"Indirect Deduction” Assessment Method and Application for CBM Resources in Coal Mining Stability Area

Based on the theory of material balance, an evaluation method of “indirect deduction” for CBM resources in coal mining stability area is proposed on the basis of the estimation model of original gas resources and loss gas volume. The method was then applied to the estimation of gas resources in the mining stable area of the 5310 working face in the Chengzhuang Mine of Jincheng Coal Group. The field drainage test shows that the estimated gas output of the whole face is basically consistent with the evaluation results, which proves the evaluation method is accurate. Besides, the surface well can immediately step into the gas production peak period after the commissioning period, and it will enter the attenuation stage after a period of stable gas production, and the gas extraction curve shows the characteristics of “flat-down” in general.