多期叠合盆地油气运聚模式

HYDROCARBON MIGRATION AND ACCUMULATION MODELS OF SUPERIMPOSED BASINS

多期叠合盆地的主要特征是盆地经历了多个演化阶段 ,并且在不同演化阶段中具有不同的盆地类型和性质。对中国西北塔里木和柴达木盆地进行了多期叠合盆地油气运聚研究。这两个盆地自震旦纪以来经历了震旦纪中泥盆世、晚泥盆世三叠纪和侏罗纪第四纪等 3个开合旋回 ,在演化过程中出现由海向陆的转化和拉张 -挤压的交替转化 ,形成了油气来自多源、油气形成多期、油气运移多方向、油气聚集多场所的油气运聚特征。多期叠合盆地有 3种基本油气运聚模式 :①放射状运移、环状聚集模式 ,以柴达木盆地西部环英雄岭构造带为代表 ,油气运移方向垂直于构造等高线的方向 ;②前陆油气运聚模式 ,以塔里木盆地库车坳陷为代表 ,油气运移方向平行于造山带挤压应力方向 ;③古生代海相克拉通盆地油气运聚模式 。

A superimposed basin is mainly characterized by several evolution stages. In different stage, the basin types and characters are different. Taking Tarim and Qaidam basins of China for examples, the basins experienced three open\|close cycles since Sinian. They are Sinian\|Middle Devonian, Late Devonian\|Triassic and Jurassic\|Quaternary cycles. The Sinian\|Middle Devonian basin is intra\|cratonic marine basin. The Late Devonian\|Triassic basin is related to back\|arc extension and compression, and it transformed from marine into continental. The Jurassic\|Quaternary basin is continental and has a bearing upon foreland basin. The evolution of superimposed basin resulted in multi\|source, multi\|phase maturation, multi\|direction migration and multi\|accumulation of oil and gas. The superimposed basins have three main migration\|accumulation models: ①radial migration and annular accumulation model, such as circle\|hero mount accumulation belt of western Qaidam basin, in which the hydrocarbon migration direction is perpendicular to the contour lines of the basin; ②foreland migration\|accumulation model, such as Kuqa depression of northern Tarim basin, in which the hydrocarbon migration is parallel to the compression stress from the mountain belts; and ③cratonic migration\|accumulation model, such as northern uplift of Tarim basin, in which oil and gas migrated and accumulated along the major faults and unconformities.