Abstract: The Cambrian Niutitang Formation in southern Guizhou is very thick, and has well-developed floor with relatively effective sealing capacity. This formation can be divided into two sections. The first section, the primary target of shale gas, is composed of black carbonaceous shale of semi-deep and deep water continental shelf facies interbedded with siltstone, 99 m thick. The second section is composed of gray siltstone and shale of shallow-water continental shelf facies, 165m thick. Sampling analysis was made on Well MY-1, the only shale gas exploratory well drilled within the Niutitang Formation in southern Guizhou. The results show that the black shale in the first section of the Niutitang Formation reveals the TOC of 0.39%-5.35%, the vitrinite reflectance (R_o) of 1.56%-2.48% (2.06% on average), and the Type I kerogen with maceral dominated by amorphous sapropelites. The rock contains quartz and clay minerals, with higher content of brittle minerals (generally higher than 50%). Both the porosity and the permeability are low, 1.13%-2.23% and 0.0011-0.0082 mD, respectively. The total gas content is up to 1.13m³/t. Well MY-1 reveals that the Cambrian Niutitang Formation in southern Guizhou has better geological conditions for shale gas reservoirs, and large potential for further exploration of shale gas.

Key words: southern Guizhou, Niutitang Formation, black shale, organic geochemistry, reservoir properties, gas content