In-situ gas contents of a multi-section coal seam in Sydney basin for coal and gas outburst management

• Published in: International journal of coal science & technology 2023-12, Vol.10 (1), p.62-13, Article 62
• Main Authors: Li, Zhongbei, Ren, Ting, Black, Dennis, Qiao, Ming, Abedin, Itmam, Juric, Jessica, Wang, Mike
• Format: Article
• Language: English
• Subjects: 1st IJCST Doctoral Students Forum; Carbon dioxide; Coal and gas outburst; Coal industry; Coal mining; Direct desorption method; Energy; Fossil Fuels (incl. Carbon Capture); Gas component; Gases; Geotechnical Engineering & Applied Earth Sciences; In-situ coal seam gas content; Measurement techniques; Methods; Mineral Resources; Mines and mineral resources; Mining accidents & safety; Natural gas reserves; Oil and gas exploration; Sorption; Sorption capacity; Strategic planning (Business)
• ISSN: 2095-8293; 2198-7823
• DOI: 10.1007/s40789-023-00614-4

The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO 2 composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components ( Q 1 , Q 2 , and Q 3 ) of the coal seam. The results show that in-situ total gas content ( Q T ) ranges from 9.48 m 3 /t for the A2 section to 14.80 m 3 /t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q 2 demonstrates the highest contribution to Q T , ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO 2 sorption behavior, with fit coefficients ( R 2 ) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content ( Q 3 ) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q 1 and Q 2 gas contents, lower sorption hysteresis, and reduced coal toughness f value. 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.