在区域构造平缓和储层物性普遍较差的背景下，天然气二次运移以气体膨胀驱动为主。
With a flat regional structural relief and poor reservoir poroperm characteristics as background, the secondary migration of gas in the region is mainly driven by gas expansion.
这三类孔同时也对应了瓦斯等气体在煤中的不同的运移状态。
According to the coal sample's pore fractal laws, the porosity of coal is divided into three categories: infiltration pore, diffusion pore and adsorption pore.
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