沉积学报2017，Vol.35Issue(3)：611-620,10.DOI:10.14027/j.cnki.cjxb.2017.03.018
羌塘盆地二叠系白云岩油苗地球化学特征及意义
Geochemical Characteristics and Significance of Permain Dolomite Oil Seepages in Qiangtang Basin
摘要
Abstract
Dolomite oil seepages and hydrocarbon source rocks of Permian Zhanjin Formation were collected systematically from Central uplift belt area in Qiangtang Basin.Based on the analytical data of group component, biomarkers and carbon isotopic compositions of n-alkanes and isopre, the author analyzed the geochemical characteristics of Permian dolomite oil seepages,and the oil-source rock correlation was also studied in the paper.The results indicated that the Permian dolomite oil seepages are high fraction saturated hydrocarbons,followed by non hydrocarbon, aromatics and asphaltene fraction are low.The ratio of saturates/aromatics of dolomite oil seepages are more than 1.0.The alkanes of dolomite oil seepages are composed of nC15-nC36,with nC17~nC20 as the main peaks,and characteristics of single peak distribution.The nC21-/nC22+ ratios from 1.0 to 4.56,the regular sterans C27-C28-C29 distributed with irregular "V"shape and predominance of C29,homohopane were detected from C31~C35, indicating dolomite oil seepages of hydrocarbon material sources were in algae and other lower aquatic organisms.The Pr/Ph values range of dolomite oil seepages were between 0.91 to 1.30,and gammacerane/C30hopane values were from 0.42 to 0.88, the content of dibenzothiophene were the highest (average 67.39%) and low dibenzofuran content (average 7.89%).4-MDBT/DBT values of dolomite oil seepages were 0.97 to 4.26, (2+3)-MDBT/DBT values were 0.37 to 1.62, showing dolomite oil seepages hydrocarbon material sources were formed in marine shale with certain salinity reduction environment.The OEP values, C29ααα20S/ ααα (20S+ 20R) values,C29αββ/(ααα+αββ) values and C3122S/(22S+22R) values etc., closed to equilibrium values 1, aromatic maturity parameters MPI1,F1 and 4,6/1,4-DMDBT calculated from the equivalent vitrinite reflectance showed that dolomite oil seepages were mature crude oil.The biomarkers of oil seepages are closely correlated to the Zhanjin Formation black mudstone, reflecting that the oil seepages were mainly originated from the Zhanjin Formation.However, carbon isotopic compositions of n-alkanes and isopre exists some differences between oil seepages and Zhanjin Formation black mudstone, indicating a mixture of sources.关键词
生物标志化合物/单体碳同位素/油源对比/二叠系/白云岩油苗/羌塘盆地Key words
Biomarkers/carbon isotopic compositions of n-alkanes and isopre/oil source correlation/Permain dolomite oil seepages/Qiangtang Basin分类
天文与地球科学引用本文复制引用
陈文彬,付修根,谭富文,曾胜强,冯兴雷,宋春彦,王东..羌塘盆地二叠系白云岩油苗地球化学特征及意义[J].沉积学报,2017,35(3):611-620,10.基金项目
中国地质调查局项目(DD20160159,1212011221114,GZH201400301) （DD20160159,1212011221114,GZH201400301）
国家自然科学基金(41172098)[China Geological Survey Project, No.DD20160159, 1212011221114, GZH201400301 （41172098）
National Natural Science Foundation of China, No.41172098] （）
