1. School of Geosciences,China University of Petroleum,Qingdao 266580,China 2. Ya'an Bureau of Land and Resources,Ya'an 625000,China 3. Research & Development Center of BGP,Zhuozhou 072751,China;
Studying the basic characteristics of near-surface scattering waves and determining the location of near-surface heterogeneities help seismic imaging,survey planning,and avoiding geological disasters.In order to study the wave fields characteristics of near-surface heterogeneous bodies,the authors used the high-order finite difference numerical simulation technique and perturbation theory method to simulate the wave field records of shallow surface scatters and analyze the basic characteristics of near-surface scattering waves.The near surface heterogeneity was located by introducing of reverse time migration imaging technology with the scattering wave field as an extrapolated wave field.The numerical results indicate that surface-wave scatterings are usually stronger than those body-wave scatterings and that forward scatterings are also stronger than backward scatterings.Moreover,near-surface scatters can be precisely imaged by the elastic wave reverse time migration.The near-surface scatters can be regarded as a secondary source,which increases the near-surface illumination.Using the scattered wave field can improve the accuracy of near-surface velocity inversion and seismic imaging.
Gaburro R, Nolan C J, Dowling T, et al. Imaging from multiply scattered waves [C].Society of Photo-Optical Instrumentation Engineers, 2007.
[2]
Fleury C . Increasing illumination and sensitivity of reverse‐time migration with internal multiples[J]. Geophysical Prospecting, 2013,61(5):891-906.
doi: 10.1111/gpr.2013.61.issue-5
[3]
Gubernatis J E, Domany E, Krumhansl J A , et al. The Born approximation in the theory of the scattering of elastic waves by flaws[J]. Journal of Applied Physics, 1977,48(7):2812-2819.
doi: 10.1063/1.324142
[4]
Wu R S, Aki K . Scattering characteristics of elastic waves by an elastic heterogeneity[J]. Geophysics, 1985,50(4):582-595.
doi: 10.1190/1.1441934
[5]
Sato H, Fehler M C, Maeda T . Seismic wave propagation and scattering in the heterogeneous earth[M]. Berlin:Springer, 2012.
[6]
Beydoun W B, Mendes M . Elastic ray-Born l 2-migration/inversion[J]. Geophysical Journal International, 1989,97(1):151-160.
doi: 10.1111/gji.1989.97.issue-1
[7]
Ernst F E, Herman G C, Ditzel A . Removal of scattered guided waves from seismic data[J]. Geophysics, 2002,67(4):1240-1248.
doi: 10.1190/1.1500386
Levander A R . Fourth-order finite-difference P-SV seismograms[J]. Geophysics, 1988,53(11):1425-1436.
doi: 10.1190/1.1442422
[10]
Almuhaidib A M, Toksöz M N . Numerical modeling of elastic-wave scattering by near-surface heterogeneities[J]. Geophysics, 2014,79(4):T199-T217.
doi: 10.1190/geo2013-0208.1
Chen X . A systematic and efficient method of computing normal modes for multilayered half-space[J]. Geophysical Journal International, 1993,115(2):391-409.
doi: 10.1111/gji.1993.115.issue-2
[15]
Robertsson J O A . A numerical free-surface condition for elastic/viscoelastic finite-difference modeling in the presence of topography[J]. Geophysics, 1996,61(6):1921-1934.
doi: 10.1190/1.1444107
Riyanti C D, Herman G C . Three-dimensional elastic scattering by near-surface heterogeneities[J]. Geophysical Journal International, 2005,160(2):609-620.
doi: 10.1111/gji.2005.160.issue-2
[19]
Campman X, Dwi Riyanti C . Non-linear inversion of scattered seismic surface waves[J]. Geophysical Journal International, 2007,171(3):1118-1125.
doi: 10.1111/j.1365-246X.2007.03557.x
[20]
Baysal E, Dan D K, Sherwood J W C .Reverse time migration[J]. Geophysics, 1983,48(11):1514-1524.
doi: 10.1190/1.1441434
[21]
Mcmechan G A . Migration by extrapolation of time-dependent boundary values[J]. Geophysical Prospecting, 1983,31(3):413-420.
doi: 10.1111/gpr.1983.31.issue-3
[22]
Whitmore N D. Iterative depth migration by backward time propagation [C]//Expanded Abstracts of the 53 rd Annual SEG Meeting,Society of Exploration Geophysicists , 1983: 382-385.
[23]
Sun R, Mcmechan G A, Lee C S , et al. Prestack scalar reverse-time depth migration of 3D elastic seismic data[J]. Geophysics, 2006,71(5).
[24]
Wu R S . The perturbation method in elastic wave scattering[J]. Pure and Applied Geophysics, 1989,131(4):605-637.
doi: 10.1007/BF00876266
Komatitsch D, Martin R .An unsplit convolutional perfectly matched layer improved at grazing incidence for the seismic wave equation[J].Geophysics, 2007, 72(5):SM155-SM167.
doi: 10.1190/1.2757586
[28]
Zhang W, Shen Y . Unsplit complex frequency-shifted PML implementation using auxiliary differential equations for seismic wave modeling[J]. Geophysics, 2010,75(4):T141-T154.
doi: 10.1190/1.3463431
