Abstract
The hydrocarbon charge history of the Paleogene in the northern Dongpu Depression was analyzed in detail based on a comprehensive analysis of the generation and expulsion history of the major hydrocarbon source rocks, fluorescence microscopic features and fluid inclusion petrography. There were two main stages of hydrocarbon generation and expulsion of oil from the major hydrocarbon source rocks. The first stage was the main hydrocarbon expulsion stage. The fluorescence microscopic features also indicated two stages of hydrocarbon accumulation. Carbonaceous bitumen, asphaltene bitumen and colloidal bitumen reflected an early hydrocarbon charge, whereas the oil bitumen reflected a second hydrocarbon charge. Hydrocarbon inclusions also indicate two distinct charges according to the diagenetic evolution sequence, inclusion petrography features combined with the homogenization temperature and reservoir burial history analysis. According to these comprehensive analysis results, the hydrocarbon charge history of the Paleogene reservoir in the northern Dongpu Depression was divided into two phases. The first phase was from the late Dongying depositional period of the Oligocene to the early uplift stages of the late Paleogene. The second phase was from the late Minghuazhen period of the Pliocene to the Quaternary. Reservoirs formed during the first period were widely distributed covering the entire area. In contrast, reservoirs formed during the second period were mainly distributed near the hydrocarbon generation sags. Vertically, it was characterized by a single phase in the upper layers and two phases in the lower layers of the Paleogene.
Highlights
Hydrocarbon charge history is an important issue in the study of pool-forming
The hydrocarbon charge history of the Paleogene in the northern Dongpu Depression was analyzed in detail based on a comprehensive analysis of the generation and expulsion history of the major hydrocarbon source rocks, fluorescence microscopic features and fluid inclusion petrography
Hydrocarbon inclusions indicate two distinct charges according to the diagenetic evolution sequence, inclusion petrography features combined with the homogenization temperature and reservoir burial history analysis
Summary
Hydrocarbon charge history is an important issue in the study of pool-forming. Determination of the hydrocarbon charge history is helpful to correctly understand the oil and gas reservoir formation and distribution and has important practical value for guiding petroleum exploration. The fluid inclusion forming periods cannot be divided according to the sequence of host minerals in the diagenetic evolution stage. Because of the complexity of the formation and evolution of oil and gas reservoirs, a single method is often limited in the hydrocarbon charge history analysis, and it should be combined with a variety of methods, to ensure the reliability of the results. The hydrocarbon charge stages were divided qualitatively based on the analysis of generation and expulsion stages of major hydrocarbon source rocks and fluorescence microscopic features (Jarmołowicz-Szulc et al 2012); the hydrocarbon fluid inclusion forming periods were divided according to the diagenetic evolution sequence of host minerals combined with reservoir burial evolution history. The hydrocarbon charge time was determined according to the inclusions’ homogenization temperature in conjunction with burial and thermal history plots
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