4-甲基甾烷在油源对比中的应用——以渤南洼陷北部陡坡带为例  

Application of 4-Methyl Steranes in Oil-Source Correlation:A case study from northern steep slope zone of Bonan Sag

作　　者：昝灵[1] 张枝焕[2] 王顺华[3] 邢辉[2] 李文浩[2] 刘祎楠[4] 席伟军[5] 

机构地区：[1]中国石油化工股份有限公司华东分公司石油勘探开发研究院,南京210011 [2]中国石油大学油气资源与探测国家重点实验室,北京102249 [3]中国石油化工股份有限公司华东胜利油田石油开发中心,山东东营257000 [4]西北大学地质系,西安710069 [5]中国石油化工股份有限公司华东胜利油田新疆勘探开发中心,山东东营257000

出　　处：《沉积学报》2012年第4期770-778,共9页Acta Sedimentologica Sinica

摘　　要：同一洼陷不同次洼的烃源岩及生成的原油,由于古气候、古沉积环境较为相似,其常规生物标志化合物和同位素特征差别非常小,给油源分析带来困难。通过GC—MS分析提取原油和烃源岩中分子化石信息,主要依据4-甲基甾烷的相对含量和不同构型的4-甲基甾烷的分布特征来进行油源对比,为类似地区的油源分析提供了一种新思路。渤南洼陷发育Es4s和Es3x两套主力烃源岩,中部次洼、西部次洼和渤南深洼Es3x烃源岩的4-甲基甾烷/C29甾烷值分别为4.51、2.79、1.27,是由于烃源岩中沟鞭藻有机质占总有机质的比例不同所造成。不同地区原油C20、C21、C23三环萜烷和ααα20RC27、C28、C29规则甾烷等特征非常相似,成熟度相当,中、西、东三个地区原油的4-甲基甾烷/C29甾烷值分别为2.89,2.39和2.06,区别明显,各个地区4-甲基甾烷的构型也不同。对比结果表明,渤南洼陷北部陡坡带Es4s和Es3x油气均为近源成藏,主要来源于其临近次洼的Es3x烃源岩。Because of the samilar paleoclimate and palosedimentary environment,regular biomarkers and isotope distinction of the source rocks and generated petroleum in the sub-sag belong to the same sag is tiny,which bring difficulties to oil-source correlation.By extracting molecular fossils information using GC-MS technology,according to the relative content of 4-methyl steranes and distribution characteristics of 4-methyl steranes isomers,oil-source correlation work are performed,which provides a new method for oil-source correlation in similar area.Es4s and Es3x two sets of source rocks are developed in the study area,they are characterized by high organic matter abundance,mature to over mature thermal evolution degrees.Organic matter of Es4s are formed in brackish-saline water with reductive environment,organic matter of Es3x are formed in fresh-saline water with reductive environment,organic matter input of both source rocks are dominated by lower aquatic organisms and terrigenous higher plants,while terrigenous higher plants are more abundant near provenance.Relative content of 4-methyl steranes of Es3x source rocks is higher than that of Es4s source rocks,indicating the better organic matter input of Es3x source rocks.The value of 4-methyl steranes/C29 steranes of Es3x source rocks in the middle,west and deep sub-sag is 4.51,2.79 and 1.27,respectively,which is caused by the different proportion of dinophyceae in total organic matter.The distribution characteristics of C20,C21,C23 tricyclic terpanes and ααα20RC27,C28,C29regular steranes of oils with alike maturity in different region is quite similar,4-methyl steranes/C29steranes value of crude oils in the middle,west and east region is 2.89,2.39,2.06,respectively,which make a big difference,while the carbon isotope characteristics of crude oils are opposite,distribution characteristics of 4-methyl steranes isomers of each region is also different.Oil-source correlation demonstrate that Es4s and Es3x crude oils of northern steep slope zone mainly originate from E

关 键 词：4-甲基甾烷 渤南洼陷 北部陡坡带 生物标志化合物 油源分析 

分 类 号：P593[天文地球—地球化学]