Kinetics of oil group-type generation and expulsion: An integrated application to Dongying Depression, Bohai Bay Basin, China

Pyrolysis of two kerogens isolated from the E 2 - 3 s 3 3 and E 2 - 3 s 4 1 source rocks in the Niuzhuang sag, Dongying Depression, Bohai Bay Basin, China, was performed in a confined system. The products were extracted with solvent and separated using micro-column chromatography into group-type fractions (saturates, aromatics, resins and asphaltenes) with the kerogen residue in each case undergoing swelling with a variety of solvents. The kinetics for generation and retention of crude oil and its group-type fractions from the kerogens were studied and the kinetic parameters applied to modeling generation and retention of crude oil and its fractions from the E 2 - 3 s 3 3 and E 2 - 3 s 4 1 source rocks on the basis of burial and thermal history of the Niuzhuang sag. The results show that the “normal oil” was generated at about 4.26 Ma and 24.85 Ma ago, but expelled at about 3.96 Ma and 17.46 Ma ago, respectively, from E 2 - 3 s 3 3 and E 2 - 3 s 4 1 source rocks. The current proportions of the expelled saturates, aromatics and NSOs are about 60%, 15% and 25%, respectively.