Geochemical characterization of aromatic hydrocarbons in light crude oil from Tazhong Uplift deep reservoirs, Tarim Basin, NW China

The aromatic compounds in the light crude oil samples from the deep Tazhong structural and the Central Uplift zones in the Tarim Basin, NW China, were investigated by gas chromatography-mass spectrometry (GC-MS). The results from the study showed the distribution of the aromatic hydrocarbon compounds in the order of monocyclic > bicyclic > tricyclic with Tazhong structural zone No. 1 showing relatively higher abundance of mono- and bicyclic aromatic compound when compared with the other structural zones. Based on the distribution of the isomers of naphthalenes in the oils and the equivalent reflectance caculated from them, the oils in the Tazhong structural zone No. 1 indicated wider range of maturity levels and are generally more mature than the other zones. The implication of this is that, the oils in the structural zone No. 1 reservoirs might have been filled with lately generated oils from older source rock.