巴西坎普斯盆地油气地质特征

Petroleum Geology Characteristics in Campos Basin,Brazil

坎普斯盆地为典型的被动大陆边缘拉伸裂谷盆地,由前裂谷期(非海相)、同裂谷期(过渡相)及后裂谷期(海相)三个构造层组成。含盐层序为区域盖层,盐下层序泥页岩和盐上层序坎普斯组泥页岩为局部盖层;主要烃源岩为下白垩统拉高亚费耶组湖相黑色钙质页岩;古近系和新近系浊积砂岩为主力储集体,上白垩统浊积岩也是重要储层,下白垩统尼欧克姆阶玄武岩是特殊储层。所开发的油藏多具有温度低、所含原油API值低、储层砂岩胶结程度低等特征。大多数已知油田集中于占整个盆地10%的面积内,其余地区是地质复杂区,也可能是未来有利油气藏勘探区。

The Campos Basin is a typical passive continental margin basin.Sedimentary rocks cover pre-rift（non-marine）,syn-rift（transitional） and post-rift（marine） structural formations.The regional sealing rocks are saline formation.The pre-salt argillaceous shale and the post-salt Campos argillaceous shale act as the local sealing rock.The chief source rock is the black Lower Crataceous Logoa Feia lacustrine calcareous shale and the chief reservoir beds are the marine and continental sandstone and carbonate rock,ranging from the Barremian to Miocene in age.Upper Crataceous-Tertiary turbidites contain oil but Lower Crataceous Neocomian basalt is as the particular reservoir.Peak of hydrocarbon generation occurred during late Miocene time and the most important pathways of migration are through salt windows and along listric faults.The exploiting reservoirs are characteristic of low temperature,low API and low degree of sandstone cementation.The most oil fields known are sited within 10% area of the entire basin and the others fall in the complex geological areas or potential exploration areas.