燕山、喜马拉雅构造运动在准噶尔盆地油气运聚中的作用

Effect of Yanshan Movement and Himalayan Orogeny on Hydrocarbon Migration and Accumulation in Junggar Basin

分析了燕山运动和喜马拉雅运动在准噶尔盆地油气运移和聚集中的作用。指出燕山运动前所有构造运动,包括印支运动,造就了准噶尔盆地的构造雏形,燕山、喜马拉雅运动就是在这种基础上,对盆地的构造格局进行了进一步的改造和深化,进而深刻地影响着盆地油气运动和聚集。燕山运动初期以波状运动为主,后期以上升运动为主,这就为前期多生油旋回生成的油气向地层超覆尖灭带、岩性尖灭带运移创造了条件;晚白垩世陆梁及南斜坡带均处于上升阶段,这就为下伏生油层系生成的油气沿不整合面向高处运移,聚集于储集条件好的白垩系提供了条件;喜马拉雅运动的第三幕(晚上新世末)是盆地唯一一次褶皱运动,在南缘山前坳陷带形成了三排背斜带,使南缘构造和油气分布复杂化,对盆地内部的地层形变虽影响不大,但对油气再次运移仍是有影响的。在盆地南缘和北缘(陆梁、夏子街)地区进行油气勘探时必须要考虑喜马拉雅运动的影响。

The effect of Yanshan movement and Himalayan orogeny on hydrocarbon migration and accumulation in Junggar basin is analyzed. It is pointed out that the all orogenies before Yanshan movement in Junggar basin, including Indosinian orogeny, brought up the rudiment structural framework and took effects of reconstructions in detail, hence, more influencing the petroleum migration and accumulation within the basin. The early Yanshan movement was dominated by undulatory motion, whereas the late Yanshan movement by ascending motion, which created the conditions for hydrocarbon generated by multiple circles migrating toward overlap pinchout and lithologic pinchout zones. In the late Cretaceous, Luliang area and its south slope belt were in ascending stage, thus providing conditions for hydrocarbon formed in underlying source sequences migrating upward along the unconformity and accumulating into better Cretaceous reservoirs. In the third episode of Himalayan movement (the end of Late Pliocene), the only folding movement took place in the basin, and forming three-row anticlines at it south-marginal foreland sag, allowing the structures and hydrocarbon distribution to be complicated. They were not greatly effected the strata framework within the basin, but somewhat influenced the re-migration of hydrocarbons there. Therefore, the effect of Himalayan orogeny should be considered for oil-gas exploration in southern and northern margins (Luliang and Xiazijie areas) of Junggar basin.