Song Hongqing

Dynamic Characteristics of Gas Transport in Nanoporous Media

Special flow mechanism and percolation characteristics for gas transport are presented in nanoporous media, which cannot be explained by the traditional motion equation of Darcys law. On the basis of theoretical analysis, we establish a low velocity nonlinear transfer equation of gas in nanoporous media and a mathematical model of gas volume flow in multi-scale porous media. By utilizing nonlinear numerical calculation methodology, a detailed quantitative analysis of the diffusion and convective rate of gas flow is presented, providing a theoretical foundation for the development of nanoporous media.

Mathematical Model for Low-Velocity Flow of Coal Bed Methane in Low-Permeability Reservoirs

A mathematical model for transport of coal bed methane(CBM) was presented, taking into account low-velocity non-Darcy flow behavior and coupling of methane desorption from coal matrix and diffusion from matrix into cleats. Under several simplifying assumptions, a simple calculation method for control area of single wells was proposed. Low-velocity non-Darcy flow behavior was characterized by pseudo threshold pressure gradient (PTPG). Numerical results show that both PTPG and desorption rate have a significant impact on determination of control radius. PTPG has a negative effect on the deployment of the peripheral reserves. Increasing PTPG would result in fewer control area. In the contrast, increasing desorption rate would lead to larger control area. The calculation method would provide engineers a better understanding of development of CBM.