Geochemical Characteristics of Dolomite Oil Seepage in Zar ing Ar ea,Qiangtang Basin of Tibet

Abstract

Abstract: The oil seepages from oil-bearing dolomite in Zaring area of Qiangtang basin are high fraction of saturated hydrocarbons (5.4% ~68.2%)without asphaltene. The geochemical characteristics of oil seepages are analyzed by group component, carbon isotope and biomarker, etc. The results show that they have low values of m (Pr)/m (Ph)by 0.60~0.98, carbon isotope values ranging from -26.88‰ to -31.09‰, not high maturity of the oils, belonging to reductive environment and dominated by microbe and algae parent materials. The relative content index of free hydrocarbon carbon isotope and biomarker and the oil source correlation indicate that the oil seepages were formed by the same source rock and origin. The Xiali source rock of Middle Jurassic in Zaring area could be main source of the oils.

Key words: oil seepage, free hydrocarbon, carbon isotope, biomarker, Zaring area, Qiangtang basin, Tibet

CLC Number:

TE112.116

CHEN Wen-bin, LIAO Zhong-li, LIU Jian-qing, FU Xiu-gen, XIONG Xing-guo, HE Yong-zhong. Geochemical Characteristics of Dolomite Oil Seepage in Zar ing Ar ea,Qiangtang Basin of Tibet[J]. Xinjiang Petroleum Geology, 2008, 29(2): 214-218.

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