Gradient for the acoustic VTI full waveform inversion based on the instantaneous traveltime sensitivity kernels

Ramzi Djebbi, Tariq Ali Alkhalifah

Research output: Contribution to journalArticlepeer-review

Abstract

The instantaneous traveltime is able to reduce the non-linearity of full waveform inversion (FWI) that originates from the wrapping of the phase. However, the adjoint state method in this case requires a total of 5 modeling calculations to compute the gradient. Also, considering the larger modeling cost for anisotropic wavefield extrapolation and the necessity to use a line-search algorithm to estimate a step length that depends on the parameters scale, we propose to calculate the gradient based on the instantaneous traveltime sensitivity kernels. We, specifically, use the sensitivity kernels computed using dynamic ray-tracing to build the gradient. The resulting update is computed using a matrix decomposition and accordingly the computational cost is reduced. We consider a simple example where an anomaly is embedded into a constant background medium and we compute the update for the VTI wave equation parameterized using vh, η and ε.
Original languageEnglish (US)
Pages (from-to)1430-1435
Number of pages6
JournalSEG Technical Program Expanded Abstracts 2015
Volume34
DOIs
StatePublished - Aug 19 2015

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