深部煤层CO2注入过程中煤体积参数变化的模拟实验

CO₂注入煤层会改造储层孔裂隙结构，对提高CO₂埋藏和强化甲烷抽采能力产生重要影响。为探究CO₂注入后的煤体结构演化规律，选择山西沁水盆地寺河矿无烟煤和新源矿焦煤样品进行模拟实验，通过测试并分析CO₂注入前后煤体积参数的变化，得到以下结论:CO₂的注入可以溶蚀煤中矿物，增加连通孔隙体积并引起有机质的膨胀；矿物溶蚀对孔隙体积变化的贡献不显著，却导致大量封闭孔转换为连通孔，其中大于40μm的大孔孔隙体积增幅最大；有机质的膨胀量较大，其对孔隙的挤压作用可能会降低煤体的连通性；CO₂注入对煤体结构的改造作用受煤级和模拟埋深条件的共同影响。 

Simulation experiment on the changes of CO2 burial process in deep coal seam

The injection of carbon dioxide(CO₂)will change the pore fissure structure of coal seam, which has important influence on improving the capacity of CO₂ burial and enhancing methane extraction. In order to explore the evolution law of coal structure after CO₂ injection, the Sihe anthracite and Xinyuan coking-lean coal in Qinshui basin were chosen to do the simulation experiment, through the test and analysis of the coal volume parameter before and after CO₂ treatment, the following conclusions were obtained:CO₂ injection can dissolve minerals in coal, which increases the volume of connected pores and causes the expansion of organic matter; the contribution of mineral dissolution to pore volume changes is not significant, while it leads to the conversion of a large number of closed pores into interconnected pores; the maximum volume increase of pore diameter is larger than 40 μm; the expansion of organic matter is comparatively large and its squeezing effect on pores may reduce the connectivity of coal; the effect of CO₂ injection on coal structure is influenced by coal ranks and simulated burial depth.