琼东南盆地北部中生代凹陷特征及油气成藏条件初探

琼东南盆地的中生代凹陷群是扩大油气勘探发现的远景区。为了实现琼东南盆地中生界的勘探突破，急需落实中生代凹陷的油气成藏条件和有利勘探领域。基于地球物理、地球化学、钻井资料及古生物资料，首次对琼东南盆地中生代凹陷开展了深入系统的分析研究。研究表明，在琼东南盆地北部崖北凹陷、崖城凸起、崖南低凸起和西南部陵南低凸起及南部隆起均存在中生代沉积地层。根据盆地构造演化分析，中生代沉积形成于燕山期太平洋板块向欧亚板块俯冲期以及其后的弧后伸展期，存在烃源岩、储层及圈闭等油气地质基本条件。琼东南盆地北部坳陷带崖城-崖北地区相比盆地其他地区中生代沉积凹陷规模大，因此本研究重点对琼东南盆地北部坳陷带崖城-崖北地区进行了系统的油气地质综合分析研究，落实了崖城-崖北地区中生界沉积地层分布，并初步评价预测了有利油气勘探区带及重点目标。研究表明，琼东南盆地崖城-崖北地区中生代凹陷发育湖相烃源岩、三角洲等储集体以及构造与地层圈闭，存在西洼南坡带和中部隆起带2个有利油气勘探区带。在这些区带加大勘探，有望获得中生界油气突破。 

Characteristic and petroleum geology of the Mesozoic sags of the northern Qiongdongnan Basin

Mesozoic sags of the Qiongdongnan Basin are prospective areas for oil and gas discovery. To make petroleum breakthroughs in Mesozoic sags in the Qiongdongnan Basin, it is urgent to clarify the conditions of hydrocarbon accumulation and the favorable areas for exploration in those Mesozoic sags. Based on geophysics, geochemistry, drilling and paleontology data, systematic research on Mesozoic sags in the Qiongdongnan Basin was carried out. The results show that Mesozoic sedimentary formations were distributed in the Yabei Sag, Yacheng Uplift, Yanan Uplift, Lingnan Uplift and Southern Massif in the Qiongdongnan Basin. According to the analysis of tectonic evolution, Mesozoic formations were formed in the back-arc extensional basin in the Yanshanian period with subduction of the Pacific Plate to the Eurasian Plate, which has the possibility of forming source rocks, reservoirs, and traps. Because the potential of Mesozoic sags is larger in the Yacheng-Yabei area of the northern depression than in other areas in the Qiongdongnan Basin, this paper focuses on the comprehensive study of petroleum geology in the Yacheng-Yabei area that includes the definition of the Mesozoic formation and defines the favorable area and prospects of Mesozoic rocks. This paper further notes that Mesozoic lacustrine source rocks, delta reservoirs, structural and stratigraphic traps developed in the Yacheng-Yabei area. The southern slopes of the western sag and central massif are two favorable areas for exploration. To expand exploration in these areas, we hope to make petroleum breakthroughs in Mesozoic formations.