Evolution of pore structure, fracture morphology and permeability during CO2+O2 in-situ leaching process of fractured sandstone

Qinghe Niu, Jie Wang, Jiabin He, Wei Yuan, Jiangfang Chang, Wei Wang, Junhong Yuan, Qizhi Wang, Yongxiang Zheng and Songhua Shang

Energy, 2025, vol. 315, issue C

Abstract: This work is organized to reveal the influence mechanism and law of CO2+O2 in situ leaching on pore permeability characteristics of stimulated deposits. Results show that geochemical reactions during the CO2+O2 ISL process are complex, the dolomite and potassium feldspar are dissolved, while the clay mineral precipitates are formed. The response characteristics and mechanisms of pore-fracture structures differ between the single and multi-fractured samples during the CO2+O2 ISL process. The pore number density of the single-fractured sample increases while porosity decreases, causing larger pores to evolve into smaller ones. While the porosity and fracture volume of the multi-fractured sample increase significantly. The permeability characteristics of fractured samples are consistent with the evolution of pore-fracture structures. The multi-fractured sample possesses a higher fracture compression coefficient and lower PLR due to the larger compressive space, the self-supporting effect of fracture network and the scouring effect of leaching solution. Although creating a single fracture in reservoir stimulation can enhance the original deposit permeability, the conductivity will gradually decline during the subsequent CO2+O2 ISL process. Optimizing reservoir stimulation techniques to create complex fracture networks within deposits can enhance overall permeability and weaken the permeability reduction effect, ensuring the efficient extraction of uranium resources.

Keywords: Chemical reaction; Mineral composition; Pore; Fracture; Permeability; Reservoir stimulation (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:315:y:2025:i:c:s0360544224041264

DOI: 10.1016/j.energy.2024.134348

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