牛庄洼陷南斜坡未熟-低熟烃源岩排烃特征探讨  

Discussion of Hydrocarbons Expulsion from Less Mature Source Rocks in the Niuzhuang South Slope of Dongyi Depression, Bohai Bay Basin

作　　者：李素梅[1] 庞雄奇[1] 金之钧 马晓昌[3] 句礼荣[4] 

机构地区：[1]石油大学盆地与油藏研究中心 [2]Sinopec勘探开发研究院,北京100083 [3]江汉石油管理局清河采油厂,湖北荆州262714 [4]胜利石油管理局滨南采油厂地质所,山东东营256606

出　　处：《沉积学报》2004年第1期161-168,共8页Acta Sedimentologica Sinica

基　　金：国家重点基础研究项目 (编号G1 9994331 0 )资助

摘　　要：牛庄洼陷及其南斜坡烃源岩孔隙度、声波时差与伊蒙矿物含量测定结果表明 ,2 6 0 0m为成岩作用早期与晚期阶段的界限 ,在早期演化阶段南斜坡没有出现明显的异常压力 ,牛庄洼陷成岩作用晚期阶段有明显的压力异常。生物标志物演化与Ro值测定反映 ,该区有机质大量成烃起始阶段为 2 70 0m ,牛庄洼陷南斜坡带 <2 70 0m烃源岩不具备大量排烃的生烃量条件与地质证据。牛庄洼陷南斜坡八面河油田原油的混合成熟度特征与混合的均一性 ,反映原油的混合作用在初次运移阶段可能即已发生 ,推测牛庄洼陷深部烃源岩在异常压力作用下通过微裂隙等间歇式排烃的同时 ,浅层未熟 低熟烃源岩生成的少量原油经由断层、应力产生的微裂隙与层理面 ,在地层压力及深部流体过剩压力参与下与成熟油混合幕式排出。烃源岩未熟 低熟阶段的排烃效率低于成熟烃源岩。It was suggested that 2 600 m is the boundary of early and later stage of diagenesis in Niuzhuang South Slope, Dongyi Depression, Bohai Bay Basin according to porosity, illite/montmorillonite ratio and acoustic transit time, and no abnormal formation pressure was observed from Es4 intervals located in the Niuzhuang South Slope. It was proved that 2 700 m is oil generation threshold (R o=0.5%) of normal oil window based on vitrinite reflectance and thermal evaluation of biomarkers as well as oil source rock correlation results previously. No solid proofs support the opinion that Es4 shales located in the Niuzhuang South Slope should be the main source rock of oil pools in Bamihe oilfield. It was assumed that less mature oils with small amount as suggested by our recent reinvestigation were expelled through faults, shale layer under formation pressure of overlying intervals periodically. Particularly, deeper fluid pressure was suggested to play active roles in hydrocarbons expulsion of shall intervals indirectly, which is created by large amount of generated and expelled hydrocarbons. Hydrocarbons generated by source rocks with wide range of thermal maturity were expelled by abnormal fluid pressure periodically and contemporaneously leading to mixing of the oils with different maturity during primary migration. Relative small amount of hydrocarbons generated and low efficiency of hydrocarbons expulsion are responsible for low immature petroleum resource of Bamihe oilfield.

关 键 词：烃源岩 排烃特征 混合相 初次运移 

分 类 号：TE122.12[石油与天然气工程—油气勘探]