In order to assess the gas potential of the dark shale of the Lower Cambrian Niutitang Formation in the northern part of Guizhou

samples were collected from 20 outcrop cross sections of the Lower Cambrian Niutitang Formation in the northern part of Guizhou and many experiment tests such as physical property

SEM

mercury porosimetry

specific surface and pore size were conducted.Preliminary study results show that the average content of quartz and clay minerals are 56.3% and 30.5% and the effective porosity and permeability are 8.24% and 0.127×10

-3

μm

2

respectively.Pore sizes cluster around 4.0 nm.The pores are dominated by mesopores.The analysis of the relation between pore volume and quartz content

clay mineral contents and TOC shows that the content of quartz is negatively correlated with the volumes of micropore and mesopore

but slightly positively correlated with macropore;clay mineral contents are just the opposite to quartz content;TOC is positively correlated with mesopore and macropore to some extent;and vitrinite reflectance has a weak positive correlation with macropore.