Author(s)

Yunfei Yang^1,2, Min Zhang^1,2*, Julin Chen^1,2, Xiaohui Chen^1,2

¹Key Laboratory of Exploration Technology for Oil and Gas Research (Yangtze University), Ministry of Education, Wuhan, China.
²College of Resources and Environment, Yangtze University, Wuhan, China.

In order to study thermal effect on distribution characteristics of regular sterane in humic coals, a suit of 25 coals derived from Kuqa Depression in Tarim Basin and Ordos Basin are studied to investigate the distribution of regular sterane in different maturity, which mainly discusses the thermal effect. The results show that the C₂₇ααα/C₂₉ααα regular sterane ratio has a linear relationship with R_o (t_max) and aromatic hydrocarbon maturity parameters in the coals from mature to high-mature stage. It suggests that the distribution of the C₂₇, C₂₉regular steranes will fail to reflect original source input in high evolutionary stage. On the basis of thermal simulation experiment results, it further proves that the distribution patterns result from the demethylation effect of C₂₉ sterane in the mature to high mature evolution stage and the C₂₇ααα/C₂₉ααα regular sterane increases with increasing maturity. The breakage of C-C key in branched chain from C₂₇, C₂₉ regular steranes to make C₂₇ααα/C₂₉ααα regular sterane ratio invariance at high and over mature stage. Therefore, the ratio can be used to distinguish the maturity in high and over mature stage.

Sterane, Maturity, Pyrolysis Experiment, Geochemistry Characteristic, Oil-Rock Correlation

Yang, Y. , Zhang, M. , Chen, J. and Chen, X. (2017) Thermal Effect on the Distribution of Regular Sterane and Geological Significance. Open Journal of Yangtze Oil and Gas, 2, 249-259. doi: 10.4236/ojogas.2017.24020.