准噶尔盆地南缘烃源岩生源特征及原油分类

以稳定碳同位素、饱和烃色谱、饱和烃色谱-质谱和热模拟生烃实验为主要手段,详细剖析了准噶尔盆地南缘地区侏罗系八道湾组、三工河组、西山窑组及古近系安集海河组烃源岩的生源特征,指出中下侏罗统煤系烃源岩生源以高等植物为主,沉积于偏氧化的淡水环境;古近系安集海河组湖相烃源岩生源以低等水生生物为主,沉积于较咸化的还原环境;侏罗系八道湾组湖相烃源岩热模拟产物的生物标志物特征说明其与煤系烃源岩存在很大差别,但真实特征尚难以确定.通过原油饱和烃的规则甾烷C29/C27以及伽马蜡烷/C30藿烷两相指标将盆地南缘20个原油或油苗分为三类;结合其生源和沉积环境特征,基本确定这三类原油分别来自中下侏罗统煤系烃源岩、古近系安集海河组湖相烃源岩以及二者的混源.

Biogenic origin characteristics of hydrocarbon source rocks and classification of oils in the south part of Junggar Basin, China

This paper discusses the biogenic origin characteristics of source rocks in J_1b, J_1s, J_2x and E_~2-3 a Formations of south Junggar Basin in detail mainly by means of the experimental results of stable carbon isotopes, GC and GC-MS on saturated hydrocarbons as well as thermal stimulation of source rocks. It points out that for the Middle-Lower Jurassic coal-measure source rocks, the biogenic origin is chiefly the higher plants depositing in oxidizing-prone fresh water and for the Eogene lacustrine facies source rocks, it is mainly the aquatic organism depositing in saline-prone reducing environment. The biomarker characteristics of thermal simulation products show that J_1b lacustrine facies source rock is quite different from coal-measure source rocks, but its true characteristics are still difficult to determine. Through the two indexes of regular sterane C_~29 /C_~27 and gammacerane/C_~30 hopane in saturated hydrocarbons, the 20 oils in the south part of the basin can be classified into three groups. After studying their biogenic origin and sedimentary environment characteristics, it is concluded on the whole that the three groups of oil derive from the Middle-Lower Jurassic coal-measure source rocks, the Eogene lacustrine facies source rocks or both of these two, respectively.