新疆准噶尔盆地YJ油田土壤油气地球化学特征及来源探讨

准噶尔盆地YJ油田是一个埋藏很深,成藏机理复杂的岩性、地层圈闭油气藏。通过侏罗系西山窑组和三工河组原油、油砂抽提物地球化学特征分析后认为,西山窑组原油具有两期成藏混合的特征,三工河组成熟轻质原油、油砂抽提物又表现出煤系烃源岩的特征。这表明,YJ油田具有多源多期充注成藏的特点。对地表土壤中甲烷碳同位素、烃类比值、三维荧光图谱的分析后认为,甲烷同位素、甲烃同位素、烃类比值与凝析油伴生气、石油伴生气的经验值相符;三维荧光既有凝析油-轻油又有轻油-重油的图谱特征。这与原油和油砂抽提物的研究结果相近,也表明该油田具有多种油源。因而认为,在未知地区对土壤油气地球化学特征进行研究,对于初步判断油气来源同样具有良好的效果。

Surface oil and gas geochemical characteristics and sources of YJ oil field in Zhungeer basin of Xinjiang

YJ oil field in Zhungeer basin is a deeply buried oil and gas pool trapped in the lithology and strata with complicated oil and gas reservoir forming genesis.According to the analysis on the geochemical characteristics of crude oil and oily sand extraction of Xishanyao group and Shan'gonghe group in Jurassic System,it is considered that the crude oil of Xishanyao group is characterized by a combined reservoir forming mechanism of two periods with the matured light crude oil and oily sand extraction showing the characteristics of coal series hydrocarbon source rock.It demonstrates that YJ oil field is characterized by multiple source and period oil forming.The analysis on methane carbon isotope,hydrocarbon ratios and 3D fluorescence pattern shows that methane isotope and hydrocarbon ratios coincide with associated gas of oil or coagulated oil.Either coagulated oil-light oil pattern or light oil-heavy oil pattern characterize 3D fluorescence.The result is close to the research achievement of crude oil and oily sand extraction,showing that the oil field is origin in multiple oil sources. Therefore the research on surface oil and gas geochemistry in unknown area can also receive good result for identifying oil and gas sources.