Our industry is in demand of imaging results beyond today’s resolution limits in order to progress in the next decades. We believe that exploiting all complex propagation effects in the seismic data is an important way to achieve this ambitious goal. This means that the end of ‘linear’ imaging methods, based on primaries only, and that multiple reflections, transmission effects and wave conversion are the key components of retrieving detailed, reliable information on both complex subsurface structures and the reservoir area.
Traditional Full Waveform Inversion concepts based on directly solving the two-way wave equation – is a highly nonlinear method, prone to local minima. Therefore, within Delphi we propose the Full Wavefield Migration (FWM) approach, which combines the best of imaging and inversion methods and exploits all higher-order scattering effects.
Extending this concept, Joint Migration Inversion (JMI) also includes the estimation of the background velocity model. Because our inversion parameters – being propagation velocity and reflectivity – connect more directly to the observed data (being arrival time and amplitude), we reduce the non-linearity of the inversion problem.
Furthermore, JMI is very much suited for application in a time-lapse fashion, where all vintages of seismic data are inverted simultaneously in order to obtain detailed, dynamic properties of the reservoir, taking into account geologic scenario information.