Abstract: In order to improve the tight sandstone permeability prediction challenges result from the poor correlation between fractal permeability model parameters and permeability and the poor 3D structure characterization with tortuosity fractal dimension, a tight sandstone permeability prediction model was established based on the fractal patterns of tight sandstone pore structure and tortuous capillary bundle model. The calculation methods of fractal dimension, tortuosity fractal dimension and characteristic length were proposed to discuss the influence of different tortuosity calculation methods on the tight sandstone permeability prediction. Research indicates that this model can effectively predict tight sandstone permeability, and the prediction is closer to that of tested value. The calculated fractal dimension shows a favorable correlation with core permeability. There is a significant difference in the tight sandstone tortuosity for different calculation methods, and appropriate tortuosity calculation method could improve the prediction accuracy of tight sandstone permeability. This research could accurately and quickly predict permeability, which will provide certain guidance for the evaluation and efficient development of tight sandstone reservoir.

Key words: tight sandstone, permeaiblity, fractal dimension, average tortuosity, 3D pattern