琼东南盆地深水区双物源沉积模式及勘探前景

基于新采集的地震资料，从物源供给模式入手，分析琼东南盆地南部陆坡区新生代地层的沉积层序、物源特征及其油气勘探前景。研究区具典型断陷一坳陷双层地质结构，表现南北向双物源特点。断陷期物源供给主要来自南部的西沙隆起和西南方向的中南半岛，同时还接受北部华南地块物源；拗陷期为以中南半岛物源供给为主。断陷期，南部沉积物在陵水组形成大规模前积体，并与北部物源形成的水下扇在凹陷中央交汇；拗陷期，三亚组发育大规模浊积水道，梅山组沉积期研究区东南方向发育较大规模的生物礁，黄流组沉积末期发育大规模下切谷。第四纪晚期，北部物源与南部物源在琼东南盆地深水区交汇。地震资料和盆地模拟显示，位于生烃凹陷上方的多期次水下扇和富砂浊积水道储集层，是良好的深水油气勘探目标。图7参19

Double provenance depositional model and exploration prospect in deepwater area of Qiongdongnan Basin

Based on the newly collected seismic data and the provenance supply mode, the depositional sequence, provenance features and oil-gas exploration prospects were analyzed. The study area has the typical double-layer geologic structure of rift-depression, and has double provenance supply in the north and south. The provenance supply in rifting period was mainly from the southern Xisha Uplift and the southwestern Indo-China Peninsula, and was also from the northern South China Block; while the provenance supply in depression period was mainly from Indo-China Peninsula. In the rifting period, the southern sediment formed a large-scale progradation body in Lingshui Formation, and encountered the subsea apron formed by the northern provenance in the central depression; in the depression period, the large-scale turbidite channel developed in Sanya Formation, the large-scale reef developed in the southeast of the study area in Meishan Formation in the depositional stage, and the large-scale incised valleys developed in Huangliu Formation in the late depositional stage. In the Late Quaternary Period, the northern provenance and southern provenance joined in the deepwater area of Qiongdongnan Basin. The seismic data and basin modeling indicate that, the reservoirs of subsea apron and sand-rich turbidite channel above the hydrocarbon-generating sag can be the good exploration targets in the deepwater area.