Mineral Composition and Brittleness of Lower Cambrian Niutitang Formation Shale in Northwest Hunan

This paper determines the mineral composition and analyzes the brittlenessof Lower Cambrian Niutitang formation shale in Northwest Hunan using XRD technology. The results show that Niutitang formation shale in Northwest Hunan has rather complicated composition, mainly consisting of quartz and clay minerals. The average content of quartz is 41.40%~60.81%, and the average content of clay minerals is 21.43%~26.40%. Calcite, plagioclase, dolomite, pyrite, potassium feldspar and other minerals are also commonly found in the samples. The brittle minerals of Niutitang formation shale are featured by rich species, high content (greater than 40% in average) and large brittleness index (higher than 50% in average). Compared to the shales in different regions both at home and abroad, Niutitang formation shale in Northwest Hunan has better fracability.