对川西平落坝气田的原生气藏和次生气藏的地质和地球化学特征进行了对比。原生气藏是形成于生烃层系内的气藏和与烃源层系上部、下部相接触或接近的非生烃层系内的气藏。根据气藏与生烃层系的关系将次生气藏分为再分配型次生气藏、非再分配型次生气藏和混合型次生气藏。平落坝次生气藏的天然气重烃含量高、相对密度高 ,甲烷含量相对低 ,非烃气体很少。原生气藏和次气藏的异戊烷 /正戊烷比值接近或比后者略高。次生气藏的异丁烷 /正丁烷比值高于原生气藏。侏罗系次生气藏的碳同位素要比原生气藏天然气碳同位素轻。原生气藏比次生气藏中含有更多的较重的残留烃。

Based on the system division of the primary and secondary gas accumulation， the  paper depicts the different characteristics between primary and secondary gas a ccumulation of Pingluoba gas field in western Sichuan. Secondary gas accumulatio n can be divided into redistributed secondary gas accumulation， non-redistribu ted secondary gas accumulation and mixed secondary gas accumulation， according  to the relationship between gas accumulation and generating rock. Primary gas ac cumulation refers to these that lie above or under the generating rock and conta ct with or are near to it,  or,lie inside the generating rock,The secondary gas  in Pingluoba has high fixed hydrocarbon content and relative density， low metha ne content and little non-hydrocarbon gas. The ratio of iso-pentane to normal-pentane of primary gas is similar to or a little higher than that of secondary  gas，however, the ratio of iso-butane to normal-butane of secondary gas is hi gher than that of primary gas. In Jurassic in the region, the carbon-isotope is  heavier in primary gas than in secondary gas,at the same time, primary gas has  more content of heavy residual hydrocarbon.