Wave-equation-based AVO inversion: A 1.5D elastic full-waveform inversion technique for improved reservoir characterization

Abstract Accurate subsurface characterization is vital for hydrocarbon exploration and the energy transition. Full-waveform inversion (FWI) potentially provides a complete data model by fully simulating elastic wave propagation in 3D, but it is computationally demanding. Linear amplitude variation with offset (AVO) inversion is computationally efficient by deploying a 1.5D data model but is limited by simplifying assumptions like primary reflections only. This study introduces elastic wave-equation-based AVO (WEB-AVO), which combines the efficiency of AVO inversion with the physical accuracy of FWI. Adopting the localized 1.5D setup from the AVO world, WEB-AVO incorporates interbed multiples, mode conversions, and transmission effects as is the aim of 3D elastic FWI. The technology can be considered as a localized target-oriented elastic 1.5D FWI with the purpose of improving quantitative reservoir characterization while using the full bandwidth of the seismic data. Forward modeling and inversion examples from synthetic and field data demonstrate the improvements obtained by WEB-AVO, compared with linear, primaries-only AVO inversion, at a fraction of the cost of full elastic 3D FWI.