砂体成因驱动下的岩性圈闭形成模式:以珠江口盆地惠州凹陷中新世强制海退砂为例  

Models of Stratigraphic Trap Formation Drived by Sandstone Genesis:A Case Study of the Miocene Forced Regressive Sandstone in Huizhou Sag,Pearl River Mouth Basin

作　　者：丁琳 黄书勤 卓海腾 李智高 李潇 刘溢世 杨佳颖 DING Lin;HUANG Shuqin;ZHUO Haiteng;LI Zhigao;LI Xiao;LIU Yishi;YANG Jiaying(Shenzhen Branch of CNOOC(China)Co.,Ltd.,Shenzhen Guangdong 518054,China;School of Marine Sciences,Sun Yat-sen University,Zhuhai Guangdong 519082,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518054 [2]中山大学海洋科学学院,广东珠海519082

出　　处：《地球科学进展》2024年第8期862-876,共15页Advances in Earth Science

基　　金：中国海洋石油集团有限公司“十四五”重大科技项目(编号:KJGG2022-0303)资助。

摘　　要：近些年来强制海退砂体作为三角洲—滨岸环境中重要的岩性圈闭储层而备受关注。选取南海北部珠江口盆地惠州地区,基于井震资料和层序地层学标准化原理在下韩江组至珠江组四段上部(T35~T50)地层内建立了高精度地层层序格架,划分出11期强制海退沉积并建立了惠州地区强制海退沉积的识别标志:①高位体系域与强制海退体系域之间存在泥质分隔带;②强制海退砂体在沉积倾向上存在不规则的厚度变化;③强制海退沉积内部存在高角度前积,并且具有顶超型特征;④存在底突变砂体,同时强制海退沉积的沉积相分析结果显示其属于浪控三角洲中的海滩脊沉积相。由于强制海退沉积具有较好的储层物性,同时容易与高位体系域、低位体系域和海侵体系域之间形成富泥带,有利于岩性圈闭的发育。结合11期强制海退沉积在平面上由北东向南西方向发散的马尾状特征以及已有油气发现的强制海退体系域砂体2(FSST2)和强制海退体系域砂体3(FSST3)沿走向上的厚度变化,认为在多期强制海退沉积的形成过程中存在着北东向南西方向流动的古沿岸流作用。此外强制海退体系域砂体2(FSST2)和强制海退体系域砂体3(FSST3)岩心上的沉积构造分析结果显示,北东区域相对于南西区域存在着较强的潮汐水动力的影响,这可能是因为2期强制海退体系域与古东沙隆起较为接近形成了中间较为狭窄的地形,进而在潮汐作用下形成了往复潮流,相对狭窄的北东区域受到往复潮流的影响较大,而相对开阔的南西区域仍以波浪作用为主,受到往复潮流的影响较小。在强制海退砂体内部主要形成楔状体内部突变尖灭型岩性圈闭和向海方向上倾的渐变尖灭型岩性圈闭2种模式,有利的储层物性以及富泥带的存在导致的砂体尖灭性使其成为了理想的岩性圈闭勘探目标。In this study,we focused on the Huizhou region within the Pearl River Mouth Basin.Through meticulous analysis of well seismic data and adherence to sequence stratigraphy standardization principles,a refined stratigraphic sequence framework was established within the T35-T50 interval.This framework facilitated the recognition of 11 distinct phases that forced the regressive deposits,thereby enabling the identification of key characteristics specific to the Huizhou area.These characteristics include the presence of a muddy separation zone between the HST and the falling-stage systems tract,irregular thickness variations in forced regressive sandstone,occurrence of high-angle forests within forced regressive deposits,and presence of sharp-based sandstone.Furthermore,the sedimentary facies analysis of forced regressive deposits revealed that they belong to beach ridge sedimentary facies,indicative of wave-controlled delta environments.Owing to the favorable reservoir properties of forced regressive deposits,mud-rich zones generally exist between the HST,low stand systems tract,and transgressive system tract,which are beneficial for the development of stratigraphic traps.Moreover,this study observed distinctive characteristics in the forced regressive deposits,including a horsetail pattern of sedimentation diverging from northeast to southwest,suggesting the presence of a paleo-longshore current flowing in the same direction.This current is in accordance with the Guangdong coastal current,underscoring the regional hydrodynamic influences shaping the sedimentation patterns.Noteworthy findings from the sedimentary structure analyses of the FSST2 and FSST3 cores highlight varying tidal hydrodynamic influences across the study area.The northeastern region,in proximity to the paleo-Dongsha uplift,exhibited stronger tidal effects than the southwestern region,which remained predominantly influenced by wave action.This study identified two primary types of stratigraphic traps within forced regressive sandstone:abrupt and grad

关 键 词：强制海退沉积 岩性圈闭 古沿岸流 混合动力作用过程 

分 类 号：P539.2[天文地球—古生物学与地层学]