取碎屑状煤芯时的煤层瓦斯含量直接测定方法研究

Direct method of determining gas content of coal beds from clastic coal core

针对直接法测定煤层瓦斯含量时难以取得完整煤芯的难题,提出了取碎屑状煤芯时的瓦斯损失量数学模型,依据该模型采用分步拟合的方法确定和k值,并形成了快速取碎屑状煤芯时的煤层瓦斯含量快速测定方法。现场试验结果表明:采用分步拟合确定瓦斯损失量时,实验测定解吸的瓦斯体积V2和(t 0 t)的相关因子基本在0.99以上,并结合煤层瓦斯含量直接测定工艺测得桐梓煤矿7#,9#和10#煤层瓦斯含量及瓦斯压力,测得结果符合该煤层多次发生突出的情况。表明运用该方法能够准确地计算煤层瓦斯含量,为煤层瓦斯含量作为区域预测煤与瓦斯突出的指标奠定了基础。

In view of the difficulties to obtain the clastic coal core when using the direct method to determine gas content of coal seam, the mathematic model of gas diffusion in taking clastic coal core was proposed in this paper, and the compensation for the methane desorption model was established by step-fitting calculation. In addition, the direct and rapid measurement method of original coal gas con- tent has been achieved by using deep-hole coring technique and gas desorption method. The practice results show that the measured related factors of gas desorption volume V2 and （to ＋ t）^α are basically above 0.99 when using step-fitting method to calculate gas diffusion. Moreover, the gas content and pressure of No.7^th, 9^th and 10^th coal seam in Tongzi coal mine were measured, and the results accord well with the real situation of outbursts occurred many times in these coal seams. Thus, the theoretical and experimental studies mentioned above can accurately calculate gas content in coal seam, and pro- vide a basis for predicting coal and gas outburst when using the prediction index of gas content.