Through core and outcrop observation

thin section examination

argon-ion milling

scanning electronic microscope and mercury data et al

this paper studied the shale rock types

Microscopic types and characteristics of the Jurassic Ziliujing Formation. The reservoirs are dominated by black shale which mainly developed interparticle pores

the micro fractures and the organic matter pores are less developed. The shale porosity is between 1.4%-4.9% and the nanoscale micro-pores with diameter less than 100 nm account for more than 85% of total porosity. Compared with the marine shale gas reservoir in the study area

the organic matter pores are less porous and pore diameters are smaller in the Jurassic shale gas reservoir. Considering the large area and thick interval with oil/gas show of the Jurassic shale

and the success of shale oil/gas exploration in some spots

the favorable areas are suggested where the shales (source rocks) are thick and thermal maturity is high. These places may have good source charge and reservoir quality as shale oil and gas reservoirs. The tight sandstone or limestone in the vicinity of the shale may also have good possibility for hydrocarbon accumulation of tight oil or conventional reservoir.