陆相坳陷盆地层序地层格架下岩性地层圈闭/油藏类型与分布规律——以松辽盆地白垩系泉头组—嫩江组为例

本文在圈闭组成和形成条件分析的基础上对坳陷盆地层序地层格架下岩性地层圈闭/油藏类型与分布规律进行了初步分析和总结,探讨了层序地层格架下不同体系域中圈闭/油藏类型的纵向分布、盆地中不同构造部位圈闭/油藏类型的横向分布规律。系统解剖了松辽坳陷盆地白垩系二级层序格架内低位、湖侵和高位体系域中圈闭/油藏类型的纵向分布和变化特征;对比分析了坳陷盆地从凹陷带(近凹中心)、过渡带(凹陷边缘)到斜坡带(环凹斜坡)圈闭/油藏类型的横向分布和变化规律。圈闭/油藏类型的纵、横向分布和变化规律表明:岩性地层圈闭/油藏的形成及类型具有纵向“层控”、横向“相控”的规律性,即纵向上受控于层序格架(体系域),横向上受控于一定构造背景下特定的沉积相带。

TYPES AND DISTRIBUTIONS OF LITHO-STRATIGRAPHIC TRAPS/RESERVOIRS IN SEQUENCE STRATIGRAPHIC FRAMEWORK IN CONTINENTAL DEPRESSIONAL BASIN:AN EXAMPLE FROM THE CRETACEOUS IN THE SONGLIAO BASIN

On the base of analyzing the constitutes and forming conditions of traps, taking the Lower Cretaceous Quantou, Qingshankou, Yaojia and Nengjiang Formations in the Songliao Basin as an example, the types and distributions of litho-stratigraphic traps/reservoirs were primarily analyzed and summarized in sequence stratigraphic framework in continental depressional basin in eastern China. The paper discussed the vertical distribution rule in different tracts according to sequence stratigraphy in lacustrine deposits and the transverse distribution rule in varied tectonic positions (or units) in continental basin. For depression basin, the transverse distribution and change rule of traps/reservoirs were analyzed by a comparison among the subsidence belt (the center of depression),the transition belt (the edge of depression) and the slop belts (around the depression). The vertical and transverse distribution and change rule indicated that the forming and types of litho-stratigraphic traps/reservoirs showed such a rule,namely, the stratabound ones in longitudinal and facies-controlling in transverse. In other words, the traps/reservoirs might be controlled by sequence stratigraphic framework (tracts) in longitudinal and by sedimentary facies belts in transverse in a certain tectonic background.