低渗透孔隙-裂隙介质气体非线性渗流运动方程

Existing researches on coal bed methane is based on Darcy's law. But experiments show that gas flow in low permeability porous media is nonlinear. Methods of experiment, theory and calculation were used to establish a new nonlinear flow law. Experiment results of gas flow in low permeability pore fissure media were analyzed. Universal characteristics of the flow were generalized. The relationship between flow velocity and pressure gradient is a continuous curve which changes from a hollow curve under a low pressure gradient to a line under a high pressure gradient. The line is extended but does not stretches to the origin so that a starting pressure gradient appears. A new law of nonlinear flow was established according to the characteristics. Dimension and physical meaning of parameters of the new law are clear. Results indicate that there is a good agreement between the new law and the experiment of gas flow in low permeability pore fissure media. Darcy's law is just a special case of the new law. The new law can be used in theoretical and practical research on the gas flow in low permeability pore-fissure media. It lays the foundations of researches on mechanisms of coal-bed gas flow and provides development of coal bed gas resources with new basis.