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尼日尔三角洲盆地深水区逆冲构造演化特征

作    者:蔺 鹏1,2, 吴胜和1, 张佳佳1, 胡光义3, 王南溯1, 黄 梅1
单    位:1 中国石油大学(北京)地球科学学院; 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
基金项目:受国家科技重大专项“西非、亚太及南美典型油气田开发关键技术研究”课题资助
摘    要:
关于尼日尔三角洲盆地陆坡深水区的逆冲构造,其逆冲背景下的构造演化阶段及古地貌变迁特征,是一个需要深入研究的问题。以尼日尔三角洲盆地某深水研究区为例,基于三维地震资料解释,识别了3个关键界面和4种构造样式,将新生界划分为3个超层序,进一步分析了SSQ1超层序内部的泥岩滑脱面;厘定了中新统逆冲构造的演化阶段,并分析了不同阶段内的地貌特征。形成于构造活动期的超层序(SSQ3)可进一步划分为3个三级层序,自下而上依次由逆冲断层、泥底辟和披覆沉积所主控,对应3个不同的构造演化阶段: ①逆冲断层主控阶段。在重力滑脱作用下,逆冲断层沿不同深度滑脱面发育,所产生的位移差导致构造变换带内地层受到剪切应力而发育撕裂断层,其走向与逆冲断层近垂直;剪切破裂面的存在使地层抗应力强度大幅降低,在地层超压作用下,构造变换带内沿撕裂断层发育泥底辟褶皱;顺陆坡倾向搬运的重力流沉积物受到逆冲相关褶皱阻挡而发生沉积,导致重力流岩性圈闭集中分布于逆冲断层上盘的地貌低部位。②泥底辟主控阶段。在差异负荷作用下,塑性超压泥岩向逆冲相关褶皱与撕裂断层相关褶皱核部集中,形成大型滑脱褶皱;泥岩的塑性变形主要发生在由不同深度滑脱面所限定的地层单元内;滑脱褶皱的存在使其两侧形成了沿陆坡倾向展布的地貌低部位,并成为重力流储层发育的有利场所。③构造平静阶段。构造活动明显减弱,在填平补齐作用下地貌逐渐趋于平缓。
关键词:尔三角洲盆地; 深水; 层序; 构造样式; 构造演化

Characteristics and evolution of compressional structure in deep-water, Niger Delta Basin

Author's Name: LIN Peng,WU Shenghe,ZHANG Jiajia,HU Guangyi,WANG Nansu,HUANG Mei
Institution: Research Institute of Exploration & Development, PetroChina Liaohe Oilfield Company
Abstract:
The structural evolution and topography controlled by thrust faults in continental slope of Niger Delta Basin deserve further study. Based on 3D seismic data in one deep water zone, three super sequence boundaries are identified, by which the Cenozoic is divided into three super sequences(SSQ1, SSQ2, SSQ3), and three detachment levels are analyzed. As about the SSQ3, it is divided into three sequences from bottom to top, representing three stages controlled by thrust fault, mud-diapir, and sedimentation respectively. In the first stage, thrust faults developed along detachment level in different depth under the control of gravity slide, and due to the translocation difference, tear fault perpendicular to the strike of thrust faults developed in transfer zone. Along the tear fault, mud-diapir fold formed under the control of overpressure mud. The gravity flow transported along the structural lows in the hanging walls of thrust faults, thus lithologic traps concentrated in minibasins. In the second stage, huge detachment fold formed due to the concentrating of overpressure mud at the core of thrust-related fold and tear-related fold under the control of load difference, in which the deformation of mud is confined by the detachment levels. The gravity flow and lithologic traps developed along the structural lows on both sides of the mud-diapir anticline. In the third stage, the structural activity weakened obviously, and the topography tended to be flat under the control of sedimentation.
Keywords: sequence; structural style; structural evolution; deep-water; Niger Delta Basin
投稿时间:2017-10-19  
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