井震联合网格层析各向异性速度建模研究及应用
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摘要
各向异性速度场及参数场的建立是各向异性叠前深度偏移技术在地震资料处理过程中取得成功的关键环节。井震联合求取各向异性参数是目前地震资料处理时常用的方法之一,但常规井震联合法通过对比地层厚度来求取各向异性参数,计算精度较低,达不到地质要求。将网格层析技术应用于三维VTI介质井震联合各向异性速度建模中,沿射线路径同时更新每个网格点的各向异性速度和参数,并通过多次迭代进一步提高速度模型的精度。应用结果表明,相较于常规井震联合法,基于网格层析的井震联合法能大幅提高各向异性速度场和参数场的计算精度,增强深度偏移结果与测井资料的吻合度,并且使得共成像点道集的远偏移距更加平直,为叠前反演提供更丰富的远偏移距信息,同时还能有效改善局部成像效果。
Estimation of anisotropic velocity and parameter is a key technology in the success of anisotropic prestack depth migration in real seismic data processing. It is one of the commonly used methods to calculate the anisotropic parameters by well-to-seismic integration for seismic data processing at present. The conventional well-to-seismic integration method can be used to obtain anisotropic parameters by comparing the formation thickness,but the accuracy is low and cannot meet the geological requirements. Grid tomography based on wellto-seismic integration was applied to anisotropic velocity modeling in 3 D VTI media. The anisotropic velocity and parameters of each grid were updated along the ray path,and the accuracy of velocity model was further improved by iterative calculation. The application results show that compared with conventional well-to-seismic integration method,grid tomography based on well-to-seismic integration can greatly improve the precision of anisotropic velocity and parameters and enhance the consistency of depth migration results and well logging data.Moreover,the common imaging point gather of long offset is more flatten,which can provide more information oflong offset for prestack inversion,and the local imaging effect of the migration results is also improved effectively.
Estimation of anisotropic velocity and parameter is a key technology in the success of anisotropic prestack depth migration in real seismic data processing. It is one of the commonly used methods to calculate the anisotropic parameters by well-to-seismic integration for seismic data processing at present. The conventional well-to-seismic integration method can be used to obtain anisotropic parameters by comparing the formation thickness,but the accuracy is low and cannot meet the geological requirements. Grid tomography based on wellto-seismic integration was applied to anisotropic velocity modeling in 3 D VTI media. The anisotropic velocity and parameters of each grid were updated along the ray path,and the accuracy of velocity model was further improved by iterative calculation. The application results show that compared with conventional well-to-seismic integration method,grid tomography based on well-to-seismic integration can greatly improve the precision of anisotropic velocity and parameters and enhance the consistency of depth migration results and well logging data.Moreover,the common imaging point gather of long offset is more flatten,which can provide more information oflong offset for prestack inversion,and the local imaging effect of the migration results is also improved effectively.
引文
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[2]魏新善,胡爱平,赵会涛,等.致密砂岩气地质认识新进展.岩性油气藏,2017,29(1):11-20.WEI X S,HU A P,ZHAO H T,et al.New geological understanding of tight sandstone gas.Lithologic Reservoirs,2017,29(1):11-20.
[3]ZHANG Y,ZHANG H Z,ZHANG G Q.A stable TTI reverse time migration and its implementation.Geophysics,2011,76(3):WA3-WA11.
[4]THOMAS M,MOTHI S,MCGILL P.Improving subsalt images using tilted-Orthorhombic RTM in Green Canyon,Gulf of Mexico.82th Annual Meeting,SEG Expanded Abstracts,2012:693-697.
[5]陈可洋.逆时成像技术在大庆探区复杂构造成像中的应用.岩性油气藏,2017,29(6):91-100.CHEN K Y.Application of reverse-time migration technology to complex structural imaging in Daqing exploration area.Lithologic Reservoirs,2017,29(6):91-100.
[6]THOMSEN L.Weak elastic anisotropy.Geophysics,1986,51(10):1954-1966.
[7]ALKHALIFAH T,TSVANKIN I.Velocity analysis for transversely isotropic media.Geophysics,1995,60(5):1550-1566.
[8]ALKHALIFAH T.Velocity analysis using nonhyperbolic moveout in transversely isotropic media.Geophysics,1997,62(6):1839-1854.
[9]GRECHKA V,TSVANKIN I.Feasibility of nonhyperbolic moveout inversion in transversely isotropic media.Geophysics,1998,63(3):957-969.
[10]DEWANGAN P,TSVANKIN I.Velocity-independent layer stripping of PP and PS reflection traveltimes.Geophysics,2006,71(4):U59-U65.
[11]WANG X X,TSVANKIN I.Estimation of interval anisotropy parameters using velocity-independent layer stripping.Geophysics,2009,74(5):WB117-WB127.
[12]BACHRACH R,OSYPOV K,NICHOLS D,et al.Applications of deterministic and stochastic rock physics modelling to anisotropic velocity model building.Geophysical Prospecting,2013,61(2):404-415.
[13]杜丽英,杜丽娟,肖乾华,等.VTI介质中弹性参数地震反演方法.石油勘探与开发,2002,29(3):59-63.DU L Y,DU L J,XIAO Q H,et al.A new approach to seismic inversion of elastic parameters for VTI media.Petroleum Exploration and Development,2002,29(3):59-63.
[14]PRIEUX V,BROSSIER R,GHOLAMI Y,et al.On the footprint of anisotropy on isotropic full waveform inversion:the Valhallcase study.Geophysical Journal International,2011,187(3):1495-1515.
[15]ZHANG Z,LIN G,CHEN J,et al.Inversion for elliptically anisotropicvelocity using VSP reflection traveltimes.Geophysical Prospecting,2003,51(2):159-166.
[16]刘茂诚.一个各向异性速度分析应用实例.石油地球物理勘探,2010,45(4):525-529.LIU M C.An application case study for anisotropic velocity analysis.Oil Geophysical Prospecting,2010,45(4):525-529.