A Study of Inorganic Pore Characteristic in Lower Cambrian Niutitang Shale in Qiannan Depression

Compared with conventional reservoir, shale reservoir has distinctive characteristics such as ultra-low porosity and permeability, rich in organic matter and special ways of shale gas occurrence. These make remarkable differences between the evaluation of shale reservoir and conventional reservoir. To make an authentic assessment study on inorganic pore in shale, this article evaluated the inorganic pore of Niutitang shale in Qiannan depression with the helping of SEM, thin section and so on. Results of the study suggested that in Niutitang shale formation there mainly developed three kinds of inorganic pores, including floc interparticle pore, micro-channel and micro-fracture. Besides, all the inorganic pore diameters there were less than 5μm, most distributed in 0.25μm-1.0μm and its inorganic porosity values range from 1.71% to 3.86%, the average value was 2.67%.