Influence of different $ CO_{2} $ phase states on fluid flow pathways in coal: insights from image reconstruction and fractal study

Abstract The $ CO_{2} $ phase state changes during the long-term interaction with coal seams. A proper understanding of the influence of different $ CO_{2} $ phase states in water-bearing coal seams is of great significance in evaluating the leakage risk during $ CO_{2} $ sequestration. The evolutio...
Ausführliche Beschreibung

Abstract The $ CO_{2} $ phase state changes during the long-term interaction with coal seams. A proper understanding of the influence of different $ CO_{2} $ phase states in water-bearing coal seams is of great significance in evaluating the leakage risk during $ CO_{2} $ sequestration. The evolution of fluid flow pathways in water-bearing coal subjected to the treatment of different $ CO_{2} $ phase states was investigated by using X-ray computed tomography (CT) technology, fractal dimension, and three-dimensional (3D) pore-scale flow modeling. The results show that the supercritical $ CO_{2} $ ($ ScCO_{2} $) treatment reduced the coal heterogeneity by 12.69% and increased the absolute permeability by 58.75%. Conversely, only 0.71% of coal heterogeneity reduction occurred after subcritical $ CO_{2} $ ($ SubCO_{2} $) treatment, increasing the absolute permeability by 24.91%. The reduction in the tortuosity fractal dimension after $ ScCO_{2} $ treatment was 2.69% larger than that of $ SubCO_{2} $ treatment, indicating that $ ScCO_{2} $ treatment was more favorable for improving the transport capacity of flow pathways. The pressure field distributions in the pore network model (PNM) were determined by coal heterogeneity and influenced by the number of flow pathways. The effect of $ ScCO_{2} $ treatment on the size, quantity, and location of preferential flow pathways in coal is more significant than that of $ SubCO_{2} $ treatment. Moreover, the proportion of preferential flow pathways in $ ScCO_{2} $-treated coal was less than 50%, much lower than that of the throats in PNMs. In contrast, the proportion of preferential flow pathways in $ SubCO_{2} $-treated coal was approximately 30% higher than that in $ ScCO_{2} $-treated coal. The distribution of preferential flow pathways also indicated that not all pores with larger radii participated in preferential flow. Furthermore, more than 50% of the pathways in the $ ScCO_{2} $-treated coal did not contribute to fluid flow, and could affect the stability of the coal seam. Ausführliche Beschreibung

Autor*in:	Luo, Peng [verfasserIn] Zhang, Zhenyu Zhang, Lei Liu, Xiaoqian Liu, Xiaobo

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2023

Schlagwörter:	CO geological sequestration leakage -water-coal interactions Fractal dimension of tortuosity Preferential flow pathways

Anmerkung:	© Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Übergeordnetes Werk:	Enthalten in: Bulletin of engineering geology and the environment - Berlin : Springer, 1970, 82(2023), 7 vom: 22. Juni
Übergeordnetes Werk:	volume:82 ; year:2023 ; number:7 ; day:22 ; month:06

Links:	Volltext

DOI / URN:	10.1007/s10064-023-03322-0

Katalog-ID:	SPR051991454