“…There have been multiple attempts so far to approximate a proper but cheaper preconditioner (e.g., Jun et al, 2015;Lu et al, 2018). Recently, Abolhassani and Verschuur (2022a) proposed a cheap, depth-based, data-domain preconditioner in the context of iterative least-squares one-way wave-equation migration (LS-WEM) for image reconstruction. This expanded abstract will build on their proposal for a cheap, depth-based preconditioner for high-resolution background velocity reconstruction with ORWI.…”