摘要
辽西低凸起是渤海湾盆地重要的含油气构造,南部油气环绕辽西凹陷南洼呈带状分布,辽西凹陷南洼对油气的贡献以及贡献多寡的问题一直存在争议,制约了该地区勘探进程。本研究通过分析围绕辽西凹陷南洼分布的油气生物标志化合物组成和地球化学特征,厘清原油与辽西凹陷南洼和辽中凹陷中洼烃源岩的关系。结果表明:①辽西低凸起南部油气带分布在辽西大断层两侧,环绕辽西凹陷南洼东北侧的油藏有LD5N、SZ36、LD5和LD4油藏,其中LD4油藏和LD5东二下段油藏具有高甲藻甾烷、低C_(30)4-甲基甾烷的低成熟特征,来源于辽西凹陷南洼沙三段和沙一段烃源岩;LD5东二上段油藏和SZ36S油藏分布在断层两侧,发育甲藻甾烷、C_(30)4-甲基甾烷和伽马蜡烷,原油处于成熟阶段,属于辽西凹陷南洼和辽中凹陷中洼混合来源;LD5N油藏和SZ36油藏具有高C_(30)4-甲基甾烷、低伽马蜡烷的特征,均为成熟原油,由辽中凹陷中洼烃源岩生成;②辽西凹陷南洼以低熟油为主,沿断层向LD5、LD4构造带深部运移充注,形成LD4和LD5东二下段油藏;LD5、LD4东二下段充满后,辽西凹陷南洼低熟油沿断层继续向浅部运移,与辽中凹陷中洼成熟油在LD5东二上段、SZ36S汇合,形成LD5东二上段、SZ36S混合类油藏,辽中凹陷中洼成熟油向SZ36油藏东北侧运移,跨过辽西大断层后在浅部形成LD5N油藏。
The Liaoxi low-uplift structural belt is an important oil-gas-bearing structure in the Bohai Bay Basin.The oil and gas in the south of the Liaoxi Depression are distributed around the south sag of the Liaoxi Depression.The contribution of the south sag of the Liaoxi Depression to oil and gas remains controversial,which restricts the exploration process in this area.In this study,the relationship between crude oil and source rocks in the south sag of the Liaoxi Depression and mid-sag of the Liaozhong Depression was clarified by analyzing the compositions and geochemical characteristics of biomarkers of oil and gas distributed around the southern sag of the Liaoxi Depression.The results show that:(1)Oil and gas reservoirs in the southern part of the Liaoxi low-uplift are distributed on both sides of the Liaoxi large fault.LD5N,SZ36,LD5,and LD4 reservoirs occur around the northeast side of the south sag of the Liaoxi Depression,among which the LD4 and LD5 reservoirs(E3d2L)have the characteristics of low maturity with high dinosterane and low C_(30)4-methylsterane and originated from the source rocks of E2s3 and E2s1 in the south sag of the Liaoxi Depression.The oil reservoirs of LD5(E3d2U)and SZ36S are distributed on both sides of the fault and are characterized by dinosterane,C_(30)4-methylsterane,and gamma-cerane.The crude oil is in the mature stage and belongs to the mixed source of the south sag of the Liaoxi Depression and the mid-sag of the Liaozhong Depression.The LD5N and SZ36 reservoirs have high C_(30)4-methylsterane and low gamma-cerane,both of which are mature crude oil generated from the mid-sag of the Liaozhong Depression.(2)The south sag of the Liaoxi Depression is dominated by low-mature oil,which migrated and charged to the deep LD5 and LD4 tectonic belts along the fault to form the LD4 and LD5(E3d2L)reservoirs.After LD5(E3d2U)and LD4(E3d2U)were filled,the low-mature oil of the south sag of the Liaoxi Depression continued to migrate to the shallow part along the fault and joined with the mature oil
作者
李威
LI Wei(CNOOC Research Institute Co.Ltd.,Beijing 100028,China)
出处
《地球化学》
CAS
CSCD
北大核心
2024年第2期195-203,共9页
Geochimica
关键词
甲藻甾烷
辽东湾
辽西凸起
辽西凹陷南洼
dinosteranes
Liaodong Bay
Liaoxi uplift
the south sag of the Liaoxi Depression
