Experimental Study On The Effect Of Different Pressure Water Injection Conditions On Coal Sample Permeability

In the coal mining process,due to the increase in mining depth,resulting in increased gas content,gas pressure increases,coupled with the complex geological conditions of our country,there are so many mine gas outburst danger.This paper addresses the problem of gas outburst by proceeding from the penetration rate of coal.However,the stress,temperature and pore pressure have been studied by many scholars so far.The research contents have been studied.The results show that there are many factors that affect the permeability of coal samples.There are many factors such as stress,temperature,pore pressure,water content and so on.More perfect.This paper mainly studies the water content of coal samples,the degree of metamorphism of coal samples,different pressurized water injection conditions and the addition of surfactants.Based on the experimental study on the permeability characteristics of coal samples at home and abroad,based on the self-developed triaxial infiltration experimental device,the anthracite from a mining area in Jiangxi Province,the coking coal in a mine area of Shanxi Lvliang and the long-flame coal in a mine in Hebei.The effects of these conditions on the permeability characteristics of coal samples were studied under different conditions.The porosity distribution characteristics of coal samples before and after pressurized water injection and the characteristics of coal pore changes with different water injection pressure were measured by mercury intrusion test.The relationship between pore structure and permeability was discussed.The contact angle and surface tension of pure water and surfactant were measured by contact angle tester,and the surfactant was screened.The capillary force was calculated by contact angle and surface tension.The effect of adding surfactant on capillary force was analyzed.Like the permeability characteristics.Through the laboratory experiment and the theoretical analysis,the system reveals its influence mechanism.The results show that:(1)The permeability of coal samples with different moisture content under different water content conditions,with the increase of water content,coal permeability decreased,and the water content is low,the increase in coal moisture on the permeability of the more obvious;It is shown that the higher the degree of metamorphism of the coal sample,the more obvious the decrease of the permeability and the greater the decrease rate with the increase of the water content.(2)The water content in the coal sample increases with the increase of the water injection pressure.However,due to the pressure water,the pore size of the coal sample increases,which leads to the decrease of the capillary force,the final permeability(anthracite,coking coal,long flame coal),when the water injection pressure increases,the permeability of the three kinds of coal samples have increased,but the increase is somewhat different.Through the experiment of mercury intrusion and scanning electron microscopy,it can be seen that the pore structure of the coal sample used in this experiment increases with the degree of metamorphism,and the permeability of the large pore and the fissure is larger.(3)The permeability of dry coal samples,saturated coal water samples and saturated F1 coal samples was found.The permeability of dry coal samples was higher than that of saturated F1 coal samples.