被动陆缘盆地逆冲、底辟构造对深水层序结构的控制——以尼日尔三角洲盆地某深水区为例  

Control of thrust and diapir structures on deep-water sequence architectures in passive continental margin basins: A case study on a deep-water zone in the Niger Delta Basin

作　　者：蔺鹏[1,2] 吴胜和 胡光义[3] LIN Peng;WU Shenghe;HU Guangyi(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Exploration and Development,PetroChina Liaohe Oilfield Company,Panjin,Liaoning 124010,China;CNOOC Research Institute,Beijing 100028,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]中国石油辽河油田公司勘探开发研究院 [3]中海油研究总院有限责任公司

出　　处：《天然气工业》2022年第9期21-34,共14页Natural Gas Industry

基　　金：中国石油天然气股份有限公司科技重大专项“辽河油田千万吨稳产关键技术研究与应用”(编号:2017E-16)。

摘　　要：被动陆缘盆地深水区是世界油气勘探的热点领域,但由大型三角洲引发的重力滑动构造导致被动陆缘盆地深水层序结构具有复杂多变的特征。为了进一步明确此类盆地深水沉积体系的展布规律、为勘探部署提供理论支撑,以尼日尔三角洲盆地某深水区为例,基于地震、测井资料的综合分析,采用地震沉积学与地震地貌学方法,研究了深水沉积单元的类型与空间分布特征,分析了深水层序结构和主控因素,揭示了被动陆缘盆地深水区逆冲/底辟构造演化对层序结构的控制机理。研究结果表明:(1)逆冲相关的微盆地是逆冲断层主控型深水层序发育的主要场所,深水层序主要为陆源重力流与逆冲成因的再搬运碎屑流在微盆地内混合形成下部朵体、上部块体搬运沉积的沉积组合,重力流在不同微盆地间重复充填—溢出过程;(2)滑脱褶皱两侧形成的狭长微盆地内部发育泥底辟主控型深水层序,深水层序主要由多期重力流水道及小型朵体叠加而成,早期水道沉积占据微盆地最深处,晚期重力流在滑脱褶皱与早期水道之间的地貌低部位处形成新的水道沉积;(3)构造平静期,受控于沉积填平补齐作用,重力流主要发生沉积过路,深水层序通常由水道和泥质披覆沉积两期沉积组成。结论认为,构造活动对深水层序结构的控制作用体现在“逆冲/底辟构造活动控制了微盆地的形成,并为深水层序的发育提供了可容空间,进而决定了深水沉积单元的空间分布特征;逆冲断层活动能触发再搬运碎屑流为深水层序提供了额外的物源”两个方面。The deep-water zone of a passive continental margin basin is a hot field of petroleum exploration around the world, and its deep-water sequence architecture is complicated and diversified by the gravity gliding structure induced by large deltas. In order to clarify the distribution laws of deep-water depositional systems in these basins and provide theoretical support for exploration deployment, this paper investigates the types and spatial distribution patterns of deep-water depositional units in a deep-water zone of the Niger Delta Basin by means of seismic sedimentology and seismic geomorphology methods, based on the comprehensive analysis of well-logging and seismic data. Then, deep-water sequence architectures and their main controlling factors are analyzed, and the control mechanisms of thrust/diapir structures on deep-water sequence architectures in delta reformed passive continental margin basins are revealed. And the following research results are obtained. First, thrust related mini-basins are the main development sites of deep-water sequences dominated by thrust faults. Deep-water sequences are mainly the sedimentary assemblage of mixed terrigenous gravity flow and reworked debris flow of thrust origin with lobe at bottom and mass-transport deposit(MTD) at top in a mini-basin. Fill-spill process of gravity flow repeats between different mini-basins. Second, deep-water sequences dominated by mud diapir are developed in slender mini-basins which are formed on both sides of the detachment fold. Deep-water sequences are mainly composed of multiphase gravity flow channels and small lobes which overlap with each other. Early channels occupy the deepest part of mini-basins, and later gravity flow evolves into a new channel deposit in the geomorphological low between detachment folds and early channels. Third, during the tectonic quiescence stage, under the control of sedimentary filling, gravity flow mainly bypass the study area, and the deep-water sequence is usually composed of two depositional stages of ch

关 键 词：被动陆缘盆地 尼日尔三角洲盆地 深水 逆冲断层 泥底辟 层序结构 控制因素 

分 类 号：P618.13[天文地球—矿床学]