Pore system feature of Lower Cambrian Niutitang Formation shale in Southeast Chongqing

The pore types and structures are critical to gas bearing capacity of shale reservoirs. Conventional scanning electron microscope, argon ion polishing, high resolution power scanning electron microscope are used to describe pore system of Lower Cambrian Niutitang Formation shale in Southeast Chongqing and discuss the relationship between pore characteristics and gas bearing capacity. There are four categories and nine classes matrix pores and three categories and four classes natural fractures in Lower Cambrian Niutitang Formation shale. Intragranular pore, dissolved pore, high angle shear fracture and low angle decollement fracture constitute the pore system of Lower Cambrian Niutitang Formation shale jointly. The pore system has the characteristics of various types, small pore diameter, poor connectivity and low permeability. Pore volume is mainly provided by the nanoscale pores. No organic pores, poor pore connectivity and regional developed decollement fractures maybe the reason why the Niutitang Formation shale has poor gas-bearing capacity. ©, 2015, Science Press. All right reserved.