东海盆地丽水凹陷CO2分布特征及成藏主控因素

基于丽水凹陷钻井和地震资料，综合天然气地球化学参数、基底断裂和岩浆底辟发育特征等，研究丽水凹陷CO₂的分布特征及其成藏主控因素.研究结果表明，丽水凹陷CO₂纵向上主要分布在灵峰组、明月峰组下段及元古界基底片麻岩中，不同层位CO₂的含量差别很大；平面上，温州13-1、丽水35-7和南平5-2 CO₂气藏均位于岩浆底辟体之上或者附近，同时周围亦发育断层，而丽水36-1高含CO₂气藏和LF-1井含CO₂气藏周围底辟不发育，均紧邻灵峰凸起西侧的控洼断裂.丽水凹陷幔源CO₂成藏主要受早中新世和晚中新世两期火山岩浆活动的影响，这两期火山活动将幔源CO₂带到地壳浅层，通过砂体侧向输导进入有利圈闭聚集成藏. 

Distribution and Major Controlling Factors of CO2 Reservoirs in Lishui Sag,East China Sea Basin

Based on the drilling data and seismic data of Lishui sag, the distribution and major controlling factors of CO₂ reservoirs are studied by combining geochemical parameters of natural gas and development characteristics of basement faults and magma diapirs. The results show that CO₂ is mainly concentrated in Lingfeng Formation, lower segment of Mingyuefeng Formation and Proterozoic basal gneiss in the vertical. Besides, the content of CO₂ varies greatly in different layers. Laterally, Wenzhou 13-1, Lishui 35-7 and Nanping 5-2 structural CO₂ gas reservoirs are located on or near the magma diapirs, and there are faults around these CO₂ gas reservoirs. Whereas, there is no diapir near Lishui 36-1 structural CO₂ gas reservoirs and LF-1 containing CO₂ gas reservoir, but they are adjacent to large depression-controlling faults which are located at west side of Lingfeng uplift. The distribution of CO₂ gas reservoirs in the Lishui sag is mainly controlled by two stages magmatic activities, which are respectively in Early Miocene and Late Miocene. Mantle-derived CO₂ gas is carried by the deep volcanic magma activities to shallow crust, then migrates along with sand body to favorable traps and forms CO₂ gas pools.