Three-dimensional finite-difference finite-element frequency-domain wave simulation with multi-level optimized additive Schwarz domain-decomposition preconditioner: A tool for FWI of sparse node datasets

Efficient frequency-domain full-waveform inversion (FWI) of long-offset node data can be designed with a few discrete frequencies, which lead to modest volumes managed during the process. Moreover, attenuation effects straightforwardly implemented in forward problem without computational overhead. However, 3D seismic modeling is challenging because it requires solving large and sparse linear indefinite system for each frequency multiple right-hand sides (RHSs). This solved by direct or iterative methods. The former allows efficient processing RHSs but may suffer from limited scalability very problems. Iterative methods equipped domain-decomposition preconditioner provide suitable alternative process domains sparse-node acquisition. We have investigated based on optimized restricted additive Schwarz (ORAS) method, Robin perfectly matched layer condition at boundaries between subdomains. preconditioned Krylov subspace whereas block low-rank lower-upper decomposition local matrices performed preprocessing stage. Multiple sources are processed groups pseudoblock method. accuracy, cost, ORAS solver assessed against several realistic benchmarks. In terms discretization, we compare compact wavelength-adaptive 27-point finite-difference stencil regular Cartesian grid P 3 finite-element method h-adaptive tetrahedral mesh. Although both schemes comparable more computationally efficient, latter being beneficial comply known such as bathymetry. RHSs, straightforward implementation attenuation, further improves convergence solver, make versatile engine large-scale FWI applications sets.