Because of the importance of preservation conditions and shale pore evolution to shale gas exploration and development

it is of great scientific significance and academic value to study the relation between them. The pore structure characteristics and evolution of black shale with different preservation conditions have been studied by means such as argon ion polishing

scanning electron microscope and nitrogen adsorption

and it is found that the pore structure of black shale under different preservation conditions are significantly different. This difference is caused by the difference of preservation conditions in the late uplift process

which is manifested in the following aspects. First

inorganic pores in black shale with good or bad preservation conditions are both less developed

and most of the original intergranular pores are filled with generated hydrocarbons. The inorganic pore characteristics between them are basically similar. Second

the organic pores in black shale are of great difference under different preservation conditions. The diameter of shale organic pores is larger in good preservation conditions

which are in round or bubble shape. While the organic pores are relatively smaller in diameter or totally absent in poor preservation condition

which are in flat or irregular shape with the certain characteristics of flattening and deformation. Third

the pore volume and specific surface area of the black shale under good preservation conditions are better than that under poor conditions. Fourth

the porosity evolution of black shale is affected by preservation conditions. The original pore morphology and distribution are controlled by facies and diagenesis process

and so are the organic matter（oil） distribution form. Thermal evolution of organic matter（oil cracking） influences the existence of organic pores. Whereas

in the late uplifting process

the pore structures（shape

size

pore volume） are affected by the quality of the preservation condition. Therefore

the size

morphology and porosity of the shale organic pores reflect the preservation conditions of shale gas in some extent.