临南洼陷古近系火山岩油藏原油多环芳烃地球化学特征及其地质意义

Geochemical Characteristics of Polycyclic Aromatic Hydrocarbons in Crude Oil of Palaeogene Igneous Reservoir of Linnan Subsag and Its Geological Significance

对临南洼陷古近系火山岩油藏中12个原油样品进行芳烃生物标志物分析,结果表明:芳烃中三环、四环芳烃化合物占优势,三芳甾烷含量较高,二环、五环、NSO杂环芳烃化合物含量较低。二环芳烃参数(TDE_1、TDE_2、TDE_3)指示典型的湖相、源自年轻源岩的原油特征。三环芳烃以菲系列化合物占主导,检出少量惹烯,表明原油是以低等水生生物为主要生源,有少许高等植物贡献。五环芳烃中芘、苯并芘丰富,侧证了低等水生生物的优势输入。NSO杂环芳烃中含量占绝对优势的硫芴反映出源岩沉积于较强的还原环境。二环芳烃成熟度参数(DNR_1、TNR_2,)、三环芳烃成熟度参数(MPI_1、F_1和F_2)、含硫芳烃成熟度参数(MDR)、三芳甾烷成熟度参数C_(28)-TAS 20S/(20R+20S)均一致显示原油处于成熟—高成熟阶段。

Aromatic hydrocarbon biomarkers of 12 crude oil samples from Paleogene volcanic reservoir in Linnan subsag are analyzed.And the results show that tricyclic aromatic compounds and tetracyclic aromatic compounds in the aromatic hydrocarbons are predominant,the content of triaromatic steroid is higher,and the content of bicyclic,pentacyclic and NSO heterocyclic aromatic compounds is low. The parameters（ TDE1,TDE2,TDE3） of bicyclic aromatics indicate the crude oil samples from typical lacustrine and young source rock. In tricyclic aromatics,phenanthrenes are predominant,and there is a little of retene,which shows that the crude oil is mainly from lower aquatic organisms and there is the contribution of a few higher plant. In pentacyclic aromatics,there are abundant pyrene and benzopyrene,which also shows that the input of lower aquatic organisms is predominant. The dominant dibenzothiophen in NSO heterocyclic aromatics reflects that the source rocks are deposited in a strong reduction environment. The maturity parameters（ DNR1、TNR2） of bicyclic aromatics,the maturity parameters（ MPI1、F1 and F2） of tricyclic aromatics,and the maturity parameter（ MDR） of sulfur-containing aromatics and the maturity parameter C28-TAS 20S/（ 20 R ＋ 20S） of triaromatic steroid all show that the crude oil is in mature to high mature stage.