The Study of the Influence of Pressure on Coalbed Permeability

The permeability of coalbed is not only controlled by geological conditions, but it is also influenced by later production process (Zhang xinmin, 1991), especially the influence of producing pressure on the permeability of coal bed near wellbore is very significant. It has less reported about the study of the influence of production status on the permeability in literature for coalbed well. For the producing well, the producing pressure drop should be properly controlled during drainage in order to prevent coal fine from moving which can decrease coal permeability. That is extremely important for the success of experimental well and the evaluation of the previous experiment process in the key stage of exploration and development of coalbed methane. The correlation between the producing pressure drop and the permeability of coalbed have been established by using the experimental technology, the results of this paper may play an instructing role for coalbed methane production. Here are major elements of this study: (1)Pore structure features and its influence on permeability of coal has been studied.(2)The permeability at different confining pressure has been measured and the influence of confining pressure on coal permeability has been studied.(3)The influence of upstream pressures on coal permeability has been studied; the range of wellhead pressure correspondence to the biggest permeability has been gotten.