**6. Conclusions**

An experimental study was conducted to investigate the pore characteristics and permeability in coal-measure sandstones based on the pulse attenuation gas permeability tester and LF-NMR. The permeability variation with the effective stress and grains and the effects of NMR pore characteristics on permeability variation were analyzed in detail. The following conclusions were obtained:


**Author Contributions:** H.H. wrote the paper, conducted the experimental study, analyzed the results; Y.S. and X.C. wrote the paper, contributed to processing the raw data and completing the figures; Z.W., M.L. and S.Q. edited the original draft and made the tables. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Fundamental Research Funds for the Central Universities (2019XKQYMS57), a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions in China, Mining fissure field characteristics in high gas working panels in Jixi mining area and its influence on gas control (No. 2021060117), Influence of geological tectonic evolution on gas occurrence and migration in Xishan mining area, and the geological survey project of the China Geological Survey (No. DD20190101).

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
