Correlation of Neogene Oil and Paleogene Source Rocks in the Middle Huanghekou Sag, Bohai Bay Basin

Several billion-ton Neogene oil fields have been successfully discovered in the middle Huanghekou sag over past few years. However, source of crude needs to be clarified, and relevant oil-source correlation was less carried out. Six rocks third member Paleocene Shahejie Formation (Es3) from five wells sixteen samples nine were investigated for with biomarkers carbon hydrogen isotopes saturated hydrocarbon monomers. The distribution characteristics n-alkanes, C19/C23 ratio tricyclic terpanes, long-chain terpene ratios (ETR), C24 tetracyclic terpane C26 terpene, conventional steranes suggest that Es3 parent material is a mixed-source input terrestrial higher plants aquatic phytoplankton. gammacerane C30 hopane low, ranging 0.094 0.134, mean value 0.118; Pr/Ph than 1.5. oils show biomarker similar Es3. monomers also corroborate depositional environment source, which characterize low salinity water during sedimentary period, brackish or freshwater delta deposition under weak oxidation–weak reduction conditions. parity dominance CPI OEP values (both greater 1), Ts/Tm (1.174 1.383, 1.278) C29Ts/C29 norhopane, high diahopane diasterane contents (C30diaH/C30H, C27diaS/C27S), sterane isomerization parameters (%22S, %20S, %ββ) confirm rock are mature enough provide sag. regional significantly different those Es4 surrounding depressions (sags), indicating strata’s absence Suitable traps need around hydrocarbon-generating center gas exploration future.