气层“两度”是指有效孔隙度与原始含气饱和度，它是计算天然气储量的重要参数。

The effective porosity and original gas saturation of gas reservoir are the important parameters in calculating gas reserves.

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胶结作用导致长1—长3和长4+5—长10砂岩丧失的平均孔隙度分别占原始孔隙的25.8%和27.5%，碳酸盐是造成砂岩物性降低的主要胶结物。

The porosity loss caused by cementation is 25.8% and 27.5% of the total porosity for the Chang 1—Chang 3 sandstones and the Chang 4+5—Chang 10 sandstones, respectively.

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