DISCOVERY OF INCISED VALLEY AND ITS PETROLEUM GEOLOGICAL SIGNIFICANCE AT CHEPAIZI AREA OF THE JUNGGAR BASIN

Incised valleys have important petroleum geological significance.Discovery and systematic research of incised valleys in Tugulu Group of Lower Cretaceous at Chepaizi area of the Junggar Basin have shown that,the incised valley system can be divided into the eastern margin system and the southern margin system by the Chepaizi Uplift.The back bulge slope belt in large compressional basins is the major area where large incised valleys are formed.Multi-stages of erosion both vertically and laterally,and the following filling accumulation and lateral aggradation result in peculiar sedimental structure and filling characteristics of incised valley system.Rapid fall of lake level caused by strong episodic tectonic compression and thrusting in the southern margin of Junggar Basin during early Cretaceous leads to inside valleys.At present,the incised valley system is the main hydrocarbon exploration target in Chepaizi area.