Experiment investigation on gas flow characteristics of coal considering the integrity of coal samples

Abstract

Gas has been one of the main causes of coal mine safety accidents. At present, the most commonly used treatment method is still gas drainage in advance. The permeability of coal seams is the most important factor affecting gas drainage. According to the coal density, P-wave velocity and fracture distribution, the coal samples are grouped to eliminate the influence of the differences of the coal samples on the experimental results. The results show that due to the decrease of samples integrity and the increase of gas osmotic pressure, the peak strength of the sample will reduce, and eventually the stable permeability will increase. Besides, the starting point of permeability will also appear earlier (relative to the peak intensity point of the samples). It is worth noting that the starting point of the sample permeability is highly consistent with the expansion point of sample volume. As the loading and unloading rate increases, the peak strength of the samples will first decrease and then increase. Similarly, the final stable permeability of the samples also shows a trend of first decreasing and then increasing.

Keywords

• gas seepage
• permeability enhancement
• coal sample integrity
• gas osmotic pressure
• different loading and unloading rates