Research on multi-mechanism synergistic effects of gas cross-scale percolation in tight gas reservoirs of Yanchang oilfield

Revealing the gas transport patterns at the microscale and nanoscale is of great scientific and engineering significance for unconventional oil and gas exploration and development. This paper first systematically analyzes the properties of gas transport mechanism under different Knudsen number conditions. Second, the coupling modes of the cross-scale multi-drive mechanism are systematically categorized, and three typical coupling calculation methods are pointed out. Again, the rationality of the cross-scale multi-agency coupling is quantitatively calculated. The results show that (a) Under the influence of Fick's diffusion equation, when K_nr > 0, the coupled ‘slip flow–Fick diffusion–Knudsen diffusion’ equation does not converge to the Knudson diffusion equation. (b) The ‘Fick diffusion–Knudsen diffusion’ coupled equation is calculated to be more than 10² times as large as the Knudsen diffusion equation.