Control Effect of Deposition Processes on Shale Lithofacies and Reservoirs Characteristics in the Eocene Shahejie Formation (Es4s), Dongying Depression, China

The lacustrine fine-grained sedimentary rocks in the upper interval of fourth member Eocene Shahejie Formation (Es4s) Dongying Depression are important shale oil exploration targets Bohai Bay Basin. They widely distributed and rich organic matter. In this study, samples were observed under optical microscope FESEM, combined with geochemical test physical property analysis to study characteristics reservoir them. Nine lithofacies recognized based on mineral composition, content matter beddings. middle-high laminated calcareous (LF1) mixed (LF2) resulted from seasonal sediment variations settled by suspension deep lake. flaggy (LF3), (LF4), massive (LF5) middle (LF6) formed redeposition. low argillaceous (LF7), felsic (LF8) (LF9) affected terrigenous input events. pore structures vary different beddings which influenced kinds arrangement minerals particles. lithofacies, ink-bottle-shaped pores dominant. slit-shaped coexist. LF1 LF2 best target for LF3, LF4, LF5 LF6 second. deposition processes control fined-grained rocks.