中国中西部前陆盆地成藏过程

Reservoiring process in foreland basins in west-central China

根据盆地充填和构造变形特征,可将中国中西部前陆盆地划分为早衰型、改造型和叠加型。早衰型、改造型和叠加型前陆盆地的结构特征决定了前陆盆地烃源岩、储盖组合等成藏条件的差异性,而晚期前陆发育对西部改造型和叠加型前陆盆地烃源岩的演化具有明显的控制作用。正是由于中国中西部不同类型前陆盆地成藏地质条件的差异,决定了其具有不同的成藏过程。燕山晚期是早衰型前陆盆地(如川西前陆盆地)最主要的成藏期,喜山晚期主要表现为天然气藏的调整、定型;喜山晚期是改造型前陆盆地(如柴北缘前陆冲断带)最主要的油气成藏期;而叠加型前陆盆地(如准南前陆盆地)具有多期成藏的特征,但喜山晚期的油气成藏最为重要。

Foreland basins in west-central China can be divided into early-failed, reconstructed and superimposed types. Their architectural features have determined the differences of reservoiring conditions, such as source rocks and reservoir-seal combination, in foreland basins. Late development of foreland has obviously controlled the evolution of source rocks in the reconstructed and superimposed foreland basins in west-central China. The differences of reservoiring geological conditions of different foreland basin types in west-central China have determined that they would have different reservoiring processes. Late Yanshanian is the major reservoiring stage of early-failed foreland basins, such as the foreland basin in western Sichuan, while late Himalayan appears as the adjusting and finalizing stages of gas reservoirs. Late Himalayan is the major reservoiring stage of reconstructed foreland basins, such as the foreland thrust belt on the northern edge of Qaidam basin. Superimposed foreland basins, such as the southern Junggar foreland basin, have the characteristics of multistage reservoiring with late Himalayan being the most important reservoiring stage.