摘要
渤海海域古近系沙河街组一二段广泛发育与扇三角洲沉积体系伴生的混合沉积.通过岩心、显微组构及岩石储层物性等钻井资料,对陆相湖盆背景下扇三角洲混合沉积的沉积环境、砂体成因机理、分布规律及储层机理进行了详细研究.研究成果表明,扇三角洲混合沉积可分为扇三角洲前缘混合沉积和前扇三角洲混合沉积两类亚相.扇三角洲前缘混合沉积包括水下碎屑流混合沉积和河口坝混合沉积成因相类型;前扇三角洲则发育前扇三角洲混合沉积.通过对混合沉积特征分析及成因相内部构成精细解剖,总结出两类陆相断陷湖盆背景下的扇三角洲体系伴生混合沉积模式,分别归结为扇三角洲重力流驱动混合模式与扇三角洲建设-废弃互层型混合模式.结合储层物性特征研究表明,渤海海域扇三角洲混积岩储层具有:(1)在中深层埋深下保持良好的原生孔隙;(2)选择性溶蚀孔隙增加了次生孔隙;(3)碳酸盐含量高,有利于储层酸化改造等储层优势的特征,对渤海海域中深埋藏储层勘探预测具有重要意义.
Mixed siliciclastic-carbonate sediments accompanied by fan-delta are well developed in the Members 1-2 of Palaeogene Shahejie Formation in the offshore Bohai Bay Basin.A study of core description,photomicrographic observation,and petrophysical properties were performed on the mixed sediment reservoirs in a lacustrine basin,attempting to unravel the depositional environment,formation mechanism,plane distribution and reservoir features of lacustrine mixed sediments.The results show that the main sub-facies within mixed fan-delta association contain mixed fan-delta front and mixed pro-fan delta.Fandelta frontcan include mixed subaqueous debris flows genetic facies and mixed estuarine bar genetic facies.Pro-fan delta develops mixed pro-fan delta.Based on sedimentary characteristics and internal architectures of each genetic facies,the development model of mixed fan-delta siliciclastic-carbonate sediments in terrestrial rift-subsidence lacustrine basin is attributed to two aspects:the mechanism of fan-delta mixed sediments that is related to gravity driven-tractive and the mechanism of fan-delta mixed sediments that goes through a process of construction-destruction interbedding.This study characterizes the major reservoir characteristics of mixed sediments,providing insights into their advantages as a new kind of petroleum reservoir:(1)a mass of primary porosity has still been preserved in the mid-deep buried depth;(2)secondary porosities have been generated by selective dissolutions;(3)high content of carbonate content assists reservoirs acidification.This sedimentology and reservoir study is expected to facilitate future exploration in mid-deep reservoirs in the offshore Bohai Bay basin.
作者
付鑫
杜晓峰
官大勇
王启明
叶茂松
Fu Xin;Du Xiaofeng;Guan Dayong;Wang Qiming;Ye Maosong(Tianjin Branch of China National Offshore Oil Corporation Limited,Tianjin 300459,China;College of Marine Science and Technology,China University of Geosciences,Wuhan 430074,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2020年第10期3706-3720,共15页
Earth Science
基金
国家科技重大专项(No.2016ZX05024-003)。
关键词
混合沉积
成因机理
储层特征
渤海海域
沙河街组一二段
沉积
mixed silicicastic-carbonate sediment
formation mechanism
reservoir characteristics
offshore of Bohai Bay basin
members 1-2 of Shahejie Formation
sedimentation
