成熟度与热模拟产物分步萃取对滞留油生物标志物的影响

明确抽提过程中不同极性有机溶剂对所获得的生物标志物参数的影响，对基于生物标志物的生烃母质研究具有重要意义。选用鄂尔多斯盆地延长组低熟富有机质泥页岩进行生、排烃热模拟实验，并结合热模拟固体残样的实测随机镜质体反射率(R_O)值，准确剖析热演化程度和溶剂极性对生源和沉积环境参数适用范围的影响。结果表明：有机溶剂极性的大小不仅会影响抽提物的产率和族组分特征，而且会显著影响抽提物中正构烷烃、三环萜烷的分布特征，但对甾烷的分布特征影响并不明显。溶剂极性和热演化的双重影响导致生物标志物参数的适用范围存在明显区别，∑C_21^-/∑C_22⁺和(nC₂₁+nC₂₂)/(nC₂₈+nC₂₉)仅在低熟—高成熟的中期阶段(R_O值介于0.70%～1.48%之间)可作为有效的生源参数，而沉积环境判识参数∑三环萜烷/∑藿烷值适用范围更窄，仅在低熟—高成熟早期阶段(RO值介于0.70%～1.34%之间)有...

Effects of thermal maturity and sequential extraction of pyrolysis products on biomarkers of retained oil

It is of great significance for the study of hydrocarbon generation parent material based on biomarkers to clarify the influence of different polar organic solvents on the obtained biomarker parameters during the extraction process. By artificial maturation experiments on low-mature and organic-rich mud shale collected from Yanchang Formation， Ordos Basin， the thermal evolution characteristics of biomarker parameters related to the organic matter source and depositional environment were discussed， combined with the vitrinite random mean reflectance （R_O） of residual rock samples at different pyrolysis temperature. Results show that the polarity of organic solvent significantly not only affects the yield and the percentages of saturates, aromatics, resins, and asphaltenes of sequential extractions， but also significantly affects the distribution characteristics of n-alkanes and tricyclic terpenes in the retained oils. However， it has little effect on the distribution characteristics of steranes. Moreover， the simultaneous effects of polarity and thermal evolution lead to a notable difference in the applicability of these parameters. The ratios \sum {\mathrm{C}}_{{\mathrm{21}}^{-}}/\text{?}\sum {\mathrm{C}}_{{\mathrm{22}}^{+}} and （nC₂₁+nC₂₂）/（nC₂₈+nC₂₉） can be used as valid biological source parameters only in the range from low maturity to the middle stage of high maturity， i.e. 0.70%<R_O<1.48%， while the depositional environmental parameter ∑TT/∑C₃₀H have a narrower maturity applicability range， i.e. 0.70%<R_O<1.34%. The organic matter source parameters， such as （C₁₉+C₂₀）/C₂₃TT， C₂₅TT/C₂₄TeT， and the regular steranes dominant distribution parameters are all significantly influenced by thermal evolution. It is worth noting that the organic matter source parameter C₂₄TeT/（C₂₄TeT+C₂₆TT） and the depositional environmental parameter Pr/Ph have good stability in the range from low maturity to high maturity， i.e. 0.70%<R_O<1.95%. When these two parameters are applied,the final evaluation results of the organic matter source and depositional environment will not be biased by the polarity of the solvent and maturity.