摘要:
松辽盆地北部深层发现的凝析油及油型气扩大了油田的勘探潜力。应用单体烃碳同位素、生物标志化合物等分析技术,结合地质背景对凝析油、天然气和固体沥青进行的地球化学研究表明:深层凝析油包括煤成凝析油和泥质烃源岩形成的凝析油,前者芳烃含量高、单体烃碳同位素重,后者饱和烃含量高、单体烃碳同位素轻,生物标志化合物对比,二者均来自于沙河子组烃源岩;油型气甲烷碳同位素轻,一般小于-45‰,且甲烷与乙烷之间碳同位素分馏明显,属原油裂解成气特征,油型气与煤型气混合可能是深层天然气碳同位素系列倒转的重要原因之一;火山岩储层中的固体沥青有机地球化学分析,有机碳含量0.08%-0.16%,氢指数49-297mg/g,尺。大约为1.87%,表征固体沥青现今的成烃潜力较小,原油向天然气转化主要发生在高成熟阶段的晚期,对应的地质年代大约是嫩江组-明水组沉积末(80-65Ma)。原油向天然气转化的事实启示,深层天然气勘探要兼顾古油藏的研究。
关键词:
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松辽盆地 /
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深层 /
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天然气 /
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碳同位素 /
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烃源岩
Abstract:
The discovery of condensate and oil-type gas from deep reservoir increased the exploring potential of petroleum in the north of Songliao basin. Applying the analytical technologies of biomarker and carbon isotope of individual compounds, combining with geological background, the geochemical characteristics of condensate, oil-type gas and solid bitumen was discussed. The condensate was generated from coals and coal-measure source rocks in deep formation of the basin. The former is characterized by high content of aromatic hydrocarbon and heavy carbon isotope of individual compounds. The latter is characterized by high content of saturated hydrocarbon and light carbon isotope of individual compounds. However, the result of correlating biomarker indicates that the both condensate are derived from the same source rock-Shahezi formation. The carbon isotope of methane of oil-type gas is light, generally less than -45‰. The difference of carbon isotope between methane and ethane is obvious belonging to natural gas from oil cracking. The mixture of oil-type gas and coal-type gas in deep reservoir may be the one major reason of reverse in hydrocarbon carbon isotope series of deep natural gas. The TOC is 0. 08%-0. 16%, the HI is 49-297 mg/ g, Ro is about 1. 87% for the solid bitumen in deep volcanic reservoir. It shows that potential of generating hydrocarbon of the solid bitumen is low nowadays, oil was cracked to natural gas during the later period of high mature stage, corresponding geologic age is about the sedimentary time between the Nenjiang formation and Mingshui formation (80-65 Ma). The fact of oil transforms into natural gas enlightens that the exploration of deep natural gas should put the study of pero-reservoir into consideration.
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