南大西洋两岸盆地海相烃源岩特征与控制因素

Characteristics and controlling factors of marine source rocks in the basins on the two sides of South Atlantic

  • 摘要: 南大西洋两岸盆地漂移期层系油气资源十分丰富,通过对两岸重点盆地漂移期主力烃源岩发育层位、生烃潜力、识别特征和分布范围对比分析,明确两岸发育早、晚两套主力海相烃源岩。其中,晚期的赛诺曼—土仑阶海相烃源岩分布范围较广。整体上,两岸北段和赤道段盆地漂移期主力烃源岩地化指标优于中段和南段盆地,西非一侧海域盆地烃源岩地化指标优于南美一侧盆地。在对重点钻井的矿物元素化验分析、沉积相和古地理分析基础之上,总结了局限海湾的古地理背景和沉积相带类型控制优质海相烃源岩发育程度和分布范围的规律,并进一步指出南大西洋两岸北段和赤道段盆地漂移期成熟生烃灶平面分布范围内的深水沉积砂体是主要有利勘探方向,以找油为主,中段含盐盆地内紧邻盐微盆的漂移期深水沉积砂体勘探潜力次之。

     

    Abstract: Oil and gas resources are rich in drifting stages in the basins on both sides of South Atlantic. Comparative researches on main marine source rocks, including hydrocarbon generation potential, seismic facies and distribution patterns suggest that there are 2 sets of main source rocks, of which the upper is more widely distributed. In a general perspective, the geochemical indexes of main source rocks in the north and Equatorial South Atlantic basins are better than those in the central basins, while the source rocks in South American basins are also better than those in West African basins. Study of typical well data, sedimentary facies and paleogeography of main marine source rocks suggest that high-quality marine source rocks are mainly distributed in confined bays and related sedimentary facies. The first priority of exploration targets should be the deep-water deposited sandstones intercalated in the matured marine source rocks. The sandstones deposited in the drifting stages close to the salt mini-basin are also recommended.

     

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