Geochemical Characteristics and Hydrocarbon Generation Modeling of the Paleocene Source Rocks in the Jiaojiang Sag, East China Sea Basin

Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage, where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential. Utilizing geochemical and basin modeling analysis, hydrocarbon generation capacity and process of the Paleocene E1y, E1l and E1m formations were investigated. Results show that E1y and E1l mudstones are high-quality source rocks with Type Ⅱ kerogen, which is dominated by both aquatic organisms and terrestrial higher plants deposited in sub-reduced environment. E1m mudstone interbedded with thin carbonaceous mudstone and coal is poor-quality source rock with Type Ⅲ kerogen, whose organic matter was originated from terrestrial higher plants under oxidized environment. Controlled by burial and maturity histories, E1y and E1l source rocks experienced two hydrocarbon generation stages, which took place in the Late Paleocene and in the Middle to Late Eocene, respectively, and had high hydrocarbon generation capacity with cumulative hydrocarbon volume of 363 and 328 mg/g, respectively. E1m source rock only had one hydrocarbon generation process in the Late Eocene, which had low hydrocarbon generation capacity with cumulative hydrocarbon volume of only 24 mg/g. The future oilgas exploration in the Jiaojiang sag should focus on hydrocarbon generation center and select targets in the central uplift formed before the Miocene with high-quality traps.