Meikuang Anquan (Feb 2022)
Ewirgol Mining Area structure and its evolution on control of coal seam gas occurrence
Abstract
In order to clarify the control effect of geological structure and its evolution on the risk of coal and gas outburst in Ewirgol Mining Area in Xinjiang, this paper uses the methods of current in-situ stress measurement, basin burial history-thermal history simulation, and statistical analysis to analyze mine stress state, buried history of coal bearing strata, metamorphism of coal seam, gas generation and loss, coal and gas outburst risk, etc. The research shows that the current in-situ stress state of Xinjiang Ewirgol Mining Area is tectonic compression stress state, and the maximum principal stress direction is NE-SW direction. The Jurassic coal-measure strata in the mine has mainly experienced two major stages of evolution, and the first stage is rapid subsidence and reached the maximum burial depth of about 4 300 m in the Late Jurassic. The coal seam was subjected to deep formation and regional dual thermal metamorphism, and experienced the highest paleotemperature of 137 ℃ to 192 ℃, forming the first gas generation peak; the second stage was affected by tectonic compression of Yanshanian movement and Himalayan movement, the coal measure strata began to tilt and uplift and denude from late Jurassic-early Cretaceous. The coal seams rapidly cooled, and coal seam gas escaped. The deep thermal metamorphism and regional thermal metamorphism in the mining area directly lead to the vertical and horizontal gradients of coal rank and gas production in the mining area. The local differentiated geological structure and evolution directly lead to the preservation of coal seam gas between the mines in the mining area. The local differential structure and evolution directly lead to the difference of coal seam gas preservation conditions among the mines. Controlled by the current state of tectonic compression, geological structure and its evolution, the vertical syncline axis (the deep part of the north wing) of Ewirgol Mining Area is more dangerous for coal and gas outburst than the shallow part of the north wing. The 2130 coal mine area in the west is more dangerous than the 1930 coal mine area in the central area, followed by the 1890 coal mine area in the east.
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