The gas content and composition are widely utilized in underground coal mining to evaluate the potential for coal and gas outbursts. This study investigates the in-situ coal seam gas content and gas sorption capacity in three coal seam sections (A1, A2, and A3) in Sydney basin to understand their implications for gas management and outburst risk in Australian coal mines. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ coal seam gas components (Q1, Q2, and Q3) and gas composition. This method offers a reliable and accurate approach for assessing coal seam gas content and composition, with an error factor of ± 15%. The results revealed gas contents in the A1 and A3 sections exceeding Level 2 Threshold Limit Values (TLV), necessitating gas drainage measures. High-pressure isothermal gas sorption experiments were conducted on coal samples from the A1, A2, and A3 seam sections to investigate their gas sorption capacity. The Langmuir model demonstrated excellent performance in describing CO2 sorption behavior, with fit coefficients R² greater than 0.99. The study observed a strong positive correlation (Pearson's coefficient >0.855) between in-situ gas content and Langmuir volume, suggesting that higher sorption capacities correspond to higher in-situ gas content in coal seams. The findings of this study highlight the importance of understanding the relationship between in-situ gas content and gas sorption capacity in managing gas emissions and mitigating outburst risks in underground coal mines. The insights derived from the study can contribute to the development of effective gas management strategies and enhance the safety and efficiency of coal mining operations in Australia.
