Abstract：QK sag is one of biggest second-level sag in Huanghua depression. There have been more than 30 years of explored history on west slope of QK sag. It cannot verify the distributed regularity of internal thin sand bodies in Es3 target that cannot meet the need for finding subtle reservoir because of poor resolution of former 3-D seismic data in this area. For that reason, by the aid of sequence-stratigraphic knowledge and 3-D high-resolution seismic data as well as 3-D constraint seismic inversion data, the paper probed a new mode of exploration of subtle oil/gas reservoir. The dominant frequency of 3-D high-resolution seismic data has been increased from original 25 Hz to 50-60 Hz and even reached to 70 Hz for shallow layers after high-resolution processing. The dominant frequency in Es3 target can also be reached to above 40 Hz. The up-dip sandstone pinchout is clearly showed in internal Es3 target on seismic sections after logging-constraint seismic inversion, which created condition for identifying subtle traps.
