  Holistic understanding of multiphase reactive flow mechanisms such as CO$_2$
dissolution, multiphase displacement, and snap-off events are vital for
optimisation of large-scale industrial operations like CO$_2$ sequestration,
enhanced oil recovery, and geothermal energy. Recent advances in
three-dimensional (3D) printing allow for cheap and fast manufacturing of
complex porosity models, which enable investigation of specific flow processes
in a repeatable manner as well as sensitivity analysis for small geometry
alterations. However, there are concerns regarding dimensional fidelity, shape
conformity and surface quality, and therefore the printing quality and printer
limitations must be benchmarked. We present an experimental investigation into
the ability of 3D printing to generate custom-designed micromodels accurately
and repeatably down to a minimum pore throat size of 140 micrometers, which is
representative of the average pore-throat size in coarse sandstones.
Homogeneous and heterogeneous micromodel geometries are designed, then the 3D
printing process is optimised to achieve repeatable experiments with
single-phase fluid flow. Finally, Particle Image Velocimetry is used to compare
the velocity map obtained from flow experiments in 3D printed micromodels with
the map generated with direct numerical simulation (OpenFOAM software) and an
accurate match is obtained. This work indicates that 3D printed micromodels can
be used to accurately investigate pore-scale processes present in CO$_2$
sequestration, enhanced oil recovery and geothermal energy applications more
cheapely than traditional micromodel methods.
