Hydrocarbon migration system in complex geological bodies at Chepaizi area,western Junggar Basin

The Chepaizi Arch is a secondary tectonic unit in the western uplift of the Junggar Basin.Two oil fields,Chunguang and Chunfeng,have been discovered,and the proven oil reserves are 6 061?10⁴ t.As to the complex geological bodies in the study area,the framework,driving mechanism and its controlling on petroleum distribution of hydrocarbon migration system have been analyzed.It has been concluded that,in the Chepaizi area which is a typical slope,the Hongche Fault Belt plays the most important role in migration,and the connected matrix sand bodies also work as pathways.Vertical and lateral migrations of big scale are very common,mainly generating structural or lithologic-structural reservoirs.In overlying and erosion belt,unconformities work as the main pathways.Lateral migrations are common,mainly generating stratigraphic or structural-stratigraphic reservoirs.In the higher positions of sand valley,entrenched valley depositional system serves as lateral pathways,resulting in lithologic reservoirs.