Abstract

The conventional elastic least-squares reverse time migration (LSRTM) generally inverts the parameter perturbation of the model rather than the reflectivity of reflected P- and S-modes, which leads to difficulty in directly interpreting the physical properties of the subsurface media. However, an accurate velocity model that is needed by the separation of seismic records of conventional LSRTM is usually unavailable in real data, which limits its application. In this study, we introduce a new practical correlative LSRTM (CLSRTM) scheme based on wave mode decomposition without amplitude and phase distortion, which frees from separation of seismic records. In this study, we deduced the migration and the de-migration operators using the decoupled P- and S-wave equations in heterogeneous media, which needs no extra wavefield decomposition in simulated data. To accelerate the convergence and improve the efficiency of the inversion, we adopted an analytical step-length formula that can be incidentally computed during the necessary de-migration process and the L-BFGS algorithm. Two numerical examples demonstrate that the proposed method can compensate the energy of deep structures, and generate clear images with balanced amplitudes and enhanced resolution even for the fault structures beneath the salt dome.

Highlights

  • Seismic migration plays an important role in constructing accurate images of the subsurface structure and lithology from seismic data

  • We deduced the de-migration operator that needs no separation of seismic records in comparison with works of the conventional elastic LSRTM (ELSRTM) of multicomponent seismic data, which reduce the cost of computation and remove the accurate velocity model dependence required by the separation of seismic records

  • We developed a new inversion scheme for the ECLSRTM method for multicomponent seismic data to obtain reflectivity images

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Summary

Introduction

Seismic migration plays an important role in constructing accurate images of the subsurface structure and lithology from seismic data. (Baysal et al [6]; McMechan [7]) utilizes a two-way wave equation to propagate the wavefields, which does not suffer from dip limitation and has a higher resolution in complex structures. LSM was first applied to Kirchhoff migration (Nemeth et al [11]; Duquet et al [12]) and later to one-way wave equation migration (Gazdag [3]), and recently was introduced into RTM (Tang [13]; Dai et al [14,15]; Wong et al [9]). The key idea of LSM is the amplitude matching strategy

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