Sedimentary Facies Analysis of the Third Eocene Member of Shahejie Formation in the Bonan Sag of Bohai Bay Basin (China): Implications for Facies Heterogeneities in Sandstone Reservoirs

The middle sub-member (Es3z) within the third member (Es3) of Eocene Shahejie formation is main source generation and accumulation hydrocarbons in lacustrine deltas Bonan depression. Exploration research work different blocks carried out separately. Types sedimentary facies, their vertical lateral evolution Es3z are not studied detail. To fill this knowledge gap, we did a detailed analysis facies lithological characteristics through integrative studies cores, well logs seismic data. Identification structures lithology reservoir zone from cores calibrated with high-quality Depositional reservoirs identified structures, grain size, log’s trends sections. was deposited fan delta front setting where five associations found, among them distributary channels consisting MCS, CSg, PCSs, MS, RCL, WCS, PBSs, RCS GBS lithofacies, natural levee containing DFs, furthermore, sheet sand associated to CBS SSM lithofacies. GM, GGM DGM lithofacies related inter-distributary deposits, whereas mouth bars consist PLS, CS CFS. history, flow direction sediments, distribution investigated mapping cross-section profiling show that sediments were sourced southeast northwest. We found thicker succession profiles towards north north-west directions. Belt channel covering wide range areas, act as potential along bar while mudstones interdistributary good seal rocks. methodology adopted has great explore deltas.