Study on fracturing monitoring and expansion law of underground gasification coal based on different gasification channel types

During the underground coal gasification process, the thermal stress produced at high temperatures will lead to coal cracking, which may cause gas leakage. Therefore, a real-time monitoring and regularity research of coal cracking is of significance for the long-term and stable operation of underground coal gasification systems. Acoustic emission (AE) technology is used to monitor coal fracturing activity in experimental models of different gasification channel types (coaxial gasification channel, coaxial gasification channel with bottom cross-hole, and V-type connection hole gasification channel). Based on the monitoring results, the influences of different operating parameters (gasification agent components and flow rates) and gasification channel types on coal fracturing activity and gasification area expansion are studied. Then, the crack distribution model constructed by moment tensor analysis is used to quantitatively analyze the crack position, type, and direction at the source of the AE during gasific