Reservoir-forming conditions and evaluation of favorabl area of shale gas in Niutitang Formation in northern Guizhou

In order to investigate the potential of shale gas from the Lower Cambrian Niutitang Formation in northern Guizhou, a study on the reservoir-forming conditions of shale gas in Niutitang Formation was conducted, and the favorable accumulation area for shale gas in northern Guizhou was evaluated according to the geochemical analysis data of the core and outcrop samples in this paper. The result shows that Niutitang Formation shale in northern Guizhou was mainly formed in the deep water shelf sedimentary facies, which features moderate buried depth (<3 000 m), great organic-rich shale thickness (30~110 m), high organic abundance (average TOC>3.0%), mainly type I organic matter, high thermal evolution level (R_o>2.0%, being over-mature), low porosity and permeability, abundant micro-nanometer pores and fissures, rich brittle mineral (average content >40%), and relatively high gas content (average 1.5 m³/t). It is indicated that Niutitang Formation in northern Guizhou has good reservoir-forming conditions for shale gas. On the basis of above studies, it is proposed that the southeastern Shiqian-Yuqing-Shibing zone in northern Guizhou is the favorable accumulation area for shale gas.