CO₂ sequestration with enhanced gas recovery (CO₂-EGR) is a promising technology, especially in the case of re-injecting the separated CO₂ from natural gas into the same gas reservoir. The description of dispersion between these two gases benefits for understanding of this miscible displacement and the related reservoir simulation. Here the dispersion properties of CO₂-CH₄ were studied in short and long sand packs through CO₂ horizontally displacing natural gas, both CH₄ and one kind of simulated natural gas - SNG (composed of 0.90 CH₄ + 0.10 CO₂ in mole fraction). We evaluated the effect of gravity and CO₂ impurity in SNG on the horizontal dispersion. The gravity effect affected the entry/exit effect and jointly caused the considerably larger dispersion coefficients in the long core than that in the short core. Due to the existence of CO₂ impurity, SNG makes itself diffuse into CO₂ more easily. Effectively it results in the larger dispersion coefficients. Simultaneously, the horizontal dispersivity of the sand pack calculated as about 0.0161 m in this work, was comparatively larger than the vertical one, resulted from the gravity effect.

CO ₂封存具有增强气体回收（CO ₂ -EGR）是有前途的技术，尤其是在的情况下，重新注入的分离的CO ₂从天然气到相同的气体贮存器。对这两种气体之间的分散性的描述有助于理解这种可混溶的位移以及相关的储层模拟。这里CO的分散性能₂ -CH ₄进行了研究在通过CO短期和长期的砂包₂水平移动天然气，既CH ₄和一种模拟天然气- SNG（由0.90 CH的₄  + 0.10 CO ₂摩尔分数）。我们评估了重力和二氧化碳的影响SNG中_2种杂质在水平方向上分散。重力效应影响进/出效应，并共同导致长芯中的分散系数比短芯中的分散系数大得多。由于存在CO ₂杂质，SNG使其更容易扩散到CO _2中。有效地导致更大的分散系数。同时，由于重力作用，在这项工作中计算出的砂包的水平分散度约为0.0161 m，比垂直分散度要大。