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Studies on the source and phase characteristics of oil and gas: evidence from hydrocarbon geochemistry in the Pingbei Area of Xihu Sag, the East China Sea Shelf Basin, China
Li, W.; Chen, J.; Liu, K.; Fu, R.; Chen, C.; Wang, Y.; Zhu, X.; Chen, X.; Zhang, T.; He, L. Studies on the Source and Phase Characteristics of Oil and Gas: Evidence from Hydrocarbon Geochemistry in the Pingbei Area of Xihu Sag, the East China Sea Shelf Basin, China. Energies2023, 16, 6529.
Li, W.; Chen, J.; Liu, K.; Fu, R.; Chen, C.; Wang, Y.; Zhu, X.; Chen, X.; Zhang, T.; He, L. Studies on the Source and Phase Characteristics of Oil and Gas: Evidence from Hydrocarbon Geochemistry in the Pingbei Area of Xihu Sag, the East China Sea Shelf Basin, China. Energies 2023, 16, 6529.
Li, W.; Chen, J.; Liu, K.; Fu, R.; Chen, C.; Wang, Y.; Zhu, X.; Chen, X.; Zhang, T.; He, L. Studies on the Source and Phase Characteristics of Oil and Gas: Evidence from Hydrocarbon Geochemistry in the Pingbei Area of Xihu Sag, the East China Sea Shelf Basin, China. Energies2023, 16, 6529.
Li, W.; Chen, J.; Liu, K.; Fu, R.; Chen, C.; Wang, Y.; Zhu, X.; Chen, X.; Zhang, T.; He, L. Studies on the Source and Phase Characteristics of Oil and Gas: Evidence from Hydrocarbon Geochemistry in the Pingbei Area of Xihu Sag, the East China Sea Shelf Basin, China. Energies 2023, 16, 6529.
Abstract
The Pingbei area is the main accumulation area of oil and gas in the Xihu Sag. The phase characteristics of oil and gas in this area are complex, and the understanding of their genesis is still unclear. In this paper, based upon discussions of crude oil and natural gas geochemical data, integrated with local geological features, we discuss the sources, migration, and phase state characteristics of oil and gas in the Pingbei area of the Xihu Sag. The study results showed that the crude oil and natural gas in the Pingbei area are coal-derived and the oil and gas produced by the humic organic matter during the maturity stage. The oil and gas source correlation showed that crude oil and natural gas have good affinity with the Eocene Pinghu Formation (PF) coal-bearing source rocks. Crude oil has the characteristics of near-source accumulation and short-distance migration while natural gas is supplied from a dual source: the coal-derived hydrocarbon rocks of PH in the deep part of the study area, supplemented by the coal-derived hydrocarbon rocks of PH on the bottom of the slope, and adjacent hydrocarbon-bearing sub sag. The distribution characteristics and geochemical migration indices of hydrocarbon showed that the oil generated from the hydrocarbon source rocks of PH in the deep Pingbei area mainly migrates vertically along the fault connecting the reservoir and the source rocks to the trap, where it accumulates, while the natural gas exhibits deep and large faults that mainly migrate vertically, supplemented by its lateral migration along the composite transport system composed of faults and sandstone layers in the slope zone. The mechanisms of produced, exhausted, and geochromatographic effects (PGE), as well as evaporative fractionation (EF) and phase-controlled migration fractionation (PMF), result in the obvious discrepancy of hydrocarbon’s properties on the vertical profiles.
Keywords
sources of oil and gas; phases of oil and gas; hydrocarbon geochemistry; enrichment mechanisms; Xihu Sag
Subject
Environmental and Earth Sciences, Geochemistry and Petrology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
