【摘要】 大民屯凹陷位于渤海湾盆地东北角 ,北部第三系沙河街组 3段中下部及前第三系潜山赋存大量的高蜡原油 ,中部为混合油分布区 ,南部为正常油。沙河街组 3,4段均为优质烃源岩 ,有机碳含量平均达 2 16 ,丰富的有机质为高蜡油的形成提供了雄厚的物质基础。除高等植物外 ,低等水生生物也是高蜡油的重要先体物质 ,多种先体物质并存 ,使得原油含蜡量骤增。大民屯凹陷沙河街组的二苯并噻吩与菲的比值都在 1 0以下 ,表明该凹陷的沙河街组整体上形成于淡水弱氧化环境 ;北部长期处于低演化阶段 ,而中、南部演化程度相对较高。这种弱氧化、低成熟的环境是高蜡油得以保存的关键。大民屯凹陷高蜡油中 ,锥满烷系列含量丰富 ,说明微生物作用对高蜡油形成有一定贡献。更多还原

【Abstract】 Damintun Sag is situated in the northeast corner of Bohai Bay Basin.The middle and lower parts of the Sha-3 member and buried hill of the Tertiary System in the north part of the sag preserve large amount of high wax crude oil;the central part of the sag contains mixed oil and the south part contains normal oil.Sha-3～Sha-4 members are fine source rocks with 2.160/0 average organic carbon contents.Abundant organic matter,including higher plant and lower hydrobionts in the source rocks,increased the wax contents.The ratio between dibenzothiophen and phenanthrine is less than 1.0,suggesting that the whole Shahejie Formation was formed in weak oxidation environment of fresh water.Besides,the north part had been long in the low maturation stage.This weak oxidation-low maturation environment is the key factor for the high wax oil to be preserved.The high contents of drimane in the oil indicate that microbial action made some contribution for the formation of the high wax oil.更多还原