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南大西洋盆地深水区盐下地质特征差异性对比

刘子玉 张树林 吕 明   

  1. 中海油研究总院
  • 出版日期:2014-12-15 发布日期:2014-12-15
  • 作者简介:刘子玉(1982-),男,河南柘城人,硕士,2008 年毕业于成都理工大学,工程师,现主要从事海外沉积储层方面的研究工作。 地址:北京市朝阳区太阳宫南街6 号院A 座1009 室,邮政编码:100028。E-mail:254129811@qq.com
  • 基金资助:
    国家科技重大专项海外大陆边缘盆地勘探开发实用新技术研究(2011ZX05030)。

Analysis of Pre-salt Geological Characteristics of Deepwater Basins in South Atlantic Ocean

Liu Ziyu, Zhang Shulin, Lv Ming   

  1. CNOOC Research Institute
  • Online:2014-12-15 Published:2014-12-15

摘要: 南大西洋两岸盆地盐下深水区已成为油气勘探的热点区域,这些盆地经历了相似的构造演化和沉积充填, 含油气地质条件也颇为相似。近年来在巴西沿岸盆地不断有重大发现,而在西非沿岸盆地盐下勘探一直未有突破。选 取桑托斯、坎普斯和宽扎3 个重要盆地,开展盐下地质特征对比研究,分析了盆地结构、沉积储层、烃源岩特征的差 异性,认为盆地构造对沉积储层起控制作用,并进一步控制了油气成藏和聚集。巴西桑托斯盆地、坎普斯盆地分别呈 现出两隆一凹三隆两凹的构造格局,凹陷带为有利生烃凹陷,隆起区为主要油气聚集带,其规模大而且分 布比较集中;而西非宽扎盆地略呈三隆两凹的格局,与坎普斯盆地构成共轭关系,但其盐下构造格局多为垒—堑 相间的翘倾断块,规模小而分散,呈狭窄条带状展布。桑托斯、坎普斯和宽扎3 个盆地盐下均发育极好湖相页岩烃源 岩,沉积于微咸水—盐湖环境,为Ⅰ—Ⅱ型干酪根,并均已被钻井所证实。巴西桑托斯和坎普斯盆地盐下主要发育两 套储层,即同裂谷晚期生物介壳灰岩和坳陷期微生物岩;西非宽扎盆地近期的油气发现表明,其盐下亦存在此类储层。

Abstract: The pre-salt deepwater of South Atlantic Ocean basins have become the hot areas of oil exploration. These basins have experienced the similar tectonic and sedimentary evolution and similar petroliferous geological conditions. Major discoveries have been continually made in the basis of Brazils coast in recent years, but no breakthroughs have been made in pre-salt exploration of the basins of West Africas coast. This paper selects three important basins – Santos, Campos and Kwanza – to compare their pre-salt geological characteristics and analyze their basin framework, sedimentary reservoirs and source rock characteristics. According to this paper, the basin framework controls sedimentary reservoir development, thus controlling oil and gas accumulations. Brazils Santos Basin and Campos Basin are in the patterns of two depressions and one uplift and two depressions and three uplifts respectively. The depressions are favorable hydrocarbon sourcing zones while the uplifts are favorable hydrocarbon accumulations zones, accumulated on a large scale and in concentration. West Africas Kwanza Basin is nearly in the pattern of three depressions and two uplifts ,it conjugates with Campos Basin. But the pre-salt structure is mainly composed of faulted blocks mixed with horsts and grabens at a small scale and in dispersion, distributed in a narrow-ribbon shape. All the three basins of Santos, Campos and Kwanza have abundant pre-salt lacustrine source rock, deposited under the salt lake environment and containing kerogen of Ⅰ - Ⅱ type. Drilling has confi rmed such source rock. Two sets of reservoir developed in the pre-salt formations of Brazil’s Santos and Campos basins, namely late syn-rift bioclastic limestone and sag microbialites. The recent oil and gas discoveries in West Africas Kwanza basin indicate that the similar reservoirs also exist in the pres-salt formations of the basin.