辽河盆地大民屯凹陷油气性质及成因机制研究

大民屯凹陷油品性质复杂,既有含蜡量小于20%的正常油,又富含蜡量>20%的特高蜡油。经过原油物性、甾萜等分析,认为高蜡油油源岩沉积环境为较正常油贫粘土、盐度相对较高、相对闭塞的弱还原环境,其母质应由陆源高等植物和低等水生生物共同构成,且经微生物改造较强烈。正常油油源以高等植物为主体,处于相对氧化且富粘土的沉积环境。通过精细油源对比认为:大民屯凹陷高蜡油主要来源于沙四下部的"油页岩",而正常油母质主要为沙四上部和沙三四的厚层泥岩。综合分析认为高蜡油成因主要受控于沉积母质和沉积环境的双重控制,且因整个大民屯凹陷较低的热演化程度而使高蜡油得以保存。 

PETROLEUM CHARACTERS AND FORMATION MECHANISM IN THE DAMINGTUN SAG OF THE LIAOHE BASIN

Oil from Damingtun Sag can be divided into normal oil with waxy content is less than 20% and high waxy oil with wax is more than 20%.Comparing with normal oil,the depositional environment of source rocks of high waxy oil is characterized by poorer shale,higher salty and relative restricted weak reduction water body,and the organic matters are mainly composed of higher plant and lower grade aquatic creatures based on physical nature,sterane and terpene analysis of crude oil.Detail oil-rock correlation shows that high waxy oil originates from "oil shale" of Es4(2),whereas normal oil sourced from shale of Es4(1) and Es3(4).Formation of high waxy oil is mainly controlled by the organic matter of source rocks and the sedimentary environment.The low thermal condition makes the high waxy oil to be preserved in the sag.