摘要
基于珠江口盆地惠州凹陷油气勘探实践,通过烃源岩地球化学指标测定、储集体发育形貌恢复及镜下岩矿表征、圈闭封盖指标实测比对、原油生物标志化合物提取、凝析气成因判别及成藏条件解剖,系统分析惠州26洼古近系恩平组油气资源潜力、大型砂砾岩优质储集层发育特性、断裂圈闭有效性及油气运聚成藏模式,总结南海东部古近系富砂砾型大中型油气田的形成条件及勘探方向。研究表明:(1)洼内古近系文昌组发育“面积广、厚度大”的半深湖—深湖亚相优质烃源岩,具有“早期大量生油、晚期大量排气”的典型倾油型烃源岩排烃特征,为恩平组油气成藏提供了充足的物质基础;(2)洼内断裂陡坡带与转换带联合控制下近源规模性砂砾岩体储集层非均质性强,具有“有利相带-颗粒组分-微裂缝”三元分级控储特性,等粒、低泥质(含量小于5%)、高含量长石组分及近断裂组合的(水下)分流河道有利于甜点储集层发育;(3)稳定湖泛泥岩封盖下的走滑增压型圈闭是油气保存的必备条件,斜交主应力的北东及近东西向断裂控圈效果最优;(4)优质烃源岩-断裂输导/封堵-砂砾岩储集层时空配置共同控制油气富集程度,自上而下划分为低充满带、过渡带和高充满带3个油气聚集单元,且近增压型通源断裂带河道主体区利于规模性油气富集。研究成果为珠江口盆地恩平组规模性富砂砾型油气藏勘探指明了新方向,并实现了油气勘探重大突破。
Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,and the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields were summarized of the Paleogene in the eastern South China Sea.The research results are obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(underwater)distributary channels near fault system,with equal grains,low mud content(<5%),and high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.
作者
徐长贵
高阳东
刘军
彭光荣
刘培
熊万林
宋朋霖
XU Changgui;GAO Yangdong;LIU Jun;PENG Guangrong;LIU Pei;XIONG Wanlin;SONG Penglin(CNOOC,Beijing 100010,China;Shenzhen Branch of CNOOC,Shenzhen 518054,China;CNOOC Deepwater Development Ltd.,Shenzhen 518054,China)
出处
《石油勘探与开发》
EI
CSCD
北大核心
2024年第1期14-27,共14页
Petroleum Exploration and Development
基金
中国海洋石油集团有限公司“十四五”重大科技项目“海上深层/超深层油气勘探技术”(KJGG2022-0403)
中国海洋石油有限公司重大科技项目“南海东部大中型天然气田勘探潜力与突破方向”(KJZH-2021-0003-00)。
关键词
珠江口盆地
惠州凹陷
惠州26洼
古近系
恩平组
砂砾岩
大中型油气田
Pearl River Mouth Basin
Huizhou Sag
Huizhou 26 subsag
Paleogene
Enping Formation
glutenite
large-and medium-sized oil and gas field
