Semi-discrete Matrix-Free Formulation of 3D Elastic Full Waveform Inversion Modeling

Full waveform inversion (FWI) is an emerging subsurface imaging technique, used to locate oil and gas bodies. The key challenges that hinder its adoption by industry are both algorithmic and computational in nature, including storage, communication, and processing of large-scale system matrices, which impose cardinal impediments upon computational scalability. In this work we will present a complete matrixfree algorithmic formulation of a 3D elastic time domain spectral element solver for both the forward and adjoint wave-fields as part of a greater cloud based FWI framework. We will discuss computational optimisation (SIMD vectorisation, use of Many Integrated Core architectures, etc) and present scaling results for two HPC systems, namely an IBM Blue Gene/Q and an Intel based system equipped with Xeon Phi coprocessors.