Sedimentary Environment and Gray Forcast of the Main Workable Coal Seams in Taiyuan Formation, Liaocheng Coal Field, Shandong

Liaocheng coal field situates in the northwestern margin of western Shandong uplift, is an unit of Carboniferous-Permian coal-bearing basin of Northern China. Taiyuan Formation, one of the main coal-bearing stratum, composed of sandstone, siltstone, mudstone, limestone and coal seams, can be divided into five complete sedimentary cycles, and 6 coal seams were found in the formation, they are the fifth to the tenth coal seams, among them, the ninth and the tenth are main workable ones. Conventional geophisical logging have been made of all the boreholes, the logs obtained mainly are apparant resistivity, spontaneous potential, natural gamma-ray logging and so on. For the research of sedimentary environment, apparent resistivity and natural gamma-ray log were used as principles. Based on the study of sedimentology and well logging, the authors discussed the sedimentary characicrs and geophisic feature, then divide the log into five facies (expresed as A, B, C, D and E), and concluded that the sedimentary environment of Taiyuan Formation was tranzitional, including barrier island, lagon, tidal flat, subtidal zone and peat swamp etc. The nineth and tenth coal seams were the products of swamping lagoon. A ccording to the study of sedimentary envirenment, the authors discussed the accumulative characteristics of the nineth and tenth coal seams and quatitatiely pridicted their thickness, and then a gray mathematical model GM (1, 1) was established to quantitatively pridict thickness of the two coal seams. The results of qualitative and quantitative pridict are bascally coincident.