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Simulated Experiments on the Method of Injection/Falloff Well Testing for Coal Bed Methane |
ZHANG Junfeng, FU Yingqian, NIU Bin, MU Dan |
Key Laboratory for Hydrodynamics and Ocean Engineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China |
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Abstract: Before carrying on a reasonable exploitation of coal bed methane, it is necessary to take the inverse computation for the parameters of coal bed by well testing analysis. The method of injection/falloff is the most commonly used in coal bed methane well testing. In order to expend the applications of the injection/falloff method in well testing and to gain more information about the coal bed, the injection/falloff well testing process is reconstructed in terms of an experimental system designed in the laboratory. The change of pressure on well bottom is obtained by controlling injection flux. It is indicated that the experimental result is consistent with the in-situ result. The method of multi-level injection is presented in the simulated experimental study to gain more information involving the pressure change on well bottom at different stages. The results show that the pressure on well bottom is nonlinearly increasing with the increase of injection flux. By controlling the injection flux, the simulated experimental process is able to sufficiently response the pressure change on well bottom, and to obtain more digital information about well bottom for further well testing interpretation. In the meanwhile, this kind of experiments could be carried out to verify the rationality and accuracy of the proposed model for theoretical interpretation by controlling and changing the given parameters of well bottom.
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Received: 20 April 2012
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