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为查明古油藏原油的成因,对羌塘盆地双湖地区侏罗系布曲组含油白云岩、含沥青石灰岩的饱和烃气相色谱和萜烷、甾烷生物标志化合物特征进行了分析,并利用GC-C-MS技术对含油白云岩、含沥青石灰岩、石灰岩中正构烷烃单体碳同位素的组成特征和分布形式进行了研究。测试结果显示,Pr/Ph值为0.37～2.07,Pr/nC17值为0.14～0.76,说明油气源岩沉积环境以浅海陆棚开放性水域为主;OEP值为0.96～1.17,奇碳优势不明显,显示了成熟—高成熟阶段的基本特征;原始有机母质构成中既有较高比例的高等植物,又有一定比例的低等水生生物混入。原油与烃源岩δ13C值分布形态具有相似的特征,正构烷烃单体碳同位素都表现为δ13C值从低碳数到高碳数降低的趋势,反映了原油来自海相沉积地层,它们具有同源的有机质母源。
In order to find out the origin of the oil in the ancient reservoirs, the gas chromatography of saturated hydrocarbons and the characteristics of the terpane and sterane biomarkers of the Jurassic Buqu Formation oil-bearing dolomite and bitumen limestone in the Shuanghu area, the Qiangtang Basin were analyzed. GC-C-MS was used to study the composition and distribution of carbon isotopes of n-alkanes in oil-bearing dolomites, bitumen-bearing limestones and limestones. The test results show that Pr / Ph value is 0.37 ~ 2.07, Pr / nC17 value is 0.14 ~ 0.76, indicating that the oil and gas source rock sedimentary environment is dominated by shallow open shelf waters; OEP value is 0.96 ~ 1.17, Showing the basic characteristics of the mature - high maturity stage; the original organic parent composition in both a higher proportion of higher plants, and a certain percentage of lower aquatic organisms mixed. Δ13C value distributions of crude oil and source rock have similar characteristics. The carbon isotopes of n-alkanes show the trend of decreasing δ13C value from low carbon number to high carbon number, reflecting that the crude oil comes from the marine sedimentary strata and that they have the same Source of organic maternal source.