The evolution of shale gas reservoirs is highly complicated, especially when the reservoir is at a great depth and has undergone complex diagenesis and multiple stages of tectonic activity. However, the evolution mechanism of material composition–pore structure–adsorption property remains unclear. In this study, pyrolysis experiments were used to obtain products of different maturities and determine the evolution processes that took place in a reservoir and total organic carbon (TOC), X-ray diffraction, field emission scanning electron microscopy, low-pressure nitrogen/carbon dioxide gas adsorption, and methane isothermal adsorption experiments were employed to analyze the material composition, pore morphology and structure, and adsorption capacity. The results showed that the TOC value of the pyrolysis samples decreased in comparison to the original sample because some organic matter was converted into hydrocarbons. As diagenesis strengthened, unstable minerals, such as feldspar and carbonate, were converted into clay minerals, while quartz remained basically unchanged. The transformation between clay minerals was quite substantial and inheritable in terms of pore structures and adsorption capacity. The change in the pore structure was mainly caused by mesopores. The evolution of the pore structure and the adsorption property were controlled by clay minerals (mainly illite–smectite mixed layer and illite) and organic matter. Both micro- and mesopores had a controlling effect on the adsorption capacity. When R_o exceeds 2.48%, there was a dramatic change in material composition, pore structure, and adsorption property, which should be given more attention in future research.

中文翻译：

---

热解实验的海相页岩物质组成-孔结构-吸附特性演化机理：中元古界下马岭组典型案例

页岩气储集层的演化非常复杂，特别是当储集层深度较大且经历了复杂的成岩作用和构造活动的多个阶段时。但是，材料组成-孔结构-吸附性能的演化机理仍不清楚。在这项研究中，通过热解实验获得了不同成熟度的产物，并确定了储层和总有机碳（TOC）发生的演化过程，X射线衍射，场发射扫描电子显微镜，低压氮/碳利用二氧化碳气体吸附和甲烷等温吸附实验分析了材料的组成，孔的形貌和结构以及吸附能力。结果表明，由于某些有机物被转化为碳氢化合物，热解样品的TOC值与原始样品相比有所降低。随着成岩作用的增强，长石和碳酸盐等不稳定矿物被转化为粘土矿物，而石英则基本保持不变。粘土矿物之间的转化非常重要，并且在孔隙结构和吸附能力方面可以继承。孔结构的变化主要是由中孔引起的。孔隙结构的演化和吸附性能受粘土矿物（主要是伊利石-蒙脱石混合层和伊利石）和有机质的控制。微孔和中孔均对吸附容量具有控制作用。什么时候 随着成岩作用的增强，长石和碳酸盐等不稳定矿物被转化为粘土矿物，而石英则基本保持不变。粘土矿物之间的转化非常重要，并且在孔隙结构和吸附能力方面可以继承。孔结构的变化主要是由中孔引起的。孔隙结构的演化和吸附性能受粘土矿物（主要是伊利石-蒙脱石混合层和伊利石）和有机质的控制。微孔和中孔均对吸附容量具有控制作用。什么时候 随着成岩作用的增强，长石和碳酸盐等不稳定矿物被转化为粘土矿物，而石英则基本保持不变。粘土矿物之间的转化非常重要，并且在孔隙结构和吸附能力方面可以继承。孔结构的变化主要是由中孔引起的。孔隙结构的演化和吸附性能受粘土矿物（主要是伊利石-蒙脱石混合层和伊利石）和有机质的控制。微孔和中孔均对吸附容量具有控制作用。什么时候 粘土矿物之间的转化非常重要，并且在孔隙结构和吸附能力方面可以继承。孔结构的变化主要是由中孔引起的。孔隙结构的演化和吸附性能受粘土矿物（主要是伊利石-蒙脱石混合层和伊利石）和有机质的控制。微孔和中孔均对吸附容量具有控制作用。什么时候 粘土矿物之间的转化非常重要，并且在孔隙结构和吸附能力方面可以继承。孔结构的变化主要是由中孔引起的。孔隙结构的演化和吸附性能受粘土矿物（主要是伊利石-蒙脱石混合层和伊利石）和有机质的控制。微孔和中孔均对吸附容量具有控制作用。什么时候R _o超过2.48％，材料组成，孔结构和吸附性能发生了巨大变化，在未来的研究中应引起更多关注。