“…A reduced order model (ROM) that aims to produce a low-dimensional representation of FOM could be an alternative to handling field-scale inverse problems, optimization, or real-time reservoir management (Schilders et al, 2008;Amsallem et al, 2015;Choi et al, 2019;Choi, Boncoraglio, et al, 2020;McBane & Choi, 2021;Yoon, Oostrom, et al, 2009). The ROM methodology primarily relies on the parameterization of a problem (i.e., repeated evaluations of a problem depending on parameters), which could correspond to physical properties, geometric characteristics, or boundary conditions (Ballarin et al, 2019;Venturi et al, 2019;Hesthaven et al, 2016;Hoang et al, 2021;Copeland et al, 2021;Choi, Coombs, & Anderson, 2020;Carlberg et al, 2018). However, it is difficult to parameterize heterogeneous spatial fields of PDE coefficients such as heterogeneous material properties by a few parameters.…”