Pore structure characterization and flow simulation of laminated shale oil reservoir in Jiyang Depression

With the development of oil and gas exploitation for unconventional reservoirs， shale oil plays a vital role in national energy security as an essential replacement resource. Laminated shale is the main lithofacies of shale oil development in Jiyang Depression， which has good storage and flow performance， and it is of great significance to clarify its microscopic pore structure distribution characteristics and flow law of shale oil to realize the large-scale benefit development of shale oil. Firstly， for the laminated shale in Jiyang Depression， high-precision core images of organic matter and inorganic matter were obtained based on focused ion beam scanning electron microscopy （FIB-SEM）. The images were preprocessed by filtering and threshold segmentation， and the pore network model of organic matter and inorganic matter was constructed by the maximum sphere algorithm， which could quantitatively characterize the nanopore distribution and topology of the matrix. Secondly， by setting the pore structure parameters of the matrix and the laminated pore， the stochastic modeling method was used to construct a mechanism model of the digital core of the laminated shale and the influence of the proportion of laminated shale and the flow direction on the flow capacity of shale oil was studied. The results show that the non-local mean filtering method can effectively remove the noise points and depict the clear pore edges， which effectively retains the integrity of initial pore and throat morphology. The inorganic pores are mainly 10–40 nm connected pores， and the number of connected pores is 12.2 times that of organic pores； the average coordination number is 3 times that of organic pores， which shows that the network connectivity of inorganic pores is superior to that of organic pores， and its pores have a dominant role in the flow capacity of shale oil. The permeability of laminated shale has obvious anisotropic characteristics， and the permeability of the parallel lamina direction is much higher than that of the vertical laminae direction. The laminae are the main flow channels of shale oil. A higher proportion of the thicknesses of the laminae indicates a greater matrix permeability， and the density of the laminas has an essential impact on the permeability of the shale matrix.