Carbon dioxide （CO2） enhanced coalbed methane （ECBM） is an effective method to im- prove methane （CH4） production and this technology has already been used to increase gas production in several field trials worl...Carbon dioxide （CO2） enhanced coalbed methane （ECBM） is an effective method to im- prove methane （CH4） production and this technology has already been used to increase gas production in several field trials worldwide. One major problem is the injection drop in the later period due to permeability decrease caused by coal matrix swelling induced by CO2 injection. In order to quantify the swelling effect, in this work, coal samples were collected from the Bulli coal seam, Sydney Basin and adsorption tests with simultaneous matrix swelling measurement were conducted. The adsorption and swelling characteristics were analyzed by measuring the adsorption mass simultaneously with the strain measurement. Then experiments were conducted to replicate the ECBM process using the indi- rect gravity method to obtain the swelfing strain change with CO2 injection. The results show that the coal adsorption capacity in CO2 is almost two times greater than that in CH4, and nitrogen adsorption is the least among these gases. A Langmuir-fike model can be used to describe the strain with the gas pressure and the swelling strain induced by gas adsorption has a Hnear relationship with gas adsorp- tion quantity. Moreover, swelling strain increase was observed when CO2 was injected into the sample cell and the swelling strain was almost the sum of the strains induced by different gases at correspond- ing partial gas pressure.展开更多
为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinken...为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinkenberg因子3种状态对CO_(2)-ECBM及有效渗透率的影响,以及CH_(4)与CO_(2)压力随该因子的动态变化情况,并将CH_(4)产气量与工程实际作了对比验证。结果表明,CH_(4)与CO_(2)有效渗透率呈先缓慢增长再急速下降后逐渐趋于平缓的态势,相较于固定Klinkenberg因子或Klinkenberg因子为0,动态Klinkenberg因子影响下的CH_(4)与CO_(2)有效渗透率更大,当Klinkenberg因子为动态变量时,受不同气体的摩尔质量与动力黏度影响,CO_(2)有效渗透率小于CH_(4)有效渗透率。在动态Klinkenberg因子作用下,煤层中CH_(4)压力下降和CO_(2)压力上升均更快,当Klinkenberg因子为固定值或0时,会高估煤层内CH_(4)压力,低估CH_(4)抽采与CO_(2)压注的影响范围,并且估值均随时间增长而增大。工程验证表明,考虑动态Klinkenberg因子作用下的CH_(4)累积产气量更接近真实情况。研究成果有助于分析CH_(4)与CO_(2)有效渗透率变化趋势,预估CH_(4)抽采与CO_(2)压注的影响范围及CH_(4)产气量,在探究煤层增渗,优化井网布置,定量评价煤田产气量等方面具有理论指导意义。展开更多
基金supported by the Australian Coal Industry’s Research Program ( No. ACARP C24019)the National Natural Science Foundation of China (No. 51604153)the National Science and Technology Major Project (No. 2016ZX05045-004-006)
文摘Carbon dioxide （CO2） enhanced coalbed methane （ECBM） is an effective method to im- prove methane （CH4） production and this technology has already been used to increase gas production in several field trials worldwide. One major problem is the injection drop in the later period due to permeability decrease caused by coal matrix swelling induced by CO2 injection. In order to quantify the swelling effect, in this work, coal samples were collected from the Bulli coal seam, Sydney Basin and adsorption tests with simultaneous matrix swelling measurement were conducted. The adsorption and swelling characteristics were analyzed by measuring the adsorption mass simultaneously with the strain measurement. Then experiments were conducted to replicate the ECBM process using the indi- rect gravity method to obtain the swelfing strain change with CO2 injection. The results show that the coal adsorption capacity in CO2 is almost two times greater than that in CH4, and nitrogen adsorption is the least among these gases. A Langmuir-fike model can be used to describe the strain with the gas pressure and the swelling strain induced by gas adsorption has a Hnear relationship with gas adsorp- tion quantity. Moreover, swelling strain increase was observed when CO2 was injected into the sample cell and the swelling strain was almost the sum of the strains induced by different gases at correspond- ing partial gas pressure.
文摘为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinkenberg因子3种状态对CO_(2)-ECBM及有效渗透率的影响,以及CH_(4)与CO_(2)压力随该因子的动态变化情况,并将CH_(4)产气量与工程实际作了对比验证。结果表明,CH_(4)与CO_(2)有效渗透率呈先缓慢增长再急速下降后逐渐趋于平缓的态势,相较于固定Klinkenberg因子或Klinkenberg因子为0,动态Klinkenberg因子影响下的CH_(4)与CO_(2)有效渗透率更大,当Klinkenberg因子为动态变量时,受不同气体的摩尔质量与动力黏度影响,CO_(2)有效渗透率小于CH_(4)有效渗透率。在动态Klinkenberg因子作用下,煤层中CH_(4)压力下降和CO_(2)压力上升均更快,当Klinkenberg因子为固定值或0时,会高估煤层内CH_(4)压力,低估CH_(4)抽采与CO_(2)压注的影响范围,并且估值均随时间增长而增大。工程验证表明,考虑动态Klinkenberg因子作用下的CH_(4)累积产气量更接近真实情况。研究成果有助于分析CH_(4)与CO_(2)有效渗透率变化趋势,预估CH_(4)抽采与CO_(2)压注的影响范围及CH_(4)产气量,在探究煤层增渗,优化井网布置,定量评价煤田产气量等方面具有理论指导意义。
