The Geological Significance for Discovery of Lower Ordovician Source Rocks in Halahatang Area,Tarim Basin

The controversy on the hydrocarbon source rocks in Tarim cratonic area has not being ceased. There is greater awareness of differences on the source horizon of Ordovician strata in the past because most of organic carbon content of Lower Ordovician carbonate rock samples are less than 0.2% in central and western Tarim basin,which does not reach the industrial standards of source rock. Hence the potential of hydrocarbon generation of Lower Ordovician in this area has been underestimated. Based on the experimental data analysis of Yingshan formation of Lower Ordovician in Ha-6 Well,it is found that the majority of samples of organic carbon content is greater than 0.2%,averaging 0.437%,of which up to 130 m of dolomitic limestone,almost all organic carbon content is greater than 0.5%,first confirming that the Lower Ordovician develops industrial source rocks in Halahatang area. The thickness of source rocks is larger and well succeeded. And its distribution well be wider if Heituwa shale links it up,and will create huge capacity of hydrocarbon generation. The discovery of Yingshan formation source rocks of high quality indicates that the Lower Ordovician possesses great hydrocarbon potentials,and it will help to broaden the exploration fields.