InterPore2025

Investigation of Pore Characteristics for CO2 Mineralization Through Digital Rock Physics

22 May 2025, 09:50

15m

Oral Presentation (MS25) Advances in Carbon Mineralization: Unveiling Multiscale Geo-processes and Coupled Mechanisms MS25

Speaker

Hyunjeong Jeon (Yonsei University)

Description

Despite extensive global efforts to mitigate climate change, CO2 emissions continue to rise, emphasizing the necessity of geologic carbon sequestration (GCS). CO2 mineralization is one of the effective methods of GCS, using CO2-fluid-rock reaction; after injection of CO2-charged water, CO2 is rapidly and permanently immobilized through carbon mineralization. In general, mafic/ultramafic rocks (e.g., basalt and peridotite) are targeted for CO2 mineralization due to their huge CO2 storage capacities with prevalence in the earth’s surface and high content of divalent metal cations. For instance, the CarbFix project targeting basaltic rocks in Iceland was successfully conducted in pilot-scale, showing that 95 % of injected CO2 was rapidly mineralized within 2 years.
It has been found that petrophysical properties such as porosity, permeability and surface area, which depend on pore space that enables fluid flow and reactions, significantly affect CO2 mineralization and control the CO2 storage potential of reservoir. Consequently, identifying pore characteristics is crucial for evaluating the impact of rock properties on CO2 mineralization. Digital Rock Physics (DRP), an advanced technology utilizing micro-CT imaging, allows for the non-destructive assessment of complex pore characteristics in rocks.
In this study, to evaluate the pore characteristics and the effect of the petrophysical properties of mafic/ultramafic rocks on CO2 mineralization, the DRP workflow, including micro-CT image analysis, was applied to rock samples (i.e., 5 basalt rocks from the CarbFix and Jeju Island in the Republic of Korea, and 1 peridotite). To do, those samples were scanned using the synchrotron at Pohang Light Source, and then high-resolution images with voxel resolution of 1.625 µm were acquired. Then, 3D pore structures of each rock sample were obtained through image reconstruction and segmentation processes, followed by estimation of the parameters such as absolute and effective porosity as well as specific surface area (SSA). Finally, permeability and pore characteristics were quantified by extracting the pore-network model.
The results so far show significant variation in the pore structures, even within the same rock type, resulting in differences in the petrophysical properties. The CarbFix basalts exhibit high porosity (~0.28) and permeability (~10-13 m2) due to macro-pores, along with high SSA attributed to the distinctive round structure of mineral precipitation. One of the Jeju basalts primarily consists of micro-pores, leading to low porosity (~0.10), but its permeability (~10⁻¹⁵ m²) and SSA are high due to a well-connected pore network and the pore size distribution. The porosity of peridotite is relatively low (~0.03), but its permeability is comparable to that of CarbFix basalt due to the presence of a fracture network. Ongoing research involves numerical modeling to quantitatively evaluate the effects of the petrophysical properties resulting from the pore characteristics on CO2 mineralization.