吐哈盆地台北凹陷沉积体系变迁对油气分布的控制

CONTROLLING THE CHANGES OF DEPOSITIONAL SYSTEM TO HYDROCARBON DISTRIBUTION IN TAIBEI SAG, TURPAN-HARMI BASIN

台北凹陷在侏罗纪以后成为吐哈盆地的沉积中心。在其发育初期沉积了煤系烃源岩 ,鼎盛时期北物源不断推进 ,南物源不断后退 ,不断向南发育的巨厚泥岩 ,形成了跨层连片的区域性盖层 ,盖层之上为北物源沉积体系 ,之下为南物源沉积体系 ,造就了绝佳的储盖组合。沉积体系的变迁对油气的分布起着控制作用 ,油气分布层位北老南新 ,主要分布于南物源沉积体系 ,且封闭于区域性盖层之下。北物源沉积体系多形成小规模次生油藏。凹陷衰退期湖盆中心直接控制了浅层油气藏的分布 ,凹陷发展后期构造活动对油气的影响主要体现在对原油气藏的调整和重组。

Taibei Say was the depositional center of Turpan-Harmi Basin after Jurassic.Coal measures hydrocarbon source rocks were deposited in the early stage;the northern material source progressed southward continuously in a period of great prosperity while the southern material source retreated,thus forming a huge thickness regional mudstone caprock.The northern material source depositional system is above the cap rock and the southern material depasitional source is below it.They construct a good reservoir-cap rock complex.The changes in depositional systems controlled hydrocarbon distribution.Most of the hydrocarbon is distributed in the southern material source depositional system,while some small scale of secondary oil and gas pools are in the northern material source depostional system.The center of lake basin of decline stage controlled directly the distribution of shallow hydrocarbon pools.The tectonic activities of the late stage of the depression development could effect the regulation and reconstitution of hydrocarbon pools.