Borehole-Constrained Multi-Parameter Full Waveform Inversion
Event name: 77th EAGE Conference and Exhibition 2015
Session: Full Waveform Inversion III
Publication date: 01 June 2015
Info: Extended abstract, PDF ( 1.54Mb )
Price: € 20
We propose a method that can use a-priori information regarding subsurface properties at a few select spatial locations and over a limited depth range to guide FWI towards a better overall solution without the need to form conventional migration images, pick horizons or determine reflector dips. A key challenge to incorporating spatially localized auxiliary constraints, such as borehole and rock-physics information, is to make them impact the whole inversion volume beyond the area adjacent to well locations. The approach we follow is to take advantage of the information imbedded in seismic data, or more specifically the FWI gradients, to perform extrapolation outside of well control. The method automatically extrapolates information in a physically meaningful way, guides FWI towards a better solution at no additional computational cost, and can be used to relax starting model accuracy and overcome some local minima. In general, constraints do not need to come from wells and can be based on rock physics or geologic knowledge about the subsurface. We successfully applied the new methodology to invert a field marine dataset. Simultaneous inversion for Vp,δ,ϵ led to improvements in gather flatness and more accurate depth positioning.