Abstract:
The Pinghu Formation in the Pingbei Slope Belt of the Xihu Depression is located in a river tidal controlled sedimentary environment, with the development of fluvial-deltaic, tidal-deltaic, and tidal flat sand bodies. Due to the complex faults, fast sedimentary phase changes, and difficulty in identifying different types of channel sand bodies in this area, it is extremely difficult to predict favorable reservoirs. Using seismic, core, and logging data, combined with single well facies, continuous well facies, and seismic facies analysis techniques, six types of fault slope breaks and three sand control modes were summarized, and a comparative analysis of sedimentary characteristics of the river tidal control system was completed; Using AVO forward simulation technology to determine gradient attributes can effectively identify waterway sand bodies. The results indicate that the study area can be divided into reverse fault step zones, forward fault step zones, and composite fault step zones; Under the overall water recession background of the Eocene epoch, the supply of sediment sources in the northwest was strengthened, and the sedimentary environment gradually shifted from being dominated by tides to being dominated by rivers; The AVO gradient attribute can transform dark spot reflections in the middle and deep layers into bright spot reflections, increasing the amplitude energy by 6~10 times, effectively identifying channel sand bodies in the middle and deep river tidal control sedimentary system.