摘要
顺坡而下的重力流(浊流)与沿坡流动的底流(等深流)之间的交互作用是当前国际沉积学研究的前沿领域与薄弱环节,交互作用沉积体系及其沉积特征相较于重力流或等深流沉积体系仍“知之甚少”。本文总结了论文作者所识别的两种典型交互作用沉积体系的形态特征、沉积特征与沉积样式,查明了交互作用成因优质储层的识别标志与分布模式。深水单向迁移水道具有不对称的剖面形态与持续稳定向陡岸一侧迁移叠加的沉积样式,可进一步分为迁移方向与参与其建造底流流向相同(顺向迁移)和相反(反向迁移)两种类型;深水单向迁移朵叶具有长轴方向与区域等深线平行的形态特征以及侧向迁移延伸方向与区域等深线一致的沉积样式。重力流(浊流)与底流(等深流)交互作用所形成的底流改造砂/交互作用砂具有与浊积砂迥异的沉积特征,如富含有孔虫和生物骨骼,无年龄倒序现象出现,突变非侵蚀接触顶界面,含有大洋水团所伴生的底栖有孔虫,可见牵引流沉积特征(如两到三段式累积概率分布特征、单峰正态的频率分布特征和位于C-M图牵引流沉积区等),这些沉积特征可作为底流改造砂的识别相标志。在剖面上,底流改造砂总是向水道迁移一侧不断迁移叠加,具有“单向叠加、有序展布”的分布模式;在平面上,底流改造砂总是沿区域等深线侧向迁移,具有“单向偏移、侧向叠置”的分布模式;时空上形成连续性好、分布范围广、面积大的超大型优质深水油气储集体。
The interaction between down-slope gravity flows(turbidity currents)and along-slope bottom currents(contour currents)is the frontier area and underappreciated topic of the current research on deep-water sedimentology,with poor understanding of its resultant depositional systems and associated sedimentological characteristics.The present study reveals morphometrics,sedimentological characteristics,and growth patterns of two typical depositional systems created by the interplay of gravity and bottom currents,and explores distribution pattern and diagnostic criteria for the recognition of potentially productive deep-water reservoirs created by the interplay of gravity and bottom currents.Unidirectionally migrating deep-water channels are characterized by asymmetrical cross-sectional geometries and unidirectional growth patterns,and can be subdivided into unidirectionally upstream-migrating channels(i.e.,channels migrating against the direction of bottom currents)and unidirectionally downstream-migrating channels(i.e.,channels migrating along the direction of bottom currents).Unidirectionally migrating submarine lobes are characterized by plan-view morphology with long axis direction parallel to regional contour lines and by growth pattern with extension direction parallel to the depositional strike of regional slope.Bottom-current reworked sands created by the interplay of gravity and bottom currents are distinguished from turbiditic sands by rich in bioskeletons and shell fragments,a lack of age inversion,sharp,non-erosional,upper contacts,and by the occurrence of traction structures(i.e.,two to tripartite subdivisions of cumulative frequency plots,unimodal distribution patterns of frequency-distribution curves,in the traction zone of CM diagrams).These sedimentological characteristics,in turn,can be taken as diagnostic criteria for the recognition of bottom-current reworked sands.Spatially,bottom-current reworked sands are preferentially deposited to the side toward which the channels migrated,and exhibit a spatial distribution pattern characterized by unidirectional migration and orderly distribution.Temporally,they are characterized by the asymmetrical,L-shaped plan-view morphology,and display characterized by unidirectional offset and lateral migration.Spatiotemporally,bottom-current reworked sands laterally migrated and stacked along the direction of regional contour lines,forming giant,potentially productive deep-water reservoirs.
作者
龚承林
徐长贵
尤丽
朱一杰
GONG Cheng-lin;XU Chang-gui;YOU Li;ZHU Yi-jie(State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;China National Offshore Oil Corporation,Beijing 100010,China;CNOOC Hainan Branch Company,Haikou 570312,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2024年第4期721-733,I0002,共14页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
中海油科技项目资助(KJZH-2021-0003-00)。
关键词
重力流与底流交互作用
深水单向迁移水道
深水单向迁移朵叶
底流改造砂
the interplay of gravity and bottom currents
unidirectionally migrating deep-water channels
unidirectionally migrating submarine lobes
bottom-current reworked sands
作者简介
第一作者:龚承林(1983-),男,博士,教授,研究方向:深水沉积、层序地层与源汇系统.E-mail:chenglingong@cup.edu.cn.
