Characteristics of shale and gas content of Niutitang Formation in Changde region of Hunan Province

The Lower Cambrian Niutitang Formation in Changde region of Hunan Province is regarded as an important shale gas exploration layer. The Niutitang Formation is mainly composed of carbon-enriched siliceous shale, carbonaceous shale and stone coal. Based on the observation of field outcrops, well cores and regional geology data, integrating with analysis of rock organic geochemistry, mineral content, reservoir space type, physical mechanical properties and gas content, the features of shale in Niutitang Formation are studied in detail. The results indicate that shale in the Niutitang Formation is characterized by stable thickness and wide distribution areas, high organic carbon content, high levels of thermal evolution, large specific surface area with micro pore and fracture, and good gas adsorption ability. The mineral composition is dominantly clastic quartz and clay minerals, with feldspar, calcite, dolomite, pyrite and so on. The shale reservoir with high brittle mineral is easy to fracture. The shale real thickness of CY1 well is more than 310m, and the gas content is 0.5-2.1 m3/t. It shows good reservoir conditions. The comprehensive evaluations by this paper indicate that this area has good shale gas exploration prospect. ©, 2015, Science Press. All right reserved.