95 Sustainable Subsurface Pore Space Utilization: Site Selection, Characterization, and Modeling

This session explores site selection, characterization, and modeling for pore space utilization, including hydrogen, natural gas, and CO2 storage, waste disposal, geothermal development, and energy recovery. Emphasis is on project interactions, synergies, and storage integrity.

Monday, 20 October 2025
8:00 AM - 12:00 PM
HBGCC, 302C

Laboratory Characterization of the Effects of Supercritical CO₂ Injection in Sedimentary Rocks

Paper number: 95-2
Program: Technical Sessions
Time: 8:20 AM – 8:35 AM

Authors

Abstract

Geological carbon sequestration is being considered as one possible approach to reduce atmospheric CO2 concentrations over the long term. Our project aims to advance methodologies for characterizing the sequestration potential of sedimentary reservoirs at depth, with a focus on medium to low-porosity sedimentary formations. The primary objective is to experimentally track and possibly quantify the impact of CO2 injection into various representative rock types, including limestone, dolostone, and sandstone, using laboratory-scale experiments. Modifications in critical reservoir properties such as porosity and permeability, as well as chemical alterations and changes in rock fabric and brines, are systematically observed and measured before and after CO2 injection. The experimental setup developed consists of a pressurized vessel, a CO2 liquid tank and a high-pressure metering pump. The setup was designed to work at reservoir pressure (CO2 supercritical state) but with higher temperature to increase reactions kinetics. CO2 is injected into brine saturated samples placed in the reactor and reactions conditions are maintained for periods ranging from 7 days to 2 months. In most cases, experiments have shown increased concentrations of major ions and conductivity as well as a pH decrease in the brines, all consistent with rock dissolution. While pH stabilized between 5 and 5.55 for most rocks, Indiana limestone reached a higher pH of 6.85, suggesting a stronger buffering effect and more pronounced interaction with brine and gas. This is further supported by higher conductivity and increased concentrations of major ions (Na, Mg, Si) in solutions from Indiana limestone, confirming greater dissolution and rock-fluid interaction compared to the other lithologies. The micro-CT images acquired before and after the reaction reveal subtle but noticeable changes in the pore structure, including both pore narrowing and, in some instances, pore enlargement. The narrowing suggests the migration of fine particles within the pore network and instances of partial or even complete clogging. Additionally, some samples exhibit clear evidence of salt precipitation on the core surface after the reaction, occasionally also showing reddish oxide stains, providing another potential explanation for the partial clogging of certain pores in the network. In Indiana Limestone and Silurian Dolomite, petrographic observations provide some indication of subtle pore-enhancing mechanisms, possibly related to etching of the pore surfaces, though these effects appear minor.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412900

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