Sedimentary Facies and Favorable Coal Seam Analysis of Leping Formation (Late Permian)in Junlian Area

Abstract

The paper studied on the stratigraphic characteristics, sedimentary facies, and the relationship between the sedimentary facies and coal accumulation through the observation and description of the drilling cores and outcrop sections of Leping Formation (Late Permian) in Junlian area. The gas production potential of different types of coal seams was illustrated from the aspects of coal seam development scale, thickness and stability. The results show that: chronostratigraphy is limited to Wuchiapingian Stage and Changhsingian Stage; lithostratigraphy is Leping Formation with lower and upper members in ascending order; two types of facies provinces are developed, the offshore plain and coastal facies province from west to east. The former belongs to the meandering river-lake-swamp sedimentary system, and the latter is a mixed source barrier coastal sedimentary system of carbonate and clastic rocks. The main coal seams C7+C8 and other coal seams are the swamping result of river, lake, tidal flat and lagoon. The favorable facies belt is river-lake-swap with certain distance away from Kangtien old land. The paper proposed that the coal seams C7+C8 in south of Sichuan Province, corresponding to M16 and M18 in the northwest of Guizhou Province and C5+C6 in the northeast of Yunnan Province, are the favorable coal measures with stable and large-scale distribution.

Keywords

• sedimentary facies
• favorable coal seam
• leping formation
• late permian
• junlian area
• coalbed methane exploration