Geological Features And Evaluation Of Mining Geological Conditions For Deep Coal Bed In Xingbei Coal Field

Hebei Province is rich in coal resources, especially in Carboniferous and Permian, which is widespread and has huge reserves. The next goes to Early Jurassic. However, with the increase of energy consumption and exploitation degree, coal resources in shallower layers is decreasing day after day, and the mining areas at home and abroad successively turn to exploit deep resources. The deep coal bed in Xingbei is one of the best targets to exploit availably with large reserve and medium burial depth. It has a lot of economic and social returns and assures the stable output of coal with high quality for coking and effective supply.The study focuses on the deep coal bed in Xingbei coal field. In this paper, it elaborates the distribution characteristics and occurrence of this coal bed, impacts on the coal quality in the metamorphic process, paleo-geography features and coal accumulating pattern of the main coal bed, and then the mining geological conditions were evaluated.Based on the theory of sequence stratigraphy, especially that of base level changes and accommodation space changes, the paper will use cores and outcrops observation to do some researches on the coal accumulation model and the sequence stratigraphy of the late Paleozoic in Xingbei coal field. The study shows that the sequence stratigraphy of the Neopaleozoic coal beds is closely related to coal-generation mechanism, migration of the coal-rich belts and the formation of coal-rich units. By stratigraphic structure analysis and 3-D visualization modeling of deep coal beds, it provides help in deep understanding of the stratigraphic structure in different ways and also provides essential geologic parameters in later evaluation and prediction of coal resource.The coal bed in this area is completely subtle in Carboniferous and Permian. The sedimentary environment is terrestrial and mutually transition marine and terrestrial facies. The coal accumulation formed in Late Carboniferous and Early Permian. The main coal bed are in Taiyuan Formation and Shanxi Formation with five available layers, four of them are exploitable in this area (No.2, 6, 7, 9) and one of them is partially exploitable (No. 2). The thickness variation coefficient of the main coal bed is lower so that it is steady exploitable. The coal type in this area is gas coal and orthobituminous coal for coking and industry. The components contain low to medium ash less than 10%, super-low, low to medium sulfur, high volatile constituent and heat output, super-low to low phosphor and rich in oil. It has strong binding property and the thickness of gelatinous layer ranges from 9.5 to 46.5 millimeters.According to the research on the mining geological conditions, the factors having impacts on the coal bed production are made clear, which contain the thickness, burial depth, structure, coal type, quality, and Ordovician limestone water and so on. No. 2 and 8 and 9 coal seams are available for motorization production and have reasonable economic technologies. The burial depth ranges from 510 to 1500 meters in this area. The difficulty will grow with depth because of the limitation of exploitation and production technologies.