OIL MIGRATION ORIENTATION OF ORDOVICIAN IN TAZHONG UPLIFT

Definition of oil migration orientation has great importance to further oil exploration.Based on the previous research,it is found out that it is incorrect that the northwest Tazhong uplift was higher and the southeast uplift was lower from Caledonian to middle Hercynian.In general,southeast part of the uplift is the highest part all along,and there are two relatively higher parts in Tazhong,one is located near well Zhong-1 in west Tazhong horst,the another,the highest part in Tazhong,is located near Tazhong well-1 in east Tazhong horst.The correlation of oil source indicates the crude oil of Ordivician in Tazhong mainly came from the source rocks in middle to upper Ordivician.According to ancient structural setting,the study on filling and accumulating orientation of the crude oil from middle to upper Ordivician shows that there are at least two orientations of oil migration in north Tazhong slope,one is from lower noetheast Tazhong to higher southeast Tazhong,another is from lower northwest Tazhong to higher Zhong well-1block.The oil and gas in Tazhong well-52,Zhong well-4 in south Tazhong slope came from Tanggubasi sag in south Tazhong and migrated a relatively short distance,which further proves the hydrocarbon source rocks in middle to upper Ordivivian in Tanggudasi sag are of good oil and gas generation potential.