Finite difference model of borehole gas emission and numerical simulation

In order to study on laws of borehole gas emission, this paper established a non-steady flow model of borehole gas emission based on Darcy's law and the continuity equation, through doing analysis of borehole gas flow mechanism and process. By applying the finite difference and discrete solution area, this study built the gas flow finite difference equations. The calculation software was implemented with Visual Basic programming language, and the simulating of the drilling gas emission process was performed with the software. The result shows that the simulated results are in good accordance with the in-situ results. The established gas flow equation above matches the actual drilling gas flow patterns. The result of study provides a theoretical basis for gas drainage.