摘要
东濮凹陷是渤海湾地区一个典型的盐湖盆地 ,其古近系的两个沉积旋回沉积了两套盐岩。其中沙河街组第三段 (Es3 )的盐岩又可细分为第四亚段 (Es4 3 )、第三亚段 (Es3 3 )、第二亚段 (Es23 ) ,主要分布在北部中央隆起带附近。盐岩层由于极为致密 ,其阻隔作用使其下部地层的地温、地层压力均较高 ,有利于下伏生油岩中的有机质向油气的转化。盐岩又是良好的盖层 ,且在高温、高压下呈塑性状态。由于盐岩的遮挡和变形 ,形成多种与盐岩有关的油气藏 ,即盐岩上部堑式背斜油气藏、盐岩侧向封堵油气藏、盐下背斜油气藏和岩性油气藏。由于Es3段盐岩的沉积中心的不断转移使得Es4 3 ,Es3 3 ,Es23 的盐层之下都有盐岩相变的砂岩而成为较佳的储盖组合 ,从而造成中央隆起带盐下油气异常富集。同时 ,虽然沙河街组一段 (Es1)的盐岩较薄 ,但其分布范围大 ,对其下部沙河街组二段 (Es2 )的油气富集起到了非常关键的作用。经分析 ,本区下一步的勘探目标为文留东部Es4 3 盐下深层地垒带、文东Es23 盐间文 93扇体、东部前梨园洼陷及西部海通集洼陷。
Dongpu depression is a typical salt-lake basin in Bohai Bay region.Two sets of halites have been deposited in the two Paleogene depositional cycles.The halites in the 3rd member of Shahejie Fm (Es 3) can be divided into three sub-units: the 4th sub-member (Es 4 3),3rd sub-member (Es 3 3),and 2nd sub-member (Es 2 3),which mostly distribute near the central uplift belt in northern Dongpu depression. Halites have been compacted and become very tight,which would become barriers and result in higher geotemperature and formation pressure in the underneath stra-ta,and would be favorable to the transformation of organic matters in the underlying source rocks into oil and gas. Meanwhile, halite is also a good cap rock, and would be in plastic state under high temperature and high pressure condition. Because of the barrier and deformation of the halites, multiple reservoir types related to halites have been formed, such as graben-like anticlinal oil and gas reservoirs in the upper part of the halite, oil and gas reservoirs laterally blocked by halite, anticlinal oil and gas reservoirs under the halites and lithological oil and gas reservoirs. As a result of the shifting of halite depocenters during the deposition of Es 3 ,there are always sandstones under the Es 3 4, Es 3 3 and Es 2 3 halites, which would become relatively good combination of reservoir and cap rock ,and even result in very rich accumulations of oil and gas beneath the halites in central uplift belt. Although the Es 1 halite is thin, its distribution area is large and it would still play the key role in the hydrocarbon accumulation in the 2nd member of Shahejie Fm (Es 2). Much attention should be further paid to those areas, such as deep horst belt under the Es 4 3 halites in eastern Wenliu,the Es 2 3 Wen 93 fan between the halites in eastern Wenliu, the Qianliyuan sag in eastern Dongpu depression and Haitongji sag in western Dongpu depression.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2003年第2期152-156,166,共6页
Oil & Gas Geology
关键词
盐岩
沉积特征
沉积旋回
古近系
岩性油气藏
勘探
东濮凹陷
halite
sedimentary characteristics
depositional cycles
Paleogene
lithological reservoir
exploration
Dongpu depression
