松辽盆地朝长地区扶杨油层油气运移模式

Hydrocarbon migration pattern of Fuyang reservoir in Chaochang Area of Songliao Basin

朝长地区扶杨油层与上覆青山口组一段烃源岩层呈"上生下储"式生储盖组合,油气运移呈现2个阶段,即首先在生烃凹陷带由于压差作用发生垂向运移,然后在储层内由于势差作用主要发生侧向运移。研究表明,三肇凹陷和王府凹陷持续埋深区,在嫩江期末开始形成了青一段地层超压带,青一段排出的油气在超压作用下,通过密集断层垂向运移至下伏的扶杨油层低压砂岩储层内;垂向运移至扶杨油层的油气,进入物性好、厚度大且连续性好的砂体,在势差作用下主要发生侧向运移,最终在运移路径上的圈闭中聚集成藏。

Fuyang reservoir together with the overlying source rock in the first member of Qingshankou Formation in Chaochang Area shows a source-reservoir-cap combination condition that is characterized by ＂upper preservation and lower generation＂ and the corresponding secondary migration of oil and gas presents two distinct stage characteristics. At the beginning, the oil and gas discharged from source rocks were subject to vertical migration through pressure difference in depression zone and then lateral migration occurred due to potential difference in the reservoir. As it can be suggested by the research, the first member of Qingshankou Formation stratum overpressure zone began to take shape from the end of Nenjiang stage in the increasingly deepening zone of Sanzhao and Wangfu Sag and hydrocarbon discharged from the first member of Qingshankou Formation under excess pressure migrated vertically to the low pressure sandstone reservoir beneath the Fuyang oil layer by means of dense faults and those hydrocarbon gradually penetrated into sand body that is good, thick and continuous. The following process was dominated by lateral migration through potential difference and eventually those hydrocarbons were trapped on their way of migration.