一种页岩含气性热演化规律研究的模拟实验方法

目前针对页岩气赋存规律研究的热模拟实验主要是沿袭常规油气热模拟方法,以粉末态样品开展模拟,研究对象为岩石生成并排出的烃类气体,这种模拟方式未明确页岩气的实质为"滞留气",并且模拟后样品无法开展扫描电镜分析,不能确定岩石孔隙结构变化规律。本文通过石英玻璃管封装块状样开展页岩生烃热模拟实验,并结合一套数据处理方法,尝试建立了一种适合页岩气研究的热模拟实验方法,研究泥页岩在不同演化阶段(Ro范围为0.596%~2.143%)不同赋存状态气体的含量以及岩石微观孔隙特征的变化情况。结果表明,泥岩及油页岩样品的排出气及解析气含量在高成熟度阶段(400℃以后)有明显增加的趋势,结合扫描电镜微观结构分析显示这是由于有机质生气量以及无机孔隙均有增加。本方法可以研究页岩热演化过程中不同赋存状态气体含量及微观孔隙结构的变化,为页岩气勘探开发提供了一种可参考的方法。

Thermal Simulation Experiment for Evaluating the Influence of Thermal Evolution on Gas-bearing Properties of Shale

The parameters of laser Raman spectra can reflect the maturity of organic matter, but there are few studies on the organic matter in the high-over mature shale and coal. The shale from the Southern China and the anthracite from Qinshui and Bide-Santang Basin are tested by laser Raman spectrum, rock eval pyrolysis and vitrinite reflectance for maturity analysis in this paper. Applied the reflectance equation proposed previously, the reflectance gained by Raman (_RmcR_o) are calculated, and correlation fitted with the pyrolysis peak temperature (T_max) and measured vitrinite reflectance (R_o). The results showed that the wedge-shaped bands/peaks, first order bands/peaks (D and G) and second order bands/peaks (S₂, S₃ and S₄) of shale and anthracite spectra are clear, meantime, the Raman reflectance (_RmcR_o) is of good correlation with pyrolysis peak temperature(T_max, R²=0.9173) and vitrinite reflectance(R_o, R²=0.9614). The Raman reflectance (_RmcR_o) shows consistency and reliability with T_max and R_o in the maturity evaluation. The multi-point test of Raman can reveal the heterogeneous variation of shale during diagenesis and has more accuracy and higher reliability in heterogeneity reflecting than single-point test previously. The shale has larger variation coefficient of _RmcR_othan that of coal and shows stronger organic matter heterogeneity. The research results can provide a basis for the evaluation of the organic matter maturity of the high-over mature shale and coal.