Distribution of Upper Paleozoic Coal Seams in the Southeastern Ordos Basin

The Ordos Basin contains abundant coal resources in the Upper Paleozoic strata. They are shallowly buried or exposed periphery of basin, forming recoverable mines and coalbed methane resources. For deeply seams however, due to complex changes difficult mining, less attention was paid before. In recent years, with exploitation tight gas related source rocks, a large amount drilling seismic data has been accumulated southeastern Basin, which makes it possible study distribution change factors controlling seams. Delineation deep development is an important basis for coal, Paleozoic. We use core, logging analyze geophysics, thickness variation, paleotopography sedimentary facies Basin. lower part Shanxi Formation (Fm.) upper Taiyuan Fm. basin characterized by low natural gamma ray, density, high resistivity sonic values. As velocity very alternates high-velocity Ordovician limestones, two sets coals below above limestones form extremely strong-amplitude reflection profile. cumulatively 1–10 m thick, averaging 2.4 m, 4 maximum induvial thickness. individual thicker than 2 cover area approximately 2500 km2, burial depths seam range from 3000 m. thick mainly distributed proximally paleokarst depression, while depression without incised origin deposited distal coeval limestone rocks. There complementary relationship between thickened zone distributary channel sandstone