松辽盆地北部西斜坡天然气成因分析

根据松辽盆地西部斜坡带天然气产出的地质背景、组分、碳同位素特征及介于该斜坡带和齐家-古龙凹陷之间的塔字号井区天然气组分变化特征综合分析认为， 运移过程中的气体组分分异使齐家-古龙的热成因气经塔字号井区运移到西斜坡时基本变成了具有生物气特征的干气； 富拉尔基地区的天然气是典型的生物气；其他大部分地区是齐家古-龙热成因气和原地生物气的混合。利用甲烷碳同位素对不同地区的生物气比例进行估算，距离齐家-古龙越远生物气所占比例越大。

ORIGIN OF NATURAL GAS IN WESTERN SLOPE ZONE IN THE NORTH SONGLIAO BASIN

The geologic setting, components and carbon isotope features of natural gas in the western slope zone in the Songliao Basin and the variation of gas components in the Ta wellblocks between the western slope zone and Qijia-Gulong sag are comprehensively studied. It is believed that the thermogenic gas in Qijia-Gulong sag would have been turned into dry gas with the characteristics of biogas through gas component differentiation in the process of migration after they migrated to the western slope zone via the Ta wellblocks; the natural gas in Fulaerji area are typical biogas; whereas the natural gas in most of the other areas are the mixture of the thermogenic gas in Qijia-Gulong sag with the local biogas. The proportions of biogas in different areas are estimated by using methane carbon isotope and the results indicate that the proportion of biogas increases along with the distance to Qijia-Gulong sag getting larger.