东海盆地椒江凹陷裂后期岩浆广泛分布,但关于岩浆作用的类型、空间分布和形成期次一直缺少系统研究,严重制约了盆地的油气勘探部署.基于新采集的高精度三维地震数据体和钻井资料,对椒江凹陷裂后期岩浆体及通道进行了识别和精细雕刻,厘定了椒江凹陷岩浆作用的发育规律以及对油气成藏的控制作用.研究表明:椒江凹陷火山岩主要分布于凹陷中东部,以溢流相为主,沿T20界面及其上下均有发育,但沿T20界面更为发育.岩浆侵入体发育岩盆、岩床和岩墙3种产状,以岩盆为主,在温州期及之前(早于43 Ma)、平湖期—花港期(43～23.3 Ma)与龙井期及之后(晚于23.3 Ma)均有发育,其中平湖期—花港期是岩浆侵入的最主要时期.研究区岩浆上涌通道的分布与北西向基底隐伏断裂有关,但与盆内新生代断层分离,无共生关系.研究认为,椒江凹陷裂后期岩浆活动对早期油气藏具有破坏或改造作用,因此,在优选潜力目标时应尽可能规避岩浆作用的影响.但另一方面,岩浆侵入形成了大量强制背斜,属于优越的圈闭类型,因此强岩浆活动区的油气勘探潜力仍值得探索.

Post-rift magma is widely distributed in Jiaojiang Sag,East China Sea Basin.However,the type,spatial distribution and formation period of magmatism have not been systematically studied,which seriously limits the oil and gas exploration and deployment in the basin.Based on the newly acquired high-precision 3D seismic data,drilling data,this paper identifies and finely describes the magma in the post-rift period,and determines the development regulation of magmatism and the control effects on oil and gas accumulation in Jiaojiang Sag.The results show that the volcanic rocks are mainly distributed in the central and eastern parts of Jiaojiang Sag,with overflow facies as the main type.They are developed along the T20 interface and up and down,but more developed along the T20 interface.There are three types of occurrences of magma intrusion,including saucer,sill,and dike,with saucer being the main occurrence.The emplacement of magma intrusions in the Jiaojiang Sag mainly include three stages:before the Wenzhou stage(＞43 Ma),during the Pinghu-Huagang stage(43-23.3 Ma),during and after Longjing stage(＜23.3 Ma),and the Pinghu-Huagang stage is the most important period for magma intrusion.The distribution of magma intrusion channels in the study area are related to the northwest striking basement hidden faults,but separated from the Cenozoic faults and have no symbiotic relationship between them.It is traditionally suggested that the magmatism in the post-rift stage may cause damage or alteration to early oil and gas reservoirs,therefore,when selecting potential targets,efforts should be made to avoid the influence of magmatic activity as much as possible.On the other hand,magma intrusion has formed a large number of forced anticlines,and their formation time is later than the peak period of oil and gas generation,which belongs to a good potential trap type.Therefore,these forced anticlines in the magma-rich activity area within Jiaojiang Sag are still worth exploring.