南沙海域万安盆地新生界含油气系统分析

万安盆地新生界含油气系统由渐新统—中中新统烃源岩、前第三纪基岩—中新统储集岩和上新统—第四系区域盖层组成。圈闭类型以断块、背斜和礁隆为主;主要烃源岩从中中新世末开始进入生、排烃高峰,现已达到高—过成熟,且以产气为主;各类圈闭大多在中中新世末前定型,并在上新世未基本成藏;油气运移方式为短距侧向运移与垂向运移并重,油气捕集方式以高阻系统为主,油气充注量达到过—正常充注。由此证实,万安盆地为一生油期较长、成藏较晚、生运聚匹配适宜、保存条件较好、油气蕴藏量丰富的含油气盆地。 

ANALYSIS ON THE CENOZOIC PETROLEUM SYSTEM IN THE WAN′AN BASIN,NANSHA AREA

The Cenozoic petroleum system in the Wan'an Basin is made of the Oligocene-Middle Miocene source rocks,the Pre-Tertiary bedrock-Miocene reserviors and the Pliocene-Quaternary caprocks.The traps are dominated by fault blocks,anticlines and reefs.The main source rocks reached the peak of hydrocarbon generation and expulsion in the end of the Middle Miocene and presently are in the high-to over-matured stage.Various traps were formed before the end of the Middle Miocene and hydrocarbon accumulation was in its way in the end of the Pliocene.Hydrocarbon migrated both horizontally and vertically in short distance and was caught up by a resistive system.The traps were over-or normal-charged.In a word,the Wan'an Basin is favorable for hydrocarbon exploration as a result of its long hydrocarbon generation,late accumulation and good preservation.