Study on geochemical characteristics of aromatic hydrocarbon of high-maturity crude oils in the Baiyun deep-water Sag
HE Da-shuang;HOU Du-jie;SUN Chao;SHI He-sheng;ZHU Jun-zhang;School of Energy Resources, China University of Geosciences;MOE Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism, School of Energy Re- sources, China University of Geosciences;Shenzhen Branch of CNOOC Ltd.;
The aromatic compound characteristics of 27 crude oil samples collected from the Baiyun Sag were studied. The distribution and relative content of the aromatic fraction indicate an oxidizing type of depositional environment, with a notable higher plant input. Alkyl-naphthalene, alkyl-phenanthrene and alkyl-dibenzothiophen, are found to be optimal parameters for assessing thermal maturity characteristics of crude oils in the Baiyun Sag. The crude oils show mature-high mature oil characteristics. By using aromatic fraction in conjunction with biomarker compounds, the crude oil can be divided into two classes: A and B. Class A has a high maturity compared to B. In this study, aromatic maturity parameters that are effective in accessing oil and gas migration mechanism are discussed, for i.e. TMNr indicates migration direction along the center of the Baiyun main depression to its surroundings; and adjacent to Panyu Lower Uplift, oil migration is from zones of high maturity in the west to zones of low maturity in the east.