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南海中南部主要盆地油气地质特征

第3〇卷第4期中国海上油气Vol. 30No. 4 2018年8月CHINA OFFSHORE OIL AND GAS Aug. 2018文章编号:1673-1506(2018)04-0045-12D^O I:10. 11935/j. issn. 1673-1506. 2018. 04. 006南海中南部主要盆地油气地质特征$赵志刚(中海油研究总院有限责任公司北京128)赵志刚.南海中南部主要盆地油气地质特征[J].中国海上油气,2018,(4:45-56.Z H A O Zhigang. Hydrocarbon geology characteristics of the main basins in mid-southern South China Sea[J]. China Offshore Oil and G as»2018, 30(4:45-56.摘要利用重磁、地震、钻井等资料,结合前人研究成果,系统分析了南海中南部主要盆地新生代构造-沉积充填演化及油气地质条件,并进一步开展了烃源岩综合评价与油气成藏研究。

南海中南部9个盆地可划分出中部伸展-裂离型、西部伸展-走滑型和南部伸展-挤压型等3大盆地群。

中部盆地群经历了始新世一早中新世断拗期、中中新世漂移期和晚中新世一现今拗陷期演化阶段,以滨浅海一半深海沉积环境为主,发育陆源海相烃源岩,以I型干酪根为主,主要发育下生上储式碳酸盐岩成藏组合;西部盆地群经历了晚渐新世一早中新世断拗期、中中新世反转期、晚中新世一现今拗陷期演化阶段,呈“早湖晚海”的沉 积充填特征,发育湖相烃源岩和海陆过渡相烃源岩,以n2—m型干酪根为主;南部盆地群经历晚渐新世一早中新世断拗期、中中新世反转期、晚中新世一现今拗陷期演化阶段,发育三角洲-滨浅海沉积体系和海陆过渡相烃源岩,以n—型干酪根为主。

西部盆地群和南部盆地群近岸发育自生自储式砂岩成藏组合,远岸发育下生上储式碳酸盐岩成藏组合。

本文研究成果进一步明晰了南海中南部盆地油气地质规律,可为下一步勘探决策提供技术支撑。

关键词南海中南部;地群;生代;造演化r沉积充填;藏组合中图分类号:T E1.1文献标识码:AHydrocarbon geology characteristics of the main basins inmid-southern South China SeaZHAO Zhigang(CNOOC Research Institute C o.,L t d.,B eijing100028 >China)Abstract:By using gravity magnetic,seism ic and drilling data and combining with previous research re­sults,this paper systematically analyzed Cenozoic tectonic-sedimentary filling evolution and oil and gas geological conditions in the m ain basins at the mid-southern South China Sea,and further carried out comprehensive evaluation on hydrocarbon source rocks and research on oil and gas accumulation.Nine basins distributing in the mid-southern South China Sea can be divided into three m ajor basin groups:ex­tension-dissociation type in the center,extension-strike-slip type in the west and extension-extrusion type in the south.Central basin group has experienced Eocene and early Miocene fault-depression peri­od,drift period in the mid-Miocene and depression period from late Miocene to now?which was domina-*国家自然科学基金项目“南海深海地质演变对油气资源的控制作用(编号:915283)”、“十三五”国家科技重大专项“曾母-北康盆地群 油气地质条件研究与勘探方向选择(编号:2016Z X0502604)”部分研究成果。

作者筒介:赵志刚,男,髙级工程师,1998年毕业于中国地质大学(武汉),获硕士学位,现主要从事海上油气地质综合研究工作。

地址:北 京市朝阳区太阳宫南街6号院海油大厦(邮编:100028)。

E-mail:zhaozg@cnooc. com. cn。

46中国海上油气2018年8月ted by shallow shore-semi-deep sea environment;land-derived m arine source rocks were developed,an d type III kerogen played the controlling role,In the central basin group,carbonate reservoir in the accu­mulation combination of lower generation and upper preservation^was mainly developed.The western basin group experienced late Oligocene-early Miocene fault-depression period,mid-Miocene inversion pe­riod and depression period from late Miocene to now,showing accumulation characteristics of“early lake and later marine”,where lacustrine source rock and transitional source rock were developed,and I—III type kerogen played the controlling role.The southern basin group experienced late Oligocene-early Mio­cene fault-depression period,mid-Miocene inversion period and depression period from late Miocene to now,where delta-shallow shore accum ulation system and transitional source rocks were mainly devel­oped and the II—III type kerogen played the controlling role.In the west basin group and the south basin group,the self-generation and self-preservation hydrocarbon accumulation combination was developed near the shore area,and the lower generation and upper preservation hydrocarbon accum ulation combi­nation was developed in the far shore area.This paper further clarifies oil/gas geologic distribution rule in mid-southern South China Sea and provides important technical support for future exploration deci­sion-making.Key words:mid-southern South China Sea;basin group;Cenozoic;tectonic evolution;sedim entary filling;accum ulation com bination南海是西太平洋最大的边缘海之一,面积约350 X l〇4km2,经历了古南海和新南海两大边缘海构造旋回,形成“南压北张、东挤西滑”的构造动力学环境,发育多种不同类型的沉积盆地1。

南海中南部是指北纬1°以南的海域,主要发育曾母盆地、文莱-沙巴盆地、万安盆地、中建南盆地、南薇盆地、北康盆地、礼乐盆地、巴拉望盆地和南沙海槽盆地(图1)。

自20世纪初开始勘探至今,已发现数百个油气田,是世界上为数不多的常规储量上百亿吨油当量的巨型油气区[34]。

国内外学者对南海中南部各盆地做了大量的研究工作12,但鲜有把整个中南部作为整体进行综合分析的研究报道。

笔者基于二维地震资料、区域重磁资料、古生物资料和30多口钻井资料,完成了新生界6个地震反射界面的区域构造综合解释、20多张沉积相平面图、近千个地球化学数据和1个典型油气田重点解剖等工作。

在大量地质工作的基础上,将南海中南部9个盆地置于南海区域演化的时空背景中,划分出中部伸展-裂离型、西部伸展-走滑型和南部伸展-挤压型等三 大盆地群,发现其构造演化、沉积充填、烃源岩和油气成藏组合特征等方面存在显著的差异,进一 步明晰了南海中南部油气地质特征,对该区域下^■步油气勘探决策具有指导意义。

South China Sea1构造演化特征南海中南部盆地群的形成主要受控于南海构造 演化过程中所经受的不同动力学背景(图2),三大第30卷第4期赵志刚:海中南部主要盆地油气地质特征深海浅海海陆过渡带陆壳洋中脊位置板块俯冲带南部盆地群中部盆地群西部盆地群图2南海区域构造演化特征Fig. 2Regional tectonic evolution of South China Sea盆地群构造演化特征差异较大。

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