subsurface geological structures below the rugged surface.From synthetic shot gathers of a complicated structure with rugged surface simulated by solving acoustic wave equations using the finite-difference method,it is known that if the shot is in the low velocity layer,the energy received on the low velocity layer is much stronger than that received on the high velocity layer,and a strong guided wave is created in the low velocity layer.The proposed prestack migration method is applied to the synthetic shot gathers.Although neither the guided wave related to the low velocity media,nor the random noise is suppressed before migration,the interfaces are clear and their positions are correct,and the planes of fault are well focused too.
引文
[1]王雪秋,孙建国,张文志.复杂地表地质条件下地震波数值模拟综述[J].吉林大学学报:地球科学版,2005,35(增刊):12-18.Wang Xue-qiu,Sun Jian-guo,Zhang Wen-zhi.TheState of the Art in Numerical Modeling IncludingSurface Topography[J].Journal of Jilin University:Earth Science Edition,2005,35(Sup.):12-18.
[2]方伍宝,李满树,孙爱萍,等.基于Born近似的波动方程静校正技术[J].石油物探,2004,43(1):26-29.Fang Wu-bao,Li Man-shu,Sun Ai-ping,et al.WaveEquation Datuming Based on Born Approximation[J].Geophysical Prospecting for Petroleum,2004,43(1):26-29.
[3]Berryhill J R.Wave-Equation Datuming[J].Geo-physics,1979,44(8):1329-1344.
[4]Berryhill J R.Wave-Dquation Datuming Before Stack[J].Geophysics,1984,49(11):2064-2066.
[5]Wiggins J W.Kirchhoff Integral Extrapolation andMigration of Nonplanar Data[J].Geophysics,1984,49(8):1239-1248.
[6]Berrill J R.Submarine Canyons Velocity Repla-cement by Wave Equation Datuming Before Stack[J].Geophysics,1986,51(8):1572-1579.
[7]Yilmaz O,Lucas D.Prestack Layer Replacement[J].Geophysics,1986,51(7):1355-1369.
[8]Reshef M.Depth Migration from Irregular Surfacewith Depth Extrapolation Methods[J].Geophysics,1991,56(1):119-122.
[9]Beasley C J,Lynn W.The Zero Velocity Layer:Migration from Irregular Surfaces[J].Geophysics,1992,57(11):1435-1443.
[10]Gray S H,Marfurt K J.Migration from Topo-graphy:Improving the Near-Surface Image[J].Canadian Journal of Exploration Geophysics,1995,31(1/2):18-24.
[11]杨锴,许世勇,王华忠,等.有限差分法波场延拓海水层基准面校正[J].中国海上油气:地质,1999,13(5):342-345.Yang Kai,Xu Shi-yong,Wang Hua-zhong,et al.Water Layer Datuming with Finite-DifferenceWavefield Extrapolation Scheme[J].China OffshoreOil and Gas:Geology,1999,13(5):342-345.
[12]Fu L Y,Wu R S,Guan H M.Removing Rugged-Topography Scattering Effects in Surface SeismicData[C]//Expanded Abstracts of 69th AnnualInternatinal SEG Meeting.Salt Lake City:69thAnnual International SEG Meeting,1999:453-456.
[13]Sava P.Migration and Velocity Analysis by WaveField Extrapolation[D].Stanford:StanfordUniversity,2004.
[14]董春晖.复杂构造地震波场数值模拟与叠前成像[D].北京:中国石油大学,2010.Dong Chun-hui.Seismic Wave Simulation andPrestack Migration for Complex Structures[D].Beijing:China University of Petroleum,2010.
[15]Mi Y,Margrave G.Prestack Depth Imaging fromTopography with a Fourier Method[C]//:ExpandedAbstracts of 71st Annual International SEGMeeting.[S.l.]:71st Annual International SEGMeeting,2001:1045-1048.
[16]张辉.起伏地表条件下的波动方程叠前深度偏移方法研究[D].东营:中国石油大学,2006.Zhang Hui.Method Study of Pre-Stack WaveEquation Depth Migration Methods Based onIrregular Topography[D].Dongying:ChinaUniversity of Petroleum,2006.
[17]叶月明,李振春,仝兆岐,等.双复杂介质条件下频率空间域有限差分法保幅偏移[J].地球物理学报,2008,51(5):1151-1159.Ye Yue-ming,Li Zhen-chun,Tong Zhao-qi,et al.Preserved-Amplitude Migration with Dual-Complexity[J].Chinese Journal of Geophysics,2008,51(5):1151-1159.
[18]Guddati M N,Heidari A H.Migration withArbitrarily Wide-Angle Wave Equations[J].Geophysics,2005,70(3):S61-S70.
[19]Fletcher R P,Fowler P J,Kitchenside P,et al.Suppressing Unwanted Internal Reflections inPrestack Reverse-Time Migration[J].Geophysics,2006,71(6):E79-E82.
[20]Virieux J.SH-Wave Propagation in HetergeneousMedia:Velocity-Stress Finite Difference Method[J].Geophysics,1984,49(11):1933-1957.
[21]Zhou H,Wang S X,Li G F,et al.Analysis ofComplicated Structure Seismic Wave Fields[J].Applied Geophysics,2010,7(2):185-192.
[22]Liu F Q,Zhang G Q,Morton S A,et al.Reverse-Time Migration Using One-Way Wavefield ImagingCondition[C]//Expanded Abstracts of 77th AnnualInternatinal SEG Meeting.San Antonio:77th Annual International SEG Meeting,2007:2170-2174.
[2]方伍宝,李满树,孙爱萍,等.基于Born近似的波动方程静校正技术[J].石油物探,2004,43(1):26-29.Fang Wu-bao,Li Man-shu,Sun Ai-ping,et al.WaveEquation Datuming Based on Born Approximation[J].Geophysical Prospecting for Petroleum,2004,43(1):26-29.
[3]Berryhill J R.Wave-Equation Datuming[J].Geo-physics,1979,44(8):1329-1344.
[4]Berryhill J R.Wave-Dquation Datuming Before Stack[J].Geophysics,1984,49(11):2064-2066.
[5]Wiggins J W.Kirchhoff Integral Extrapolation andMigration of Nonplanar Data[J].Geophysics,1984,49(8):1239-1248.
[6]Berrill J R.Submarine Canyons Velocity Repla-cement by Wave Equation Datuming Before Stack[J].Geophysics,1986,51(8):1572-1579.
[7]Yilmaz O,Lucas D.Prestack Layer Replacement[J].Geophysics,1986,51(7):1355-1369.
[8]Reshef M.Depth Migration from Irregular Surfacewith Depth Extrapolation Methods[J].Geophysics,1991,56(1):119-122.
[9]Beasley C J,Lynn W.The Zero Velocity Layer:Migration from Irregular Surfaces[J].Geophysics,1992,57(11):1435-1443.
[10]Gray S H,Marfurt K J.Migration from Topo-graphy:Improving the Near-Surface Image[J].Canadian Journal of Exploration Geophysics,1995,31(1/2):18-24.
[11]杨锴,许世勇,王华忠,等.有限差分法波场延拓海水层基准面校正[J].中国海上油气:地质,1999,13(5):342-345.Yang Kai,Xu Shi-yong,Wang Hua-zhong,et al.Water Layer Datuming with Finite-DifferenceWavefield Extrapolation Scheme[J].China OffshoreOil and Gas:Geology,1999,13(5):342-345.
[12]Fu L Y,Wu R S,Guan H M.Removing Rugged-Topography Scattering Effects in Surface SeismicData[C]//Expanded Abstracts of 69th AnnualInternatinal SEG Meeting.Salt Lake City:69thAnnual International SEG Meeting,1999:453-456.
[13]Sava P.Migration and Velocity Analysis by WaveField Extrapolation[D].Stanford:StanfordUniversity,2004.
[14]董春晖.复杂构造地震波场数值模拟与叠前成像[D].北京:中国石油大学,2010.Dong Chun-hui.Seismic Wave Simulation andPrestack Migration for Complex Structures[D].Beijing:China University of Petroleum,2010.
[15]Mi Y,Margrave G.Prestack Depth Imaging fromTopography with a Fourier Method[C]//:ExpandedAbstracts of 71st Annual International SEGMeeting.[S.l.]:71st Annual International SEGMeeting,2001:1045-1048.
[16]张辉.起伏地表条件下的波动方程叠前深度偏移方法研究[D].东营:中国石油大学,2006.Zhang Hui.Method Study of Pre-Stack WaveEquation Depth Migration Methods Based onIrregular Topography[D].Dongying:ChinaUniversity of Petroleum,2006.
[17]叶月明,李振春,仝兆岐,等.双复杂介质条件下频率空间域有限差分法保幅偏移[J].地球物理学报,2008,51(5):1151-1159.Ye Yue-ming,Li Zhen-chun,Tong Zhao-qi,et al.Preserved-Amplitude Migration with Dual-Complexity[J].Chinese Journal of Geophysics,2008,51(5):1151-1159.
[18]Guddati M N,Heidari A H.Migration withArbitrarily Wide-Angle Wave Equations[J].Geophysics,2005,70(3):S61-S70.
[19]Fletcher R P,Fowler P J,Kitchenside P,et al.Suppressing Unwanted Internal Reflections inPrestack Reverse-Time Migration[J].Geophysics,2006,71(6):E79-E82.
[20]Virieux J.SH-Wave Propagation in HetergeneousMedia:Velocity-Stress Finite Difference Method[J].Geophysics,1984,49(11):1933-1957.
[21]Zhou H,Wang S X,Li G F,et al.Analysis ofComplicated Structure Seismic Wave Fields[J].Applied Geophysics,2010,7(2):185-192.
[22]Liu F Q,Zhang G Q,Morton S A,et al.Reverse-Time Migration Using One-Way Wavefield ImagingCondition[C]//Expanded Abstracts of 77th AnnualInternatinal SEG Meeting.San Antonio:77th Annual International SEG Meeting,2007:2170-2174.
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