Abstract:

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.

Key words: piedmont depression, depositional system, reformation, hydrocarbon distribution, Taibei Sag