Sequence Stratigraphy in Deep-water Deposition——A Case Study of 3D Exploration Block in Bengal Fan

Deep-water sequence stratigraphy is a hot spot in international sedimentary research, and submarine fan is the best place for studying the depositional process. It is very difficult to conduct sequence division in deepwater strata because there are no typi-cal sequence stratigraphic interfaces, such as truncation, and onlapping. The sequence stratigraphy division in deep-water settings is discussed with 3D high-resolution seismic and logging data in Bengal fan. Combined with the seismic reflection amplitude, continu-ity and configuration, five typical seismic facies have been idenfied in the study area, including U-shaped facies, dome-shaped facies, parallel seismic facies with high amplitude, parallel seismic facies with mid-low amplitude and transparent and chaotic reflecting facies. Integrated with the previous study results, these five kinds of seismic facies are deep water gravity sedimentation units, corre-sponding to incised channel, channel-levee complex, turbidity lobes, deep-water drape sediment and mass-transport deposits, respec-tively. Most of deep-water sequences started at a relatively low sea level, with huge gravity units well developed in the deepwater setting. The deep-water sequences terminate when the sea level rised rapidly, marked by the sedimentation of condensed section. The maximum flooding surfaces are usually located at the bottom of deep water gravity flow deposits and on the top of deep-sea draped sediment. The sequence boundaries can be recognized by the distribution characteristics of the sedimentary units, which have appar-ent response features in the logs and RMS attribute map.