Testing Bulk Properties of Powder-Based 3D-Printed Reservoir Rock Proxies

Abstract

3D printing with powders offers the most analogous method to the natural way in which clastic reservoir rocks are formed, resulting in pore network textures and morphologies similar to natural rocks. To characterize pore networks and their transport properties in rock proxies 3D-printed from powdered materials, solid proxy reservoir rocks were 3D-printed in aluminum, steel, ceramic, and gypsum powders. These proxies were analyzed using traditional destructive and nondestructive reservoir characterization methods. While CT and helium porosimetry helped identify connected porosity, mercury porosimetry provided information on the pore-throat size distribution. X-ray fluorescence was used to identify elemental composition of each material. Thin-section petrography provided further information on proxy pore network microstructure. Despite designing a solid digital model, 3D printers using powder materials can impart significant porosity as a byproduct of the printing process that can be used for repeatable flow and geomechanical experiments in proxies. Ceramic and aluminum proxies showed the lowest porosity. Gypsum proxies had the highest porosity (36%) and range of porosities (5–36%). Metal proxies (aluminum and steel) showed low porosity and minimal mercury intrusion. Proxies were printed in two sizes (8 mm × 15 mm and 25 mm × 25 mm). Larger proxies were lower in porosity except in the case of gypsum because of post-processing artifacts. Ceramic and gypsum proxies showed significant compressibility at high mercury intrusion pressures. Proxies printed in silica sand were the most analogous to natural reservoir rocks despite their high porosity (36–51%) and pore-throat size mode (70 μm).

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