随着我国经济的快速发展，油气资源消耗速度急剧加快、对外依存度快速攀升，常规能源的供应成为我国能源安全的潜在威胁。作为非常规能源的重要组成部分，页岩油气资源在我国的储备量巨大，高效的开发利用对于解决我国能源紧缺问题具有十分关键的作用。原位转化技术是一种高效且低成本的页岩油气开采方式，目前是勘探开发的重点方向。作为页岩中有机质的主要组成部分，干酪根不仅是页岩油气的生成母质，也是油气重要的赋存介质。干酪根的热解和力学性质研究对于深入认识页岩油气的原位转化过程具有重要的意义。一方面，干酪根热解产油产气的动态演化是原位加热过程的核心；另一方面，在原位转化过程的前期准备中，水力压裂是直接影响到原位转化效率的核心过程，而水力压裂产生的裂纹网络受到页岩与干酪根介观尺度力学性质的影响。

基于以上的背景，本学位论文围绕干酪根的热解、分子结构模型和介观尺度力学性质方面开展研究，针对干酪根热解机制与影响因素、页岩与干酪根的介观尺度力学性质两大关键科学问题，通过实验、多尺度模拟及理论分析方法相结合，开展干酪根的研究工作。

从实验出发，通过热解-气相色谱/质谱分析联用技术对四川盆地的三种 Ⅲ 型页岩干酪根的热解行为进行实验研究，探究了热解温度与初始温度跟干酪根热解产物的种类、组成和相对含量的关系。阐明了热解产物在不同条件下的变化规律。

干酪根的分子结构模型与热解反应性的关联在实验上难以直接观测，因此使用反应力场分子动力学方法，建立了具有不同初始密度和压缩温度的多种干酪根分子结构模型。通过在不同温度下进行热解，分析了模型的初始密度和初始压缩温度的影响，揭示了温度对于 Ⅲ 型干酪根热解产物的影响。

基于细观力学理论，结合 Eshelby 等效夹杂原理和 Mori-Tanaka 方法，建立了对页岩干酪根复合材料介观尺度模型等效弹性张量进行求解的细观力学公式，结合有限元计算，建立了多维度、含多种形状干酪根夹杂的页岩干酪根复合材料模型并进行求解。通过与细观力学理论结果对比，得出了夹杂形状、占比与页岩无机基体弹性模量对等效弹性模量和泊松比的影响。

With the fast development of China’s economy, the consumption of oil and gas resources has accelerated rapidly, and the dependence on foreign resources has risen quickly. The supply of conventional energy has become a potential threat to China’s energy security. As a prominent part of unconventional energy, shale oil and gas resources have huge reserves in China. Efficient development and utilization play a key role in solving the problem of energy shortage in China. The in-situ conversion technology is an efficient and low-cost mining method in the exploration process of shale oil and gas resources, which is currently a crucial direction of development. As the main component of organic matter in shale, kerogen is not only the source material of shale oil and gas, but also an important reservoir of oil and gas. The study on the pyrolysis and mechanical properties of kerogen is of great significance for further understanding the in-situ conversion process of shale oil and gas. On the one hand, the dynamic evolution of kerogen pyrolysis to produce oil and gas is the core of in-situ heating process; On the other hand, in the early preparation of in-situ conversion process, hydraulic fracturing is the essential process that can directly affect the efficiency of in-situ conversion, and the crack network generated by hydraulic fracturing is affected by the mesoscopic mechanical properties of shale and kerogen.

Based on the above background, this thesis focuses on the pyrolysis, molecular structure model and mesoscale mechanical properties of kerogen. Aiming at the two critical scientific problems: kerogen pyrolysis mechanisms and influencing factors, and mesoscale mechanical properties of shale and kerogen, this thesis conducts research on kerogen by combining experimental, multiscale simulation and theoretical analysis methods.

Three kinds of type III shale kerogen in Sichuan Basin were pyrolyzed by pyrolysis-gas chromatography/mass spectrometry, and the pyrolysis behavior was studied. The relationship between pyrolysis and initial temperature and the type, composition and relative content of kerogen pyrolysis products was explored. The changing rules of pyrolysis products under different conditions were elaborated.

It is difficult to directly observe the relationship between the molecular structure model of kerogen and its pyrolysis reactivity in experiments. Thus, the method of reactive force field molecular dynamics was used to deal with the molecular structure model of kerogen, and a variety of initial models with different initial densities compression temperatures were established. Through pyrolysis of various initial models at different temperatures, the influence of initial densities and compression temperatures of the kerogen molecular structure model on its pyrolysis was clarified, and the influence of temperature on the pyrolysis products of type III kerogen was expounded.

Based on the theory of meso-mechanics, combined with the Eshelby equivalent inclusion principle and Mori-Tanaka method, a meso-mechanics formula was established to solve the equivalent elastic tensor of the mesoscale model of shale/kerogen composites. Combined with finite element method calculation, finite element models of shale kerogen composite with multi-dimension and multi-type kerogen inclusions were established and calculated. By comparing the results of finite element simulation and meso-mechanics theory, the influence of inclusion shape, proportion and elastic modulus of shale inorganic matrix on equivalent elastic modulus and Poisson's ratio of shale/kerogen composites was obtained.