北康盆地主要地质界面时代确定及油气地质意义

基于高分辨率二维地震资料，结合区域构造背景，开展了南海西南部北康盆地主要不整合界面及特征识别、年代重新厘定以及油气地质意义分析等工作。研究结果表明，北康盆地新生代发育6个区域性不整合界面，分别对应于礼乐运动、西卫运动、南海运动、南沙运动、万安运动和广雅运动。其中，T3不整合是后南海扩张期的分界，对应于南沙运动及南海西南次海盆的扩张终止。Mulu-1井井震对比显示，T3对应于中中新世不整合面（MMU），时代为16 Ma。该界面总体表现为强振幅、下部地层强烈削蚀、界面起伏大，上下地层结构、产状、地震反射特征发生突变，是构造变形前后两大套地层的分界面，对局部圈闭形成及油气成藏具有重要意义。

AGE DATING OF MAIN GEOLOGICAL INTERFACES AND ITS SIGNIFICANCE IN OIL AND GAS GEOLOGY IN BEIKANG BASIN

Using the high-resolution 2D seismic data currently acquired and upon the basis of the regional tectonic background, the comprehensive seismic data interpretation for the Beikang Basin is carried out. Main unconformity interfaces are identified, stratigraphic age redetermined, and their geological significance to oil and gas geology discussed. The results suggest that there are six unconformities in the region respectively corresponding to the Liyue movement, Xiwei movement, South China Sea movement, Nansha movement, Wan'an movement and Guangya movement. Among them, the T3 unconformity is the boundary of the post-spreading period of the South China Sea caused by the Nansha movement, marking the cessation of the South China Sea spreading. Well-seismic correlation of Well Mulu-1 shows that the unconformity surface (T3) corresponds to the Middle Miocene unconformity surface (MMU) of 16 Ma characterized by high amplitude, strong erosion and large undulation. Abrupt changes in stratigraphic structure, occurrence, and seismic reflection characteristics occur above and below the interface. It is the boundary face between the deformed and undeformed strata, and bears great significance to local structures and hydrocarbon accumulation.