Sedimentary characteristics and exploration potential of large-scale sublacustrine fan in the southeast slope belt of Bozhong Sag

There is a large area of sublacustrine fan at the southeast slope of the Bonan low uplift in the Bohai Sea area in the E₃d₂^l period.And its provenance origin and distribution area are quite different from the sedimentary characteristics of conventional sublacustrine fans in the Bohai Sea.Due to this significant difference, some disputes about the type and division of the facies belts are aroused, and whether it can be a reservoir is still an open question.As the exploration of the middle-deep sand bodies in the Bohai Sea is enhanced increasingly, the first task is to determine the sedimentary facies type and sand-rich property of its lithosomic bodies and the research focus is to analyze its genetic mechanism.Considering no exploration well is drilled in this area and its burial depth is larger, paleogeomorphologic setting and palaeobathymetric environment were reconstructed in this paper according to the theory of sequence stratigraphy.Then, based on source-channel-sink coupling theory and seismic geometry characteristics, the provenance was confirmed to be a periodical event.In addition, the transport mechanism of its subaqueous debris flow was analyzed, and the developmental site, formation mechanism and sedimentation type of lithosomic bodies were defined.Finally, by virtue of the multi-attribute analysis, the inside of the large-scale sublacustrine fan in the study area was characterized, and the distribution of favorable reservoirs was predicted.The research results can be used as the reference for the exploration of lithologic oil and gas reservoirs in this area.