Quantification of chromatographic fingerprints of mixed crude oils and its exploration significance: A case study of the southern fault zone in Gaoyou Sag

The discovered crude oils in the southern fault zone of Gaoyou Sag are binary mixtures mainly derived from the second and fourth members of the Funing Formation. An artificial mixing experiment of two typical end-member oils in the laboratory indicates that the chromatographic fingerprint of artificially mixed oil samples changes linearly with mixing proportions, so it is an effective method to quantify mixture proportions.An important key is to screen the fingerprint peaks. The application of a quantitative identification model created using an artificial oil mixing experiment can quantify the contribution of different oil sources and its migration path way. The model shows that the contribution rate of source rocks from the fourth member of Funing Formation is 80% in well X33, 30% in well X5-5, 40% in well F4-9, and 10% in well F5. Results indicate that the model has broad exploration applications for mixed crude oils in the southern fault zone of Gaoyou Sag. Source rocks from the second member of Funing Formation contribute more oil in the higher locations of the sag. Reservoirs are found in the first member of Funing Formation and the first member of Taizhou Formation.