巴西圣埃斯皮里图盆地油气地质特征及勘探方向

近几年来，桑托斯（Santos）、坎波斯（Campos）2个盆地取得了较大的油气发现，而紧邻这2个盆地的圣埃斯皮里图（Espirito Santo）盆地油气发现较少，勘探程度较低。为了揭示该盆地的油气成藏规律，指明勘探方向，对该盆地的沉积特征、构造演化、烃源岩、圈闭和储集层等进行了深入研究和剖析，初步摸清了该盆地的油气分布规律、成藏主控因素和模式。该盆地位于巴西东海岸被动大陆边缘盆地群，先后经历了裂谷期、过渡期、漂移期3个演化阶段，相应地发育了盐下、盐岩和盐上3套层序。受盐岩底辟作用影响，形成特征迥异的盐下和盐上双层构造，其中盐下受裂谷体系控制，总体上表现为倾向分带的“斜向棋盘”格局，盐上为重力滑覆体系，发育了较多的盐构造类型。阿普第阶Cricare组Neocomian湖相页岩为最好的烃源岩，油气主要分布在上白垩统-新近系的盐上浊积砂中，以岩性圈闭为主。分析认为，浊积砂的分布和运移通道是油气成藏主要控制因素，盆地目前存在6个勘探方向，其中靠近陆岸的斜坡区是油气运移和聚集的最有利区。 

Petroleum geology characteristics and exploration directions in Espirito Santo Basin,Brazil

In recent years, a great discovery of petroleum has been made in the Santos and Campos basins; however, little has been made in the Espirito Santo Basin which is adjacent to the two basins. Exploration level of the basin is also low. We studied the sedimentary characteristics, tectonic evolution, source rock, trap and reservoir in detail, and found the petroleum distribution rules, main factors and modes of petroleum accumulation, in order to reveal petroleum enrichment regularity and point out exploration directions in the Espirito Santo Basin. The basin belongs to the passive continental margin basin group near the east coast of Brazil, successively experiencing rifting, transitional and drifting periods, and accordingly developing sub-salt, salt and supra-salt rock sequences. Influenced by the salt diapirism, the basin has formed a very different sub-salt and supra-salt double-layer structure, within which the sub-salt structure shows a propensity for "oblique board" zoning in general under the control of a rift system and the supra-salt structure, controlled by a gravity slide system, has developed various types of salt structure. The Aptian stage Cricare group Neocomian lacustrine shale is the best hydrocarbon source rock and petroleum is mainly distributed in the Upper Cretaceous-Neogene supra-salt turbidite sand, dominated by lithologic traps. The analysis shows that distribution of turbidite sand and migration pathways are the main controlling factors of petroleum accumulation, and the basin has 6 exploration directions at present, among which the near shore slope area is the most favorable for petroleum migration and accumulation.