DOI: 10.25911/hgam-8n67
title: Segmented 3D images of supercritical CO2 dissolution into brine in Bentheimer sandstone tracked using X-ray micro-computed tomography

description: Segmented 3D images acquired during supercritical CO2 dissolution into brine in a Bentheimer sandstone core under the experimental conditions relevant to geologic carbon sequestration (45 degrees Celsius, 1250 PSI). Size of the processed cylindrical sample is 2421 voxel (9.50 mm) in diameter and 4428 voxel (17.37 mm) in height. The voxel size of the data is 3.923732 micron.
description: This dataset presents supercritical CO2 (scCO2) dissolution into brine in a Bentheimer sandstone core imaged via X-ray micro-computed tomography, and it is expected that the dataset will contribute to better understanding of dissolution trapping in geologic carbon sequestration. The dissolution experiment was conducted in a high-pressure, high-temperature system built in-house at the `National Laboratory for X-ray Micro Computed Tomography (CTLab)’ based at Research School of Physics, the Australian National University (ANU) under experimental conditions relevant to geologic carbon sequestrations at 45 degrees Celsius and 1250 PSI. Initially, scCO2 was trapped in the pore space of the Bentheimer sandstone (porosity equals 0.20) after cycles of drainage-imbibition experiments. In the subsequent dissolution experiment presented in this dataset, fresh brine with no dissolved CO2 was injected from the bottom to the top of the core at volumetric flow rate equals 0.02 ml/min, equivalent to Darcy velocity of 1.5E-5 m/s, to investigate dissolution of the trapped scCO2 into brine. The tomographic data (not included in this dataset; acquired in 2020) were acquired simultaneously as brine was injected via the helical scanning trajectory. Acquisition time for each scan was approximately 30 min, with the resultant voxel size equaling 19.47176 micron. The tomographic data were digitally registered to the high-resolution tomographic data acquired before the dissolution experiment for alignment of pore features and the trapped scCO2 phase, with the voxel size of the 9 resultant registered dissolution scans presented in this dataset (d1-9) equaling 3.923732 micron. The size of the cropped cylindrical sample is 2421 voxel (9.50 mm) in diameter and 4428 voxel (17.37 mm) in height. Identification of the physical phases in this study was accomplished via a `Converging Active Contours' (CAC) routine based on the intensity histogram of the tomographic images of the dissolution scans, where the scCO2 phase and the combined brine-and-solid phase were determined based on the intensity histogram of the tomographic images of the dissolution scans; the partially segmented images were then overlaid with the segmented dry scan to produce the finalized three-phase segmented images, where voxels labeled 1 represent the solid sandstone phase, 2 the brine phase, and 3 the scCO2 phase. Subsequent noise reduction measure includes relabeling scCO2 clusters smaller than 234 voxels (equivalent to sphere of radius 15 micron) as brine and relabeling floating grain in the scCO2 phase as scCO2. The initial scCO2 saturation in d1 was 11.9%, and remained unchanged in d2 with mobilization of scCO2 clusters observed between the scans. The scCO2 saturation decreased monotonically in subsequent scans, reaching 1.2% in d9. Data are in .nc format and can be read in ImageJ software via NetCDF plugins (http://www.unidata.ucar.edu/software/netcdf/).