一种页岩含气性热演化规律研究的模拟实验方法

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

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。

At present, thermal simulation experiments on accumulating rules of shale gas mainly follow the conventional method, which uses powder samples as the simulation object and does not define the shale gas as retention gas. Moreover, the powder samples after simulation cannot be observed by Scanning Electron Microscopy （SEM） , and thus the evolution rules of pore structure cannot be determined. A new thermal simulation experiment method for shale gas, which uses a quartz glass tube to package the sample, and the linear regression method to analysis the data has been established. The changes of gas content and microscopic pore characteristics in shale during different phases of evolution （Ro range of 0. 596% -2. 143% ） were studied. Results show that the contents of vent gas and desorbed gas in mudstone and oil shale increase obviously in high-mature stage with temperature higher than 400℃. Combined with SEM analysis, it can be inferred that this trend may be caused by the increasing of inorganic pores and gas generated from organic matter. This method can provide change information of shale gas contents and pore characteristics during the thermal transformation, which is more suitable for the study on the shale gas exploration and development.