Pore characteristics and its significance on shale gas reservoir: a case study of the Longmaxi shale in the Nanchuan region, Chongqing, South China

Micro pore structure of shale has attracted much attention, which can be discussed based on the improved classical model. The Longmaxi shale is as research object. The results show the TOC ranges from 0.50% to 2.65%, equivalent reflectance is between 2.22% and 2.75%, and clay mineral content ranges from 23.7% to 35.4%. The porosity and total surface area are between 1.77% and 3.69%, 26.67 m(2)/g and 38.46 m(2)/g, respectively. Volume and surface area of micro-pores are primarily determined by the diameter, less than 10 nm. Meso-pores are more likely to develop in organic particles. The morphology of pores is in cylindrical and parallel-plate shape. The improved BET model can be utilised to calculate dimensions and surface area of the micro-pores. The D-R equation usually overestimates the volume of the micro-pore. The H-J model and carbon black model by the V-T method verify the effectiveness of the improved BET model.