煤层气赋存的分形特征研究

本文利用红外热成像手段，对微小煤样内的甲烷吸附区进行了观察，并评估其吸附特征与在煤中的分布规律.研究表明煤中存在不同尺度与甲烷吸附能力的甲烷富集区，吸附/解吸甲烷时，甲烷富集区比邻近区域具有更明显的升温/降温现象.通过图像处理的方法对不同吸附压力条件下的红外热像图中的甲烷富集区进行提取，采用盒维数进行统计发现甲烷富集区符合分形规律.试验表明随着吸附压力升高，甲烷富集区的分形维数增大，分布初值减小.对两个不同煤田的煤层气富集区进行统计表明：从微米级到千米级尺度范围内，甲烷富集区分布具有分形特征，且分形维数均在1.5~2.00之间.

Study on fractal characteristics of coalbed gas occurrence

The adsorption area of methane in micro coal samples is observed by infrared thermography, and its adsorption characteristics and distribution in coal were evaluated. The results show that different scale methane enrichment area exists in coal. Methane enrichment area has more obvious warming/cooling phenomenon than adjacent area, When methane is adsorbed/desorbed. The heat-imaging of coal adsorbed methane is processed. The relationship between the scale and number of methane enrichment area and is calculated by box counting dimension. It is found that the methane enrichment region conforms to the fractal law. The experimental results show that with the increase of adsorption pressure, the fractal dimension of methane enrichment area increases and the initial value of distribution decreases. The distribution of Coal Bed Methane (CBM) content in two different coalfields is statistically analyzed. The results show that:from the micron to kilometre scale, the distribution of methane rich regions is fractal, and the fractal dimension is between 1.5~2.00.