Study On Simulation Experiment Of Gas Loss Quantity And The Influencing Factors During The Sample Process Of Coring Tube

In order to reveal the temperature alteration caused by the friction between the coring tube wall and the coal seam in the coring process,the main influencing factors of the gas loss quantity of coal core in the coring process are studied,and the simulation experiments of gas loss quantity during the coring process of coring tube are tested.Firstly,the temperature measurement device of coring tube wall in the coring process is developed,and the temperature change curve of coring tube wall in the coring process is obtained.Based on this,the external heat input of the simulating coring process is set.And then by setting up the coring process simulation platform in the laboratory,the simulation experiments of gas loss quantity during the sample process of coring tube of different coal core gas pressure,different sampling depth and different core tube wall heating rate are carried out,and the error analysis are carried out on it.The conclusions are as follow:?1?The real temperature change of the pipe wall in process of core drilling is divided into three stages: slow rising stage,fast rising stage and descenting stage of temperature,respectively corresponding to the drilling,collecting coal sample and the drilling process.?2?Compared with the desorption of coal core in constant ambient temperature under the same coal core gas pressure,desorption speed of sample process of coring tube simulation experiment increases obviously in 0¹5 min,and cumulative desorption quantity of coal core is increased during the same time period,and the gas loss quantity of coal core in sample process of coring tube extraction increases.?3?Under the condition of equal core depth and core tube wall heating rate,with increase of coal core gas pressure,the error of loss gas quantity calculated by using t^1/2 method is larger,but for the determination of gas content,due to the increase of gas content with gas pressure,the error influence of loss gas quantity is reduced.?4?Under the condition of equal coal core gas pressure and core tube wall heating rate,with the increase of core depth,the time of coring becomes longer,and the error of loss gas quantity calculated by using t^1/2 method is larger,and proportion of the error in the gas content is also greater.?5?Under the condition of equal coal core gas pressure and core depth,with increase of the core tube wall heating rate,the error of the loss gas quantity calculated by using t^1/2 method is larger,and proportion of the error in the gas content is larger.?6?From three different aspects of coal core gas pressure,core depth and core tube wall heating rate,the core depth has the greatest influence on the gas loss quantity in sampling process of coring tube,and reliability of gas loss quantity is the worst calculated by using t^1/2 method.