Geophysics SIG Meeting – September (Online)

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Speaker: Paul West – S-Cube 

Topic: Extracting seismic AVO parameters directly during full-waveform inversion of raw field data

Full-waveform inversion run to the full bandwidth of seismic field data is able to generate a multiple-free depth-migrated reflectivity volume directly from raw field data. It does this by mapping short-offset sub-critical reflectivity into velocity and density. Subsequent spatial differentiation of these models then extracts the primary reflectivity. The resultant PSDM image is equivalent to a fully non-linear, iterated, true-amplitude, acoustic, reverse-time migration. This approach gives the correct resultant near-normal-incidence reflectivity even when it is not possible to determine the separate relative importance of velocity and density to the reflectivity. It is straightforward to extend this acoustic FWI workflow to extract amplitude-versus-offset parameters that are exactly analogous to those generated by conventional migration. It is commonly assumed that full-elastic FWI would be required in order to extract AVO; that assumption is not correct. Elastic analysis is required to interpret AVO, but the extraction of AVO parameters is always undertaken using only acoustic migration; here FWI is no different. Consequently, everything that an interpreter normally requires from field data can be extracted easily and quickly from the raw data using only FWI – no processing, de-multiple, de-ghosting or explicit migration are required. We demonstrate this workflow for both synthetic and field data.

Paul West – S-Cube

Paul has over 25 years of experience in the seismic services sector. Having worked across the globe for industry leading technology companies and innovative smaller enterprises, he is now based in London with S-Cube. He works with industry and research partners to solve the most complex sub-surface modelling challenges with cloud-native, advanced formulations of waveform inversion.