Abstract：In order to study the effect mechanism of high pressure water injection on the methane desorption characteristics of coal，a series of experiments have been designed and conducted. Combining the connected porosity and pore size distribution law determined by the press mercury test and the residual mass of water in coal samples after water injection experiments finished，the difference of methane desorption law has been confirmed. The results show that：(1) Under the same methane absorption pressure of different coals，the larger porosity is，the better methane desorption capacity is. (2) The methane desorption capacity is mostly affected by the methane equilibrium absorption pressure of the same coal. The larger absorption pressure is，the better desorption capacity is. (3) According to the pore size distribution law and increment of water in coal mass samples，the critical pore size of coal sample is calculated under different water injection pressures. The critical pore size affects directly the methane desorption capacity；and the smaller pore size is，the lower desorption rate is. (4) The relationship of methane desorption rate and the critical pore size of water flowing into coal by data fitting accords with the Langmuir law function.
HOSSEIN J，FARUK C. Determination of multi-component gas and water equilibrium and non-equilibrium sorption isotherms in carbonaceous solids from early-time measurements[J]. Fuel，2007，86(10/11)：1 601-1 613.
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2011, Vol. 30 
