Submarine fan reservoirs are important accumulation zones for oil, gas, and natural gas hydrates, offering significant potential for hydrocarbon exploration. During the deposition period of the Sanya Formation in the southern part of the Changchang Sag of the Qiongdongnan Basin, a large submarine fan developed. However, the internal structure, source-sink system, and formation mechanism of this fan remain poorly understood, posing significant challenges to exploration in this area. This paper examines the source-to-sink sedimentary processes and deposition of submarine fans, using the Changchang Sag, in the Qiongdongnan Basin in the Northern South China Sea, as an example, which will provide valuable general guidance for deep water oil and gas exploration. Based on the theories of seismic stratigraphy and seismic sedimentology, this paper utilizes techniques such as seismic facies analysis, seismic attribute optimization, paleogeomorphology reconstruction, and source-to-sink sedimentary system analysis to analyze the 3D seismic data of the study area. Research indicates that the Sanya Formation in the Changchang Sag of the Qiongdongnan Basin comprises three depositional units: submarine fan, feeder channel, and Semi-deep marine to deep marine mudstone. The submarine fan is a fan formed by the coupling and convergence of submarine fans sourced from the southwest and southeast. Internally, it is divided into three sub-facies: the proximal fan of the sand-rich submarine fan, the main body of the sand-rich submarine fan lobes, and the distal lobes of the sand-rich submarine fan. The submarine fan sourced from the southwest extends nearly north-south and is primarily fed by sediment transported through three large, banded ancient valleys. The sedimentary filling is characterized by three-phase progradation. The submarine fan sourced from the southeast extends nearly east-west and is primarily fed by sediment transported through a single large, banded ancient valley. The sedimentary filling is characterized by two-phase lateral accumulation. During the deposition period of the Sanya Formation, certain areas of the southern uplift belt were exposed for extended periods and subjected to weathering and erosion. Sediments are transported to large ancient valleys through small supply channels. A large number of sediments were transported to the southern slope of the Changchang sag through the provenance channel system such as large ancient valleys and slope belts and deposited in the center of the sag. These make up a complete system of large ancient uplifts and submarine fan source-to-sink sedimentary systems.The sedimentary model is a lobed submarine fan controlled by semi-restricted ancient valleys and expansive basins.

中文翻译：

---

南海琼东南盆地进积侧增生海底扇源汇过程及成因机制


海底扇油气藏是石油、天然气和天然气水合物的重要富集区，油气勘探潜力巨大。琼东南盆地长昌凹陷南部三亚组沉积时期发育大型海底扇。然而，对该扇的内部结构、源汇系统和形成机制仍知之甚少，给该领域的勘探带来了重大挑战。以南海北部琼东南盆地长昌凹陷为例，探讨了源-汇沉积过程和海底扇沉积，为深水油气勘探提供有价值的总体指导。 。基于地震地层学和地震沉积学理论，利用地震相分析、地震属性优化、古地貌重建、源汇沉积体系分析等技术对研究区三维地震资料进行分析。研究表明，琼东南盆地长昌凹陷三亚组由海底扇、支线河道、半深海—深海相泥岩3个沉积单元组成。海底扇是由西南和东南方向的海底扇耦合汇聚形成的扇体。内部分为富砂海底扇近端扇、富砂海底扇叶主体和富砂海底扇远叶3个亚相。来自西南方向的海底扇几乎向南北延伸，主要由通过三个大型带状古代山谷输送的沉积物供给。 沉积充填具有三相进积的特征。源自东南部的海底扇几乎呈东西向延伸，主要由通过单个大型带状古代山谷输送的沉积物供给。沉积充填具有两期侧向堆积的特点。三亚组沉积时期，南部隆起带部分区域长期暴露，遭受风化剥蚀。沉积物通过小型供应渠道输送到大型古老山谷。大量沉积物通过大型古河谷、斜坡带等物源水道系统被输送到长昌凹陷南坡并沉积在凹陷中心。这些构成了完整的大型古隆起和海底扇源-汇沉积体系。沉积模式是受半限制性古河谷和扩张盆地控制的叶状海底扇。