应用边界元模拟方法分析复杂海底地震散射特征
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摘要
边界元法对随机起伏的复杂海底界面具有良好的适应性。比较了边界元法与有限差分法对复杂断层模型的模拟精度,并验证了边界元法的有效性。利用边界元法对复杂海底模型进行波场模拟,反映起伏海底界面对地震波传播的影响;利用统计参数描述复杂海底地貌特征,将崎岖海底界面划分为快、慢变化和强、弱起伏等4种特征类型。根据不同统计参数的选择建立崎岖海底理论模型,利用边界元法对不同类型的崎岖海底理论模型进行模拟研究,同时与实际海底资料相对比,分析了复杂海底地震散射特征。此项研究成果可为复杂海底地区目标导向地震观测系统设计和采集参数优化提供理论依据。
The boundary-element method(BEM) has a good adaptability for simulating irregularly rough and complex seabed.The simulation accuracy of BEM for a complex fault model was compared with that of the finite-difference method,and the effectiveness of BEM was confirmed.BEM can be used to conduct wave simulation of rough seabed models,reflecting the impacts of rough seabed on seismic wave propagation.The statistical parameters were used to describe complex seabed topography,and then four types of rough seabed interface can be identified,i.e.fast lateral change,slow lateral change,strong vertical relief and weak vertical relief.The theoretical models of rough seabed can be build by selecting various statistical parameters,and BEM was used to make simulation of different theoretical models of rough seabed.Simultaneously,some actual seabed data was compared and the seismic scattering characteristics of complex seabed were analyzed.These results will provide some theoretical foundations for the seismic acquisition design of complex seabed and the optimization of seismic acquisition parameters.
The boundary-element method(BEM) has a good adaptability for simulating irregularly rough and complex seabed.The simulation accuracy of BEM for a complex fault model was compared with that of the finite-difference method,and the effectiveness of BEM was confirmed.BEM can be used to conduct wave simulation of rough seabed models,reflecting the impacts of rough seabed on seismic wave propagation.The statistical parameters were used to describe complex seabed topography,and then four types of rough seabed interface can be identified,i.e.fast lateral change,slow lateral change,strong vertical relief and weak vertical relief.The theoretical models of rough seabed can be build by selecting various statistical parameters,and BEM was used to make simulation of different theoretical models of rough seabed.Simultaneously,some actual seabed data was compared and the seismic scattering characteristics of complex seabed were analyzed.These results will provide some theoretical foundations for the seismic acquisition design of complex seabed and the optimization of seismic acquisition parameters.
引文
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[8]KAWASE H.Time-domain response of a semi-circular canyonfor incident SV,P,and Rayleigh waves calculated by the dis-crete wave number boundary element method[J].Bull.Seism.Soc.Am.,1988,78:1415-1437.
[9]BOUCHON M,CAMPILLO M,GAFFET S.A boundary in-tegral equation-discrete wavenumber representation methodto study wave propagation in multilayered media having irreg-ular interfaces[J].Geophysics,1989,54:1134-1140.
[10]FU L Y.Seismogram synthesis for piecewise heterogeneousmedia[J].Geophys.J.int.,2002,150:800-808.
[11]FU L Y.Numerical study of generalized lippmann-schwingerintegral equation including surface topography[J].Geophys-ics,2003,68(2):665-671.
[12]FU L Y,WU R S.Infinite boundary element absorbing bounda-ry for wave propagation simulations[J].Geophysics,2000,65(2):596-602.
[2]SNCHEZ-SESMA F J,CAMPILLO M.Diffraction of P,SV andRayleigh waves by topographic features:a boundary integral for-mulation[J].Bull.Seism.Soc.Am.,1991,81:2234-2253.
[3]徐世浙,王庆乙,王军.用边界单元法模拟二维地形对大地电磁场的影响[J].地球物理学报,1992,35(3):380-388.
[4]徐世浙,阮百尧,周辉,等.大地电磁场三维地形影响的数值模拟[J].中国科学:D辑,1997,27(1):15-20.
[5]符力耘,牟永光.弹性波边界元法正演模拟[J].地球物理学报,1994,37(4):521-529.
[6]FU L Y,WU R S.A hybrid BE-GS method for modeling re-gional wave propagation[J].Pure and Applied Geophysics,2001,158:1251-1277.
[7]SCHUSTER G T.The application of boundary integral equa-tions to interactive modeling[C]∥The 3rd MIDAS Meeting.New York,1982.
[8]KAWASE H.Time-domain response of a semi-circular canyonfor incident SV,P,and Rayleigh waves calculated by the dis-crete wave number boundary element method[J].Bull.Seism.Soc.Am.,1988,78:1415-1437.
[9]BOUCHON M,CAMPILLO M,GAFFET S.A boundary in-tegral equation-discrete wavenumber representation methodto study wave propagation in multilayered media having irreg-ular interfaces[J].Geophysics,1989,54:1134-1140.
[10]FU L Y.Seismogram synthesis for piecewise heterogeneousmedia[J].Geophys.J.int.,2002,150:800-808.
[11]FU L Y.Numerical study of generalized lippmann-schwingerintegral equation including surface topography[J].Geophys-ics,2003,68(2):665-671.
[12]FU L Y,WU R S.Infinite boundary element absorbing bounda-ry for wave propagation simulations[J].Geophysics,2000,65(2):596-602.
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