首页|Self-adaptive numerical dispersion suppressed method for shallow seismic simulation
Self-adaptive numerical dispersion suppressed method for shallow seismic simulation
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NETL
NSTL
Taylor & Francis
Near-surface in seismic exploration generally refers to the low deceleration zone and a sectionof stratum below it, which can be described in geophysical language as “low velocity”, “low Q”,and “Free surface”, etc. Due to the presence of low-velocity layers in near-surface, shallow seismicsimulation is plagued by numerical dispersion. Numerical dispersion affects the accuracyof seismic wave simulation, especially severe in shallow areas containing low-velocity layers. Toimprove the simulated quality, denser grids or higher-order difference schemes are used, butboth of which would seriously reduce computational efficiency, especially for frequency-domainnumerical modeling. Differentiation is replaced by difference in wave field simulation, whichwould inevitably result in numerical errors. These numerical errors are manifested as the differencebetween the phase velocity of the discretized wave field and the medium velocity. Thewaves with different wavenumber components have different phase velocities, and the largerthe wavenumber, the more that its phase velocity lags the group velocity. Based on this theoreticalanalysis, a regularization factor is added to the frequency-domain acoustic wave equationto correct the phase velocity of high wavenumber components. According to the Von Neumannstability requirements, a regularization factor that adaptively changes with simulation parametersis derived. Compared to the fixed regularization factor, adaptive regularization factor canbetter match the velocity field and protect the effective wave field to the maximum extentwhile suppressing numerical dispersion. The improved acoustic wave equation can effectivelysuppress numerical dispersion without increasing the number of grids. Different numerical modelsdemonstrate the effectiveness and efficiency of the improved acoustic equation with theadaptive regularization factor for suppressing numerical dispersion.
NETL
NSTL
Taylor & Francis
