低熟富有机质泥页岩热模拟排出油饱和烃地球化学特征

The Geochemical Characters of Saturated Hydrocarbon from Expelled Oil in Thermal Simulation Experiment about Low Maturity Shale of Organic Matter

对鄂尔多斯盆地铜川地区延长组低熟富有机质泥岩开展热模拟实验,实测了各模拟温度点固体残渣的镜质体反射率,分析了排出油在各成熟阶段的饱和烃分子地球化学特征及其分子参数的适用性,发现排出油的姥植比和伽马蜡烷指数、Σ三环萜烷/Σ藿烷值在实测镜质体反射率0.58~1.95范围内都可以反映出低盐度还原的沉积环境特征。排出油的正构烷烃峰型变化反映了样品成熟度的升高。其他饱和烃成熟度参数各适用不同的范围,OEP值适用于实测镜质体反射率0.70~1.34范围内;Pr/nC17与Ph/nC18适用于实测镜质体反射率1.01~1.48范围内;Ts/(Ts + Tm)仅适用于实测镜质体反射率0.70~1.01范围内;20S/(20S + 20R)-C29甾烷和ββ/(αα + ββ)-C29甾烷两参数并不能很好地适用于本次排出油成熟度的评价,可能只适用于实测镜质体反射率1.01~1.34范围内。

After exploring the simulation experiment of low maturity organic rich mudstone from Tongchuan area, Ordos Basin, the vitrinite reflectance measurement of experimental solid residues, and the results of GC-MS of the expelled oil, we found that Pr/Ph, gammacerane index and tricyclic terpanes/hopanes can indicate the low salinity restore environment. N-alkanes from expelled oil show that the maturity increased. The maturity parameters of other saturated hydrocarbons can be used in different ranges. OEP is applicable to the measured vitrinite reflectance range of 0.70~1.34;Pr/nC17 and Ph/nC18 are applicable to the measured vitrinite reflectance range of 1.01~1.48;Ts/(Ts + Tm) is applicable to the measured vitrinite reflectance range of 0.70~1.01. The parameters of 20S/(20S + 20R)-C29 sterane and ββ/(αα + ββ)-C29 sterane are not suitable for the maturity of the expelled oil. It may only be applicable to the measured vitrinite reflectance in the range of 1.01~1.34.