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Localised Time-lapse 3D Elastic Full Waveform Inversion Using Finite-difference Injection and Wavefield Extrapolation
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Summary
We present a novel methodology for inverting 3D elastic time-lapse data for local target structures of the Earth’s interior. Since we are particularly interested in the small property change in a deep target region, we extrapolate sources and receivers on the Earth’s surface to a virtual surface in the vicinity of the region of interest, in order to facilitate and stabilise full waveform inversion (FWI) scheme. The key is i) finite-difference injection method (FDIM) for source representation onto the small deep region; and ii) wavefield extrapolation (WE) for receiver side, which takes fully into account elastic behaviour outside the region. Here in this presentation, for the first time, we present the combination of FDIM and WE in order to perform time-lapse 3D elastic FWI for localised structures deep beneath the Earth’s surface. This localised FWI allows us not only to significantly reduce computational costs and memory requirements, but also to stabilise inversions and avoid spurious model update. In this paper, we compare mainly the first gradients of the localised time-lapse 3D elastic FWI with those obtained by FWI for a whole area.
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