中国陆源碎屑盆地层序地层与储层展布

不同类型盆地的层序充填样式、展布特征存在较大差异。前陆盆地的层序发育主要受控于逆冲挠曲变形和负载释放的交替作用,层序展布上表现为极度的不对称;克拉通盆地因地形平坦,海平面升降对层序发育起主要控制作用,层序特征在较大的范围内表现出很好的一致性;断裂不同规模、不同级次的幕式活动控制了陆内裂谷盆地层序各级次旋回的发育,因此,盆地层序往往具有多级旋回的特征;大型坳陷盆地由于水体广阔,层序特征可与被动陆缘类比;山间坳陷盆地的层序发育主要受幕式构造活动、古气候以及物源等因素的影响;山前断陷盆地的层序发育则主要受走滑拉分作用的控制。上述这些差异必然会导致不同盆地的生储盖类型及其配置关系有较大差别。就一般而言,各级次旋回中由上升到下降的转换位置是烃源岩发育的位置;上升半旋回和下降半旋回中形成的各类砂体是主要的储集体。

SEQUENCE STRATIGRAPHY AND RESERVOIR DISTRIBUTION

Sequences of different basins differ considerably in depositional pattern,distribution characteristics.The sequences of foreland basins are mainly dominated by alternation of thrus flexure deformation and unloading,and their distribution is very asymmetric;the sequences in cratonic basins are mainly controlled by eustasy,and coincident in broad extent;the sequeces of inland rift basins are controlled by different scales and different orders of episodic fracture movements,thus resulting in multicycle sequences;sequences of large depressions are similar to those of passive continental margins;those of intermontane basins are related to episodic movement,paleoclimate and source materials;those of piedment fault depressed basins are related to strike slip and pull apart movements.The above mentioned differences are bound to cause considerable differences in types and collocation of source reservoir cap rock association.In general,the turning positions between rising and downing processes of the cycles are favourable places for source rooks;the sand bodies formed in semi rising and semi downing cycles are the main reservoirs.