机构地区:[1]中国地质大学(武汉)资源学院,武汉430074 [2]中海石油(中国)有限公司深圳分公司,广东深圳518054 [3]中海石油深海开发有限公司,广东深圳518054 [4]中国地质大学(武汉)地球物理与空间信息学院,武汉430074
出 处:《吉林大学学报(地球科学版)》2024年第6期1860-1882,共23页Journal of Jilin University:Earth Science Edition
基 金:国家自然科学基金项目(41872149,41572084);中海油“十四五”揭榜挂帅项目(CCL2022SZPS0238)。
摘 要:珠江口盆地珠一坳陷勘探重心逐渐由浅层转入深层古近系,古近系火山物质普遍发育,是影响深部碎屑岩储层物性的重要因素之一。本次研究综合利用镜下薄片观察、元素面扫描、碎屑锆石形态特征和年代学等方法,结合研究区火山发育背景,对珠一坳陷古近系碎屑岩储层火山物质的性质展开研究。结果表明:研究区古近系碎屑岩储层中主要发育酸性、中性、基性的火山物质。酸性火山物质常具有高硅低碱质特征,富Al和K元素,蚀变产物以高岭石、伊利石等黏土矿物为主,其形成与酸性岩浆喷发有关,常与流纹岩岩屑等伴生,并可识别出同沉积火山锆石,主要分布于陆丰凹陷;中性火山物质Si元素质量分数中等,富K元素,蚀变产物主要为自生石英,常与安山岩岩屑伴生,在恩平23构造带和恩平27构造带均有分布,少量分布于陆丰13构造带;基性火山物质Si元素质量分数极低,富Fe和Mg元素,蚀变产物以铁镁质黏土矿物和浊沸石为主,主要分布于惠州凹陷,偶见于西江凹陷。另外,研究区陆丰13构造带局部发育少量偏碱性的火山物质,主要通过蚀变产物为磷灰石来判别。凝灰质储层普遍呈低孔、低渗特征,但在特定的成岩条件下,少量火山物质以及火山物质的溶蚀性质能够起到增孔和保孔的作用,对后期油气充注具有一定的改善作用。The focus of exploration gradually shifted from shallow to deep Paleogene strata in ZhuⅠdepression,the Pearl River Mouth basin.Volcanic materials are widely developed in Paleogene strata,which is one of the important factors affecting the physical properties of deep clastic rock reservoirs.This study comprehensively utilizes methods such as thin section,element surface scanning,morphological characteristics and U Pb dating of detrital zircons,combined with the volcanic background of the study area,to study the volcanic materials properties of the Paleogene detrital reservoirs in the ZhuⅠdepression.The results showed that the Paleogene in the study area mainly developed acidic,intermediate,and basic volcanic materials.Acidic volcanic materials often have a high mass fraction of Si,rich in Al and K.The alteration products are mainly clay minerals such as kaolinite and illite,and their formation is related to acidic magma eruptions.They are often associated with acidic volcanic rock fragments such as rhyolite and can be identified as synsedimentary volcanic zircons,mainly distributed in the Lufeng sag.The intermediate volcanic materials have a moderate Si mass fraction and are relatively rich in potassium.The main alteration product is authigenic quartz,often associated with intermediate volcanic rock fragments such as andesite.It is distributed in Enping sag,eastern Yangjiang sag,and Lufeng sag.The basic volcanic materials have extremely low Si mass fraction and is rich in Fe and Mg.The alteration products are mainly mafic clay minerals and zeolite,mainly distributed in the Huizhou sag,with a small amount distributed in the Xijiang sag.In addition,a small amount of alkaline volcanic materials is locally developed in the Lufeng sag 13 structural belt of the study area,which is mainly distinguished by the alteration product being apatite.Low porosity and low permeability are commonly observed in tuffaceous reservoirs,but under specific diagenetic conditions,the locally developed small amount of volcanic materials
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