3-D PRINTING PORE SYSTEMS TO PHOTOCOPY RESERVOIR ROCKS

3D printing is a new technology that provides unique opportunity of manufacturing reservoir rock copies by transforming digital models into lab-testable samples. This technology also enables resurrection of physical samples from microscopy or tomography image data when rock samples are rare or absent.

We present a novel approach of implementing petrophysical analysis for pore systems of reservoir rock combining digital rock imaging, 3-D printing, and mercury injection porosimetry. 3-D printed rock copies were used for experimental analysis of pore system properties (porosity, surface area, and pore size distribution) and flow properties (permeability). The same set of petrophysical properties was analyzed on digital models that were compared to the results from rock copies. Mercury injection tests performed on core plug samples and 3-D printed models helped identify the accuracy and resolution of 3-D printing materials and manufacturing processes.

This workflow for 3-D printing rock copies was conducted on core plugs of the Berea sandstone. Plug subsamples were CT scanned and segmented into digital models (3 mm on each side) of pore and grain phases. The resolution of CT images was 4.5 microns; the resolution of 3-D printing varied from 10 to 300 microns. Digital models of Berea sandstone grain matrix (solid phase) extracted from CT volumes were upscaled at 10x magnification. Each solid phase model was 3-D-printed in plastic. These “copies” and original rock samples were compared using two approaches: 1) mercury porosimetry on natural rock and 3-D printed copies and 2) statistical measurements on digital pore models and CT scans of 3-D printed samples.

Comparison of porosity and pore throat size distribution measured on 3-D printed models and natural samples indicated that additional pore space was likely introduced during the 3-D printing process. This artifact should be accounted for in future attempts to 3-D print pore networks.