caa a22 4500 477047246 CHVBK 20180405111333.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00882055 doi (NATIONALLICENCE)springer-10.1007/BF00882055 Tube wave modeling by the finite-difference method with varying grid spacing [Elektronische Daten] [Joachim Falk, Ekkehart Tessmer, Dirk Gajewski] A finite-difference approach of aP-SV modeling scheme is applied to compute seismic wave propagation in heterogeneous isotropic media, including fluid-filled boreholes. The discrete formulation of the equation of motion requires the definition of the material parameters at the grid points of the numerical mesh. The grid spacing is chosen as coarse as possible with respect to the accurate representation of the shortest wavelength. If we assume frequencies lower than 250 Hz then the grid spacing is usually chosen in the range of a few meters. One encounters difficulties because of the large-scale difference between the grid spacing and the size of the borehole, usually several centimeters. These difficulties can be overcome by a grid refinement technique. This technique provides the construction of grids with varying grid spacing. The grid spacing in the vicinity of the borehole is chosen such that the borehole is properly represented. An example demonstrates the accuracy of this technique by comparisons with other methods. Unlike many analytical methods, the FD method can handle complex subsurface geometries. Further numerical examples of walk-awayVSP configurations show tube wave propagation within fluid-filled boreholes of realistic diameters. Birkhäuser Verlag, 1996 Borehole modeling nationallicence finite-difference method nationallicence grid refinement nationallicence Falk Joachim Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut Tessmer Ekkehart Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut Gajewski Dirk Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut pure and applied geophysics Birkhäuser-Verlag 148/1-2(1996-03-01), 77-93 0033-4553 148:1-2<77 1996 148 24 https://doi.org/10.1007/BF00882055 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00882055 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Falk Joachim Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut NATIONALLICENCE 700 1- Tessmer Ekkehart Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut NATIONALLICENCE 700 1- Gajewski Dirk Institut für Geophysik, Universität Hamburg, Bundesstraße 55, D-20146, Hamburg, Germany aut NATIONALLICENCE 773 0- pure and applied geophysics Birkhäuser-Verlag 148/1-2(1996-03-01), 77-93 0033-4553 148:1-2<77 1996 148 24 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer