Shale reservoirs are characterized by various pores with micro-and nano-pores well developed.Commercial shale oil development can be achieved by means of staged fracturing in horizontal wells.The interaction between oil molecules and pore wall is more complex than that between methane molecules and pore wall

but it is still unclear about the migration mechanism of shale oil in inorganic and organic nano-pores at present.Accurate simulation of the microscopic migration mechanisms of shale oil and the coupled flow in multi-pore media is of great significance to productivity evaluation and production prediction in shale oil reservoirs.Considering wettability and mechanisms of liquid adsorption

velocity slip and physical property change

we established the apparent permeability model for fluids in micro-and nano-scale multi-pore media based on the complex structural parameters (including tortuosity

porosity and organic pore content)

to explore the effects of different migration mechanisms on the apparent permeability of micro-and nano-scale multi-pore media.Subsequently

the mathematical model with matrix

natural fracture and artificial fracture coupled was set up for multistage fractured horizontal wells in shale oil reservoirs.Besides

the finite element method was used to solve the mo-del

and to analyze the factors affecting productivity.The results show that when the pore radius is less than 10 nm

the effect of velocity slip in micro-and nano-pores is significant

while when the pore radius is greater than 100 nm

the effect of microscopic migration mechanisms may be neglected.The less the number of organic pores and the more the number of fractures

the greater the productivity of multistage fractured horizontal wells will be.The optimal fracture network is that has neither spacing nor overlapping between the adjacent fractures.The highlight of the study is to enrich the theories on oil and gas migration in micro-and nano-pores

so as to contribute to the development simulation of shale reservoirs with theoretical methods.