Effect of CO2 Injection on Permeability Alterations of the Sandstone Formation During CO2 Storage in Low-Temperature Water Zones

Abstract The injection of carbon dioxide (CO2) into low-temperature water-bearing formations presents a promising approach for long-term carbon storage. However, the interaction between CO2, formation water, and reservoir rock can lead to permeability reduction, affecting well injectivity and carbon storage efficiency. This study investigates the effects of CO2 injection on the permeability in low-temperature water zones through experimental investigations. Permeability alteration is assessed under various injection pressures, temperatures, and injection flow rates to understand the impact of CO2 dissolution and hydrate formation. Experiments were conducted at 0–5°C, and flow rates of 10–60 mL/min. This research preliminary aims to ascertain the hydrate forming potential of CO2 in low temperature reservoirs through laboratory investigations as a means of non-leaking carbon storage. The permeability of the intact sandstone core sample was measured with water using Darcy's law before running the CO2 hydrate formation tests. The measured permeability is found to be 115 mD on average. Then CO2 was injected for a long period of time with varying injection pressures, temperatures, and injection flow rates to examine whether CO2 hydrates were formed or not in each test. Increased pressure differential between the inlet and outlet was considered as the indication of hydrate formation. The result of these hydrate formation tests has been presented in a previous research of the same authors. After completion of the tests the permeability of the core sample was measured with water again which yields a mean value of 25.5 mD. It was found that there was a 78% reduction in permeability after the core has undergone hydrate forming test. The reason behind this permeability alteration was attributed to the CO2 dissolution in the core that produced solid fines that plugged pores of the core sample. This was evidenced by the appearance of the core after tests that showed visible vessels/channels at the surface of core sample. The implication of the research result is that a significant decline in CO2 injectivity is expected, and this issue should be considered in designing CO2 injection projects in low-temperature water zones.