Shale pore quantitative expression method based on three-dimensional FIB-SEM image

The invention relates to the field of petroleum and gas geologic exploration and development, especially a method for recognizing the type of internal three-dimensional pores in shale and the quantitatively expressing the structure information of the internal three-dimensional pores in shale petroleum and gas exploration through FIB-SEM. The method comprises the steps: carrying out the high-precision three-dimensional imaging of inorganic substances, organic substances and pores in the shale at micrometer and nanometer scales through the FIB-SEM, and obtaining a three-dimensional FIB-SEM image; carrying out the alignment of all two-dimensional images of the three-dimensional FIB-SEM image, correcting the nonuniformity of the image brightness, and filtering the noise of the image; segmenting the preprocessed image into a pore region, an organic substance and an inorganic substance; marking all pores the pore region of the image, and dividing the pores into an organic pore, an inorganic pore and a boundary pore