Abstract：At present,the drainage control of CBM vertical wells in an increasing production stage is mainly controlled according to the drainage theory and engineering experience for qualitative control,lack of a mathematical model based on the theory of quantitative control for drainage. A mathematical model of reasonable pressure dropping rate in increasing production stage is established based on well testing,seepage and isothermal adsorption theory,and laboratory test,and the analysis of model parameters affecting the pressure dropping rate and the accuracy of the model are performed. Scene drainage data analysis and mathematical model calculation results contrast show that the accuracy of the model provide a guidance for the CBM vertical wells of scene production.

Keyword：CBM;increasing production stage;pressure dropping rate;permeability;