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我国东部断陷盆地含油气系统具有与盆地结构及勘探程度相对应的多层次性 ,其基本单元是以单一生烃凹陷 (洼陷 )为中心的子系统。复式含油气系统的基础是在盆地中存在不同地质时期的活跃烃源岩 ,它是强烈的多期块断运动和高地热场的产物。断层的活动强度及活动时间和期次控制了盆地中油气系统的分布及特征。用生物标志物进行油源对比可以划分系统并确定其分布范围 ,从而进一步研究成藏规律。以济阳坳陷中的沾化凹陷为例说明复式含油气系统的形成及特征。盆地中三套主要的生油层系分别是始新统的沙河街组第三段、第四段及渐新统的沙河街组第一段。这几套生油岩形成于不同的沉积环境 ,经历了不同的成熟演化阶段并形成了各自的原油。三类原油的特征明显地反映在其中生物标志物的组成上。以这三套生油层系为核心 ,三个成藏期为标志 ,形成了复式含油气系统。这些系统有着各自的生储盖组合 ,运移通道及分布范围 ,它们在空间中叠置或交叉 ,在时间上呈现阶段性。
The petroleum systems in the eastern rift basin of the eastern China have the multi-level corresponding to the basin structure and exploration degree. Its basic unit is a subsystem centered on a single hydrocarbon-generating depression (depression). The basis of the double-petroliferous system is that there are active source rocks of different geological periods in the basin, which are the products of intense multi-period block motion and geothermal field. The activity intensity of faults and the time and period of activity control the distribution and characteristics of petroleum systems in the basin. Using biomarkers for oil source comparison can divide the system and determine its distribution range, so as to further study the law of accumulation. Taking Zhanhua Depression in Jiyang Depression as an Example to Illustrate the Formation and Characteristics of the Multiphase Petroleum System. The three major oil-bearing formations in the basin are the third and fourth sections of the Shahejie Formation of the Eocene and the first segment of the Shahejie Formation of the Oligocene. These oil-bearing rocks formed in different depositional environments, underwent different stages of maturity and evolution and formed their own crude oil. The characteristics of the three types of crude oil are clearly reflected in the composition of the biomarkers therein. Taking these three oil-bearing formations as the core and the three hydrocarbon accumulation periods as signs, a compound petroleum system has been formed. These systems have their own reservoir-cap combination, migration pathway and distribution range, they overlap or cross in space, showing the stage in time.