庙西凹陷中南洼烃源岩评价及其勘探启示

Evaluation on Source Rocks in Miaoxi Middle-Southern Sag and Its Aspiration to Exploration

张宏国 官大勇 宿雯 王广源 麻旭刚

ZHANG Hongguo GUAN Dayong SU Wen WANG Guangyuan MA Xugang

中海石油(中国)有限公司天津分公司渤海油田研究院, 天津 300452

Research Institute of Bohai Oilfield, Tianjin Branch of CNOOC Ltd., Tianjin 300452, China

渤海边缘洼陷整体勘探程度较低,烃源岩生、排烃能力分析是研究重点。为明确庙西凹陷中南洼地区油气富集规律,从烃源岩分析和油源对比入手,明确低熟油优势运移通道类型,进而预测油气富集层位与区带。研究表明,中南洼地区发育巨厚沙三段,其有机质母质类型以混源为主,沉积水体为半咸水-咸水环境,现处于低熟阶段,为蓬莱25-6油田主要油源,证明其为研究区主力生烃层系。烃源岩热演化与排烃强度分析表明庙西凹陷中南洼烃源岩热演化程度较低,而低熟油初次运移动力较弱,因此单一型的油气二次运移通道运移量高于复合型通道,沿断层近距离运移馆陶组就近成藏几率较大。研究区中部走滑带断层活动性强且深切油源,主干走滑和其派生断层形成背斜形态圈闭,具有良好的勘探潜力。

The exploration degree on marginal sags in Bohai Sea is low,and the exploration key is to study the hydrocarbon generation and expulsion capability of source rocks.In order to make clear about the hydrocarbon accumulation regularity in Miaoxi middle-southern sag,analysis of geochemical characteristic of source rock and oil-source correlation have been conducted,and the advantage hydrocarbon migration pathways for low mature oils have been made clear.In addition,the hydrocarbon rich target series and zones have been forecasted.The study results indicated that Sha-3 Member is thick and well developed in Miaoxi middle-southern sag,the organic matter matrix type of source rock are mainly mixed type,deposited in brackish water and salty water environments,being main oil sources for Penglai 25-6 oilfield with low mature oil.It has been proved that Sha-3 Member is the main hydrocarbon generation series for the study area.The analyzing results about thermal evolution of source rock and hydrocarbon expulsion intensity indicated that the thermal evolution degree of source rock is low in Miaoxi middle-southern sag,and the driving force for primary hydrocarbon migration is low.Therefore,the amount of hydrocarbon migrated through single type of secondary pathway is higher than that through compound pathway,and the chance of hydrocarbon accumulation in Guantao formation through short distance migration by faults was higher.Faults activity was strong in middle strip-slip zone,and cut deeply the source rocks.The main strip-slip faults and the derivated faults cut anticlines,and the faulted anticline traps have great exploration potential.

"十二五"国家科技重大专项"渤海海域大中型油气田地质特征"(2011ZX05023-006-002)

https://doi.org/10.3969/j.issn.1008-2336.2015.01.052