南美东缘被动陆缘盆地石油地质特征与资源潜力评价

Petroleum geology and resources evaluation of eastern continental margin basins of South America

为明确南美东缘被动陆缘盆地群油气资源潜力,在系统分析19个被动陆缘盆地群石油地质特征的基础上,首次以成藏组合为单元评价被动陆缘盆地群资源潜力,探讨下步勘探方向:1)南美东缘整体经历"裂谷"—"过渡"—"被动陆缘"3个构造演化阶段;2)发育2套主要烃源岩,即白垩系裂谷期湖相烃源岩和被动陆缘期海相烃源岩;白垩系(占总可采储量69%)和第三系(占总可采储量29%)是2套主要的储集层;盖层为白垩系层间泥岩、第三系海相泥页岩,中段盆地群发育一套白垩系膏盐岩区域性盖层;油气主要富集在中段含盐盆地(可采储量占总量96.32%);盆地群主要发育上部、中部和下部3套大的成藏组合;3)预测总待发现油气可采资源量为132 451百万桶,平面上主要分布在坎波斯、桑托斯、埃斯普利托桑托、圭亚那和马尔维纳斯盆地;纵向主要集中在上部成藏组合;坎波斯盆地上部成藏组合,是最有利的勘探区域,其次为桑托斯盆地的中部和下部成藏组合。

In order to fully understand the resource potential of the continental margin basins in eastern South America, through hydrocarbon accumulation factors analysis of the 19 continental basins, the petroleum features of the continental margin basins in eastern were systematically concluded, based on which the resource potential of these basins was evaluated by taking play as basic evaluation unit. The results show that： 1） the eastern margin is through rift-transition-continental structural evolution periods; 2） two major source rocks i.e. the Cretaceous rift lacustrine source rock and continental margin marine source rock are developed; resources mainly concentrate in Cretaceous（69%） and Tertiary（29%） reservoirs; Cretaceous interlayer mudstone and tertiary marine shale are the main seal rocks, and salt develops in the middle basins is another major regional seal; resources mainly distribute in the central salt developed basins（about 96.32% of the total recoverable reserves of continental margin basins）; 3） the total undiscovered oil and gas resources are 132 451 Mmbo, mainly in Campos, Santos, Espirito Santo, Guyana and Malvinas in plane and the upper play in vertical; the upper play of Campos basin is the most favorable exploration area, and the middle and bottom plays of Santos are the secondary targets.