Geochemistry Characteristics of Source Rocks and Oil-Source Correlation in the Gaosheng Area of the Western Depression in the Liaohe Basin, Northeastern China

The hydrocarbon generation potential of source rocks in the high-rise area of the Western Depression of the Liaohe Basin is high. However, the source of the oil is still unclear. The characteristics of source rocks and crude oil are analyzed by rock pyrolysis and saturated hydrocarbon chromatography-mass spectrometry, and then the oil-source correlation is determined. The results show that the crude oil in the Gaosheng area mainly comes from the Es4 (Shahejie Member 4) source rocks. A comparison of the oil and source rock correlation provides direct evidence to identify oil transport systems. The source material of Es4 source rocks is diverse and deposited in a weakly reductive to reductive brackish environment. It is formed by the double input of terrigenous higher plants and aquatic organisms, and the higher plants are the main source. The evaluation results show that Es4 contains mainly type II1 and type II2 kerogen, which are medium to good source rocks. The oil generation potential is 2.5 x 10(6)-50 x 10(6) t/km(2), indicating that the source rocks have sufficient hydrocarbon supply capacity and have the potential to form large reservoirs. The results of this study have important reference significance for further study of the accumulation process of other blocks in the Liaohe Basin.