Himalayan Geology, Vol. 41 (2), 2020, pp. 241-248, Printed in India
Experimental simulation on N2 injection for enhancing supercritical CO2 injectivity in anthracite reservoir
JIA JINLONG1,2*, CAO LIWEN3
1School of Xingfa Mining, Wuhan Institute of Technology, Wuhan, Hubei, 430073, China
2The Key Laboratory of Coal-based CO2 Capture and Geological Storage, Jiangsu Province, Low Carbon Energy Institute, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China
3School of Resources and Earth Science, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China
*Email (Corresponding author): 690201733@qq.com
Abstract: The injectivity of deep anthracite reservoir decreased significantly, which induced by supercritical CO2 (ScCO2) injection. In this paper, we had an investigation on N2 injection for improving ScCO2 injectivity in anthracite reservoir by the ScCO2-ECBM experimental stimulation apparatus, and had a discussion on the mechanism of N2 injection for enhancing ScCO2 injectivity in anthracite reservoir. The experimental data demonstrated that the anthracite original permeability was 3.10×10-5μm2, the permeability decreased to 5.80×10-8μm2 after ScCO2 saturated adsorption. However, the permeability of anthracite increased to 2.73×10-5μm2 as N2 displaced the 99.6% volume of ScCO2 in anthracite. The permeability of anthracite decreased to 3.39×10-8μm2 as the ScCO2 was injected to anthracite once again. The experimental results indicated that the N2 injection was a method to improve the permeability of deep anthracite reservoir effectively, and the permeability of coal seam could recover to the order of original permeability. In addition, the experimental results also indicated that the coal seam permeability change induced by ScCO2 injection was recoverable. N2 injection to the coal seam had a partial pressure effect, which could accelerate the ScCO2 desorption from coal matrix and flood the ScCO2 migration.
Keywords: Supercritical CO2; Anthracite reservoir; N2 injection; Injectivity.
