Experimental Study On Gas Desorption Laws Of Tectonically Coal

In this paper, using laboratory experiments and theoretical analysis, gas desorption properties are studied at different adsorption balance pressures and sizes for different types of tectonically soft coals. Values of desorption indexes K₁ and⊿ h₂ are measured for different types of tectonically coals ,and the function of K₁ and⊿ h₂ are induced and validated. Based on desorption laws, the differences between K₁ and⊿ h₂ in gas desorption forecast are showed. By analysis on desorption results of different types of tectonically coals, it is obtained that gas desorption preliminary speed relates to deformed types for tectonically coals. For coal samples from soft and hard layers in the same coal seam, at the same temperature,size and pressure, gas desorption preliminary speeds of soft coals are much higher than hard coals. Gas desorption preliminary speeds increase and desorption speeds weaken faster with increasing deformed degree of tectonically coals. The ratio of initiatory gas desorption volume and long time (120min)gas accumulative volume is calculated and analyzed. Sequentially, new method calculating gas losing volume is presented as follows: gas desorption losing volume equals to volume induced by t method plus initiatory gas desorption volume. By measuring drilling gas desorption indexes of tectonically coals, it is known that K₁ relates to broken degree of coals. It is pivotal that adopt logical equation calculating the value of K₁ which indicates drilling gas desorption for different broken degree of tectonically coals. It is concluded that drilling gas desorption index⊿ h₂ is more logical than K₁ for different deformed types of coals.