| Taking the middle and upper sections of the Pinghu Formation on the Pinghu slope in Xihu Sag as an example,
by synthesizing the research achievements of coastal sedimentary systems at home and abroad, this study innovatively
integrates paleogeomorphology, sedimentary characteristics of tidal flat areas, and coastal sedimentary models to explore
their impacts on tidal dynamics and sedimentary system distribution, providing key basis for subsequent large-scale
lithologic trap oil and gas exploration and development. Comprehensive application of drilling and logging data, seismic
data, and sedimentary process numerical simulation techniques is conducted to simulate the spatio-temporal evolution of
the sedimentary system. Through qualitative description and quantitative measurement, the distributions of unique
sedimentary units such as tidal channels, tidal gullies, tidal sand ridges, and tidal sand sheets are clarified, the controlling
effects of coastal topography and sea-level changes on tidal sedimentary sand bodies are revealed, and three sedimentary
models, namely barrier coast, barrier-free underwater low-relief coast, and barrier-free gentle slope coast, are constructed
to improve the theoretical framework of coastal sedimentary systems. Further comparative analysis between numerical
simulation and actual data shows that barrier coast sand bodies are sheet-like distributed during low sea-level periods,
while underwater low-relief coast sand bodies are ribbon-like distributed during high sea-level periods. For the first time,
large-scale tidal sand ridges in barrier and underwater low-relief sedimentary environments and restricted tidal channel
sand bodies are identified as key targets for oil and gas exploration |
