偏移距域/角度域共成像点道集与偏移速度的关系
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摘要
为了得到波动方程偏移距域共成像点道集(ODCIGs)和角度域共成像点道集(ADCIGs)与偏移速度的关系,在匀速单层水平反射情况下,对ODCIGs和ADCIGs随偏移速度的变化进行了定量的推导,得到偏移速度偏小时ODCIGs与半偏移距成双曲关系,反之成椭圆关系;结合深度聚焦分析,得到偏移速度偏大时,ADCIGs中视入射角大于真入射角,反之,小于真入射角;在速度偏小时,ADCIGs上剩余时差(RMO)与视入射角的正切值成椭圆关系,反之成双曲关系.在地震有效入射角度范围内,ADCIGs对于偏大的偏移速度更加敏感.在偏移速度分析(MVA)中,从稍大的速度开始分析会对速度分析更加有利.
In order to probe the relationships between wave equation offset domain common image gathers (ODCIGs)/angle domain common image gathers (ADCIGs) with migration velocity, we quantitatively derive the changes of ODCIGs and ADCIGs along with migration velocity on the assumption of uniform velocity medium with a horizontal reflector. We come to conclusion that ODCIGs are hyperbolas with half offset; on the contrary, they are ellipses. Combined with the results of depth focusing analysis, we find the apparent incident angles in ADCIGs are larger than the real incident angles when the migration velocity is larger than the true one and vice versa. With lower migration velocity, the residual moveout (RMO) on ADCIGs is an ellipse with the tangent of apparent incident angle; otherwise, it′s a hyperbola. In the valid seismic incident angle, ADCIGs are much more sensitive to the higher migration velocity. As to migration velocity analysis (MVA), it is suggested to start with a little higher initial velocity.
In order to probe the relationships between wave equation offset domain common image gathers (ODCIGs)/angle domain common image gathers (ADCIGs) with migration velocity, we quantitatively derive the changes of ODCIGs and ADCIGs along with migration velocity on the assumption of uniform velocity medium with a horizontal reflector. We come to conclusion that ODCIGs are hyperbolas with half offset; on the contrary, they are ellipses. Combined with the results of depth focusing analysis, we find the apparent incident angles in ADCIGs are larger than the real incident angles when the migration velocity is larger than the true one and vice versa. With lower migration velocity, the residual moveout (RMO) on ADCIGs is an ellipse with the tangent of apparent incident angle; otherwise, it′s a hyperbola. In the valid seismic incident angle, ADCIGs are much more sensitive to the higher migration velocity. As to migration velocity analysis (MVA), it is suggested to start with a little higher initial velocity.
引文
Bartana,A.,Kosloff,D.,Ravve,I.,2006.Discussion and re-ply on“angle-domain common-i mage gathers by wave-field continuation methods”.Geophysics,71(1):X1-X4.
Biondi,B.,Symes,W.W.,2004.Angle-domain common-i m-age gathers for migration velocity analysis by wavefield-continuationi maging.Geophysics,69(5):1283-1298.
Biondi,B.,Tisserant,T.,2004.3D angle-domain common-i mage gathers for migration velocity analysis.Geophysi-cal Prospecting,52:575-591.
Liu,Z.,1995.Migration velocity analysis(Dissertation).Col-orado School of Mines.
MacKay,S.,Abma,R.,1992.I maging and velocity esti ma-tion with depth-focusing analysis.Geophysics,57(12):1608-1922.
Prucha,M.,Biondi,B.,Symes,W.,1999.Angle-domaincommon i mage gathers by wave-equation migration.69th Annual Internat.Mtg.,Soc.Expl.Geophys.,Ex-panded Abstracts,824-827.
Rickett,J.E.,Sava,P.C.,2002.Offset and angle-domaincommon i mage-point gathers for shot-profile migration.Geophysics,67(3):883-889.
Sava,P.C.,Fomel,S.,2003.Angle-domain common-i magegathers by wavefield continuation methods.Geophysics,68(3):1065-1074.
Soubaras,R.,2003.Angle gathers for shot-record migrationby local harmonic decomposition.73rd Annual Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,889-892.
Stolk,C.C.,Symes,W.W.,2004.Kinematic artifacts inprestack depth migration.Geophysics,69(2):562-575.
Stolk,C.C.,De Hoop,M.V.,Symes,W.W.,2005.Kine-matics of prestack shot-geophone migration.75th Annu-al Internat.Mtg.,Soc.Expl.Geophys.,Expanded Ab-stracts,1866-1869.
Xie,X.,Wu,R.,2002.Extracting angle domain informationfrom migrated wavefield.73rd Annual Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,1360-1363.
Xu,S.,Chauris,H.,Lambar′e,G.,et al.,2001.Common-angle migration:A strategy for i maging complexmedia.Geophysics,66(6):1877-1894.
Biondi,B.,Symes,W.W.,2004.Angle-domain common-i m-age gathers for migration velocity analysis by wavefield-continuationi maging.Geophysics,69(5):1283-1298.
Biondi,B.,Tisserant,T.,2004.3D angle-domain common-i mage gathers for migration velocity analysis.Geophysi-cal Prospecting,52:575-591.
Liu,Z.,1995.Migration velocity analysis(Dissertation).Col-orado School of Mines.
MacKay,S.,Abma,R.,1992.I maging and velocity esti ma-tion with depth-focusing analysis.Geophysics,57(12):1608-1922.
Prucha,M.,Biondi,B.,Symes,W.,1999.Angle-domaincommon i mage gathers by wave-equation migration.69th Annual Internat.Mtg.,Soc.Expl.Geophys.,Ex-panded Abstracts,824-827.
Rickett,J.E.,Sava,P.C.,2002.Offset and angle-domaincommon i mage-point gathers for shot-profile migration.Geophysics,67(3):883-889.
Sava,P.C.,Fomel,S.,2003.Angle-domain common-i magegathers by wavefield continuation methods.Geophysics,68(3):1065-1074.
Soubaras,R.,2003.Angle gathers for shot-record migrationby local harmonic decomposition.73rd Annual Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,889-892.
Stolk,C.C.,Symes,W.W.,2004.Kinematic artifacts inprestack depth migration.Geophysics,69(2):562-575.
Stolk,C.C.,De Hoop,M.V.,Symes,W.W.,2005.Kine-matics of prestack shot-geophone migration.75th Annu-al Internat.Mtg.,Soc.Expl.Geophys.,Expanded Ab-stracts,1866-1869.
Xie,X.,Wu,R.,2002.Extracting angle domain informationfrom migrated wavefield.73rd Annual Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,1360-1363.
Xu,S.,Chauris,H.,Lambar′e,G.,et al.,2001.Common-angle migration:A strategy for i maging complexmedia.Geophysics,66(6):1877-1894.
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