Continental shale oil reservoirs in China are characterized with abundant clay minerals
well-developed laminae
and complex and diverse lithologies. The crude oil is accumulated in organic pores
inorganic pores
and bedding fractures
featuring multi-scale distributions. Therefore
it is very difficult to accurately characterize the flow mechanism of shale oil reservoirs and precisely predict their apparent permeability. Based on the nano-confinement effects and different flow boundary conditions
flow velocity equations were derived for organic pores
inorganic pores
and micro-fractures. Meanwhile
considering the distribution characteristics and arrangement-combination patterns of pores and fractures
a comprehensive apparent permeability prediction model for the fractured continental shale reservoirs was established. Taking the Jiyang depression shale oil reservoir as a case study
a systematical analysis was conducted on the effects of pore-fracture combination patterns
total organic carbon (TOC)content
nano-confinement effects
and fracture distribution characteristics on the apparent permeability of shale reservoirs. The results show that in continental shale oil
the low-velocity nonlinear flow behavior is mainly controlled by the liquid-solid interfacial slippage effects and adsorption boundary layer effects. The slippage effects in organic pores help increase the flow velocity
whereas the adsorption boundary layer effects in inorganic pores play a role in flow inhibition. The arrangement patterns of pores and fractures exert significant influences on the apparent permeability
with particularly pronounced nonlinear characteristics observed in serial arrangement
indicating the great impact of TOC content on flow behavior. Furthermore
under low-pressure gradient conditions
macropores such as inorganic pores and micro-fractures are the main flow channels
and the apparent permeability of micro-fractures increases nonlinearly with the increase in fracture density. The increase in fracture aperture significantly enhances its permeability
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