High-quality source rocks in Nanpu Sag

The Nanpu Sag is one of the hydrocarbon-rich depressions in the Bohai Bay Basin.The 4th section of the 3rd member of the Shahejie Formation(Es34) is the most important source rock with 250m effective thickness,about 100m high-quality source rock and above 0.8% vitrinite reflectivity.In the high-quality source rock with TOC exceeding 5% develop clay layers rich in organic material coming from amorphous and algal solids and fine-grained calcite lamination,which are the result of seasonal stratification of lake and algal blooming.The biomarker components indicate that the organic material of the source rock mainly comes from hydro-biont,which existed in a fresh water and deoxidation environment,and to a less extent from land organic matter.The resource evaluation indicates that the oil-generating amount of Es34 is about 6×109t which accounts for 40% of the total in the Nanpu Sag and the resource amount is about 7.5×108t.