| Abstract:As one of the important oil and gas-rich sags in Junggar Basin, Mahu sag is mainly distributed in Permian, Triassic and Jurassic, and the oil and gas properties are complex. On the basis of previous work, this study takes the source rock samples of Fengcheng Formation (P1f), Xiazijie Formation (P2x), Lower Urho Formation (P2w) and Karamay Formation (T2k) in Mahu Sag and the crude oil samples of Baikouquan Formation (T1b) in Aihu Oilfield as the main research objects. Through TOC analysis, rock pyrolysis, carbon isotope, saturated hydrocarbon chromatography, saturated hydrocarbon chromatography-mass spectrometry and single well burial history-thermal history analysis, the source of crude oil in Baikouquan of Mahu Sag was clarified. The results show that the organic matter abundance of Fengcheng Formation in Mahu Sag is obviously better than that of the source rock of Lower Wuerhe Formation, and the organic matter abundance is high. The organic matter type is mainly type II kerogen, which has high oil generation potential. The crude oil of the Baikouquan Formation has reached the mature stage, which is mainly derived from the weak oxidation-weak reduction sedimentary environment. Through oil-source correlation, it is found that the biomarkers of crude oil in Mahu Sag and Fengcheng Formation source rocks are well comparable, reflecting that the crude oil in this area mainly comes from the contribution of Fengcheng Formation source rocks. There are two stages of crude oil filling in the Baikouquan Formation reservoir, which are the early Jurassic and early Cretaceous crude oil filling, and the hydrocarbon generation and expulsion of the source rocks of the Fengcheng Formation. |
