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使用高压超临界CO2地球化学反应器在实验室模拟CO2在地下煤层的埋藏过程,反应器中的温度为40℃,压力为9.8MPa,反应时间为72h,通过氦比重仪和压汞仪对不同煤级煤的孔隙结构变化进行了研究.结果表明:经过超临界CO2-H2O的作用后,无烟煤的真密度从1.51g/cm3增加到1.59g/cm3,其余几种煤真密度变化不大,视密度均有减小趋势,其中褐煤和瘦煤减小幅度为0.1g/cm3;褐煤总孔容变化最大,增加主要表现在大孔阶段,增幅为85%,孔隙度增幅达118%,其余煤种的总孔容和孔隙度也有不同程度增高.CO2的埋藏过程对中低煤级的影响主要是其大中孔,而对高煤级主要影响其微孔发育,无烟煤微孔孔容的增大使得煤的表面积进一步增大,从未处理的24.3m2/g增加到27.6m2/g,从而对气体的吸附能力将越来越强;对退汞曲线的滞后性分析表明,CO2的埋藏过程对“墨水瓶”孔隙度将产生一定的影响.
The high pressure supercritical CO2 geochemical reactor was used to simulate the burial process of CO2 in the underground coal seam in the laboratory. The temperature in the reactor was 40 ℃, the pressure was 9.8MPa and the reaction time was 72h. The results show that the true density of anthracite coal increases from 1.51g / cm3 to 1.59g / cm3 after the supercritical CO2-H2O effect, and the density of the remaining coal does not change much, The density of lignite and lean coal decreased by 0.1g / cm3; the change of total pore volume of lignite was the largest, the increase was mainly in the macroporous stage, with an increase of 85% and an increase of porosity of 118% The total pore volume and porosity of coal species also increased to varying degrees.Carbon dioxide burial process on the low-grade coal is mainly its large and medium-sized hole, while the main impact of high-grade coal micropores, anthracite micropore porosity Increasing the surface area of coal further increases from 24.3m2 / g to 27.6m2 / g, thus increasing the adsorption capacity of the gas. The analysis of the hysteresis curve of the mercury curve shows that the burial of CO2 The process will have an impact on the “ink bottle” porosity.