苏北盆地富油气凹陷形成与分布特征

CHARACTERISTICS OF FORMATION AND DISTRIBUTION OF PROLIFIC SAGS IN THE NORTHERN JIANGSU BASIN

江夏 周荔青

Jiang Xia Zhou Liqing

中国石油大学, 北京 102249 2. 中国石油化工集团公司 外事局, 北京 100728 3. 中国石油化工股份有限公司 石油勘探开发研究院, 北京 100083 4. 中国石油化工股份有限公司 华北分公司, 郑州 450006

China University of Petroleum, Beijing 102249, China 2. Foreign Affairs Bureau, SINOPEC, Beijing 100728, China 3. SINOPEC Exploration & Production Research Institute, Beijing 100083, China 4. SINOPEC North China Company, Zhengzhou, Henan 450006, China

苏北盆地已发现的油气田主要分布在南部东台坳陷的高邮、金湖、溱潼等3个富油气凹陷,其形成条件如下:1)盆地沉降中心由西向东迁移中,形成了金湖、高邮、溱潼等持续快速沉降型凹陷,其烃源岩厚度大,有机质品质好,热演化程度高;2)处于盆地西部大型河流入湖区的金湖、高邮凹陷西部,形成了与阜二段优质烃源岩配套的阜宁组有利储集相带。而盆地中部的溱潼、高邮凹陷东部地区,除下部原生成油气组合发育多套有利生储盖组合外,油气垂向运移较活跃,上部次生成油气组合成藏条件良好;3)在吴堡运动的残留坳陷区——高邮、金湖、溱潼凹陷,烃源岩整体埋藏深度大,热演化程度高,油气资源丰度高,次生油气藏发育;4)在金湖、高邮、溱潼等中西部凹陷,阜宁组二段主力烃源岩沉积期的火山作用较强,地表热力环境及丰富的无机养分促使这一区域低等水生生物特别发育,发育了优质烃源岩。同时,这3个凹陷岩浆作用期次较多(达3~4期),地温梯度较高,使得烃源岩热演化程度高、转化率高。

The oil-and-gas fields discovered so far in the Northern Jiangsu Basin mainly distribute in the Gaoyou,Jinhu and Qintong prolific sags locating in the Dongtai Depression which is in the south of the basin.The formation conditions are as follows: 1) During the migration of subsidence center from west to east in the basin,the sustainable and rapid subsidence type of sags such as Jinhu,Gaoyou and Qintong are created with thick source rocks,premium quality organics and high degree of thermal evolution;2) In the west part of Jinhu and Gaoyou sags which locate in the entrance area of big rivers to lakes in the west of the basin,the favorable Funing Formation reservoir facies belt corresponding to Fu2 Formation premium source rocks is generated.While in the east part of Qintong and Gaoyou sags which locate in the center of the basin,in addition to many favorable combinations of source-reservoir-seal rocks formed with primary oil and gas in the lower part,the vertical migration of oil and gas is fairly dynamic,and the upper secondary oil-and-gas pools have conducive reservoir-forming conditions;3) In the resi-dual depression area of the Wubao movement,namely the Gaoyou,Jinhu and Qintong sags,source rocks are buried with great depth,resulting in high degree of thermal evolution,rich abundance of oil and gas,and good development of secondary oil and gas reservoirs;4) In the central and west sags such as Jinhu,Gaoyou and Qintong,sedimentary volcanism is significant for major hydrocarbon source rocks of Fu2 Formation.Surface thermal environment and abundant inorganic nutrients help grow rich lower hydrobiont in this area and develope premium hydrocarbon source rocks.Meanwhile,magmatism stages for the 3 sags are 3-4,with high geothermal gradient,which is conducive to high degree of thermal evolution and conversion yield.

https://doi.org/10.11781/sysydz201004319