叠合断陷盆地油气成藏条件分析———以东海丽水—椒江凹陷为例

通过对东海丽水—椒江凹陷的构造、沉积地层和成藏要素的分析，系统阐述了其成藏条件。结果表 明：丽水—椒江凹陷古新世主断陷期分为4 幕断陷，其中初始断陷Ⅰ幕以湖相沉积环境为主，之后过渡为 海相沉积环境，该凹陷存在3 组烃源岩及3 套储盖组合，其中下古新统月桂峰组湖相暗色泥岩有机质丰 度高，且其类型以Ⅱ型为主，生烃潜力良好，为该区主力烃源岩；古新统储集层以砂岩为主，其中灵峰组和 月桂峰组砂岩为Ⅲ—Ⅳ 类储层，明月峰组砂岩为Ⅲ_a—Ⅱ_b 类储层，物性受凹陷内顶封型异常高压系统改 造优化。断陷早期的（扇）三角洲、滨湖、滨海砂体和上灵峰组上部及明月峰组下部的浅海泥构成的下储盖 组合靠近主力烃源岩层，且异常高压系统增储滞排，因此储盖配置条件良好，勘探前景佳。预测凹陷内洼 槽带生烃中心上方、灵峰潜山两侧及丽西次凹西斜坡的优势成藏构造带是研究区内有利的远景勘探区带， 并识别划分出三大类共11 个有利构造带。

Hydrocarbon accumulation condition of superimposed rift-subsidence basin:A case study from Lishui-Jiaojiang Sag in the East China Sea

Lishui-Jiaojiang Sag is the representative offshore superimpose rift-subsidence basin of China. Paleocene is identified as the main faulting period of the sag, which can be divided into four episodic rifting. There was lacustrine environment in the first episodic rifting, and then the sedimentary environment changed into marine environment. There are three groups of hydrocarbon source rocks and three sets of reservoir-cap assemblage. The lacustrine mudstone of Yueguifeng Formation has high abundance of organic matter, mainly belongs to the type Ⅱ, has good potential of hydrocarbon generation, and is regarded as the main hydrocarbon source rocks of this area. Paleocene sandstone is the main reservoir of the sag, sandstone reservoirs of Lingfeng Formation and Yueguifeng Formation belong to the type Ⅲ and Ⅳ, sandstone reservoirs ofMingyuefeng Formation belong to the type Ⅲa and Ⅱb, reservoir property is changed by the top-sealing abnormal high pressure system. The reservoir-cap assemblage composed by the early faulted （fan） delta, lakeside and coastal sandstone together with the shallowsea mudstone ofthe top of Lingfeng Formation and the bottom of Mingyuefeng Formation has nice exploration potential, because the main hydrocarbon source rocks and the abnormal high pressure system approach the assemblage and there are favourable reservoir-cap configuration conditions. The favorable zones predicted are located above of the hydrocarbon generating center of Lishui-Jiaojiang Sag, on both sides of the Lingfeng buried hill and the westen slope of West Subsag ofLishui Sag, and can be divided into three major categories and 11 favorable structure belts.