东海陆架盆地丽水凹陷油气成藏规律及区带优选

Hydrocarbon accumulation rule and exploration target optimization in Lishui Sag,East China Sea continental shelf basin

利用地球物理及地球化学资料,结合盆地模拟技术,系统分析丽水凹陷油气成藏地质要素,认为烃源岩、储集层、输导体系及构造运动是其油气成藏的主控因素。研究区古新统烃源岩类型多样,生排烃历史复杂,分布特征存在差异,致使凹陷内油气性质和分布的不同;储集层非均质性强烈,导致油气差异聚集,且油气藏主要分布于三角洲前缘和扇三角洲部位;输导体系在不同区域的差异性决定了油气藏组合类型的多样性和油气藏分布的复杂性;古新世至中新世的2期构造运动(瓯江运动、玉泉运动)影响了烃源岩的热演化,改造和破坏了油气藏,成为制约油气发现的主要因素。总结丽水凹陷的油气成藏规律为近源成藏,储层物性制约成藏,断裂活动决定成藏,并提出2个最有利油气勘探区带为中部反转构造带和西斜坡反向断裂带。

Using geophysical and geochemical data combined with basin modeling,this paper analyzed the basic geological conditions of hydrocarbon accumulation,and discussed that the main controlling factors are source rocks,reservoir,migration pathway system and tectonic movement.The types of Paleocene source rocks are diverse,the hydrocarbon-generating and expulsing history is complex,the distribution characteristics are different,and so the characters and distribution of oil and gas in Lishui Depression exist differences.Intense heterogeneity of reservoir in research area leads to different aggregation extent of oil and gas,and the main distribution areas of oil and gas reservoir are delta front and fan delta.The difference of migration pathway system in different regions decides diversity of reservoir combination types and complexity of the distribution of reservoirs.From Paleocene to Miocene two tectonic movements（Oujiang and Yuquan movements）affected the evolution of hydrocarbon source rocks,modified and destroyed reservoirs,and become the main factor of oil and gas discovery.Summarizing rules of them are proximal accumulation,restriction of reservoir property for accumulation and decision of faulting for accumulation.The best exploration belts are in central inverted structure belt and reverse fault belt of the western ramp.