The study of geological processes at the pore-scale has significant implications to understanding many real-world phenomena related to flow in porous media (e.g., hydrogeology, petroleum geology and engineering, CO2 sequestration). While numerical and experimental analyses of sedimentary-rock pore systems have advanced to the characterization of nanometer-scale features, correlation of data across multiple scales of investigation (e.g., between seismic data, core samples, thin-section images, and SEM images) is still challenging. The differences arise in petrophysical properties (e.g., permeability) calculated on the same pore network under varying experimental conditions (e.g., pressure, temperature). 3D printing is a rapidly evolving technology that enables the manufacture of intricate 3D pore-network models (defined in this research as proxies) that can be investigated experimentally and compared to numerical simulations repeatedly.

The main objective of my Ph.D. research has been to improve our understanding of the accuracy of 3D-printed pore networks in comparison to natural rocks. In addition, the researched aimed at: 1) the improvement of building and post-processing workflows for accurate geometric replication of pore networks by each 3D printing technique; 2) the establishment and enhancement of validation workflows to test transport properties of rock proxies (e.g., porosity and permeability); and 3) the characterization of artifacts related to 3D printing, post-processing, and validation methods for several common 3D printing methods.

While all 3D printers build models layer-by-layer, the physical and chemical properties of build materials, the build process itself, and post-processing methods vary widely. My research results provide the extent to which major 3D printing techniques (binder jet, polyjet, stereolithography, and fused depositional modelling) and associated materials (powders, polymers, resins, and plastics) can generate useful proxies of common porous sandstones (Idaho gray, Berea, and Fontainebleau) that can be tested in the laboratory as natural porous rocks. The accuracy and resolution of each technique was evaluated by testing the 3D printers with simple pore proxies (built from simple numerical models) and natural rock proxies (built from computed tomography data of natural porous rocks). With future advances in 3D printer resolution and materials, the fidelity with which we can reproduce natural rock pore systems should improve.