A Generic Multi-parameters FWI Framework Based on Symbolic Expressions

Summary The extension of full waveform inversion to multi-parameter is the straightforward step towards achieving its full capability, i.e. extracting high resolution information about the sub-surface properties of the Earth based on seismic data. Elastic and visco-elastic FWI begin to be computationally affordable at large scale using the latest HPC technologies and thus to introduce the option to invert for more parameters such as shear wave velocity and attenuation. FWI code design is a key point to allow geophysicists to test new inversion parameterization with minimal code developments. In this study we present a framework based on the abstraction of the parameters inverted. We describe how our framework allows us to use different wave equation propagators with different optimization schemes in a transparent and flexible way. We also show how using a symbolic expression parser to automatically compute required chain rules can greatly reduce the effort needed to implement and test new parameterizations while preserving computational efficiency of the code. We finally present how this symbolic parser can be used to easily implement master-slave relationships between inverted and passive parameters. We then present some FWI tests using different types of parameterizations on the SEAM synthetic model.