海相源岩排烃动力学实验模拟与地质应用研究

This project will carry out experimental study of hydrocarbon expulsion from grain-sized marine source rocks using semi-open system under programmed heating conditions. We will study the source rock samples in different maturities using organic geochemical, mineralogical and petro-physical methods, and analyze the chemical and isotopic compositions of expelled and retained hydrocarbons after comparing the residual rock samples with natural rocks. We will try to study the hydrocarbon generation properties in grain-sized marine source rock throught comparing with the experimental results in closed gold system using the kerogen sample from the same sample. After calculating the kinetic parameters of hydrocarbon generation and expulsion, the hydrocarbon expulsion efficiency as well as the chemical and isotopic fractionation will be calculated. After analyzing the changes of mineral and petrophysical properties, the changes of porosity,throat path and permeability, kerogen structure,micropore and nano-scaled pore will be studied. The microscopic observation will be applied to the samples of different maturities for studying the hydrocarbon expulsion paths and characteristics. The interaction between organic and inorganic compositions of the source rocks during the process of hydrocarbon generation will also be studied. The geochemical characteristics of secondary cracking into gaseous hydrocarbons from the residual hydrocarbons of marine source rocks will be studied through the observation, structral and chemical analysis to the residual hydrocarbons in high to over maturity stages. This project is going to yield promising results by integrating geochemical and structural analysis, micro to nano-scaled observation, as well as kinetic experimental simulation, which are significant for understanding the hydrocarbon expulsion of marine source rocks in deep areas.

利用程序升温的半开放高压模拟系统进行基于全岩的海相源岩排烃动力学实验模拟，对不同热演化阶段的样品进行有机地球化学、矿物学、岩相物理学研究，对不同阶段的排出烃与残留烃进行分析，并与自然演化样品进行比较。通过与同一样品提取干酪根的金管生烃动力学实验比较，尝试回答全岩状态下的生烃特点。计算排出烃与残留烃动力学参数及地质条件下不同热演化阶段的排烃效率、排烃过程中烃类的组份同位素分馏等。通过不同阶段全岩样品的矿物与岩相分析，研究源岩在生排烃过程中岩石物性如孔隙、喉道、渗透率的变化，研究源岩中干酪根结构、微孔及纳米孔的变化，观察排烃路径与显微排烃特征，对海相源岩生排烃过程中有机无机的相互作用进行探索研究。对高过成熟阶段的样品进行残余有机质的观察、结构与化学组成分析，研究海相源岩残余烃二次裂解的地球化学特征。本研究将地化分析、结构分析与显微观察及动力学模拟相结合，对深入认识深层海相源岩排烃具有重要意义。

本次研究以海相页岩、湖相泥岩、煤和炭质泥岩四种不同类型的烃源岩为研究对象，进行基于全岩的玻璃管封闭体系热模拟、基于全岩的Rockeval开放体系热解动力学和基于全岩的金管封闭体系热解动力学三种实验方法，探讨在不同热演化阶段不同类型烃源岩的生-留-排烃特征，为有效评价烃源岩页岩油气生成潜力提供了重要的实验依据。初步得到以下结论：.（1）根据液态烃和气态烃C1-5的产率划分了油窗、湿气窗和干气窗范围。页岩和煤的油窗范围分别为0.6-1.3%Ro，0.5-1.2%Ro；页岩和煤的湿气窗范围分别为0.9-3.0%Ro，0.8-2.7%Ro；干气窗范围分别为1.3-4.0%Ro，1.2-4.0%Ro。在油窗、湿气窗和干气窗范围内，海相页岩和湖相泥岩的残留烃族组分主要是饱和烃、芳烃和非烃，沥青质含量相对较少；煤的残留烃族组分主要是沥青质、芳烃和非烃，饱和烃含量极少。.（2）基于全岩的Rockeval开放体系热解动力学实验：在通用地质升温速率下，具有排烃因素的颗粒与代表纯有机质生烃的干酪根热解氢指数、排烃速率、排烃效率及残留烃量都表现出了明显的差异。.（3）基于全岩的金管封闭体系热解动力学实验：在统一频率因子A=1E+1013s-1时，不管是海相页岩还是湖相泥岩，轻烃组分C6-13与重烃组分C14+排出烃的活化能分布较集中，这说明烃源岩达到生排烃门限时，生排烃作用瞬时发生。在相同的热演化阶段，不管是平凉组海相页岩还是延长组湖相泥岩轻烃组分C6-13排出烃的主活化能都要高于重烃组分C14+，说明轻烃的排出需要比C14+更高的能量，即轻烃的排出更难发生。平凉组海相页岩与延长组湖相泥岩比较，延长组湖相泥岩轻烃组分C6-13和重烃组分C14+的排出烃的主活化能值都要高于平凉组海相页岩，说明延长组湖相泥岩具有较高的排烃门限和较强的残留烃能力。实验结果与实际地质情况基本一致。