Stereotomography

Abstract

Stereotomography was proposed [Formula: see text] ago for estimating velocity macromodels from seismic reflection data. Initially, the goal was to retain the advantages of standard traveltime tomography while providing an alternative to difficult interpretive traveltime picking. Stereotomography relies on the concept of locally coherent events characterized by their local slopes in the prestack data cube. Currently, stereotomography has been developed in two and three dimensions, and precious experience has been gained. The expected advantages have been demonstrated fully (in particular, the efficiency and reliability of the semiautomatic stereotomographic picking strategies), and further studies have increased the method’s potential and flexibility. For example, stereotomographic picking can now be done in either the prestack or poststack domain, in either the time (migrated or unmigrated) or depth domain. It appears that the theoretical frame of stereotomography can reconcile, very satisfactorily and efficiently, most methods proposed for velocity-macromodel estimation for depth imaging. Moreover, an extension of the method to full-waveform inversion already exists and opens the way for very interesting developments.

Layer-stripping full waveform inversion with damped seismic reflection data

“…Initial velocity model can be derived from migration velocity analysis or traveltime tomography (Lambaré, 2008;Zhu et al, 2008;Zhou, 2006) or Laplace domain waveform inversion methods Cha, 2009, 2008). The acoustic wave equation is only an approximation to the wave physics in real 3-D world.…”

“…For transmission acquisition geometry, several factors, including the high-frequency assumptions, limit the resolution of this method to the order of radius of first Fresnel volume (Williamson and Worthington, 1993;Williamson, 1991). In reflection tomography, velocity-depth ambiguity, sparse ray-angle coverage and continuous reflection event tracking, require additional effects to constrain the inversion process (Lambaré, 2008;Zhou, 2006;Bube et al, 1995). Compared with traveltime tomography, full waveform inversion (FWI) tries to fit synthetic with observed waveforms and does not need phase picking.…”

A parallel evolution strategy for an earth imaging problem in geophysics

“…Similarly, the stereotomography is regarded as one of the most promising methods for building a smooth velocity model. It exploits the arrival time of locally coherent events within an automatic procedure to select a seismogram collection [27]. Some applications to synthetic and real data sets are shown in [7,8].…”

“…Hence, before applying the fullwaveform inversion, a starting model is generally built. To do this, the most common techniques are first-arrival travel-time tomography (FATT) [30], stereotomography [27] or, more recently, inversion in the Laplace domain [41]. For many years, FATT has proven to be stable in generating smooth velocity models of the subsurface.…”

“…In industry, first-arrival travel-time tomography [30] is the most popular method to generate an accurate initial propagation velocity model. More recent methods such as stereo tomography [27] and inversion in the Laplace domain [41] are being investigated in academia. It must be also mentioned here that the use of multiscale strategies can mitigate the nonlinearity and reduce the dependence on the starting velocity model for FWI [34,45].…”