Zhang M.-F.,CAS Institute of Geology and Geophysics |
Zou H.-L.,Petrochina |
Feng B.-Z.,Geological Survey of Province Gansu |
Zhang X.-J.,Petrochina |
And 3 more authors.
Natural Gas Geoscience | Year: 2013
Source rocks from a Tertiary inland lake in the Qaidam Basin (west, China) were analysed for aromatics using capillary gas chromatography-mass spectrometry (GC-MS). The triaromatic members of the new series, phenylnaphthalenes (PhNs) and terphenyls (TrPs), are found in different types of source rocks. The isomeric composition of phenylnaphthalenes and terhenyls was found to depend on thermal maturity. In the samples with lower maturity abundances of 1-PhN and o-TrP are higher. Increase in sample maturity is indicated by an increase in the relative abundance of 2-PhN as well as m-TrP and p-TrP. Three thermal maturity parameters of the organic matter based on the relative abundances of the PhN and TrP isomers are proposed: PhNR=2-PhN/1PhN, TrP1=p-TrP/o-TrP, and TrP2=(m-TrP+p-TrP)/o-TrP. In general their values are positively correlated with vitrinite reflectance (RO) in a range of 0.47%-1.32%, While correlation of the conventional biomarker maturity parameters (C29 ααα sterane -20S/(20S+20R), C31αβ hopane 22S/(22S+22R), MPI1 ratio) are less apparent with vitrinite reflectance (RO) in a range of 0.92%-1.32%. So the new parameters perhaps are effective reflecting degree of thermal evolution of organic matter in the mature-highly mature stage.