蒙皂石层间水化性质和脱水过程对有机质热解生烃的作用及机制研究

The dehydration of the interlayer water in smectite is coincided with hydrocarbon generation in sediment, however, the related mechanism is unclear. In order to explore the effect mechanism of interlayer hydration properties and dehydration process of smectite in the hydrocarbon generation, the present proposal starts with the interlayer water of smectite, and studies the key mineralogical factors which affect the interlayer hydration properties dehydration process of smectite by using several in situ test technologies. After collecting and preparing the smectite samples of characteristic dehydration stages, the hydration properties as well as the solid acidity (the concentration, types, and strength of the solid acid sites) of these samples are investigate to figure out the constrain mechanism between two of them. Some organic compounds, which are selected as the model organics for the simulation of the hydrocarbon-sourced organics, are pyrolyzed under the open and close systems in the presence of smectite samples to study the effect mechanism of the hydration properties and solid acidity of smectite with different water content in thermal decomposition of organics. Based on a combined analysis of the potential correlation among the interlayer dehydration process of smecite and the related mineralogical factors, the solid acidity and the corresponding catalytic activity of smectite in different dehydration stages, the effects and related mechanism of interlayer hydration and dehydration of smectite in hydrocarbon generation during diagenesis can be found out. The fundamental information obtained from this proposed project will provide theoretical and experimental bases for better understanding the mircro-mechanism of the swell clay minerals in promoting the oil generation.

地层中蒙皂石矿物脱层间水过程与有机质生烃具有同步性，然而，尚未开展具体机制研究。为深入探讨蒙皂石层间水化性质及脱水过程对有机质生烃的作用机制，本项目拟从蒙皂石的层间水入手，结合多种原位测试方法，开展蒙皂石矿物层间水化性质及脱水过程的关键矿物学影响因素研究。同时采集和制备特征性脱水阶段的蒙皂石矿物（含不同水分子层数），通过对其水化特征和固体酸性（酸浓度、酸位类型、酸强度）特征的研究，探索蒙皂石脱水过程对其固体酸性的影响机理；并选用合适的模型有机质模拟生烃母质，开展特征脱水阶段蒙皂石矿物层间水化性质及固体酸性对开放和封闭体系下模型有机质热解的影响机制研究。通过对蒙皂石脱层间水过程及相关矿物学影响因素、特征脱水阶段蒙皂石矿物的固体酸性和催化生烃活性的内在联系的综合分析，最终揭示蒙皂石层间水化及脱水过程对有机质热解生烃的作用机制，为探明膨胀性粘土矿物催化生烃的微观机制提供理论和实验依据。

本项目以蒙皂石矿物（不同混层比伊蒙混层矿物、带不同数量负电荷以及含不同类型层间阳离子蒙脱石）为主要研究对象，开展了蒙皂石矿物脱水过程-固体酸性-催化活性之间的内在联系研究, 进而深入探讨了蒙皂石矿物层间水化性质及脱水过程对有机质生烃的作用机制。所获得的认识如下：.蒙皂石矿物脱水过程-固体酸性-催化活性之间的内在联系：蒙皂石矿物的层间阳离子类型及数量、层间水含量、层电荷数量及分布位置以及矿物类型是影响蒙皂石矿物水化性质和脱水过程以及固体酸性的关键因素。其中，影响蒙皂石矿物水化性质及固体酸性的决定性因素为层间阳离子类型及数量和层间水含量。层间阳离子的电价与半径的比值（Z/R）越高，阳离子对层间水的极化能力越强，水分子生成B酸的能力越强；阳离子的电负性越大，形成L酸位的能力越强。蒙皂石矿物的固体酸活性位点是其催化活性的来源。.蒙皂石矿物对有机质生烃的作用机制：1）不同类型固体酸位在系列热解反应中担任不同的角色。B酸对有机质发生霍夫曼消除反应、加氢裂解、异构化等反应具有显著催化作用，L酸可促使有机质脱羧。2）对不同类型有机质的热解研究发现，蒙皂石矿物对有机质的热解既具有热解促进作用，对一些有机质还存在热解抑制作用。热解促进或热解抑制取决于有机质特征基团类型和蒙皂石矿物的固体酸性和微结构特性，其主要通过反应路径的改变而发生。有机质自身所带基团之间的相互作用以及与蒙皂石矿物片层之间的静电作用，蒙皂石层间位阻效应等是影响复合体中有机质热稳定性的重要因素。3）发现膨胀性粘土矿物的层间反应区域对上述热解促进或热解抑制作用具有增强效应，提出其本质在于层间域存在高酸性强度的固体酸位以及黏土矿物片层所带负电荷以及层间位阻效应。同时，通过D元素示踪方法，证实催化生烃过程中，蒙皂石矿物的层间水可以进入有机质生烃的热解产物中。