摘要
源汇系统定量化研究是沉积学领域的前缘,是精细重构源汇过程、指导油气储层预测的重要手段。利用重矿物和锆石U-Pb年龄对珠江口盆地惠州凹陷惠州27转换带进行物源示踪、定量恢复源区沉积物相对贡献,进而重构古近纪源汇过程,探讨源汇控储作用。研究结果表明,中始新统文昌组重矿物类型复杂、ZTR指数(碎屑岩中碎屑锆石(Zircon)、电气石(Tourmaline)、金红石(Rutile)在透明重矿物碎屑中所占的比例)小,上始新统恩平组重矿物类型简单、ZTR指数大。研究区文昌组—恩平组主要受盆内中生界岩浆岩基底和盆外珠江水系供源。其中文昌组沉积物98%来自于盆内中生界岩浆岩基底;下恩平组沉积物58.4%来自于盆外珠江东北部支流、36.5%来自于盆内中生界岩浆岩基底;上恩平组沉积物73.7%来自于盆外珠江东北部支流、22.2%来自于盆内中生界岩浆岩基底。研究认为,恩平组沉积期现代珠江尚未形成,但珠江东北部支流(即古珠江)已独立发育且携带大量华夏地块碎屑物质汇入惠州凹陷,导致了惠州27转换带“文昌期盆内近源—恩平期盆外、盆内混源”的源汇转换过程,而非简单的“盆内近源—盆外远源”转换。源汇转换过程改变了恩平组储层的岩石组分,进而改善了储层物性,也使得其储层非均质性变强。本研究定量解析了惠州凹陷古近纪源汇转换过程,为陆相断陷盆地定量源汇及其应用提供了新视角。
Objectives:Quantitative analysis of the source-to-sink system is the leading edge of the field of sedimentology,and is of great significance for accurate reconstruction of source-to-sink process and prediction of hydrocarbon reservoirs.Methods:We use the heavy mineral assemblages and zircon U-Pb ages to trace the provenance of the Huizhou-27 transfer zone in the Huizhou Sag,Pearl River Mouth Basin,and quantitatively reconstruct the sediment contribution of potential source areas.In addition,we reveal the source-to-sink process and discuss the control of source-to-sink system on the hydrocarbon reservoir.Results:The results show that the heavy mineral assemblages of the middle Eocene Wenchnag Formation are complex with low ZTR values(the ZTR index is the percentage of detrital zircon,tourmaline and rutile in the transparent heavy mineral detritus of a clastic rock),while the heavy mineral assemblages of the upper Eocene Enping Formation are relatively simple with high ZTR values.This study further confirms that the Wenchang Formation to the Enping Formation were mainly fed by intrabasinal Mesozoic magmatic basement and extrabasinal Pearl River system.For the Wenchang Formation,ca.98%sediments were derived from the intrabasinal Mesozoic magmatic basement;for the lower Enping Formation,ca.58.4%sediments were derived from the northeastern tributaries of the Pearl River,while ca.36.5%sediments were derived from the intrabasinal Mesozoic magmatic basement;for the upper Enping Formation,ca.73.7%sediments originated from the northeastern tributaries of the Pearl River,while ca.22.2%sediments originated from the intrabasinal Mesozoic magmatic basement.Conclusions:We infer that the modern Pearl River system,including the northeastern and western tributaries,was not yet formed during the depositing of the Enping Formation,but the northeastern tributaries(i.e.,the paleo-Pearl River)had developed independently.Rather than a simple provenance transition from intrabasinal to extrabasinal,the paleo-Pearl River transported abundant sediments from the Cathaysia Block into the Huizhou Sag,resulting in the transition of the source-to-sink system from“the Wenchang Formation with intrabasinal provenance”to“the Enping Formation with mixed provenance”.This transition of source-to-sink system changes the rock composition of reservoir in the Enping Formation,which improves the reservoir physical properties but enhances the reservoir heterogeneity.This study presents a quantitative analysis of the transition of the source-to-sink system in the Paleogene Huizhou Sag,and provides insights into the quantitative source-to-sink process and its applications in continental rift basins.
作者
李一超
龚承林
邱欣卫
祁鹏
何雁兵
余一欣
LI Yichao;GONG Chenglin;QIU Xinwei;QI Peng;HE Yanbing;YU Yixin(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing,102249;College of Geosciences,China University of Petroleum(Beijing),Beijing,102249;Shenzhen Branch of China National Offshore Oil Corporation Ltd,Shenzhen,Guangdong,518054;Research Institute of China National Offshore Oil Corporation,Beijing,100028)
出处
《地质论评》
CAS
CSCD
北大核心
2024年第4期1403-1418,共16页
Geological Review
基金
国家自然科学基金资助项目(编号:41972100)
中海油科技项目(编号:CCL2020SZPS0168、CCL2021RCPS0169KQN)的成果。
关键词
源汇系统
锆石U-PB年龄
重矿物
储层
珠江口盆地
source-to-sink system
zircon U-Pb age
heavy mineral
reservoir
Pearl River Mouth Basin
