钻孔初始瓦斯流量规律研究

Research on Laws of Initial Gas Emission Flow from Borehole

为获得钻孔初始瓦斯流量解吸规律,理论分析发现,钻孔初始瓦斯流量与钻孔半径、钻进深度、钻进时间、地应力、煤体强度和瓦斯压力有关。运用自行研制的钻孔初始瓦斯流量实验室测定装置,采集5组有代表的煤样,固定其他5个变量,在不同瓦斯压力下进行50次测定试验(其中48组数据有效)。研究表明:单位长度钻孔中涌出的钻孔初始瓦斯流量之和,即钻孔初始瓦斯涌出量与瓦斯压力近似成正比关系,瓦斯压力越高,钻孔初始瓦斯涌出量越大。对同一煤样,在气体压力相同条件下,充入CO_2时打钻测得的钻孔初始瓦斯涌出量远比充入N2时大的多。钻孔初始瓦斯涌出量的变化能较好的体现煤层突出危险性的变化。

The theoretical analysis shows that the initial gas emission flow from borehole is related to the drilling radius,drilling depth,drilling time,ground stress,strength of coal body and gas pressure. Five sets of typical coal samples were collected,and five other variables were fixed,and a self-developed experimental device for initial gas emission flow from borehole was applied in this research.After 50 times of test,48 sets of valid data were collected. Based on the experiment,it has been found that the initial gas emission quantity from borehole is the sum of the unit length of the initial gas emission flow from borehole and approximate proportional to the gas pressure. In another word,the higher of gas pressure,the more of initial gas emission quantity from borehole. Furthermore,in the same condition of gas pressure,the initial gas emission quantity from borehole by being filled with CO2 was much more than that by N_2.Hence,it could be concluded that the change of the initial gas emission quantity from borehole can reflect the change of coal seam outburst risk.