【摘要】 白云凹陷位于南海北部珠江口盆地深水区地壳强烈薄化带,快速沉降和高地温背景使得油气生成运聚非常复杂。应用油气地球化学、流体包裹体系统分析和2D盆地模拟相结合的方法,研究了白云凹陷目前已发现油气类型、充注幕次、成藏期次和古压力演化,结果表明:白云凹陷存在5类原油和2类天然气,油气充注具有"油早气晚"的特征。白云凹陷珠江组和珠海组储层油包裹体主要分为3类:成熟油包裹体(黄色荧光)、较高成熟油包裹体(黄绿色荧光)、高成熟油包裹体(蓝白色荧光,与天然气充注关系较为密切)。白云凹陷早期存在油气充注,后期普遍经历气洗作用而使古油藏遭受破坏。应用古压力-埋藏深度投点法确定至少存在2期充注:第1期为13.1～7.3Ma,主要为成熟油充注;第2期为5.5～0Ma,主要为高成熟油和天然气充注。压力演化模拟表明,较明显的生烃增压主要开始于白云运动时期,主要经历3期泄压:第1期成藏意义不大,第2期对早期油运移有重要意义,第3期对油气晚期成藏意义重大。本文成果对白云凹陷油气富集规律研究及下一步油气勘探有重要指导作用。更多还原

【Abstract】 The Baiyun sag is located in the strongly thinned zones of continental crust in deepwater area of the Pearl River Mouth basin(PRMb),and the rapid subsidence and high geothermal gradient made the petroleum migration and accumulation very complicated.Combining the analysis of petroleum geochemistry,fluid inclusion and 2Dbasin modelling,the hydrocarbon types,charging episodes,accumulating periods and paleopressure evolution discovered in the study area of Baiyun sag have been studied.The results reveal that there are five types of oil and two types of natural gas existing in the Baiyun sag,and the charging history is characterized by"oil in the early stage and gas in the late period".Reservoir oil inclusions observed in the Zhujiang Formation and Zhuhai Formation of the Baiyun sag mainly consist of three types:mature oil inclusion(yellow fluorescence),relative higher mature oil inclusion(yellow-green fluorescence),and high mature oil inclusion(blue-white fluorescence,which is closely related to gas charging).The Baiyun sag has undergone early hydrocarbon charging,and the paleo-reservoirs were universally damaged by gas washing occurred in the later stage.By applying the paleopressure-burial depth projection method,at least two periods of hydrocarbon charging were determined.The first period was in the range of13.1～7.3Ma,dominated by mature oil charging,and the second period was in the range of 5.5～0Ma,dominated by high mature oil and natural gas charging.The pressure evolution simulation suggests that the major hydro-carbon-generating pressurization initiated at the period of Baiyun movement,and basically three discharging stages had been experienced.The first one is of little significance to the hydrocarbon accumulation,the second one is of great significance to the early oil migration,and the third one with the longest duration is of great significance to the late oil and gas accumulation.The conclusions of this paper could provide an important guidance for studying the hydrocarbon enrichment laws and the next exploration in the Baiyun sag.更多还原