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Elastic least-squares reverse time migration in vertical transverse isotropic media
- Source :
- GEOPHYSICS. 84:S539-S553
- Publication Year :
- 2019
- Publisher :
- Society of Exploration Geophysicists, 2019.
-
Abstract
- Using adjoint-based elastic reverse time migration, it is difficult to produce high-quality reflectivity images due to the limited acquisition apertures, band-limited source time function, and irregular subsurface illumination. Through iteratively computing the Hessian inverse, least-squares migration enables us to reduce the point-spread-function effects and improve the image resolution and amplitude fidelity. By incorporating anisotropy in the 2D elastic wave equation, we have developed an elastic least-squares reverse time migration (LSRTM) method for multicomponent data from the vertically transversely isotropic (VTI) media. Using the perturbed stiffness parameters [Formula: see text] and [Formula: see text] as PP and PS reflectivities, we linearize the elastic VTI wave equation and obtain a Born modeling (demigration) operator. Then, we use the Lagrange multiplier method to derive the corresponding adjoint wave equation and reflectivity kernels. With linearized forward modeling and adjoint migration operators, we solve a linear inverse problem to estimate the subsurface reflectivity models for [Formula: see text] and [Formula: see text]. To reduce the artifacts caused by data over-fitting, we introduce total-variation regularization into the reflectivity inversion, which promotes a sparse solution in terms of the model derivatives. To accelerate the convergence of LSRTM, we use source illumination to approximate the diagonal Hessian and use it as a preconditioner for the misfit gradient. Numerical examples help us determine that our elastic VTI LSRTM method can improve the spatial resolution and amplitude fidelity in comparison to adjoint migration.
- Subjects :
- Physics
Source time function
010504 meteorology & atmospheric sciences
Mathematical analysis
Isotropy
Seismic migration
010502 geochemistry & geophysics
01 natural sciences
Least squares
Reflectivity
Transverse plane
Geophysics
Geochemistry and Petrology
Anisotropy
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 19422156 and 00168033
- Volume :
- 84
- Database :
- OpenAIRE
- Journal :
- GEOPHYSICS
- Accession number :
- edsair.doi...........a49725e834efb1d0ba73abf2916037ac