Abstract:

Reservoir geochemistry can be applied to trace the oil migration orientations, reservoir charging pathways and to predict the location of potential source kitchens and “satellite” reservoirs. The tracing indicators related to carbazoles and benzocarbazoles have been widely and successfully applied in hydrocarbon exploration. More and more studies indicate that the sulfur and oxygen heterocyclic aromatic compounds such as dibenzothiophenes and dibenzofurans have been proved to be effective geochemical molecular markers for tracing oil migration orientations and charging pathways. The organic geochemistry study of the Fushan Depression (one of major depressions in the Beibuwan Basin, South China Sea) in the year of 2004 indicated that the discovered accumulations in the Huachang oil and gas field were mainly migrated and charged from the northeast to the southwest along the Huachang Sub-uplift. It can be predicted that the oils in the Huachang Sub-uplift should be sourced from the source kitchen at the Bailian Sag. The Huadong and Bailian zones located on the east of the Huachang Sub-uplift should be the most favorable prospecting zones, which have been proved by the hydrocarbon exploration discoveries afterwards and the latest reservoir geochemistry study. The isopleth maps of geochemical parameters can be used not only to determine the oil migration orientations, but also to predict the favorable charging pathways.

Key words: reservoir geochemistry, oil migration orientation, source kitchen, Fushan Depression