Downward and upward continuation of 2-D seismic data to eliminate ocean bottom topography’s effect
Wang Xiang-Chun1, Xia Chang-Liang2, and Liu Xue-Wei1
1. Key Laboratory of Geo-detection (China University of Geosciences, Beijing), Ministry of Education, Beijing 100083, China.
2. Overseas Business Department of Geophysical Research Institute, BGP of CNPC, Zhuozhou 072750, China.
Abstract：
In order to eliminate the effect of ocean bottom topography on seismic wave field, we transformed curved (x, z) coordinate system grids into rectangular (ξ, η) coordinate system grids and derived a 2-D scalar acoustic wave equation in the ξ, η domain. The seismic wave field collected at the sea surface was downward continued to the ocean bottom by the inverse finite difference method with the water velocity and then was reversely continued to the ocean surface by the finite difference method using the layer velocity from just below the ocean bottom in the (ξ, η) domain. Simulation calculations and practical application show that this method can not only remove the reflection travel time distortion but also correct the dynamic parameter changes caused by the ocean bottom topography. The inverted velocity after wave field continuation is much more accurate than before continuation and the image section was greatly improved compared to the original wave field.
WANG Xiang-Chun,XIA Chang-Liang,LIU Xue-Wei. Downward and upward continuation of 2-D seismic data to eliminate ocean bottom topography’s effect[J]. APPLIED GEOPHYSICS, 2010, 7(2): 149-157.
[1]
Ai, Y. S., and Zheng, T. Y., 1998, Wavefield continuation depth filtering: Chinese Journal of Geophysics, 41(3), 400 - 407.
[2]
Berryhill, J. R., 1979, Wave-equation datuming: Geophysics, 44(8), 1329 - 1344.
[3]
Bevc, D., 1997, Flooding the topography; wave equation datuming of land data with rugged acquisition topography: Geophysics, 62(5), 1558 - 1569.
[4]
Fornberg, B., 1998, The pseudospectral method: Accurate representation of interfaces in elastic wave calculations: Geophysics, 53(5), 625 - 637.
[5]
Hestholm, S., and Ruud, B., 1994, 2D finite-difference elastic wave modeling including surface topography: Geophysical Prospecting, 42, 371 - 390.
[6]
Hestholm, S., and Ruud, B., 1998, 3-D finite-difference elastic wave modeling including surface topography: Geophysics, 63(2), 613 - 622.
[7]
Liu,Y.,Li,C.C.,and Mou Y.G.,1998, Finite-difference numerical modeling of any even-order accuracy,Oil Geophysics Prospecting, 33(1), 1 - 10.
[8]
Nielsen, P., and Skovgaard, O., 1994, Using the pseudospectral technique on curved grids for 2D acoustic forward modeling: Geophysical Prospecting, 42, 321 -341.
[9]
Tessmer, E., Kosloff, D., and Behle, A., 1992, Elastic wave propagation simulation in the presence of surface topography: Geophysics. J. Int., 108, 621 - 632.
2010, Vol. 7 
