Study on microscopic pores and permeability changes of coal frozen by liquid nitrogen based on CT scanning

ABSTRACT

Liquid nitrogen freezing has a certain promoting effect on improving the permeability of coal samples. In order to study the quantitative changes in the pore structure and permeability of coal samples after liquid nitrogen freezing, this paper carried out a three-dimensional reconstruction of the pore space structure of coal samples based on CT scanning experiments, and based on this, the porosity, connected pore volume, the equivalent pore radius, pore coordination number and permeability were studied based on the reconstruction model. The results show that the porosity of the coal samples in group B is 42.02% higher than that in group A after freezing with liquid nitrogen, the average value of the total connected pore volume, pore equivalent radius and coordination number of coal samples in group B are greater than those in group A, and they have increased by 16.5%, 2.95% and 14.8% respectively; the permeability in group B is 26.86% higher than that of group A, indicating that the pore connectivity and permeability of the coal samples in the liquid nitrogen freezing group have been significantly improved.

KEYWORDS:

• CT scanning
• liquid nitrogen freezing
• pore structure
• permeability

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Liaoning Province Doctoral Research Start-up Fund Project [No.2023-BS-203].