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Abstract Based on the methods and technologies of coal-bed methane(CBM) exploration by coal seam in hydrofracture on the ground，and the desorption characteristic of CBM after the effects of high pressure water injection into the coal mass sample，a great deal of experiments about CBM desorption features in coal sample after water injection have been designed. Through these experiments，desorption features of CBM after the effects of high pressure water whether or not have been illustrated；and the comparison of desorption whether water injection or not could be showed in order to apply in actual coal seam. The experimental equipments which acted on our own manufactured devices including adsorption，water injection and desorption，all of the necessary experiments have been conducted. During the process of experiments，adsorption，high pressure water injection，desorption experiment are conducted one by one. In order to acquire the desorption law of coal samples at different conditions，the combination experiments of coal，gas adsorption pressure and desorption which injected water or not have also been studied. The results show that：(1) At the same balanced gas adsorption pressure，the natural desorption percentage of poor coal sample #1–1 is 56.17% and exceeds the blind coal sample #2–1，the value of which is 51.50%. The result is equated to the actual coal mine. (2) The desorption percentages of coal mass containing gas are mostly affected by whether water injection or not. When the water injection pressure was equal to gas adsorption pressure，the desorption percentages of the coal samples #1–1，#1–2 and #2–1 are 40.15%，47.17%，27.09% respectively，and the percentages are only 50%－70% of the natural state. The most affection one is the blind coal sample #2–1，and the least one is the poor coal sample #1–2. (3) Followed by the pressure of water injection increasing，the ultimate desorption percentages gradually decrease more or less at nonlinear law and go to remain stable at last. The percentages of desorption will tend to stable if water injection pressure reached a limited value. (4) Time effects of desorption are related to water injection. In natural state，desorption could be stable at very short time，but after water injection the balance will need long time.
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Received: 01 November 2010
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2011, Vol. 30 
