3D Printing Berea Sandstone: Testing a New Tool for Petrophysical Analysis of Reservoirs

Three-dimensional (3D) printing is a unique technology that enables building of 3D pore-network proxies from digital models. Proxies allow us to experimentally test petrophysical properties (e.g., porosity and permeability) that can supplement reservoir rock analysis. In this study, we tested the resolution and accuracy of a polyjet 3D printer for generating rock proxies from a digital model of Berea sandstone. A 20x25-mm (length x diameter) cylindrical sandstone "macroplug" (21.6% porosity) and a smaller 3.5x4.0-mm "microplug" (21.3% porosity) were analyzed with mercury intrusion porosimetry and were scanned with computed tomography at 10 and 4 mu m per voxel, respectively. A microplug digital model, with a porosity of 21.3%, a volume of 8 mm(3), and a modal pore-throat diameter of 18 mu m, was extracted from tomographic data and rescaled at 10x magni cation to meet the minimum pore resolution of the 3D printer (similar to 132 mu m). Proxies and core-plug samples were compared for porosity and pore-throat size distribution using two approaches: (1) mercury porosimetry; and (2) digital measurements from tomographic data. This comparison revealed a decrease in proxy porosity by similar to 2 percentage points and a decrease in pore-throat diameter by similar to 56 mu m relative to natural samples. These discrepancies could arise due to insufficient magni cation of the digital model or due to incomplete removal of the wax support material from the proxy pore space. Development of enhanced cleaning methods for pore space in polyjet proxies is needed to generate more accurate reservoir rock models.