The coal forming environment and coal reservoir characteristics of Late Permian in Panjiang area

Guizhou Panjiang area is not only one of the largest coal industrial bases, but also important area for coalbed methane exploration and development in south China. To reveal the main coal forming environment of Longtan Formation in Panjiang area, paleosalinity and sulfur content of main coal were studied with coal petrology and sedimentology. In addition, the influence of coal accumulating environment on the properties of coal was discussed. There are some findings:first the main coals have rich vitrinite and high V/I, the vertical change of V/I is smaller-larger-smaller; Second, sulfur content in the lower part of Longtan Formation is high (more 3%), and in the upper it is 1% on average. These show that the coal forming environment may have experienced partial dry-wet-partial dry evolution process, and changed from the salting lagoon to the freshing lagoon due to great amount of rainfall. The good linear relationships between ash content, porosity and V/I indicate that the coal forming environment has certain effect on the physical properties of coal reservoirs.