Sequence Stratigraphic Pattern and Forecast of Subtle Reservoir of the Shahejie Formation in Huanghua Depression

The Shahejie formation in the central part of Huanghua depression is one of the most important oil-bearing and exploration formations.Based on sequence stratigraphy and analyses of cores,logging and seismic information,two second-order sequences,seven third-order sequences and twenty one system tracts were identified in Shahejie formation of the central part of Huanghua depression.The sequence stratigraphy frame was established and the relationship between the frame and sediment,structural evolution was analyzed.Fan delta system,lacustrine delta system,inshore subaqueous fan system,tubidite system in deep water and lacustrine system were identified in this formation based on modern sedimentology.The results show that the sand bodies of highstand and lowstand are favorable explore targets in Qinan depression.