摘要
【目的】印度扇近海盆地古新世—始新世时期位于赤道区域,发育大规模碳酸盐岩台地。然而,受限于二维地震资料品质与数量,碳酸盐岩台地沉积特征及演化尚不清晰,台地内部结构刻画不足,进一步制约了该区更加深入的油气勘探工作。【方法】通过搜集以往及新采集二维地震、钻井资料,开展印度扇近海盆地古新统—始新统碳酸盐岩台地地震相识别,刻画不同时期台地内部平面及垂向展布特征,探讨台地沉积演化历史,总结影响台地发育的主控因素。【结果】基于地震资料系统分析,共识别出6种地震相类型,其中丘状或透镜状—中弱振幅—中低连续—中低频相对应于生物礁沉积相,具有较好储层物性。在地震相分析基础上,将研究区碳酸盐岩台地划分为4个沉积演化阶段,分为初始发育阶段、繁盛阶段、衰退阶段及淹没阶段。【结论】通过区域构造演化、海平面升降、古气候演变背景分析,结合碳酸盐岩台地时空分布特点,认为岩浆侵入形成先期古高地地形限制古新世—始新世时期碳酸盐岩台地的空间分布、形态、规模大小,海平面升降与古气候演变影响台地形态。研究为揭示区域海平面变化及驱动机制提供依据,对该地区开展油气勘探工作提供支撑。
[Objective]The offshore Indus Basin was located in the equatorial region during the Paleocene-Eocene period,and a large-scale carbonate platform was developed.However,limited by the quality and quantity of two-dimensional(2D)seismic data,the sedimentary characteristics and evolution of the carbonate platform are not clear,and the internal structure of the platform is not depicted sufficiently,which further restricts the deepening of oil and gas exploration in this area[.Methods]Through the collection of previous and newly acquired 2D seismic and drilling data,the seismic facies identification of the Paleocene-Eocene carbonate platform in the offshore Indus Basin was performed,the internal plane and vertical distribution characteristics of the platform in different periods were depicted,the sedimentary evolution history of the platform was discussed,and the main controlling factors affecting the development of the platform were summarized.[Results]Based on the systematic analysis of seismic data,six types of seismic facies have been identified.Among them,mound or lenticular shape-medium weak amplitude-medium low continuous-medium low frequency corresponds to reef sedimentary facies,with good reservoir physical properties.Based on seismic facies analysis,the carbonate platform in the study area is divided into four sedimentary evolution stages,including initial development,prosperity,recession,and inundation stages.The initial stage is dominated by platform lagoon facies,mainly showing vertical growth and limited sedimentary thickness.In the prosperity stage,large-scale carbonate rocks were deposited on the early thin carbonate platform,and the thickness of the reef shoal facies was significantly increased.In the recession stage,the platform edge obviously retreats,the area decreases,and the platforms are isolated.In the inundation stage,the range of the platform were further reduced,and the reef and shoal facies were deposited,and the platform was gradually inundated by seawater in the late stage.[Conclusions]Based on the analysis of the background of regional tectonic evolution,sea level rise and fall,and paleoclimate evolution,combined with the space-time distribution characteristics of the carbonate platform,it is believed that the pre ancient highland terrain formed by magma intrusion limits the spatial distribution,shape,and scale of the carbonate platform in the Paleocene-Eocene period,and sea level rise and fall and paleoclimate evolution affect the platform shape.In the petroleum accumulation process of the reef reservoir,the distribution of effective hydrocarbon source rocks,migration pathways,and the spatial distribution of reef and carbonate reservoirs are the three most important control factors.The isolated platform in the middle of the study area is far from the source rock,and the oil and gas filling is insufficient,which has been confirmed in the drilling.There are many reefs in the south of the study area with different scales.In addition,a large number of northeast(NE)trending faults are developed in the area,which connect the Paleogene and Neogene,and are good channels for oil and gas migration.The study provides a basis for revealing regional sea level changes and driving mechanisms,as well as support for oil and gas exploration in the region.
作者
李森
梁杰
廖晶
龚建明
张银国
陈建文
孙晶
王建强
袁勇
杨传胜
李章鹏
LI Sen;LIANG Jie;LIAO Jing;GONG JianMing;ZHANG YinGuo;CHEN JianWen;SUN Jing;WANG JianQiang;YUAN Yong;YANG ChuanSheng;LI ZhangPeng(Qingdao Institute of Marine Geology,China Geological Survey,Qingdao,Shandong 266237,China;Laboratory for Marine Mineral Resources,Laoshan Laboratory,Qingdao,Shandong 266237,China;School of Marine Geosciences,Ocean University of China,Qingdao,Shandong 266100,China)
出处
《沉积学报》
北大核心
2025年第2期622-634,共13页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(42076220)
中国博士后科学基金面上项目(2020M682134)
青岛海洋科学与技术试点国家实验室山东省专项经费(2021QNLM020001-1)。
关键词
印度扇近海盆地
碳酸盐岩台地
地震相分析
沉积演化
主控因素
offshore Indus Basin
carbonate platform
seismic facies analysis
sedimentary evolution
main controlling factor
