摘要：

东营凹陷南部缓坡带沙四下亚段是重要的油气勘探层段，但其沉积充填过程及有利砂体分布规律认识仍不清楚，制约了储集体预测与勘探部署。本文以源—渠—汇系统理论为指导，综合区域地质、测录井、岩心、碎屑锆石年代学及地震解释等资料，恢复研究区沙四下亚段古地貌与古水系，系统识别物源区、搬运通道和沉积体系，并在此基础上建立源—渠—汇耦合模式。研究表明，研究区沙四下亚段沉积期物源具有近源与远源共同供给特征，其中，西南部鲁西隆起和东南部广饶凸起为主要近源区，西北部接受无棣凸起方向的远源输入；搬运通道主要包括古沟谷和断槽两类，西部以断槽通道为主，东部以古沟谷通道为主，西北部表现为远源物质沿断槽输送的特征。南部缓坡带沙四下亚段沉积体系具有明显的分区差异性，物源输入、搬运通道类型及沉积环境配置共同控制了沉积物由盆缘向湖盆内部的输送-沉积过程：研究区西部和东部以近源供给控制的浅水三角洲沉积为主，西北部则表现为远源输入背景下的DFS发育特征。在此基础上，进一步建立了西部近源断槽输送模式、东部近源古沟谷输送模式和西北部远源断槽输送模式，揭示了不同源—渠—汇配置关系对砂体展布样式及有利储集体发育区带的控制作用。研究成果可为东营凹陷南部缓坡带沙四下亚段有利储集体预测提供地质依据。

关键词: 东营凹陷, 沙四下亚段, 源-汇系统, 物源体系, 耦合模式

Abstract:

The lower fourth member of the Shahejie Formation (Es_4x) in the southern gentle slope zone of the Dongying Sag is an important target interval for hydrocarbon exploration. However, the sedimentary infill process and the distribution patterns of favorable sand bodies remain insufficiently understood, which restricts reservoir prediction and exploration planning. Guided by the source-channel-sink system theory, this study integrates regional geological data, mud logging, wireline logging, core observations, detrital zircon geochronology, and seismic interpretation to reconstruct the paleogeomorphology and paleodrainage of the Es_4x interval in the study area, systematically identify provenance areas, transport pathways, and depositional systems, and establish source-channel-sink coupling models. The results show that sediment supply during deposition of the Es_4x interval was jointly derived from both proximal and distal sources. The Luxi Uplift to the southwest and the Guangrao Uplift to the southeast served as the main proximal source areas, whereas the northwestern part of the study area received distal sediment input from the Wudi Uplift. Two main types of transport pathways were recognized, namely paleovalleys and fault troughs. Fault-trough pathways dominate the western part of the study area, whereas paleovalley pathways are more common in the eastern part; the northwestern part is characterized by distal sediment transport along fault troughs. The depositional systems of the Es_4x interval in the southern gentle slope zone display pronounced spatial heterogeneity. The transport and deposition of sediments from the basin margin to the lacustrine basin interior were jointly controlled by sediment supply, transport-pathway type, and depositional setting. The western and eastern parts of the study area are dominated by shallow-water delta systems controlled by proximal sediment supply, whereas the northwestern part is characterized by the development of distributary fluvial systems (DFS) under a distal-source regime. On this basis, three source-channel-sink coupling models were established: a proximal-source fault-trough transport model in the western part, a proximal-source paleovalley transport model in the eastern part, and a distal-source fault-trough transport model in the northwestern part. These models reveal how different source-channel-sink configurations control sand-body distribution patterns and the development of favorable reservoir zones. The results provide a geological basis for predicting favorable reservoirs in the Es_4x interval of the southern gentle slope zone of the Dongying Sag.

Key words: Dongying Sag, lower fourth member of the Shahejie Formation, source-to-sink system, provenance system, coupling model

中图分类号: 

• P618.13

• TE122